Essential Macleod使用说明书

xiaoil · 发表于 2004-11-26 18:56:00

共大家学习,也可在光学薄膜技术交流群内来下载,群号码(16112861)

[此贴子已经被作者于2005-10-25 18:05:34编辑过]

ic5 · 发表于 2004-11-26 20:02:00

你的说明书放在哪里啊?大家拭目以待啊!

tyf3328 · 发表于 2004-11-27 04:18:00

我也没看到啊，在哪里啊？能给我一份吗？我的邮箱：tyf3328@163.com

xiaoil · 发表于 2004-11-27 16:13:00

不好意思!昨天我整理好了,请大家留下电子邮箱.我会发给大家!

nieguangyu · 发表于 2004-11-27 19:54:00

我也要

kahn927@163.com

ic5 · 发表于 2004-11-27 21:40:00

非常的感谢！

ic5@oecr.com

李伟华 · 发表于 2004-11-27 23:33:00

谢谢。

leios@sina.com

ycxmy · 发表于 2004-11-28 04:48:00

谢谢。

ycxmy@163.com

martin1980 · 发表于 2004-11-28 17:14:00

martin_1980_1980@163.com

xiexie!

xiaoil · 发表于 2004-11-28 18:18:00

请大家留容量稍大点的邮箱,否则可能发送不了,谢谢!!!

xiaoil · 发表于 2004-11-29 22:14:00

APPLICATION WINDOW

When the Essential Macleod is started, the Application Window appears. The application window is always present and forms the background to the package. The window title is always Essential Macleod. Below the title bar is the menu bar and while the Essential Macleod window is blank, there are four available menus, File, Tools, Options, and Help.

During the operation of the program, the various designs, results, plots and so on appear in document windows within the application window. The document windows do not carry their own menu bar. Following standard Windows practice, they share the application window menu bar. Thus the Essential Macleod menu bar continually depends on the particular document window that is active. If it is a design window then the menu items refer to the design, if a material then they refer to material parameters, and so on. Clicking in a different document window to make it active automatically changes the menu bar.

This manual considers the various types of document window in turn and lists the choices available in their menus. This may seem complicated when reading the manual, but in actual use the choice is usually obvious and there is a help command, discussed shortly, that gives on-line information. This on-line information is intentionally compact. There is nothing worse than wanting a simple answer while, instead, screen after screen of detailed information pours out. The detailed information is, therefore, in this manual. You may never actually read it. We rarely read manuals either.

In accordance with standard Windows practice the menus and their items may be called either by a mouse click on the appropriate choice or by keystrokes. The keystroke for accessing any of the menus is a combination of the Alt key and the letter that is underlined in the menu title. The File menu, for example, can be accessed by pressing Alt F or Altf. The case is not important. Once the menu is activated then an individual choice of menu item may be made by pressing the underlined key by itself or with Alt. For example, once the File menu has been activated, the choice of New... may be made by pressing n or N or Altn or AltN. To close the menu without making any choice press Alt. Control menus can be accessed in different ways. For a dialog box press AltSpace bar. For a document window press Alt- (hyphen or minus). Quick closing is AltF4 for dialog boxes and CtrlF4 for document windows. Clicking the close button, provided it is available, will also give quick closing. Most of these choices are obvious from the structure of the package. In dialog boxes with simple choices, use the arrow keys to change the selected option. In a document window the Tab key or the Enter key, will usually pass to the next cell for data entry.

A window can be reduced to an icon by selecting the Minimize button. Alternatively, it can be maximized by selecting the Maximize button. Both of these buttons are at the top right corner of the window. The form of the icon denotes the type of window that it represents.

The package is entirely compatible with standard Windows practice and the instructions outlined above represent only an abbreviated set of what is available. They will be assumed in everything that follows and will not be repeated.

The Application Menu

The common commands are described below.

File Menu (Application)

New...

Selection of New... reveals a submenu. There are six choices, Design, Material, Optical Constant, Table, Stack, and Substrate. Each selection produces an appropriate dialog box or document window that refers to the choice made. The selection can be made with the Mouse in the usual way or by pressing any of the arrow keys.

Design brings up a design window with the default design contained in it in the form of a table of media and layers. This is considered further below in the Design Window chapter.

Material brings up a document window headed Material that contains a blank table for entry of new optical constants and wavelength data. More details are given in the Material Window chapter.

Optical Constant brings up a new window for deriving optical constants from transmittance and reflectance data. See the section on Optical Constant Extraction for more information.

Table creates a new table after the user has indicated the number of columns required in an initial dialog box. The table is blank and the Read Only status is not set so that it can immediately be edited in the usual way. For more details, see the later section on Edit Menu (Table).

Stack brings up a new document window for the design and analysis of combinations of substrates and coatings. See the Multicoat section for more information.

vStack brings up a new document window for the design and analysis of combinations of substrates and coatings that are not parallel. See the vStack chapter for more information.

Substrate brings up a document window headed Substrate that contains a blank table for entry of new internal transmittance and wavelength data. More details are given under the heading of Multicoat.

Open...

Open brings up a dialog box that permits any of the files that have been created by the program to be reopened. File types include designs, performance plots, performance tables, and data for optical constant extraction. These types can be selected in the drop down list at the foot of the box.

Open Material...

Open Material brings up a dialog box containing a list of all available materials for selection.

When a material is selected, a material window with the optical constants and wavelength data appears ready for editing, plotting or printing.

Open Substrate...

Open Substrate... behaves in a similar way. In this case a list of substrate files is presented for selection and the resulting table displays either internal transmittance or density against wavelength. The display can be switched from one version to the other by a menu command under the Substrate Edit menu. The data can be edited or plotted in the usual way. More details are given in the section on Multicoat.

Open Reference...

Open Reference activates a dialog box like the Open command but it is for reference files. Reference files contain data that is required by the program for certain calculations like the assessment of color. They are therefore treated differently from regular data files and are kept separately from them. Alteration or modification should be undertaken only with extreme caution. Data files can be converted into reference files and vice versa.

Page Setup...

Page Setup... allows the page margins to be set in a dialog box.

Printer Setup...

Printer Setup... opens a dialog box offering a choice of available printers and access to the printer options.

1

2

3

4

These menu items correspond to the most recently opened files.

Exit

Quits and unloads the Essential Macleod. If entered or generated data are unsaved the program will display an alert box asking for instructions.

Tools Menu (Application)

Materials

This item is similar in many ways to the Open Material... command of the File menu. There whenever a material was selected, the dialog box closed. Here however the command brings up a materials list that is permanently visible until closed. This means that many material windows can be opened and displayed at the same time. The display of optical constants at the wavelength shown can be toggled by the Show Optical Constants command in the Edit menu for this window. To change the display wavelength, edit it in the window.

Double clicking any of the materials brings up a window displaying the stored optical constants. These can be edited if required, as discussed later in the manual.

Load ZEMAX Coating File

The Essential Macleod includes the capability of exporting coating designs to the ZEMAX series of lens design packages, created by Focus Software Inc., to be included in performance assessments. ZEMAX reads these designs together with data on materials from a coating file. The Load ZEMAX Coating File command loads the ZEMAX coating file into the Essential Macleod where it can then be edited. Before the file can be loaded it must be identified and registered. This is carried out by the ZEMAX... command in the Options menu, described below.

Options Menu (Application)

General...

The Essential Macleod Options dialog box that is activated has several features, and is divided into four tabs Data Sources, Windows, Plotting and Cone. Selecting the tab displays a group of options.

Data Sources Tab

The upper text box contains the path and name of the current Materials Folder. This can be changed and the new folder will then be the one automatically used. A record of material databases that have been used by the package is maintained and these paths are available in a dropdown list activated by the arrow to the right of the folder name. Since a change in materials folder could have serious consequences for an existing design, it is arranged that the Materials Folder option is available only when there is no open design file.

It can be very useful to have different material files for different applications. For example, the default wavelength units in the package as provided are nm and these should be changed to microns if much infrared work is to be done. One material database can then be completely in microns and one completely in nm. It is helpful to give the materials folder a meaningful name such as IR or Visible or UV. Sometimes in the early stages of a design, nondispersive materials are used. A special folder with nondispersive materials may then be useful, called, perhaps "Non Dispersive".

Later in the manual you will find that it is very easy to create new material databases and to import materials into them. A useful way of working is to create a new materials database at the start of any new project. Only those materials that apply to the project need be imported into it. The database folder can also be used to store the design, plot and table files. Although there is no design folder in the list of options, the package will return to the same design folder each time it is loaded until another is used to store files. The data and design files are completely separated from the material files by their extensions. At the end of the project the folder will contain all the files necessary to resurrect it and it can be saved to an archive and then deleted. This technique insulates the standard materials from changes that are made only in connection with a particular project yet the special set of units that may have been used, the particular materials, the designs and so on are all preserved.

Reference files are stored in a reference folder. These are files containing data necessary for the operation of the package. In the Essential Macleod the important files in the reference folder are those containing definitions of color matching functions and of source output for the color calculations. The reference folder is also used extensively in the Function enhancement to the Essential Macleod. The Options dialog box includes a field that gives the folder where the reference files are located. Once this has been defined it will seldom be necessary to change it but the possibility does exist.

Windows Tab

When Cascading Close is checked any plots and tables in open windows that are associated with a given design will be closed when the design window is closed. When it is not ticked then windows will not be automatically closed.

If the Prompt to save old Tables and Plots before closing box is checked then the user will be asked if any plots or tables that have been changed from the version that is stored on disk should be saved before being closed.

Keep old Plots and Tables displayed is a useful option. It is very easy to accumulate many opened plots and tables. These do use up memory and should be closed as soon as they are no longer immediately needed. If this option is not checked then a new table or plot will simply replace any older one. If the option is checked then the new plot or table will coexist with the older.

Plotting Tab

The plots can be produced with either ticks on the axes or a complete grid. Show Grid on Plots decides which is to be used. Note that the plots saved by the program are stored as data rather than images. If this option is changed then all plots that are recalled from store will follow the current choice even though they may have been created with the other in force. Note that it is very easy to remove a grid from an individual plot or to restore it once removed.

Nominal Plot Segment Length has an important role in plotting. The package uses a special adaptive technique. Plots are drawn with variable spacing of successive values of the independent variable so that closely packed fringes will be reproduced without having to use a very small and inefficient interval on smoother parts of the characteristic. An algorithm calculates a starting interval from the thickness of the coating, the wavelength range and the size of the plot. During plotting, the interval is continuously varied. The nominal plot segment length is a parameter that defines the closeness of points required for the plots in general. It should rarely need to be altered. However, if you find that the kind of plot that is normally being produced is fairly flat but is taking a long time because there are too many points, then this number may be increased. If, on the other hand, the fringes are so closely packed that the program is jumping across them, then this number should be reduced. The number should be adjusted in very small increments. Halve it or double it at the most with each adjustment. It is very easy to set it so that an impossibly large number of points is required.

When the axes for plots are automatically selected, the X-axis range is scanned to estimate the total Y-axis range. This range is then used to drive the adaptive plotting algorithm. If the Y-axis range is very small, then this will force the adaptive plotting algorithm to look for very fine changes in the calculated Y values. Such plots will take a long time to calculate but they will not add any useful information. To prevent this, a minimum range can be specified. If a Y-axis is being automatically generated, then the estimated Y range is constrained to be no less than the minimum range for the performance parameter. If the Y-axis has been defined and is not automatic, the minimum range values do not apply. If you wish to modify the default minimum range values, the Minimum Ranges button displays a form where you can specify the minimum range to be used for each of the available performance categories.

Plots can be generated with two Y-axes. Sometimes it may not be clear which Y-axis is used for a particular trace. Y-axis identification defines the default method by which axes are identified. If Identify Y Axes is checked then the titles for the Y-axes will be prefixed by the appropriate identifier and each trace will have its legend prefixed by the identifier for its Y-axis. Y-axis identification can also be manually performed in the Plot window.

A default appearance (background color, font characteristics etc.) can be specified for all plots. To set the default appearance, save a plot that has the desired appearance, then open the Plotting tab in General Options, click on Choose and select the saved plot. To remove a previously chosen plot file, click on Delete. Note that Delete does not delete the plot file.

Cone Tab

This tab provides control over the cone calculation provided by the Stack Editor. Nominal Cone Segment Length controls the adaptive calculation used by Cone when calculating the cone response at a particular wavelength, frequency or incident angle. It is similar to Nominal Plot Segment Length described above.

Bandwidth Step controls the step size when the bandwidth is non-zero.

Gaussian beams do not have a distinct cutoff where there is no irradiance. The beam intensity falls off with a Gaussian distribution. When calculating the performance of a coating illuminated with a Gaussian beam, the Essential Macleod will not calculate performance beyond a specified ratio of the Gaussian beam’s semi-angle. This has the effect of truncating the edges of the beam. When the ratio is sufficiently large, the effect on the calculations will be negligible. The default value for the ratio is 2. At this limit, the intensity of the beam has fallen to 0.0003 times the on axis intensity, which should be satisfactory for most applications. To change the value of this ratio, modify the Gaussian Calculation Scale Factor value. Making the value larger improves the calculation results at the expense of a greater calculation time.

Designs Tab

This tab provides control over the order in which layers are displayed, the formula ordering convention and the intervals used for derivative calculations.

For the Display Order, there are two possible options: Medium at Top and Substrate at Top. When Medium at Top is selected, designs are displayed with the incident medium at the top of the list and layers are numbered from the medium with the layer next to the medium numbered 1. When Substrate at Top is selected, designs are displayed with the substrate at the top of the list and layers are numbered from the substrate with the layer next to the substrate numbered 1.

The Formula Order is used to specify which end of the formula is next to the incident medium. Medium at Left specifies that the incident medium is at the left end of the formula string. Medium at Right specifies that the incident medium is at the right end of the formula string. The formula editor indicates which convention is in effect so that you do not have to remember.

Wavelength Delta Factor defines the interval used for calculating the first derivative of the optical constants. The default value has been selected to give the best performance for the majority of designs.

Update Tab

This tab provides control over the automatic checking for updates.

If automatic checking has been enabled, then, each time the Essential Macleod is started, it will first check to see if the specified number of days has elapsed since the last time a check for updates was made. If it has, then the program will connect to the Thin Film Center web site to determine if a new update is available. If there is a new update, you can choose to download and install the update now or just continue using the Essential Macleod. If you choose to download the update, the Essential Macleod will close so that the program file can be modified.

If Automatically check for updates is checked, then the Essential Macleod will check for updates at the specified interval. The interval is specified by entering the number of days in the box after Check for updates every.

Color Tab

This tab specifies the wavelength intervals to be used when calculating color parameters. The Wavelength Interval for Performance is used when requesting a color calculation from the menu. The Wavelength Interval for Refinement is used when calculating the value of a color target during refinement or synthesis. Specifying larger values increases the speed of color calculations but the accuracy is reduced.

Print Tab

This tab specifies the header and footer to be used for printed output. The header and the footer may be multi-lined and have three sections: left, middle and right. A bar ("|") character is used to separate the sections.

For example, the header definition:

Left|Middle Section

on more than

one line|Right

would appear as follows on printed output:

Left Middle Section Right

on more than

one line

Several symbols may be used in the header and footer. These are:

%o The type of document being printed. For example in a design this will be replaced by "Design"

%f The name of the file being printed as displayed in the title bar of the window.

%t The date when the document was printed. This will be formatted according to the date format specification at the bottom.

%d The current page number

%% Inserts the "%" character.

There are several pre-defined date formats available. These are:

Format Name

Description

General Date

Display a date and/or time. For real numbers, display a date and time, for example, 4/3/93 05:34 PM.If there is no fractional part, display only a date, for example, 4/3/93. If there is no integer part, display time only, for example, 05:34 PM. Date display is determined by your system settings.

Long Date

Display a date according to your system's long date format.

Medium Date

Display a date using the medium date format .

Short Date

Display a date using your system's short date format.

Long Time

Display a time using your system's long time format; includes hours, minutes, seconds.

Medium Time

Display time in 12-hour format using hours and minutes and the AM/PM designator.

Short Time

Display a time using the 24-hour format, for example, 17:45.

You can also design your own date format using these formatting commands:

Character

Description

(:)

Time separator. In some locales

, other characters may be used to represent the time separator. The time separator separates hours, minutes, and seconds when time values are formatted. The actual character used as the time separator in formatted output is determined by your system settings.

(/)

Date separator. In some locales, other characters may be used to represent the date separator. The date separator separates the day, month, and year when date values are formatted. The actual character used as the date separator in formatted output is determined by your system settings.

c

Display the date as ddddd and display the time as ttttt, in that order. Display only date information if there is no fractional part to the date serial number; display only time information if there is no integer portion.

d

Display the day as a number without a leading zero (1 – 31).

dd

Display the day as a number with a leading zero (01 – 31).

ddd

Display the day as an abbreviation (Sun – Sat).

dddd

Display the day as a full name (Sunday – Saturday).

ddddd

Display the date as a complete date (including day, month, and year), formatted according to your system's short date format setting. The default short date format is m/d/yy.

dddddd

Display a date serial number as a complete date (including day, month, and year) formatted according to the long date setting recognized by your system. The default long date format is mmmm dd, yyyy.

aaaa

The same as dddd, only it's the localized version of the string.

w

Display the day of the week as a number (1 for Sunday through 7 for Saturday).

ww

Display the week of the year as a number (1 – 54).

m

Display the month as a number without a leading zero (1 – 12). If m immediately follows h or hh, the minute rather than the month is displayed.

mm

Display the month as a number with a leading zero (01 – 12). If m immediately follows h or hh, the minute rather than the month is displayed.

mmm

Display the month as an abbreviation (Jan – Dec).

mmmm

Display the month as a full month name (January – December).

oooo

The same as mmmm, only it's the localized version of the string.

q

Display the quarter of the year as a number (1 – 4).

y

Display the day of the year as a number (1 – 366).

yy

Display the year as a 2-digit number (00 – 99).

yyyy

Display the year as a 4-digit number (100 – 9999).

h

Display the hour as a number without leading zeros (0 – 23).

hh

Display the hour as a number with leading zeros (00 – 23).

n

Display the minute as a number without leading zeros (0 – 59).

nn

Display the minute as a number with leading zeros (00 – 59).

s

Display the second as a number without leading zeros (0 – 59).

ss

Display the second as a number with leading zeros (00 – 59).

t t t t t

Display a time as a complete time (including hour, minute, and second), formatted using the time separator defined by the time format recognized by your system. A leading zero is displayed if the leading zero option is selected and the time is before 10:00 A.M. or P.M. The default time format is h:mm:ss.

AM/PM

Use the 12-hour clock and display an uppercase AM with any hour before noon; display an uppercase PM with any hour between noon and 11:59 P.M.

am/pm

Use the 12-hour clock and display a lowercase AM with any hour before noon; display a lowercase PM with any hour between noon and 11:59 P.M.

A/P

Use the 12-hour clock and display an uppercase A with any hour before noon; display an uppercase P with any hour between noon and 11:59 P.M.

a/p

Use the 12-hour clock and display a lowercase A with any hour before noon; display a lowercase P with any hour between noon and 11:59 P.M.

AMPM

Use the 12-hour clock and display the AM string literal as defined by your system with any hour before noon; display the PM string literal as defined by your system with any hour between noon and 11:59 P.M. AMPM can be either uppercase or lowercase, but the case of the string displayed matches the string as defined by your system settings. The default format is AM/PM.

Here are some examples of user-defined date formats:

Format

Display

m/d/yy

12/7/58

d-mmm

7-Dec

d-mmmm-yy

7-December-58

d mmmm

7 December

mmmm yy

December 58

hh:mm AM/PM

08:50 PM

h:mm:ss a/p

8:50:35 p

h:mm

20:50

h:mm:ss

20:50:35

m/d/yy h:mm

12/7/58 20:50

JPEG

Plots created in the Essential Macleod can be exported as JPEG images. This tab provides controls for creating the JPEG data. Quality (1 – 100) controls the image quality. The higher the number the better quality picture will be produced, but the size of the JPEG file will also be increased. When Gray Scale is checked, the JPEG picture will not be in color. Optimize Compression improves the file size produced without reducing picture quality. When Progressive is checked, the JPEG will be generated so that a low quality image is displayed quickly and improves as the rest of the JPEG is loaded. This option is primarily used when the picture is to be displayed by a remote user downloading the picture file over a slow link.

3D Plot Tab

A default appearance (background color, font characteristics etc.) can be specified for all 3D plots. To set the default appearance, save a 3D plot that has the desired appearance, then open the 3D Plot tab in General Options, click on Choose and select the saved plot. To remove a previously chosen plot file, click on Delete. Note that Delete does not delete the plot file.

Default Design...

When a new design is created, a default design is used. The design that is generated by the program may not be completely suitable for all users. For example, someone who normally works in the infrared may wish to have a design with parameters suitable for the infrared rather than the visible region. It may also be that there could be a number of different standard designs that could be varied according to the particular project. This option makes it particularly easy to change from one standard design to another. The option asks the user to choose a design that will be used as the default. This default is stored with the particular materials database and will change when the database is changed.

General Units...

General units defines the units that are used when displaying information. This permits you to work in the units of your choice such as nanometres or microns, % transmittance or absolute transmittance. For more information, see the section on units in this manual.

Chart Styles…

Chart Styles defines the styles of plotted data in the Essential Macleod. For various different types of plotted data, you can define the color, line style, and thickness of the line that will be plotted. You can also control the symbol style, color and size.

ZEMAX

Use this option to select the file to be used as the ZEMAX coating file. Whenever you export a design file to ZEMAX, the design will be stored in this file.

Register

This option displays the built-in registration form. Please use this form to tell us about yourself and request a site key

License

This option displays the current license and allows you to transfer a license from one computer to another. You can also enter a site key here.

Change Password

This option allows you to change the password required when transferring a license out from the computer. See the section on licensing for more information.

Help Menu (Application)

Contents

The Help menu is always available to the right of the other menus. Contents brings up the contents list which contains broad categories rather like the contents page of a book. The items in the contents list can be selected by clicking with the mouse in the normal way.

Search For Help On...

Selection of this menu item presents the user with a list of index terms. When one of the items is selected, the window shows the sections where the term appears. The mouse combined with the Display button can then select the section for examination.

Obtaining Technical Support...

This item lists the address, fax number and telephone number for receiving support.

About The Essential Macleod...

This gives information about the program including its version and the installed enhancements.

Check for Updates...

This command checks for available updates to the Essential Macleod via the Internet. If an update is available, you can then download and apply the update by clicking on the Download button. If you choose to download the update, the Essential Macleod will close, the update will be downloaded and then applied to the existing installation.

Insert/Overstrike

The bar at the foot of the Application Window displays two information boxes. The first of these will be blank at this stage. The second will contain the words Insert or Overstrike. Pressing the insert key, Ins will toggle from one to the other. These two parameters indicate the behavior of a design table when the Enter key is used to move from one cell to the next. In insert mode, pressing Enter at the end of a row will cause a new row to be inserted. In overstrike mode the cursor will move to the next existing row

xiaoil · 发表于 2004-11-29 22:18:00

DESIGN WINDOW

Note that the correction changes the normal incidence thickness to correct the behavior at oblique. The design table values still apply to normal incidence. Any pasting operation ignores the match angle. Formula..., however, does recognize the match angle and does correct layers accordingly. If Formula… ever appears to be operating in a curious way, check the match angle option to make sure it has not been set to an incorrect angle.

Changing the match angle is straightforward. The new value is entered in the dialog box. The operation first returns the layers to normal incidence and then applies the new angle. The current match angle can always be found by selecting the match angle menu item and looking at the displayed value.

Global Edit…

This command changes either all layers in the design or selected layers only, if at least one layer has been selected to values entered on the Global Edit form.

If a value is entered into one of the fields, then the layers will be updated with the new value. If the field is left blank, then the value held in the layer will be not altered. Clicking on OK causes any changes to be made. Clicking on Cancel causes the edit operation to be aborted. In the example the material of the layers will be changed to MgF2, the packing density will be set to unity and the void density will be set to zero.

Edit Materials...

Edit materials offers a simple way of changing the materials in a design. The user simply inserts the translation in a dialog box. Note that this changes the materials in the design only. Those listed against symbols in the formula are not changed.

Parameters Menu (Design)

Performance...

The performance parameters consist mainly of the choice of the quantities and scales of the axes in the performance plots that are to be produced. One or two Y axes may be defined. Tables will use the same parameters and range of independent variable and just the independent variable interval for the tables needs to be separately specified. The content of the table will be defined by the performance requested in the Vertical Axis tab. A typical dialog box for entry of the performance parameters is shown below and is reasonably self-explanatory. Items not available for the particular choice of dependent quantity are gray and cannot be accessed.

The package computes the response, the dependent variable, in terms of a variable parameter, the independent variable. Except for a very few special cases, throughout the package the vertical axis in the plots corresponds to the dependent variable while the horizontal axis corresponds to the independent variable.

The dependent variable, the performance, may be chosen from the scrolling list under Vertical Axis. This list comprises

Transmittance Magnitude (%) Reflectance Magnitude (%) Transmittance Phase (deg) Reflectance Phase (deg) Density Absorptance (%) Reflectance GD (fs) Reflectance GDD (fs^2) Reflectance TOD (fs^3) Transmittance GD (fs) Transmittance GDD (fs^2) Transmittance TOD (fs^3) Transmittance Delta (deg) Transmittance Psi (deg) Reflectance Delta (deg) Reflectance Psi (deg) Transmittance CDC (fs/nm) Reflectance CDC (fs/nm)

GD indicates Group Delay, GDD, Group Delay Dispersion and TOD is Third Order Dispersion. These quantities are important in components for ultrafast applications and are directly related to the derivatives of phase shift with respect to the angular frequency of the light.

CDC indicates Chromatic Dispersion Coefficient. This quantity is similar to Group Delay Dispersion in that it indicates pulse spreading. It is more commonly used in the communications field.

Derivatives with respect to wavelength of those quantities that are not already derivatives can be specified by entering the appropriate derivative order in the derivative field. For example, the first derivative can be specified by entering unity in the box. Please note the comments under Derivatives in the Essential Macleod earlier in this manual.

The independent variable is specified in a similar scrolling list under Horizontal Axis. There are essentially four different types of independent variable, wavelength, frequency, incident angle and layer thickness. The actual terms displayed in the scrolling list follow the names that have been entered in the General Units dialog box.

The thickness of a chosen layer may be used as the independent variable. This is immediately applicable to the case of an etalon with variable spacer layer but there are often cases where the sensitivity of performance to variations in the thickness of a particular layer are in question.

Plots and tables using the current values of the parameters can always be initiated from the Performance menu. However, the Performance Parameters dialog box gives immediate access to either plots or tables without the necessity of returning to the menu. If the OK button is chosen then the only immediate action taken will be to change the current values of the parameters to those entered so that they will then be used by the plot and table commands in the Performance menu. They will not be stored permanently in the design file until it is actually saved.

To aid in identifying traces on a plot, plot parameters may be automatically added to the plot legend by checking the Add to Label box next to each parameter. If the Plot Targets box is checked, then the targets will be added to the plot if the performance type of the targets matches the performance specification of the plot.

Refinement

Choosing Refinement in the Parameters menu brings up a submenu that gives access to the various parameters that must be set before effective refinement and synthesis is possible. There are two aspects of the parameters that need definition. First there are the specifications of the desired performance levels. These are called Targets and they are common to all the various techniques. Then there are various attributes that must be set correctly for the particular technique that is to be used. The principal technique in the Essential Macleod is Optimac, a powerful synthesis method that can also carry out refinement. Four further refinement techniques are Nonlinear Simplex, called nonlinear to distinguish it from a similarly named but different technique used in the solution of linear equations, a statistical method known as Simulated Annealing, and two derivative method: Conjugate Gradient and Quasi-Newton. Additionally, the Needle synthesis method is available for generating designs.

Refinement and synthesis are discussed in a later dedicated section.

3D Performance...

The 3D performance parameters consist mainly of the choice of the quantities and scales of the axes in the 3D performance plots that are to be produced. A typical dialog box for entry of the 3D performance parameters is shown below and is reasonably self-explanatory. Items not available for the particular choice of dependent quantity are gray and cannot be accessed.

The package computes the response, the dependent variable, in terms of two variable parameters, x and y.

The dependent variable, the performance, may be chosen from the scrolling list under Z Axis. This list is the same as in the Vertical Axis in the Performance Parameters dialog.

The independent variables are specified in similar scrolling lists under X Y Axes. There are essentially four different types of independent variable, wavelength, frequency, incident angle and layer thickness. The actual terms displayed in the scrolling lists follow the names that have been entered in the General Units dialog box.

The thickness of a chosen layer may be used as the independent variable. This is immediately applicable to the case of an etalon with variable spacer layer but there are often cases where the sensitivity of performance to variations in the thickness of a particular layer are in question.

The surface computed in a 3D plot is calculated at a fixed number of equally spaced points in the x and y directions. The Number of Intervals parameter specifies then number of points calculated.

3D Plots using the current values of the parameters can always be initiated from the Performance menu. However, the 3D Performance Parameters dialog box gives immediate access to a plot without the necessity of returning to the menu. If the OK button is chosen then the only immediate action taken will be to change the current values of the parameters to those entered so that they will then be used by the 3D plot command in the Performance menu. They will not be stored permanently in the design file until it is actually saved.

Performance Menu (Design)

The Performance menu controls the calculation of performance figures by the package. Access to the menu items is possible only when a design window is active and the calculation initiated by the choice of one of the items will refer to the design in the active window. There are two principal ways in which the results of a calculation may be presented. They may be plotted or tabulated and either may be chosen from the menu. Another aspect of performance of a design is its susceptibility to errors, also available from this menu.

Plot

Plot initiates the plotting of performance in a plot window. The aspects of performance and the range over which they are to be plotted have already been chosen under the item Performance in the Parameters menu.

The Plot window is now the active one and so the menu bar changes to reflect that. The principal changes are that the Performance and Parameters menus disappear and the choices under the others are limited.

Many aspects of the plot can be modified. The section on the Plot Window later in this manual describes how plots may be modified. Note that the performance data do not change when the plot parameters are altered. If a change is made to the wavelength region outside the range of the original calculations then the altered plot will simply be blank over the new part of the region. To extend the wavelength region outside the original limits it is necessary to return to the design window and select Performance in the Parameters menu. The dependent variable is not limited in this way.

Plot Over

Plot Over permits the plotting of a second curve to be made over a first. The first curve must have been made using the current design. Once the first curve has been produced, then an adjustment to the design or a change in the calculation parameters, such as angle of incidence, may be made and then the performance of the new arrangement plotted over the first.

Plot Over will be grayed out if the design file is changed. To plot the results of a different design over those of a first, the Add command in the File menu should be used. Plot the results of the first design. Save the plot as a plot file using the Save As... command (the short cut key F12 is the quickest and most convenient way of doing this). Change to the alternative design. Plot the results. While the plot window is active, choose Add Line... from the File menu (Altf followed by d) and select the plot just saved. The plots will be combined.

Table

Table produces a table of results according to the options selected in the Performance menu item in the Parameters menu for the design window.

The table has the usual cells with individual results but as it is produced the table has the attribute read only and so is protected from change. This is a safety feature to guard the integrity of the data.

There may be occasions when some editing of the data is necessary. The legend against Design right at the top of the table is a good place to put a very short note, for example. For this reason the read only nature of the file can be changed. With the table window active select the Edit menu. There are two active items, Copy Table and Read Only. The read only status will be indicated by a tick to the left of the menu item. Select Read Only to toggle the status. When the tick is not visible, the table may be edited. It is good practice to return the status to read only after editing and immediately save the table.

Copy allows the table to be copied to the clipboard and pasted subsequently into any other suitable application, especially a word processor.

More information about the table menus will be found in a later section.

Errors...

One of the most difficult areas in the design of optical coatings is the assessment of the sensitivity of the coating to errors. The errors in manufacture are generally rather larger than the first order approximations that can be readily handled by analytical techniques and so the most successful ones involve Monte Carlo modeling of the deposition process. Random errors drawn from suitable infinite populations are introduced and their effects over a large number of simulations are assessed. This is the technique on which the Errors... menu item is based. It is a very straightforward implementation.

Errors calculates successive performance curves for the design with thickness errors drawn from a normal population. The parameters dialog box appears first.

The mean and standard deviation are to be prescribed and can either be Absolute or Relative. Relative would be the usual choice and here the error is proportional to the thickness of the layer. In other words with relative errors a thickness D [D=nd/l0 for optical thicknesses and d/l0 for geometrical thicknesses] will become D(1+error). With absolute errors the thickness D would become (D+error). The particular arrangement chosen will depend on the process used in monitoring - an absolute error in termination that does not depend on layer thickness is quite common (quartz crystals for example) - but for routine error analysis probably the relative option will be more meaningful. The number of cases is just the number of different curves with different random errors drawn from the same infinite population. If Include Locking is checked, then only the layers that are not locked will be altered. If Include Links is checked, then one of the layers in each set of linked layers will be randomly altered and then the other layers in the link set will have their thicknesses adjusted so that they have the same ratio of thicknesses to the randomly altered layer as in the original unperturbed design. For example, if layer 1 is 15nm thick and layer 2 is 30nm thick, and these layers are linked, then during Errors, layer 1 will be randomly altered and layer 2 will be set to be twice as thick as layer 1.

The seed can be changed manually but normally this will not be necessary as it is generated automatically. Even if the seed is repeated exactly, the error plots will not necessarily repeat because of a scrambling process that is carried out on the results of the error generator before they are used to generate a normal population from which the actual errors are drawn at random. The seed simply initializes the basic generator but does not affect the processing and so if it is reset at any time, the mixing and scrambling that is already operating, yields a subsequent set of numbers that are completely different from those generated the first time. Only if the program is reloaded will the random errors be completely reset. Then to repeat the calculations exactly the same initial seed should be used.

Once the correct parameters have been entered click the Plot button. The program will draw a series of curves each of which represents the performance of the coating with a different set of thickness errors all drawn at random from the infinite population with the parameters that have just been entered. By varying the error parameters and replotting an assessment of manufacturing tolerances can readily be made.

Tables of results are not generated because of their size and the difficulty of assessing large tables of results. The plot files do contain accessible data that can be extracted if necessary.

Color

The following color parameters are available: Tristimulus, Chromaticity, CIE L*a*b*, CIE L*u*v*, CIE L*u’v’, Hunter LAB, CIE1960 u,v, Correlated Color Temperature (CCT), Reciprocal Correlated Color Temperature (RCCT), Dominant Wavelength (Wd), Complementary Wavelength (Wc), Excitation Purity (Pe) and Colorimetric Purity (Pc). For the CIE L*a*b* color space, the hue and chroma correlates are also calculated. For the CIE L*u*v* color space, the hue, chroma and saturation correlates are also calculated.

The dialog box that appears has several fields for completion.

Source lists the sources. The standard sources are CIE A, B, C, D55, D65, D75 and equal energy. Black body and other sources can readily be added especially if the Function Enhancement is present. Instructions are in the earlier section on Color.

Observer lists the sets of tristimulus values that are to be used. As supplied, these are CIE 1931 and CIE 1964. Again other observer definitions can be added if required.

Mode specifies whether the transmitted or reflected color will be calculated.

Polarization specifies the polarization to be used for oblique incidence calculations.

Context specifies the coating context to be used for the calculations.

Incident Angle contains a set of three parameters that specify the range of incident angles and interval to be used in the calculation.

Show White Point places a symbol on the plot or creates a table entry that shows the coordinates of the source.

Show Color Patch creates a window that displays a visual impression of the color(s) of the coating.

The Plot tab allows you to choose a standard plot or select two color parameters to plot. The standard plots available are: Tristimulus XY, Chromaticity xy, CIE 1976 UCS, CIE 1976 h*c*(ab), CIE 1976 h*c*(uv). The Chromaticity xy plot is plotted on a chromaticity diagram. The CIE 1976 UCS plot is plotted on a UCS diagram. The CIE 1976 h*c*(ab) and CIE 1976 h*c*(uv) plots are plotted on a polar diagram. If a Custom plot is selected, then the X Axis Parameter and Y Axis Parameter specify the color parameters to use in the plot.

The Table tab allows you to choose the color parameters to be included in the table output. Parameters are selected by clicking on them. Each selected parameter is highlighted in the list. In the figure below, the table will contain three parameters: Tristimulus X with Chromaticity x and y.

Errors drops down an extra part of the form that allows you to see the effects of random thickness errors on the color of a coating in the same manner as the Errors command.

The mean and standard deviation are to be prescribed and can either be Absolute or Relative. Relative would be the usual choice and here the error is proportional to the thickness of the layer. In other words with relative errors a thickness D [D=nd/l0 for optical thicknesses and d/l0 for geometrical thicknesses] will become D(1+error). With absolute errors the thickness D would become (D+error). The particular arrangement chosen will depend on the process used in monitoring - an absolute error in termination that does not depend on layer thickness is quite common (quartz crystals for example) - but for routine error analysis probably the relative option will be more meaningful. The number of cases is just the number of different curves with different random errors drawn from the same infinite population.

The seed can be changed manually but normally this will not be necessary as it is generated automatically. Even if the seed is repeated exactly, the error plots will not necessarily repeat because of a scrambling process that is carried out on the results of the error generator before they are used to generate a normal population from which the actual errors are drawn at random. The seed simply initializes the basic generator but does not affect the processing and so if it is reset at any time, the mixing and scrambling that is already operating, yields a subsequent set of numbers that are completely different from those generated the first time. Only if the program is reloaded will the random errors be completely reset. Then to repeat the calculations exactly the same initial seed should be used.

Once the correct parameters have been entered, click the Plot button or the Table button. The program will show the color of the coating with a different set of thickness errors all drawn at random from the infinite population with the parameters that have just been entered. By varying the error parameters and replotting an assessment of manufacturing tolerances can readily be made.

If you do not wish to include the error variation in the color output, click on the Errors button to close the error parameters part of the form. Plotting or generating a table with the errors part closed will calculate the color of the coating design without random variation.

Active Plot

This command starts an Active Plot using the current plot parameters. For more information on active plots, see the active plot chapter (page *).

3D Plot

3D Plot initiates the plotting of performance in a 3D plot window. The aspects of performance and the range over which they are to be plotted have already been chosen under the item 3D Performance in the Parameters menu.

The 3D Plot window is now the active one and so the menu bar changes to reflect that. The principal changes are that the Performance and Parameters menus disappear and the choices under the others are limited.

Many aspects of the plot can be modified. The section on the 3D Plot Window later in this manual describes how 3D plots may be modified. Note that the performance data do not change when the 3D plot parameters are altered.

Lock/Link Menu (Design)

Locking and Linking are constraints that are used in some of the refinement and synthesis procedures. A locked layer is excluded from any variation and remains constant in both index and thickness. Layers that are linked together vary as a group in exactly the same manner. These constraints are useful both in the creation of a design where the structure is largely known but fine tuning has to be carried out on various parts and in reverse engineering for the investigation of possible process defects. There are also cases where coatings are to be designed to be deposited over already existing structures, the hard coating on spectacle lenses is an example.

Lock

Locking affects the way that the layers are treated in some of the refinement techniques. If a layer is locked it takes no part in refinement but retains its initial thickness throughout the operation. To lock a group of layers they should first be selected by clicking in the selection box. Shift click will select a contiguous group of layers while Ctrl click will select a noncontiguous layer. Once the layers are selected, the Lock command locks them. Note that once the locking column appears in the design table, locking or unlocking of individual layers is probably more easily achieved simply by clicking on the locking cell to toggle the locking status. Locking is very useful when it is known that the core of a coating should be unchanged. A good example is a quarterwave stack that is to be converted into an edge filter. Only the few outermost layers need be involved in any refinement.

Unlock

Unlock unlocks the selected layers. The remarks under Lock apply here also. It is easy to check that all layers are unlocked because then the lock column in the design table automatically disappears.

Link

Layers that are linked move together during refinement. There may be several different groups of layers in a particular design that are linked together. One linked group is distinguished from another by having a different reference number for the link. Layers with the number zero against them in the link column are unlinked. Those that are labeled 1 move together as a group. Those labeled 2 also move together but as a different group from those labeled 1, and so on. The number given to the link is that of the first layer that is involved in the linked group. Locked layers cannot form part of a link and a link must have more than one member. Sometimes a linked design may be edited so that the links move away from their original positions. Then a new and separate link may automatically be given the same designation as an existing link. In that case the new link numbers can be easily altered manually so that they can be distinguished from the earlier set.

Unlink

This cancels any links that apply to the selected group of layers. To cancel a particular link only one member of the linked set need be selected. A good indication that all layers in a design are unlinked is that then the link column automatically disappears. If it does not then a residual link must exist somewhere in the design.

Lock All

This command locks all layers. This is useful when just a few outermost layers are to be unlocked. All may be locked using this command and then the few that are to be refined may be manually unlocked.

Unlock All

This unlocks all layers in a design.

Link All Materials

For each material used in a design, this command links all the layers in a design that use the same material. It is very useful in reverse engineering applications where, for example, you want to look at the effect of variations in tooling factor on the performance of a design.

Tools Menu (Design)

The Tools menu gives access to several devices for altering the coating design and also is a useful route to the editing of layer materials.

Compact Design

Compact Design will remove all layers of thickness less than a defined limit and close up the design. The layers are removed in a way that has minimum impact on the performance. The thinnest that meets the removal criterion is removed first and then the design is closed up. Then the design is resurveyed and the thinnest layer meeting the criterion removed, and so on.

Refine Design

The techniques available in the Essential Macleod are Simplex, (often called nonlinear simplex to distinguish it from a similarly named technique in linear programming), Optimac, Simulated Annealing, Conjugate Gradient, Quasi-Newton and Needle synthesis. Optimac can accomplish synthesis or refinement.

Simplex also has the facility to refine in terms of layer thickness or of packing density, or of both. Packing density can be used in different ways either to simulate inhomogeneous layers or other production variations in reverse engineering, or simply to refine in terms of refractive index instead of thickness or even both simultaneously.

Selection of any of the techniques in this menu immediately initiates the refinement or synthesis process, unlike the corresponding command in the parameters menu that brings up first a parameters dialog box.

Refinement and synthesis are considered in greater detail below.

Index Profile...

This produces a plot of refractive index against thickness in whatever thickness units are current. Start Layer and End Layer are optional and, if the entire design is to be shown, a short length of substrate and incident medium are also optional. The following figure shows a quarter-half-quarter antireflection coating. In the index profile the incident medium is on the left and the emergent medium, or substrate, on the right

Materials

Selection of this item displays and activates the materials window for the current material database. The materials window and the operations that can be carried out on materials will be detailed below. Here we give just a brief account.

Materials may be chosen from this window for further examination, for editing, display and exporting.

Material names can be dragged in the window to change their order. For example the materials used most often may be arranged near the head of the list. Since this list determines the order in the small lists that are used for design editing it can be very useful in speeding up the design entry and editing process.

Options Menu (Design)

The Options Menu permits changes in certain aspects of the configuration of the package. These items are listed in greater detail above in the Applications Window Menu section.

General...

A dialog box permits the alteration of some of the details of the operation of the program. Note that although the materials folder is displayed, this is for reference only. The arrow to the right of the text box and the name of the materials folder within the box are both grayed out. It is not permitted to change the current materials folder when a design is open. This dialog also permits you to change the display order of the layers.

Default Design...

The default design is the one that is created by the New... command under the File menu. Although this design will be chosen from those that presently exist, it is a separate entity. If the design that was picked as the default is subsequently changed, or even deleted, the default design will remain intact. The default design is attached to the materials database. If the database is changed the default design will change with it. This means that the default design can always be appropriate to the particular database.

Window Menu (Design)

The Window menu has the same function throughout the package where it appears. It permits the organization of the presentation of the various open windows to be rearranged or to be switched from cascade to tile. The icons indicating reduced windows can be straightened up into rows. The various open windows are listed and can be brought to the front and activated by selecting the correct menu item.

Help Menu (Design)

This menu is identical throughout the package. It gives access to the on-line help facility and also displays a box with information about the program and about the installation. More information is given earlier under Essential Macleod Application Window.

Modeling a Rugate

In the Essential Macleod, a rugate coating is modeled as a set of layers where the packing density of each layer is varied through the set to provide the desired index profile. The Generate Rugate command in the Edit menu is a tool that simplifies the generation of the set of layers.

The limits of the index variation may easily be established by setting the Material parameter to a material that represents the highest refractive index that is present in the coating, setting the Void Material to a material that represents the lowest refractive index that is present in the coating and setting the Void Density to 1. As the packing density varies from 1 to 0, the refractive index will vary from the Material refractive index to the Void Material refractive index. Since the layer refractive indices are calculated using the packing density function, other relationships between packing density and refractive index can also be used (for example the valid packing density range may be 0 to 2 instead of 0 to 1).

The total thickness of the rugate structure is specified in optical by the Total Thickness value. The Reference Wavelength must also be specified. Number of Layers specifies the number of layers that are used to model the rugate structure. Increasing the number of layers improves the accuracy of the calculations at the expense of increased calculation time. A good starting point is to set the number of layers so that each layer is about one eighth of a wave thick at the shortest operating wavelength of the structure. To check the quality of the performance calculations, increase (or reduce) the number of layers and calculate the performance again. If there is little or no change in performance, then the number of layers is sufficient.

The Packing Density Formula is used to enter a set of statements that specify how the packing density varies through the set of layers. The formula consists of one or more statements. Each statement consists of an optional Condition, and an Assignment. A Condition is specified by an Expression followed by a colon (":") An Assignment is a Variable name followed by an equal sign ("=") followed by an Expression and ends with a semi-colon (";"). Any text after an exclamation point ("!") is ignored up to the end of the line.

When a rugate structure is being generated, the statements in the Packing Density Formula are executed in order from top to bottom. If a statement has a Condition, then the Assignment is only executed if the value of the Expression in the Condition is not zero. If the statement does not have a Condition, then the Assignment is always executed. The Assignment calculates the value of the Expression and stores the value in the Assignment Variable. Variables are automatically created if they do not already exist. There are several special variables:

L

The current layer number. This variable cannot be modified. The first layer is numbered 1 and the last layer has the value N.

N

The number of layers as entered in the Number of Layers box. This variable cannot be modified.

TotalThickness

Total Thickness as entered in the Total Thickness box. This variable cannot be modified.

LayerThickness

The Thickness of one layer: (TotalThickness / N). This variable cannot be modified.

Thickness

Cumulative Thickness to center of current layer: (L-1) * LayerThickness + LayerThickness / 2. This variable cannot be modified.

ReferenceWavelength

Reference Wavelength as entered in the Reference Wavelength box. This variable cannot be modified.

PackingDensity

The Packing Density of the current layer. After all the statements have been executed, the current layer’s packing density will be the value of this variable. This variable can be modified.

The following operators are supported in Expressions: () sub-expressions^ power*, / multiplication, division% modulus (remainder)\ integer divide+, - addition, subtraction, =, , =, logical comparison, | logical "and", logical "or"

An operator that is listed on a line above another operator has a higher precedence. The following functions are also supported (they are not case sensitive): Abs, Sin, Cos, Tan, ACos, ASin, Atn, Log, Log10, Exp, Sqr, Int, Frac, Ceil, and Floor. Trigonometric functions accept and return angles expressed in radians or degrees, depending on the setting of Angle Units.

For example, the formula:

PackingDensity = (1 + sin(360 * L/N))/2;

generates a rugate structure consisting of a single period of a sine wave.

Click on Preview to generate an index profile plot of the rugate structure. This allows you to verify that the correct structure has been generated. The rugate structure can be made available to the design in two ways: Clicking on Generate will put the layers of the rugate structure onto the clipboard. These layers can be pasted into any design in the normal way. Clicking on Replace Design will cause the current design’s layers to be completely replaced with the layers of the rugate structure. Selecting a variable name in the Packing Density Formula and then clicking on Plot Value will display a plot showing the value of the variable as a function of thickness. This is useful for making sure that the variable’s value is set correctly during rugate generation.

Here is a more complicated example. In this example, we want to generate the following refractive index profile:

There are three parts to this rugate. The first part is the rise in refractive index from 1.0 to 1.7. This is achieved by the first 90 degrees of a sine wave profile. The second part is a sine wave profile of 32 cycles modulated by a half sine wave profile. The last part is a fall in refractive index from 1.7 to 1. This is achieved by the following Generate Rugate form:

The first four lines set up the three parts of the rugate. The first and last parts are each one tenth of the total thickness and the second part is eight tenths of the total thickness. InFirstPart is 1 during the first tenth and 0 elsewhere. InLastPart is 1 during the last tenth and 0 elsewhere. InMiddlePart is 1 when both InFirstPart and InLastPart are 0 and 1 elsewhere. Selecting InMiddlePart and then clicking on Plot Value gives the following plot:

ProportionOfFirstPart, ProportionOfMiddlePart and ProportionOfLastPart start at 0 and linearly increase to 1 in each appropriate part.

The envelope for the middle part is generated by a sine function that uses ProportionOfMiddlePart to generate an angle that varies from 0 to 180 degrees.

The periodic component is generated by another sine function whose period is one half an optical thickness. The periodic component is scaled so that it varies from –0.5 to +0.5 – a total range of 1.

The last three statements generate the packing density variation. These statements use the Condition component to control which statement provides the packing density as a function of thickness. For the first part, the first 90 degrees of the sine function are used to raise the packing density from 0 to 0.5 (the midpoint of the packing density range used here). In the middle part, the periodic component is multiplied by the envelope and the result is then shifted up by 0.5 to give a packing density that varies from 0 to 1. The last part is generated by a sine function starting at 90 degrees and reducing to 0.

Generating Complex Designs

In the Essential Macleod, the Formula tool is used to generate designs with regular features. Some designs have more complex features that cannot be expressed by using Formula, such as chirped reflectors. For these designs, the Generate Design tool can be used to generate the layers in the design.

A Generate Design definition consists of default layer parameters represented by single letter symbols, the number of layers in the design and a Formula that specifies the parameters of each layer as a function of layer number.

The Formula is used to enter a set of statements that specify how the layer parameters vary through the set of layers. The formula consists of one or more statements. Each statement consists of an optional Condition, and an Assignment. A Condition is specified by an Expression followed by a colon (":") An Assignment is a Variable name followed by an equal sign ("=") followed by an Expression and ends with a semi-colon (";"). Any text after an exclamation point ("!") is ignored up to the end of the line.

When a design is being generated, the statements in the Formula are executed in order from top to bottom. If a statement has a Condition, then the Assignment is only executed if the value of the Expression in the Condition is not zero. If the statement does not have a Condition, then the Assignment is always executed. The Assignment calculates the value of the Expression and stores the value in the Assignment Variable. Variables are automatically created if they do not already exist. There are several special variables:

L

The current layer number. This variable cannot be modified. The first layer is numbered 1 and the last layer has the value N.

N

The number of layers as entered in the Number of Layers box. This variable cannot be modified.

OpticalThickness

The total optical thickness of the design excluding the current layer. This variable cannot be modified.

PhysicalThickness

The total optical thickness of the design excluding the current layer. This variable cannot be modified.

LayerOpticalThickness

The optical thickness of the current layer.

LayerPhysicalThickness

The physical thickness of the current layer.

LayerLocked

The lock state of the current layer. A value of 0 means the layer is not locked. A value of –1 means the layer is locked.

LayerLink

The link number of the current layer.

LayerPackingDensity

The Packing Density of the current layer.

LayerVoidDensity

The Void Density of the current layer.

LayerN

The refractive index of the current layer. This variable cannot be modified.

LayerK

The extinction coefficient of the current layer. This variable cannot be modified.

MaterialN

The refractive index of the current layer material. This variable cannot be modified.

MaterialK

The extinction coefficient of the current layer material. This variable cannot be modified.

VoidMaterialN

The refractive index of the current layer void material. This variable cannot be modified.

VoidMaterialK

The extinction coefficient of the current layer void material. This variable cannot be modified.

Layer

This is used to initialize the parameters of the layer. It should be used before any layer parameters are modified.

Thickness

Cumulative Thickness to center of current layer: (L-1) * LayerThickness + LayerThickness / 2. This variable cannot be modified.

ReferenceWavelength

Reference Wavelength as entered in the Reference Wavelength box. This variable cannot be modified.

PackingDensity

The Packing Density of the current layer. After all the statements have been executed, the current layer’s packing density will be the value of this variable. This variable can be modified.

The following operators are supported in Expressions: () sub-expressions^ power*, / multiplication, division% modulus (remainder)\ integer divide+, - addition, subtraction, =, , =, logical comparison, | logical "and", logical "or"

An operator that is listed on a line above another operator has a higher precedence. The following functions are also supported (they are not case sensitive): Abs, Sin, Cos, Tan, ACos, ASin, Atn, Log, Log10, Exp, Sqr, Int, Frac, Ceil, and Floor. Trigonometric functions accept and return angles expressed in radians or degrees, depending on the setting of Angle Units.

For each layer generated, the formula must perform a layer initialization as follows:

Layer = symbol

Where symbol is a defined symbol in the table shown at the top of the form.

For example, the formula:

Odd = ((L % 2) =1); Even = ((L % 2) = 0); Odd: Layer = L; Even: Layer = H;

will generate an design of alternating H and L layers with no modifications to the layer parameters.

Click on Preview (Optical) to generate an index profile plot of the design as a function of optical thickness. Click on Preview (Physical) to generate an index profile plot of the design as a function of physical thickness. These commands allow you to verify that the correct structure has been generated. The design can be made available in two ways: Clicking on Generate will put the layers of the design onto the clipboard. These layers can be pasted into any design in the normal way. Clicking on Replace Design will cause the current design’s layers to be completely replaced with the layers of the formula. Selecting a variable name in the Formula and then clicking on Plot Value (Optical) or Plot Value (Physical) will display a plot showing the value of the variable as a function of optical thickness or physical thickness respectively. This is useful for making sure that the variable’s value is set correctly during design generation.

This example shows the implementation of an amplitude thickness modulated design presented in Chapter 3 of "Thin Film Design Modulated Thickness and Other Stopband Design Methods by Bruce E. Perilloux ISBN: 0-8194-4525-8 Pub SPIE Press 2002. The function for modulating the thickness is given as:

In the Generate Design tool, this function appears as:

Pi = 3.1415926; k = 0.5; f = 0.358; f1 = 0.02;

(L % 2) = 1: Layer = H; (L % 2) = 0: Layer = L;

LayerOpticalThickness = LayerOpticalThickness * (1 + k* sin(2 * Pi * f1 * L) * cos(2 * Pi * f* L ));

The first four lines define constants for the formula. The next two lines specify that the design is made from alternating layers of H and L material. H material is used on the odd numbered layers and L material is used on the even numbered layers. The final line performs the modulation function. The optical thickness of the layer is modified by the modulation function.

A 50 layer design using Ta2O5 for the H material and SiO2 for the L Material, with the optical thickness in the table set at 0.25 at a reference wavelength of 1000nm produces the following reflectance performance:

ContextsContexts are used to specify the behavior of Agile Materials. An Agile Material is a material whose optical constants depend upon the Context. An Agile Material has a name and for each Context, a material name. When a calculation is performed using a particular Context, the optical constants of the agile material are those of the corresponding material in the Context.

Contexts are used during performance calculation and during refinement. Using Contexts, it possible to refine designs for production on multiple substrates, refine designs for production using a range of different real materials. This includes producing a single design for manufacture in coating plants that produce different optical constants for the same raw material.

The design above is a antireflection coating that has been optimized for Glass and Silica substrates. This Design has one agile material: Substrate. To see the specifications for Substrate, click on the Context tab.

The Context that is shown is the Normal context. In this Context, the Agile Material Substrate has the optical constants of the material Glass. You can use the dropdown arrow to select a different Context.

In the Context named Alternative, the Agile Material Substrate has the optical constants of the Material SiO2. By specifying different contexts, the properties of the coating on Glass and on SiO2 can be calculated. The performance parameters dialog (Parameters menu - Performance) allows you to specify a Context when calculating performance, so, for example, you can display the performance of the coating on both substrates on a single plot.

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