所测得的结果比Wolfe等人测量的体材料的结果要大，这和样品是薄膜状态有关，也和测量精度有关。
分析了材料光学常数随温度变化对带通滤光片和截止滤光片中心波长的影响。提出了提高光学薄膜器件稳定性，尤其是温度稳定性的方法。认为：提高膜层填充密度，优化膜系设计，研制新型镀膜材料，以克服薄膜材料光学参数随温度变化对薄膜器件稳定性带来的影响，是改善光学薄膜器件稳定性，尤其是温度稳定性的重要途径。
提出掺杂和制备三元混晶可以改善半导体材料折射率温度系数的理论和方法，并通过制备三元混晶的方法研制了新型的红外高折射率材料Pb1-xGexTe。
研究了不同基板温度下沉积的不同组份的Pb1-xGexTe薄膜样品的变温光学特性。发现Pb1-xGexTe材料的折射率随组分的增大而减小，但其折射率温度系数随组分的增大逐渐由PbTe材料的负折射率温度系数转变为Pb1-xGexTe材料的正折射率温度系数。
研究了Pb1-xGexTe材料短波吸收边和基板温度、环境温度、组份之间的关系。发现Pb1-xGexTe材料的短波吸收边随组分的增大短移，但随基板温度的上升长移。Pb1-xGexTe材料的吸收边温度系数随组分的增大减小，但随基板温度的上升而增大。
确定了折射率温度系数接近于零，能和ZnSe材料相匹配的Pb1-xGexTe材料的组份。认为X=0.20附近的Pb1-xGexTe材料折射率温度系数最佳，用它和ZnSe材料相匹配，能够有效地减小滤光片的温度漂移。
用Pb1-xGexTe和ZnSe材料研制了3.74μm和10.8μm两个通道的带通滤光片的温度漂移比不掺Ge的常用PbTe和ZnSe镀制的滤光片温度漂移小一个数量级，其温度稳定性达到了空间工程的要求。
光学薄膜器件光学性能的温度稳定性，对航空航天工程光学遥感仪器的性能好坏起着至关重要的作用，也促使作者进行了这方面的研究工作。值得提出的是红外光学薄膜器件的温度稳定性研究和新型红外镀膜材料Pb1-xGexTe的研制，目前在国际红外光学薄膜领域也还是一个前沿性的研究课题。新材料不但在温度稳定性上显现出卓越的性能，而且在光谱透过区域、折射率控制等方面均显现出其他红外镀膜材料所无法比拟的优势。这些结果的取得，标志着我国在红外光学薄膜器件温度稳定性研究这一课题上已经达到国际领先水平。随着Pb1-xGexTe材料制备工艺的不断完善，Pb1-xGexTe材料一定会在红外光学薄膜领域发挥更重要的作用。
ABSTRACT OF DISSERTATION
With the optical thin-film filter technology is continuously developed and the region of its application is extended, research on temperature stability of infrared thin-film optical filters is proposed. Because environmental temperature of optical thin-film filters decreases from room temperature (about 300K) to 85K when they are applied in the space engineering, its central wavelength will drift and the spectral characters be changed. It has a severe effect on the performance of infrared remote sensing equipment, even make them useless. Therefore, temperature stability of infrared thin-film optical filters is an important topic and is particularly urgent for those filters applied in space remote sensing engineering. We have made a deep insight under projects supported by space engineering and the Fund of Beforehand Research of National Defense. Some fruitages have been achieved.
We investigate various factors having effects on the stability of optical thin-film filter and make a further study on their mechanism. The results reveal that: moisture, environmental temperature and radiation are mostly factors that effect the stability of thin-film filters, which modify the performance of thin-film filters because they change optical constant n, k and d of thin-film materials. Under the atmosphere, moisture is the most principal factor for stability of optical thin-film filters, however, under cryogenic temperature or in the space remote sensing application, the effect of environmental temperature on performance is overweight.
We manufacture the first homemade set of measuring system for the characters of optical thin-film filters under various temperatures, and study the system error in the course of measurement caused by adding the filter and Dewar container to system. It is found that decreasing the incident angle, appreciably tilting the window of Dewar container and path of beam may eliminate these system errors. It is proposed that some attentions should be paid for filters used in space engineering under the mode of focal plane. The error of measuring system for transmittance is less than 0.5%, the precision of index of refraction is in the second decimal digit, and the precision of temperature coefficient of refractive index is in the fourth decimal digit.
Under various environmental temperature, we study the characters of commonly-used infrared optical thin-film materials deposited under different substrate temperature, and present the temperature coefficient of refractive index of commonly-used infrared optical thin-film materials in film:
It can be found that values are greater than those of bulk materials measured
by Wolfe et al., which related with both film materials and the precision of
measurement.
We study the effect of change of optical constants of materials with temperature on central wavelength of band-pass and cut-off filters and present the method of improving the stability of optical thin-film filters, particularly temperature stability of filters. We propose that improving the packing density of layers, optimizing the design of filters, and developing the new thin-film materials, may diminish the effect of changes of optical parameters of thin-film materials with temperature on stability of filters, and are important methods of improving stability of optical thin-film filters, particularly temperature stability.
We propose theory that doping and preparing ternary mutual solution can improve temperature coefficient of refractive index of semiconductors. Therefore, we grow up a new kind of high refractive infrared material – Pb1-xGexTe in the basis of preparing ternary mutual solution.
Under various environmental temperatures, we study the characters of Pb1-xGexTe thin films, which have different components, deposited under different substrate temperature. It can be found that refractive index decrease with increasing of component, but temperature coefficient of refractive index gradually shift from negative coefficient of PbTe to positive of Pb1-xGexTe.
We study the correlation between foundation absorption edge of Pb1-xGexTe thin films and substrate temperature, and environmental temperature, and component. It can be found that foundation absorption edge occur blue-shift with increasing of component, and red-shift with increasing of substrate temperature. The temperature coefficient of foundation absorption edge decreases with increasing of component, and increases with increasing of substrate temperature.
We determine the optimal component of Pb1-xGexTe, which temperature coefficient of refractive index approaches to 0 and can match ZnSe. When x=0.20, the temperature coefficient of refractive index of Pb1-xGexTe is the best. The central wavelength drift of filters is effectively minimized when Pb1-xGexTe is matched with ZnSe.
It can be shown that the temperature drifting of band-pass filters at the wavelength 3.74 m and 10.8 m made up of Pb1-xGexTe and ZnSe is lower a order of magnitude than that of filters made up of PbTe and ZnSe undoped of Ge, and its temperature stability has reached the norm of usage of space engineering.
The temperature stability of performance of optical thin-film filters, which has a key effect on the performance of space optical remote sensing equipment, spurs our researches. It’s deserved to be pointed out that researches on temperature stability of infrared optical thin-film filters and new optical thin-film material Pb1-xGexTe, are internationally the latest frontiers of the field of infrared optical thin films at present. The new material has shown not only excellent performance in temperature stability, but also unique advantage in aspect of spectral transmission and refractive index controllability. All achievements above show that, our country has lead in the research on temperature stability of infrared optical thin-film filters and reach a higher international level. With the development of technology of preparing Pb1-xGexTe, it will play an important role in the field of infrared optical thin films.
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[转帖]红外光学薄膜器件的温度稳定性研究
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[转帖]红外光学薄膜器件的温度稳定性研究
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