你研读下面的数据就可以明白了。
LEN NEW Cherry Hill Catadioptric System 74.986 20
EBR 12.5
OBH -25.0
DES OSLO
UNI 1.0
SNO1 Reversible lens having best performance in 1985 ILDC contest. It is a good
SNO2 example for sign conventions and pickups in complex systems involving mirrors.
SNO3 Note that the prism aperture is round. To make it square, you can define
SNO4 special apertures, turn surface drawing off for each surface, and draw the
SNO5 square vertices using bdi information (see pentprsm.len for an example).
SNO10 PRISM
// SRF 0
AIR
TH 112.5
AP 25.0
NXT // SRF 1
AIR
TH 0.01
NOT The contest rules stated that the stop and image had to be outside the lens.
NXT // SRF 2
GLA BK7
LMO ELE
RD 87.69109102159
TH 8.0
AP 20.0
NXT // SRF 3
GLA SF6
RD -55.6814740121
TH 30.0
PK AP -1
NXT // SRF 4
AIR
LME
RD -220.8055680452
TH 1.0
PK AP -2
NOT Entry dblt
NXT // SRF 5
GLA BK7
TH 60.0
AP 30.0
NXT // SRF 6
AIR
TH 2.0
PK AP -1
NOT Prism fwd
NXT // SRF 7
GLA SF6
LMO EGR
RD -327.3830921607
TH 18.0
AP 35.0
NXT // SRF 8
AIR
RD -76.08981397546
TH 3.0
PK AP -1
NXT // SRF 9
GLA BK7
RD -63.47978601779
TH 6.0
AP 35.0
NXT // SRF 10
RFL
RD -208.7130231955
PK THM -1 0.0
PK AP -1
NXT // SRF 11
PK GLA -3
PK CV -2 0.0
PK THM -3 0.0
PK AP -2
NXT // SRF 12
PK GLA -5
PK CV -4 0.0
PK THM -5 0.0
PK AP -4
NXT // SRF 13
PK GLA -7
LME
PK CV -6 0.0
PK THM -7 0.0
PK AP -6
NOT Objective
NXT // SRF 14
PK GLA -9
LMO ELE
TH -30.0
PK AP -8
NXT // SRF 15
RFL
TH 30.0
AP 42.4264068711929
DT 1
TLA -45.0
BEN
APN 1
AY1 A -42.4264068711929
AY2 A 42.4264068711929
AX1 A -30.0
AX2 A 30.0
ATP A 1
AAC A 4
NXT // SRF 16
AIR
LME
PK TH -12 0.0
PK AP -11
DRW OFF
NOT Prism back
NXT // SRF 17
PK GLA -14
LMO ELE
PK CVM -13 0.0
PK TH -14 0.0
AP 20.0
NXT // SRF 18
PK GLA -16
PK CVM -15 0.0
PK TH -16 0.0
PK AP -15
NXT // SRF 19
PK GLA -18
LME
PK CVM -17 0.0
PK TH -18 0.0
PK AP -17
NOT Exit dblt
NXT // SRF 20
AIR
CBK 1
GPRT On
WV 0.588
WW 1.0
END 20
DLNR 1 3
DLFP 1 1.0
DLMN 1 -1.0
DLMX 1 1.0
DLFP 2 -1.0