Camera Optics

1
Camera Optics Sensitivities to Defocus,
Decenter and Tilt

• Axel Brachmann
• - SLAC -

2
Outline

• Create discussion with mechanical design team
• 3 degree FOV design at 644 nm (center R - band)
• (Lynn Seppala, 2002)
• Separate analysis of 0, 1 and 1.5 degree
  half-fields
• L1, L2, L3, Dichroic filter, Image plane (and L3
  Image plane combined)
• L2 as corrector

3
Defocus, Decenter, Tilt
Decenter
Tilt
4
Geometric Encircled Energy at 5 mm Radius
5
Example 1 80 of encircled energy in 5 um spot
6
Example 2 80 of encircled energy in 5 um spot
7
Maximum Defocus
Uncorrected With L2 -correction
L1 35 ?m 800 ?m
L2 30 ?m -
DF 2000 ?m gt 5000 ?m
L3 120 ?m 370 ?m
L3 IP 6 ?m 70 ?m
IP 6 ?m 80 ?m
8
Maximum Decenter
Uncorrected With L2 -correction
L1 330 ?m 420 ?m
L2 270 ?m -
DF 3400 ?m -
L3 2300 ?m -
L3 IP 2300 ?m -
9
Maximum Tilt
Uncorrected With L2 -correction
L1 35 arcsec -
L2 11 arcsec -
DF 1400 arcsec 1700 arcsec
L3 75 arcsec 750 arcsec
L3 IP 5 arcsec 13 arcsec
IP 5 arcsec 12 arcsec
10
Next

• Analyze remaining parameter (ROC, Glass
  thicknesses, etc.)
• Improve correction
• Analyze / compare other designs, such as recent
  3.5 degree
• FOV short tube design
• Use FEA results in simulations

11
Optical Analysis of FEA Results
L1 - thermal distortion simulation John Hodgson
(SLAC)
Front Surface
Back Surface
12
Zemax surface type Grid Sag
(Case study L1 of 3.5 degree FOV Short tube
design)
Surface definition using ROC
FEA data of undistorted lens (L1)
RMS RADIUS 0o FOV 4.255 ?m
1.75o HFOV 4.031 ?m
RMS RADIUS 0o FOV 4.030 ?m
1.75o HFOV 4.005 ?m
13
Spot diagrams for distorted lens L1
RMS RADIUS 0o FOV 13.547 ?m
1.75o HFOV 24.114 ?m
-1.75o HFOV 16.070 ?m