1. Integration and Alignment of Optical Subsystem Roy W. Esplin Dave McLain

2. Integration and Alignment of Optical Subsystem Outline Verify vacuum system and cryogenic system are operational Fit check all optical components Align optics to internal optical bench Align internal optical bench to vacuum enclosure Transfer boresight from internal optical bench to alignment cube on exterior of vacuum shell Iterate to final alignment by adjusting focus and clocking of focal plane assemblies (FPAs) over several thermal cycles 2

3. Alignment of optics to internal bench Install mirrors and lens at positions determined by precise machining Install LWIR grating and MWIR grating replacement mirror at nominal locations Mount unexpanded, 633-nm laser on XY stage; set angle using flat F1 (SDL’s) Translate laser until beam strikes center of mirror M1 (dichroic not installed) Measure distance from face of internal optical bench to laser beam (optical axis) Center laser beam on grating by translating grating Adjust grating angles until 15 th order is reflected straight back by lens L1 and line of dispersed orders is perpendicular to internal bench. Increment grating angles to put 15.3 order at lens L1 center. Install dichroic and adjust its mount for best centering of laser beam on mirrors M2 and M3 Translate & tilt M4 to center laser beam on M3 and lens L2 3 M1 M2 Dichroic F1 M3 L1 Grating L2 M2

4. Align Internal Optical Bench to Vacuum Enclosure and Map Boresight into Cube Align surface 1 on internal optical bench parallel to surface 2 on exterior of vacuum enclosure and translate internal optical bench so optical axis is at correct location on the window using a Coordinate Measuring Machine (CMM) Map boresight angles into alignment cube using CMM Measure any angular changes in the cube when vacuum pulled on enclosure using theodolite 4 SDL Alignment cube Surface 1 Surface 2 Window

5. FPA Alignment Initial FPA location and orientation set using Judson’s measurements of FPA detector locations relative to package XY coordinates of FPA origin relative to holes at 12, 3, 6 and 9 o’clock on FPA package Detector Z location relative to mounting flange Clocking of FPA in package relative to holes as well as vertical members on both sides of printed circuit board Focus shim between lens housing and FPA sets focus Shims between FPA package and shimming fixture used to get controlled translation and clocking adjustment of FPA. Iterate to best alignment Functional Test setup described on next slide 5 Shimming fixture Translation shims Rotational shims

6. Functional Test Setup 6 COB12-Ch. A/D Computer Detectors and dispersed image of point source 12 spectra (one for each detector) Poor Focus Good Focus Area Within Dashed Lines Purged with LN2 Wavelength (um) Interferometer OAP Steering Mirror Pinhole Translatable Platform Lens Simulated Telescope Exit Pupil (Exit pupil is only 1-inch in diameter)

7. Use of Metrics From Functional Test to Align FPA Iterate to best lateral location of FPA by measuring spectral location of 50% points Iterate lateral FPA adjustment iterate to best FPA clocking using steering mirror to move dispersed spectrum off the top and bottom of the detectors Iterate to best focus by maximizing both the spectral slope and rate that response falls off as dispersed spectrum is moved off top and bottom of detectors 7