Using the blackbody without a collimating lens

Pupil image viewing the bare blackbody source, set to a cold temperature. The washers and bolt heads that attach the blackbody to the larger copper block appear as bright circles, which are partly seen in the cold stop perimeter. Rotating the cal turn table moves the spots diagonally. We will need to shim the mirror to be able to look directly at the center of the black body and avoid the warm washers.

Judicious adjustment of the fold mirror mount on the cal turntable lets us avoid the warm bolt heads on the blackbody source. The angular tolerance of this configuration is about +/- 0.5 deg.