ISPI Optical Design

The ISPI optical design originated with a design produced by Charles Harmer (NOAO) for the U. Florida IR camera FLAMINGOS. This design was a close match to our science-defined specifications, was already optimized for the Mayall 4-m, and allowed cost savings by joint procurement of optics. Hence we adopted it for ISPI, with a slight reoptimization of element spacings for the Blanco telescope by Harmer and Maxime Boccas (CTIO).

This is a refractive, collimator-camera system with an intermediate cold pupil image. The f/3 camera employs one aspheric element; all other surfaces are spheres. Design performance is shown graphically below with spot diagrams (box size is 2x2pixels, ie. 36x36 microns)
The camera optics coupled to the Blanco 4-m give the following performance for 80% encircled energy diameter:


Band Best in Field Worst in Field Spot Diagram
J 0.36" 0.48" J Spot Diagram
H 0.36" 0.48" H Spot Diagram
K 0.48" 0.55" K Spot Diagram


Note: The best and worst are not obtained respectively on axis and in the corner

The optics have been produced by Janos Technology, Inc. The FLAMINGOS implementation has had first light confirmation of excellent image quality on Kitt Peak telescopes.


Ray Trace

March 22, 2004