Image analysis system and methods for ir optics

Apparatus for testing infrared (IR) optics, said apparatus having an optical path and comprising:

• an arrangement for holding and positioning an IR optic to be evaluated along the optical path so that it can form images when illuminated with IR radiation;
• a source of radiation that emits IR radiation for travel along said optical path over a spectral band that at least encompasses the operating wavelength of the IR optic being tested;
• an optical system arranged along the optical path for directing IR radiation from a source for travel toward said IR optic;
• a mechanism for selectively blocking and unblocking said optical path during a predetermined period, said mechanism having a first position in which it blocks IR radiation and at least one other position in which it presents a preselected transmissive target to said IR optic, the temperature of said mechanism remaining unchanged from the beginning to the end of said, predetermined period so that, while blocked, only background IR radiation reaches said IR optic, and while unblocked, IR radiation from said transmissive target, along with background IR radiation, reaches said IR optic;
• an IR camera having an image detector for observing the image plane of said IR optic to generate images of said blocked optical path and transmissive target the intensity of which vary as a function of spatial location on said IR image detector of said IR camera;
• and
• a processor for determining from said images the background IR radiation present in said optical path.