Baffle Design For Earth Radiation Rejection In The Cryogenic Limb-Scanning Interferometer/Radiometer

James C. Bremer

doi:10.1117/12.959333

3 November 1980 Baffle Design For Earth Radiation Rejection In The Cryogenic Limb-Scanning Interferometer/Radiometer

James C. Bremer

Proceedings Volume 0245, Cryogenically Cooled Sensor Technology; (1980) https://doi.org/10.1117/12.959333
Event: 24th Annual Technical Symposium, 1980, San Diego, United States

Abstract

The Cryogenic Limb-Scanning Interferometer/Radiometer (CLIR) is being developed to observe infrared emissions of the earth's upper atmosphere from space. The earth's surface is an extended source of intense background radiation with a small angular separation from the desired scene. The CLIR employs an off-axis Gregorian Telescope whose primary mirror and baffles are cooled by an open-cycle cryogen system. A system of specular annular baffles has been developed to minimize both stray light problems and cryogen consumption by retro-mapping the aperture into itself. Each off-axis ray which enters the aperture and strikes the specular baffle surface is reflected so that it passes out of the aperture and is not absorbed on a cryogenic surface. The specular baffle which lies closest to the aperture is an ellipsoid whose foci trace out the circular aperture on revolution about the axis. Its theoretical "ray trace" efficiency is 100 percent. A subsequent baffle has an elliptical cross section whose near focus traces out the central hole in the ellip-soidal baffle and whose far focus traces out the aperture. Its theoretical efficiency is about 90 percent. These baffles reduce the earth radiation heat load on the cryogenic cooler by an order of magnitude,changing it from the dominant cause of cryogen consumption to a relatively small effect. An aperture shield is also desirable to reduce cryogen consumption, stray light, and contamination.

Citation Download Citation

James C. Bremer "Baffle Design For Earth Radiation Rejection In The Cryogenic Limb-Scanning Interferometer/Radiometer", Proc. SPIE 0245, Cryogenically Cooled Sensor Technology, (3 November 1980); https://doi.org/10.1117/12.959333

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available