Browse Prior Art Database

Passive Laser Cooler

IP.com Disclosure Number: IPCOM000093860D
Original Publication Date: 1966-Mar-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 3 page(s) / 53K

Publishing Venue

IBM

Related People

Johnson, CM: AUTHOR

Abstract

An injection laser is cooled to a temperature of approx. 77 degrees K aboard a satellite. Such is effected by employing substantially only passive radiators relying on s elective wavelength emission and reflection.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 53% of the total text.

Page 1 of 3

Passive Laser Cooler

An injection laser is cooled to a temperature of approx. 77 degrees K aboard a satellite. Such is effected by employing substantially only passive radiators relying on s elective wavelength emission and reflection.

GaAs injection laser 2 is surrounded by cube 4 which is highly reflecting at all wavelengths except that at which the laser 2 emits, namely, at 0.84 microns, and except that at which a black body radiates at 77 degrees K. For proper functioning of the cooling system for the injection laser, the following assumptions are made. The earth and the satellite structure are each assumed to be at an average temperature of 300 degrees K. The earth's albedo is assumed to have the spectral distribution of a 5000 degrees K black body and the satellite is in synchronous orbit about 20,000 miles above the earth's surface. The laser transmitter aperture area, collecting dish 6, is a square meter.

Each of three sides of cube 4 and its bottom surface has an emissivity of 0.9 in the vicinity of 37 microns. That side of the cube that normally faces the sun is a highly polished metal reflector for black body radiation at 5000 degrees K. The remaining surface 8 of cube 4 facing the collector dish 6 is highly reflecting in the vicinity of 10 microns, 300 degrees K black body radiation, as well as in the vicinity of 0.5 microns, 5000 degrees K black body. Within surface 8 of the cube 4 is a 1 cm/2/ window 10 containing a bandpass filter for radiation around 0.84 microns. Such filter is highly reflecting for radiation on either side of 0.84 microns.

The satellite, principally collecting dish 6, is assumed to have an emissivity of
0.3, conservative, at 10 microns, and the laser shield is assumed to have a reflectivity of 0.95 at 10 microns on the f...