Model LS-2X Laser Source Detector Test System.
Abstract
Proper, characterization of infrared photodiodes requires a series of optical tests that include blackbody response, spatial uniformity, pulse response, and wavelength sensitivity measurements. The results of these optical tests will depend upon many fundamental properties of the detector crystal, namely absorption depth of the radiation, bulk lifetimes of injected carriers, surface recombination effects, carrier drift and diffusion effects, trapping effects and other mechanisms. Some of these effects are not clearly understood but may play important roles in such application as high speed pulse detectors, laser heterodyne receivers, or large area high resolution detector arrays. Spears has shown that proper spatial and temporal characterization of HgCdTe CO2 laser heterodyne receivers must be done at the operating frequencies. A realistic characterization of the pulse response of an infrared detector must be made at the operating wavelength, generally that of peak detector response. Certain fixed frequency gas lasers such as CO2, CO, or HF can provide sufficient power and speed for detector characterization but they have limited wavelength coverage and are often cumbersome to use. On the other hand, Pb-salt tunable diode lasers can provide more than 100 micro w of power emitted from nearly a point source, subnanosecond risetime pulses and wavelength selectability between 2.8 and 30 micrometers. These characteristics make diode lasers an ideal source for pulse spatial response measurements of infrared detectors.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 1980
- Accession Number
- ADA086540