A 2.8 micron infrared heterodyne radiometer

A gain modulated, Dicke switched Infrared Heterodyne Radiometer (IHR) has been designed, developed, and tested which is capable of measuring the atmospheric absorption characteristics within a 200 MHz bandwidth about selected hydrogen fluoride (HF) laser transitions between 2.7 and 3.1 micrometers. The IHR has been installed in a KC-135 test aircraft. Provisions for remote control and remote calibration were incorporated into the radiometer. The heterodyne receiver sensitivity (NEP) of the IHR is 1.3 times 10 to the -19th power W/Hz and the calculated temperature resolution (delta T sub S/T sub S) is given for a variety of source temperatures and total transmittances (alpha).