Acousto-optic tunable filter

摘要

An improved acousto-optic tunable filter infrared analyzer system useable in a variety of industrial and commercial combustion control applications includes an acousto-optic tunable filter having a crystalline material selected from the group consisting of mercurous chloride, mercurous bromide and mercurous iodide. Selectively polarized infrared radiation is passed at a predetermined plane of incidence to the crystal axis, which plane contains both the (110) and (001) axes. The system relies upon a narrow band pass tunable acousto-optic filter which is selectively tuned by predetermined rf frequency signals to selectively transmit the narrow band pass of interest which corresponds to a specific molecular species for identification and analysis. The system includes a microcomputer and associated memory function to measure and compare detected signals from an infrared detector which converts the filtered infrared signal to an electrical signal. The memory provides control signals for the computer and for controlling the sequence and frequency of rf energy applied to tune the filter. In this way, the near to far range infrared can be analyzed for absorption bands corresponding to predetermined molecular species such as combustion product gases, and a feedback signal generated to control the combustion process.