A Photodetector for the Diagnostics of Turbulent Gas Flows and Flames by the Method of Absorption Spectroscopy with Diode Lasers

摘要

A photodetector device that is intended for absorption measurements at a level of 10(-2)-10(-3) under the conditions of large intensity fluctuations of probing radiation, nonstationary broadband illumination of the photodetector, and in the presence of electromagnetic interference is described. Using a differential measurement circuit, an absorption signal is formed in the analog manner and amplified to a level of similar to 1 V directly near the photodetector. During periodic wavelength scanning, the influence of the broadband illumination and vibrations is compensated at the beginning of each scan. This compensation is preserved during a current scan and renewed in each subsequent scan due to the use of sample-and-hold amplifiers. The device can be used in the diagnostics of turbulent gas flows and flames.