Laser Doppler anemometer

摘要

A laser Doppler anemometer includes at least a first and second laser source, an optical system for directing laser beams from the sources to a specific region of a fluid flow containing particles in order to produce a virtual interference fringe pattern and at least one photodetecter positioned for receiving the scattered light from the flowing fluid. At least one of a temperature regulation and current regulation circuit is provided for stabilizing the wavelength of at least one of the laser sources. The first and second laser sources are set to different emission wavelengths and a regulating circuit is provided for maintaining the difference frequency between the first and second sources constant. The difference frequency is in turn utilized to control the temperature regulation and/or current regulation circuit for at least one of the laser sources to achieve stabilized operation thereof.