Development of velocity measurement technique by pulsed laser Doppler anemometry
Abstract
The conventional point measuring ability of laser Doppler anemometry is extended to a line measurement. Two immediate requirements follow from this modification. The first is that of monitoring several points along the line measuring volume simultaneously, leading to a multichannel data collection and analysis system. The second stems from the diminished beam intensity in the measuring volume due to its extension and the need to restore scattered light intensity by increasing laser power or scattering particle diameters. Two parallel lines of study are used. The first aims at developing the optics and signal processing necessary to produce and analyze the Doppler signals. A CW argon ion laser is used operating in a conventional laser Doppler configuration, with the exception of the output lens, which is cylindrical and produces a line intersection within the measurement field. Progress with the argon ion system consists of the completion of the optical arrangement in conjunction with an air jet and suitable particle seeding, capable of producing sonic jets. The second parallel element aims at overcoming the low light level in the measuring volume using the high powers available with pulsed lasers.
- Publication:
-
The 1985 AFOSR/AFRPL Chem. Rocket Res. Meeting
- Pub Date:
- February 1985
- Bibcode:
- 1985crrm.rept.....E
- Keywords:
-
- Computer Systems Programs;
- Laser Anemometers;
- Laser Doppler Velocimeters;
- Laser Outputs;
- Pulsed Lasers;
- Continuous Wave Lasers;
- Light Scattering;
- Microcomputers;
- Photodiodes;
- Photomultiplier Tubes;
- Signal Processing;
- Velocity Measurement;
- Lasers and Masers