MSE, Inc has developed a self contained and permanently aligned Laser Doppler Velocimeter/Anemometer (LDV/LDA). The miniLDV probe contains a laser, miniature beam shaping optics, receiving optics, and a detection system.
The sensor is 1.25″ (32 mm) in diameter and 6.5″ (165 mm) long, and the fixed distance between the sensor and the probe volume (standoff distance) can be selected to be 1.30, 1.97, 3.94, 5.91, or 9.45 inches (33, 50, 100, 150, or 240 mm)*. The size of the probe volume (measurement domain) depends on the standoff distance and ranges from 30 by 60 by 200 μm (x by y by z) to 100 by 200 by 1200 μm. The miniLDV is also available in two-component and three-component versions.
In a laser doppler velocimeter, two coherent laser beams are crossed (forming the probe volume) to generate interference fringes. When a particle or microscopically textured surface move through this region, it reflects bursts of light corresponding to its passage through the regions of constructive interference. Since the spacing between the fringes is constant, the velocity of the particle or surface is proportional to the frequency of the reflected bursts. MSE’s miniLDV also features frequency shifting (moving fringes) to measure direction as well as speed. The miniLDV sensor has a measurement range from 1 mm/sec to 300 m/sec with a repeatability uncertainty of 0.1% and an accuracy of 99.7%.
The miniLDV System consists of the miniLDV probe, Processing Engine, and the 1D Burst Processor Acquisition Manager software package. Optionally available are linear traversing systems (one or two axes) with manual or electronic drive (electronic traverses are controlled from within the software) and a computer with the software installed and verified by MSE technicians. The miniLDV probe is also available with an integrated Processing Engine as the Integrated miniLDV.
If the standard probes do not suit your needs, feel free to contact us and inquire about our custom solutions.
You can read all about how an LDV/LDA works here.
*These distances are measured in air. When aimed into an experimental vessel with a different fluid, the probe volume will be farther from the probe and it will be slightly larger. Please refer to the specifications at left for examples.
The miniLDV probe is protected under U.S. Patent No. 6,654,102.