Diffractive beam splitter for laser Doppler velocimetry.
A miniaturized sensor head for the optical measurement of velocities of fluids based on laser Doppler velocimetry is demonstrated. Holographic optical elements mounted on a glass substrate are used for beam splitting and deflection. Volume holograms in dichromated gelatin exhibit good optical efficiency (75% transmission of a cascade of two holographic optical elements). With diffractive devices one can achieve achromatic behavior that makes the sensor insensitive to wavelength drifts or mode hopping of a semiconductor laser.
Schmidt
J
J
Völkel
R
R
Stork
W
W
Sheridan
J T
JT
Schwider
J
J
Streibl
N
N
Durst
F
F