Miniature illuminator for laser Doppler velocimeter assembled on micromachined silicon optical bench (original) (raw)

Miniature illuminator for laser Doppler velocimeter assembled on micromachined silicon optical bench

Miniaturized Systems with Micro-Optics and MEMS, 1999

We have built a miniature illuminator for Laser Doppler velocimeter on micromachined optical bench utilizing a novel optical scheme. We used two intersecting coherent beams from the two opposing facets of semiconductor laser die to form a standing interference pattern needed for the particle detection and velocity measurement. Such devices are of interest to NASA for investigating wind patterns and dust loading on planets with atmosphere. They can be applied to other problems where the liquid or gas flux must be characterized without disturbing the flow. In addition, the small probe volume makes possible local flow characterization and profiling. The device fabrication, and the results of the fringe characterization and velocity measurements are presented and discussed.

Integrated Laser Doppler Velocimeter made by Ion-Exchanged in Glass Substrate

HAL (Le Centre pour la Communication Scientifique Directe), 1997

A fully integrated laser Doppler velocimeter made by ion-exchange in a glass substrate is presented. Thanks to the integration of both the emission and reception systems, no optical adjustment are required. Beside, when flush mounted on a wall, this LDV does not collect the unwanted reflected light caused by the proximity of that wall. It is thus well suited for velocity measurements in boundary layers. In this paper, the fabrication technique is thoroughly described and some qualifications are commented. In the prospect of wall shear stress measurements, it is also shown that, by optimizing the waveguiding structure, highly localized velocity measurements are accessible.

Integrated Laser Doppler Velocimeter made by Ion-Exchange in Glass Substrate

Developments in Laser Techniques and Fluid Mechanics, 1997

Long-range, noncoherent laser Doppler velocimeter

Optics Letters, 1991

An experimental demonstration of a long-range, noncoherent laser Doppler velocimeter (LDV) is presented. The LDV detects incoming Doppler-shifted signal photons by using the sharp spectral absorption features in atomic or molecular vapors. The edge of the absorption feature is used to convert changes in frequency to large changes in transmission. Preliminary measurements of wind velocity using seeded aerosols showed that the LDV results agreed with mechanical anemometer measurements to within the accuracy of the LDV measurements. With optimization the LDV will provide accurate range-resolved and vibration-tolerant wind-speed measurements at large distances.

Solid state and fibre optic laser doppler velocimeters

Optics and Lasers in Engineering, 1984

Laser Doppler velocimetry (LDV) has become established as an important technique for the measurement of velocities of macroscopic objects and fluids: the dynamic range is large (-10p6-lo5 ms-') and

All semiconductor laser Doppler anemometer at 155 μm

Optics Express, 2008

We report to our best knowledge the first all semiconductor Laser Doppler Anemometer (LIDAR) for wind speed determination. We will present the design and first experimental results on a focusing coherent cw laser Doppler anemometer for measuring atmospheric wind velocities in the 10 meters to 300 meters distance range. Especially, we will demonstrate that both the output power as well as the demanding coherence properties required from the laser source can be accomplished by an all semiconductor laser. Preliminary tests at a distance of 40 meters indicate a typical signal to noise ratio of 9 dB. This result is obtained at a clear day with an update rate of 12 Hz.

A fisheye lens as a photonic Doppler velocimetry probe

Interferometry XVI: Applications, 2012

A new fisheye lens design is used as a miniature probe to measure the velocity distribution of an imploding surface along many lines of sight. Laser light, directed and scattered back along each beam on the surface, is Doppler shifted by the moving surface and collected into the launching fiber. The received light is mixed with reference laser light in each optical fiber in a technique called photonic Doppler velocimetry, providing a continuous time record.

Development of a New Velocity Measurement Technique: The Laser Bessel Velocimetry

2015

The present thesis describes the design, construction and testing of a new velocity measurement optical technique system. The technique has similarities with the laser Doppler velocimetry (LDV) in that it uses scattered light detection, in order to measure one component of the velocity vector of moving flows or solid surfaces. It uses the fringes of a Bessel beam produced by an axicon to generate the measurement volume. This technique, which we call Laser Bessel velocimetry (LBV), is noninvasive and permits continuous velocity measurements of moving particles. The experimental measurement set-up including the laser source, the optical devices, a moving stage with known velocities, a photodetector to capture scattered light and signal processing and data acquisition components, was developed and used to provide a proof of concept of this new technique. The set-up was also tested with a commercial LDV system. Two types of refractive linear axicons have been used to generate a Bessel t...

Design, Assembly, and Testing of a Photon Doppler Velocimetry Probe

2011

A novel fiber-optic probe measures the velocity distribution of an imploding surface along many lines of sight. Reflected light from each spot on the moving surface is Doppler shifted with a small portion of this light propagating backwards through the launching fiber. The reflected light is mixed with a reference laser in a technique called photon Doppler velocimetry, providing continuous time records.

Miniature illuminator for laser Doppler velocimeter assembled on micromachined silicon optical bench (original) (raw)

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