Integrated Laser Doppler Velocimeter made by Ion-Exchanged in Glass Substrate (original) (raw)

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

Developments in Laser Techniques and Fluid Mechanics, 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.

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

Design of integrated scanning laser Doppler velocitmeter using arrayed waveguide gratings

Physics Procedia, 2009

An integrated scanned differential LDV has been proposed using planar lightwave circuit (PLC) technology. By using the proposed LDV, the measurement position can be scanned in depth direction without any mechanical movement. The PLC technology is utilized in the proposed design for achieving a compact optical circuit. The characteristics of the proposed LDV are simulated with a design model based on grating equations for AWGs. The simulation result reveals that the measurement position can be changed over the range of 46 mm in the depth direction without mechanical movement when the displacement between output sides of two waveguide arrays is 30 mm.

Design of a 3-D rapidly scanning laser Doppler velocimeter with low SNR signal processing

1989

who gave invaluable guidance and assistance throughout this project. Without his cncouragement, support and guidance, it would have been difficult to accomplish this work. He also would like to thank Dr. Dana A. Walker and Dr. Alfred L. Wicks for serving on the Advisory Committee and for their helpful comments and suggestions on this project. The author would also like to thank Dave Redding of IBM for his invaluable assistance with the IBM RT-PC, John McDonough of the LeCroy ' corporation for his assistance with the transient recorders. He also wishes to thank his friends, in and outside of Blacksburg, for their time and support. This project was supported under a grant from the Air Force Office of Scientific Research. List of Symbols XVÜÜ 1.2 Previous Work: Scanning LDV A brief description of a few scanning LDV systems developed and used so far, is given by Antoine (1985) and Simpson (1989). Bendick (1971) described an on-axis scanning LDV that used a translational oscillating mirror. This system was used for instantaneous velocity measurements in steady and pulsating water flow in a glass tube of 6 mm 1. D. The operation of this design is limited to scan speeds of 0.4 m/s due to the inertia of the moving optics. A two-color dual-beam backscatter LDV system accomplishing a scan by translating a lens in the direction of the optical axis was reported by Grant and Orloff (1973). Scan rates were limited to 1.5 m/s because of inertial considerations. More information concerning the application of this design is given by Orloff and Biggers (1974) and Orloff, et al. (1975). A backscatter scanning system was reported by Rhodes (1976). It is able to scan a distance of 30 cm at a frequency of 30 Hz, and measure velocities at 16 discrete positions using a large rotating wheel containing 16 ports. For more information concerning this design, see Gartrell and Jordan (1977) and Meyers (1979). An optical system capable of measuring true instantaneous velocity profiles was reported by Nakatani, er al. (1978). lnstead of using a moving scanning device, it employcd a cylindrical lens to form a vertical measurement volume along a straight line. The design is relatively impractical and expensive Introduction 9 'Description of' RSLDV Optical Configuration ' 30

Laser Doppler velocity measurement system

2010

Laser Doppler Velocimetry technique (LDV) isa measuring technique which has been developed since early 1980s. LDV has many advantages such as non-invasive measurement of one or all three components of velocity vector, measured dimensional vector of velocity, high accuracy, high resolution, wide measurement range ... Commercial Equipment based on LDV principle was applied to measure flow in industrial applications, in biomedical applications, etc. ... However, most of them are the specialized equipment which have high cost. In terms of technical training and education, LDV experiment is one of the basic experiments of application in high-tech optical measuring techniques, showing the skills of application of the principle of optical measurement applications in practical conditions. A model LDV system was designed and complete development within the lab for training purposes.

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.

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

1999

We have built a miniature illuminator for Laser Doppler velocimeter on micromachined silicon 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

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...

Photodiode-free Doppler velocimeter based on self-mixing effect in commercial VCSELs

2008 IEEE Sensors, 2008

In this paper, we explore a new signal acquisition method for laser Doppler velocimeter based on the self-mixing technique. The self-mixing technique is applied on commercial multimode transverse Vertical-Cavity Surface-Emitting Lasers (VCSELs) and the signal is acquired by amplification of the junction voltage of the laser diode when it was usually picked-up with an external photodiode. The sensor developed exhibits up to 25dB signal-to-noise ratio for a wide velocity range. We present a study of the sensitivity of such photodiode-free sensors versus the laser static conditions and we compare the results with usual photodetected signals. Finally we expose the advantages of this technique and propose new applications for self-mixing sensors.

Laser Doppler velocimeter for laboratory training

Seventh International Conference on Education and Training in Optics and Photonics, 2002

The laser Doppler velocimeter was developed specially for students laboratory training. The experimental kit consists of the classic dual beam laser Doppler system and the set of the dynamic objects such as moving phase screen and scattering flows. Signal processing and data analysis is performed using personal computer that allows for flexible training.