Laser diode self-mixing interferometry for velocity measurements

Alexandra S Alexandrova,Carsten P Welsch,Vasilis Tzoganis

doi:10.1117/1.oe.54.3.034104

Alexandra S Alexandrova, Carsten P Welsch + Show 1 more

Open Access

https://doi.org/10.1117/1.oe.54.3.034104

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Abstract

A diode laser velocimeter based on laser self-mixing has been developed and characterized as a reliable, precise, comparably cheap, and compact monitor. The resolution of this sensor at different incident angles and for a variety of solid and liquid targets moving at velocities between 0.1 and 50 m/s is presented. This includes a theoretical analysis of the underlying measurement principle, highlighting possibilities to extend the measurement capabilities to even higher velocities by altering the sensor design. Finally, an outlook on future applications of the sensor for detailed studies of supersonic gas jets used in beam diagnostics and atomic physics applications is given.

Highlights

The field of self-mixing (SM) interferometry has been growing since the mid 1960s, with significant growth in the late 2000s due to better fabrication techniques of semiconductor lasers, which has opened up the possibilities to work with cheaper and higher-quality lasers in a wide range of applications
The SM technique can be applied using any type of laser, and both the target and property of the laser itself should be correctly taken into account
The signal was received from the built-in photodiode, which is usually used for monitoring the laser diode (LD)

Summary

Introduction

The field of self-mixing (SM) interferometry has been growing since the mid 1960s, with significant growth in the late 2000s due to better fabrication techniques of semiconductor lasers, which has opened up the possibilities to work with cheaper and higher-quality lasers in a wide range of applications. In the case of supersonic gas jets, they combine low internal temperatures with high directionality, and as a result, they are very interesting as experimental targets in different fields of science.[6] For the optimization and verification of the properties of such a monitor, it should be characterized with high accuracy, in particular with regard to its velocity and density profile. In these applications, gas jet velocities can be up to 2000 m∕s and can be inhomogeneously distributed across the jet. All currently used methods for such a characterization are either not reliable[7,8] or require a powerful laser system.[9]

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