/pdf/fiber-optic-and-free-space-michelson-interferometer-4essasu70q.pdf

Fiber Optic and Free Space Michelson Interferometer — Principle and Practice

Knowing a thermal expansion coefficient and measured exact thermal expansion, it is possible to design a very sensitive sensor measuring temperature differential. A Michelson interferometer is used to determine temperature changes. It measures linear expansion on a metal object, e.g. a copper rod, as a change in length in response to a change in temperature. Based on the obtained interferograms and knowing the value of thermal expansion coefficient, temperature differential can be calculated. The accuracy of the procedure can be determined by using the exact differential method based on the measurement errors for linear expansion, and initial length. The contribution of this paper is the employment of Michelson interferometer to design a very sensitive differential thermometer measuring with the accuracy of one thousandth degree Celsius. It results from the achieved precision of measuring the optical path length changes in the range of hundreds nanometers. The advantage of this sensor is its precision and noncontact procedure.

Precise optical differential thermometer sensor based on interferometric measurement of thermal expansion coefficient

We describe the achievements of the Karpenko Physicomechanical Institute of the Ukrainian National Academy of Sciences in the development of new methods and tools for the ultrasonic computer tomography of structural materials in the last decade. The results of investigations of thick-plate products with welded joints performed by using a transmission ultrasonic computer tomograph are presented. We also describe the technologies of evaluation of the space distribution of scattering power of the metal in thick-walled pipelines by recording scattered ultrasonic signals with the help of an ultrasonic computer tomograph. These technologies prove to be promising for implementation at the objects of nuclear power plants. The results of experimental testing of the technologies of passive ultrasonic computer tomography are discussed.

Development of the technologies of ultrasonic tomography for the engineering diagnostics of structural materials

Michelson interferometer stabilized scheme for surface acoustic waves detecting

A new detection scheme of surface acoustic waves by Michelson interferometer has been proposed. A substantial advantage of this scheme lies in its being stabilized against vibration and independent sensitivity of the width of an optical beam. These effects were achieved by creating an interference field on the surface of a photodetector. The measurement scheme proposed was analyzed by means of a numerical modeling method. Experiments confirming the fact of the sensitivity of the proposed detection scheme being independent of vibration and width of optical beam have also been made.

Stabilized detection scheme of surface acoustic waves by Michelson interferometer

It is proposed to use reduction rulers to estimate the autocorrelation function and the power spectrum of a stationary random signal for a finite sample for different variants of non-uniform data sampling. Various methods of its construction are analyzed, both according to the well-known Golomb ruler and convenient for practical application of the line using non-uniform data sampling with switching the sampling frequency at two close frequencies. The results of numerical modeling of the accuracy of the signal power spectrum estimation using standard deviation are presented.

I. Romanyshyn

Papers

Stabilized detection scheme of surface acoustic waves by Michelson interferometer

A New Method for Estimating the Power Spectrum of a Stationary Random Signal Based