Izvestiya of Saratov University.
ISSN 1817-3020 (Print)
ISSN 2542-193X (Online)


laser interferometry

Nanodisplacement measurements by frequency-modulated laser autodyne

Background and Objectives: Measurements of nanodisplacements are relevant for various applications of self-mixing laser (autodyne), in particular when they are combined with microwave probe methods, which are sensitive not only to the profile, but also to the inhomogeneities of the material and the its internal structure. A laser autodyne method for measuring the nanodisplacement by triangular frequency modulation of the laser radiation is proposed.

Distance Measurement with Harmonic Modulation of Self-Mixing Laser Wavelength at External Optical Feedback

Background and Objectives: Self-mixing interferometry of absolute distances is currently well represented by the method of frequency modulation of the laser diode supply current (FMCW). In recent years a harmonic modulation of the power current of a self-mixing laser began to be used. The advantage of the harmonic modulation method is due to the absence of the need to adjust the deviation of the radiation wavelength when changing the distance to the reflector.

Method for Measuring Acceleration by the Spectrum of Self-Mixing Signal of Semiconductor Laser

Background and Objectives: Traditional methods for measuring the acceleration by changing the position of extremums on the time axis, as well as methods based on the use of least squares and wavelet analysis, require significant signal processing efforts: filtering and allocating extremums or significant time for processing an autodyne signal.

Self-mixing Interferometry of Distance at Wavelength Modulation of Semiconductor Laser

Theoretical description for method of distance measurement at alteration emission wavelength of semiconductor laser, operated in self-mixing regime, has been presented. The result of computer modeling of self-mixing signal at harmonic wavelength modulation of laser diode has been represented. Spectral harmonic selection of low-frequency spectrum of self-mixing signal for distance measurement has been theoretically substantiated.

Laser Interferometry for Study of the Diffusion Process in Glycerol−Water System

Mutual diffusion process in glycerol−water system was studied by laser interferometry technique. Descriptions of optical schemes, experimental technique using multi-beam laser microinterferometer and method of digital interferogram processing are presented. Kinetics of spatial distribution of the refractive index of a medium during mass transfer process is determined and diffusion coefficients are found.