Mr. Aleksey V. Pigarev Profile

Aleksey V. Pigarev

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Publications (2)

Proceedings Article | 23 February 2018 Paper

Novel method of optical image registration in wide wavelength range using matrix of piezoelectric crystals

Aleksey Pigarev, Timur Bazarov, Vladimir Fedorov, Oleg Ryabushkin

Proceedings Volume 10526, 105262E (2018) https://doi.org/10.1117/12.2290831

KEYWORDS: Crystals, Sensors, Optical components, Image registration, Absorption, Laser crystals, Signal attenuation

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Most modern systems of the optical image registration are based on the matrices of photosensitive semiconductor heterostructures. However, measurement of radiation intensities up to several MW/cm² -level using such detectors is a great challenge because semiconductor elements have low optical damage threshold. Reflecting or absorbing filters that can be used for attenuation of radiation intensity, as a rule, distort beam profile. Furthermore, semiconductor based devices have relatively narrow measurement wavelength bandwidth.

We introduce a novel matrix method of optical image registration. This approach doesn’t require any attenuation when measuring high radiation intensities. A sensitive element is the matrix made of thin transparent piezoelectric crystals that absorb just a small part of incident optical power. Each crystal element has its own set of intrinsic (acoustic) vibration modes. These modes can be exited due to the inverse piezoelectric effect when the external electric field is applied to the crystal sample providing that the field frequency corresponds to one of the vibration mode frequencies. Such piezoelectric resonances (PR) can be observed by measuring the radiofrequency response spectrum of the crystal placed between the capacitor plates. PR frequencies strongly depend on the crystal temperature. Temperature calibration of PR frequencies is conducted in the uniform heating conditions. In the case a crystal matrix is exposed to the laser radiation the incident power can be obtained separately for each crystal element by measuring its PR frequency kinetics providing that the optical absorption coefficient is known. The operating wavelength range of such sensor is restricted by the transmission bandwidth of the applied crystals.

A plane matrix constituting of LiNbO₃ crystals was assembled in order to demonstrate the possibility of application of the proposed approach. The crystal elements were placed between two electrodes forming a capacitor which was interconnected to the lock-in detection system. The radiofrequency response to the applied voltage from the generator was measured simultaneously for all elements.

Proceedings Article | 27 April 2016 Paper

Impedance spectroscopy for measuring low optical absorption coefficients of nonlinear optical crystals

Aleksey Pigarev, Aleksey Konyashkin, Oleg Ryabushkin

Proceedings Volume 9894, 98941T (2016) https://doi.org/10.1117/12.2227731

KEYWORDS: Crystals, Laser crystals, Absorption, Temperature metrology, Nonlinear crystals, Calorimetry, Crystal optics, Mathematical modeling, Dielectric spectroscopy, Sensors, Crystals, Laser crystals, Dielectric spectroscopy, Chromium, Silica, Calibration

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