Ilya E. Kozhevatov

High-precision methods and devices for in situ measurements of thermally induced aberrations in optical elements

An optical system that comprises two devices for remote measurements, a broadband optical interferometer and a scanning Hartmann sensor, is described. The results of simultaneous measurements with both devices and the results of numerical modeling of sample surface heating are presented.

Experimental study of thermal lens features in laser ceramics

Thermal lens measurements were made by means of a high-accuracy phase shift interferometer that combines a lambda/1000 sensitivity and 10 microm transverse resolution. The effect of random small-scale modulation in thermally induced phase distortion predicted earlier was proved experimentally. The statistical parameters of modulation were measured depending on heating power for two different ceramic samples. The experimental data agree well with results of numerical simulation.

Simple method of measurement of phase distortions in laser amplifiers

Two alternative methods for determining phase distortions of radiation in the heated active element of a high-power Nd:glass laser are compared: direct phase measurement with the Mach–Zehnder interferometer and phase front reconstruction from measured distributions of depolarization factor. It is shown that the latter method can quite quickly and accurately determine the wavefront distortions of laser radiation with minimal interference to the optical scheme of the laser.

Thermal lens and laser oscillating in CaF 2 and BaF 2 ceramics

In struggle for record average and peak power of laser radiation it was found out that many characteristics before used materials dont answer increasing inquiries. There was a problem of searching new alternative materials. One of such materials can be a ceramic. For lasers with high average and peak power a polycrystalline ceramics offers well-known advantages: large aperture like in glass, high thermal conductivity like in single crystals, higher than in single crystal thermal shock parameter, possible control of spectroscopic characteristics and low cost. Recently, 67kW CW ceramics laser was reported. At such power the important role is played by the thermal effects which studying in ceramics becomes actual. In this paper, we present a theoretical model of thermal effects in laser ceramics and their experimental confirmation.

New method for measurement of far IR beam intensity profile

A novel method for measuring the intensity profile of far-infrared radiation is presented. The idea is to measure nonstationary thermally induced variations in optical thickness of a target heated by the studied radiation. The optical thickness variations are observed by an interferometer. Beams with an aperture up to 60 mm may be measured with a spatial resolution of I mm.

Interferometry based technique for intensity profile measurements of far IR beams

We present a novel, to the best of our knowledge, method for measuring the intensity profile of far-IR beams. The method is based on the measurements of nonstationary variation in optical thickness of a fused-silica plate heated by the studied radiation. The optical thickness is observed by means of a reflecting interferometer. Purpose-made experimental setup allows one to measure beams with an aperture of up to 60 mm with a spatial resolution of 1 mm. The accessibility of the utilized technologies and the possibility to easily increase the aperture are the major advantages of this approach. The probable area of application for the method is measurements of beams produced by powerful industrial far-IR lasers.