Home – Home – Jornals – Avtometriya 2004 number 5

An optoelectronic method for measuring a surface profile using interference patterns of partially coherent light is considered. An industrial system for measuring surface defects was developed. A block diagram and specifications of the system are presented. A method for estimating the surface profile depth using the polyzonal interference patterns of partially coherent light is proposed. Results of experimental verification of the method are provided.

Results of applying the optical method of signal indication in vortex flowmeters are presented. The challenge is to estimate the influence of two geometrical parameters of the flowmeter optics on the signal-to-noise ratio and find their optimal values. The first of them, that is, the observation angle, is important for improving the signal-to-noise ratio. The second parameter, namely, the spatial distance between the laser and the vortex generator, is important for vortex detectability. In contradiction to the general approach dealing with a zero-cross passing method of signal processing, the Fast Fourier Transform is used to obtain the signal. Based on the obtained results, some recommendations on parameter optimization are presented.

New automated optoelectronic systems for measuring the geometrical parameters of complex-shaped items, including elements of the gas-air track of gas-turbine engines, are described. The main specifications of the systems, their distinctions, and examples of introduction to various branches of the industry are presented.

Accuracy characteristics of the optical method for object dimension measurement on the basis of Fresnel diffraction patterns are considered. The effect of nonuniform illumination of an object inspected on the accuracy of determining its boundaries is analytically estimated. An effective algorithm for reducing the measurement error (caused by this effect) is proposed. It takes into account values of the amplitude and derivative of the illuminating field in the neighborhood of object boundaries and, thus, reduces the error by a factor of several tens.

The possibility of applying the wavelet transforms to reconstructing complex nonperiodic object motion in optical homodyne interferometry is considered. Results of numerical simulation of reconstructing the object displacement function by an interference signal using the Fourier and wavelet transforms are presented and compared.

A method for recognition of a digital code written by a laser on a cylindrical surface of the stopper of fuel elements is analyzed. The method is based on representing (encoding) each image pixel by a direction of the dominant orientation of its local vicinity. The encoded image is compared with a set of standards. The value of the symbol recognized is determined by a standard with which the maximum number of coincidences was obtained. A code reading device based on a CCD camera and a circular illuminator is presented. Experimental results confirming the efficiency and reliability of the method are given.

Automatic devices for reading and recognition of coded (symbolic) information from surfaces of fuel elements are considered. Hardware and software techniques of solving one of the main problems of creating such devices, namely, shadowing of an image zone, are presented. The distinctive feature of the created devices is the possibility of quick adapting to available technological lines. An original design of image projection devices, which ensures reliable information reading for arbitrarily oriented items on the production line, is presented. An algorithm ensuring a high probability of information recognition (above 93 %) is proposed. Results of testing the devices are given.

Results of investigating the technique of measuring the diffraction efficiency of optical elements, which is based on scanning an element surface by a light beam with a limited aperture, are presented. Results of measuring the diffraction efficiency of a Fresnel lens, which are obtained by integral and scanning techniques are compared. The concept of a device for diffraction efficiency measurement by the two methods is considered. Experimental results are discussed.

An optoelectronic system for automatic control of geometrical parameters of car

The problem of calculating a reflector for formation of a directivity diagram represented by a vector function of one argument is considered. A general representation of a reflector surface in the form of envelope of the family of paraboloids of revolution is obtained. Each paraboloid of the family transforms a spherical beam from a point source into a beam with a plane wavefront of the given direction. The type of correspondence between beams from the source and beams of the directivity diagram is found. A reflector for transforming a spherical beam into a cylindrical one is computed. A modified method for the case of radiation focusing into a line is considered.

An analytical solution to the problem of spectral width of the operating range of a polarizer using a multilayer interference Brewster coating is obtained. A sequence of alternating surfaces with refractive indices and is considered. It is shown that the width of polarizer

Results on investigating physical properties of some new nonlinear crystals are presented. Comparative analysis of frequency converters based on them is given. Second harmonic generation of lasers, which is the first implemented and minutely described frequency conversion in and crystals with sufficient efficiency for its quantitative description, is analyzed. It is shown that application of and for direct (single-stage) frequency conversion of femtosecond lasers into the mid-infrared has advantages over multistage setups and direct frequency conversion in The possibilities of applying frequency converters based on the investigated crystals in lidar systems to analyze atmospheric composition are considered.