Optoelectronics, Instrumentation and Data Processing (v.53, #6)

Results of studying the errors of indirect monitoring by means of computer simulations are reported. The monitoring method is based on measuring spectra of reflection from additional monitoring substrates in a wide spectral range. Special software (Deposition Control Simulator) is developed, which allows one to estimate the influence of the monitoring system parameters (noise of the photodetector array, operating spectral range of the spectrometer and errors of its calibration in terms of wavelengths, drift of the radiation source intensity, and errors in the refractive index of deposited materials) on the random and systematic errors of deposited layer thickness measurements. The direct and inverse problems of multilayer coatings are solved using the OptiReOpt library. Curves of the random and systematic errors of measurements of the deposited layer thickness as functions of the layer thickness are presented for various values of the system parameters. Recommendations are given on using the indirect monitoring method for the purpose of reducing the layer thickness measurement error.
Keywords: multilayer coatings; thin films; layer thickness measurement; computer simulation; indirect monitoring method

This paper presents the results of modeling the most important component of a one-step technology of fabricating kinoform lenses in thick photoresist layers with increased diffraction efficiency due to the formation of backward slopes of Fresnel zones with a steepness of up to 90° using oblique laser beams. It is shown that this method of fabricating volume structures makes it possible to significantly increase the steepness of backward slopes of the zones in low-contrast photoresists (k = 3) and to form practically vertical slopes in moderate-contrast photoresists (k = 10).
Keywords: diffraction efficiency; writing technology; diffractive optical element profiles; photoresist contrast; backward slopes of diffraction zones; oblique beams.

The variation in the shift of spectral structures due to the Zeeman effect in a spatially nonuniform magnetic field has been studied. It has been found that this shift can be varied by changing the width and shape of spectral structures, their forms, and methods and conditions of recording. A method of accounting for magnetic-field nonuniformity for optically thin and thick media has been proposed.
Keywords: magneto-optical resonances; Zeeman effect; modulation derivative method

Three-Axis Micro-Opto-Electro-Mechanical Angular Velocity Transducer Based on the Optical Tunneling Effect by V. I. Busurin; A. T. Fam; M. A. Zheglov; V. M. Medvedev (562-569).
A three-axis micro-opto-electro-mechanical (MOEM) angular velocity transducer model based on the optical tunneling effect was developed. The transfer function was determined, and the effect of destabilizing factors on the characteristics of the three-axis MOEM angular velocity transducer was evaluated. The dynamic range of the MOEM transducer based on the optical tunneling effect was calculated.
Keywords: three-axis MOEM transducer; tunnel effect; angular velocity; minimum detectable value; noise; dynamic range

Estimation of the Alignment Parameters of a Scanning Device with a Multirow Focal Plane Array by G. I. Gromilin; V. P. Kosykh; K. V. Kozlov; V. N. Vasil’ev (570-575).
Scanning devices based on multirow focal plane arrays providing increased resolution impose much more stringent requirements on alignment than single-row arrays. This paper presents a new method for measuring and estimating the scanning speed and the angle of orientation of a multirow focal plane array relative to the scanning direction — the parameters that determine the quality of the discrete image formed. The method is based on an analysis of the image of a simple test object — an optical slit. An algorithm for estimating these parameters is proposed which provides high-accuracy estimates under fairly weak requirements for the image quality of the test object. The estimation accuracy was calculated analytically and confirmed by simulation modeling.
Keywords: scanning device; focal plane array; time delay integration; orientation of focal plane array; scanning speed

A method for classifying moving objects having a seismic effect on the ground surface is proposed which is based on statistical analysis of the envelopes of received signals. The values of the components of the amplitude spectrum of the envelopes obtained applying Hilbert and Fourier transforms are used as classification criteria. Examples illustrating the statistical properties of spectra and the operation of the seismic classifier are given for an ensemble of objects of four classes (person, group of people, large animal, vehicle). It is shown that the computational procedures for processing seismic signals are quite simple and can therefore be used in real-time systems with modest requirements for computational resources.
Keywords: object classification; passive seismic location; spectral features; maximum likelihood method

Efficiency of Bilateral Filter Application in Problems of Optical Flow Calculation by V. V. Titkov; S. V. Panin; P. S. Lyubutin; V. O. Chemezov (583-590).
It is proposed to use weight coefficients of the bilateral filter to calculate the measure of similarity of image regions in optical flow calculation algorithms. The efficiency of using this measure is studied by an example of a three-dimensional recursive search algorithm. Weight coefficients are used for calculating the optical flow with subpixel accuracy by the Lucas–Kanade algorithm. A possibility of reducing the optical flow calculation error by means of using the proposed approaches is demonstrated by an example of processing of various types of images. A method of choosing the parameters of the weight functions of the bilateral filter is described and analyzed.
Keywords: optical flow; bilateral filter; three-dimensional recursive search; displacement vector; Lucas–Kanade algorithm; measure of similarity

Frequency Analysis of Recurrence Variational P-Splines by E. A. Kochegurova; A. I. Kochegurov; N. E. Rozhkova (591-598).
Frequency responses of the procedure of spline-smoothing of information coming in real time are obtained. A recurrence spline is studied from the standpoint of the theory of linear dynamical systems. The estimation of quality and sustainability of the recurrence spline filter are described. The spline conversion laws identified in a frequency analysis are confirmed by the indicators of smoothing quality in the time domain.
Keywords: recurrence algorithm; spline filter; free spline; variational spline; system function; hardware function

Simultaneous Localization and Mapping System on the Basis of a CoreSLAM Approach by D. A. Baramiya; M. S. D’yakov; S. A. Kuzikovskii; M. M. Lavrentyev (599-603).
A new method of loop closure based on storage of local maps of obstacles and meant for reducing accumulated localization errors is proposed. The advantage of this method in comparison with the earlier one is in the decreased amount of RAM. Testing results for the developed system and comparisons with analogs are presented.
Keywords: simultaneous localization and mapping (SLAM); loop closure; particle filter; position prediction; iterative closest point (ICP) algorithm

This paper describes a method for estimating the location of an radiating target for the case of substantial prior uncertainty with respect to operating conditions of a triangulation measurement system. The results of comparative analysis and practical recommendations on using the method are given.
Keywords: radiation source; triangulation measurement system; location; bearings; cluster; selection; principles of “breeding” and “clustering” of estimates

The knowledge of optical and dielectric properties of ferroelectric films, in particular, strontium–barium niobate films, in the terahertz spectral range is needed to use these films as a basis of active elements and structures for detection and control of terahertz radiation. The properties of strontium–barium niobate films with x = 0.5 grown on oriented sapphire substrates with a deposited electrode are studied by the method of terahertz time-domain spectroscopy in the spectral range of 0.2–1.3 THz. It is found that strontium–barium niobate films can be used to develop devices for detection and control of terahertz radiation.
Keywords: terahertz spectroscopy; strontium–barium niobate; ITO; ferroelectric films; pyroelectric detectors

Dynamics of Growth of the Native Oxide of Cd x Hg1−x Te by G. Yu. Sidorov; V. A. Shvets; Yu. G. Sidorov; V. S. Varavin (617-624).
The growth of the native oxide of the CdxHg1−xTe (MCT) compound is studied by methods of laser and spectral ellipsometry. It is found that a non-absorbing oxide film is formed from the very beginning in the case of MCT oxidation with hydrogen peroxide vapors, whereas oxidation with atmospheric oxygen leads to the formation of absorbing layers on the surface at the first stages of the process. When the oxide film thickness reaches 1–2 nm, the oxidation rate drastically decreases. If MCT samples that were stored for a long time (for years) in air at room temperature are heated at T = 200 °C, the optical thickness of the oxide film decreases.
Keywords: native oxide; MCT; ellipsometry

Superthin Solar Cells Based on AIIIBV/Ge Heterostructures by N. A. Pakhanov; O. P. Pchelyakov; V. M. Vladimirov (625-629).
A comparative analysis of the prospects of creating superthin, light-weight, and highly efficient solar cells based on AIIIBV/InGaAs and AIIIBV/Ge heterostructures is performed. Technological problems and prospects of each variant are discussed. A method of thinning of AIIIBV/Ge heterostructures with the use of an effective temporary carrier is proposed. The method allows the process to be performed almost with no risk of heterostructure fracture, thinning of the Ge junction down to several tens of micrometers (or even several micrometers), significant enhancement of the yield of good structures, and also convenient and reliable transfer of thinned solar cells to an arbitrary light and flexible substrate. Such a technology offers a possibility of creating high-efficiency thin and light solar cells for space vehicles on the basis of mass-produced AIIIBV/Ge heterostructures.
Keywords: AIIIBV/Ge-based superthin solar cells; AIIIBV/Ge heterostructures; AIIIBV/GaInAs-based solar cells

Polarization Pyrometry of Layered Semiconductor Structures under Conditions of Low-Temperature Technological Processes by I. A. Azarov; V. A. Shvets; S. A. Dulin; N. N. Mikhailov; S. A. Dvoretskii; D. G. Ikusov; I. N. Uzhakov; S. V. Rykhlitskii (630-638).
Principal issues of using pyrometry for temperature monitoring in low-temperature processes in the technology of production of semiconductor structures are considered by an example of growing mercury–cadmium–telluride (MCT) layers on the GaAs substrate by the method of molecular beam epitaxy. Optical and thermophysical models are proposed to describe the processes of radiant heat transfer in a vacuum chamber. Based on these models, it is demonstrated that radiation from the heater and the signal reflected from the chamber walls, which are comparable in magnitude with the measured radiation emitted by the sample, should be taken into account in interpreting data measured by a pyrometer. Methods of useful signal identification are found. Experiments on temperature measurement by a pyrometer mounted on the MCT growth chamber are performed. Results of these experiments are in good agreement with theoretical predictions.
Keywords: thermal radiation; polarization pyrometry; growth temperature; radiant heat transfer; molecular beam epitaxy of MCT

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