We describe the process of preparing an experimental study of a coded aperture in the visible spectral range. In the experiments, shadowgrams are supposed to be recorded with a conventional imaging sensor. A feature of the work is a proposed coded aperture implementation method based on surface evaporation by laser ablation. As a coded aperture base material, a glass substrate with a titanium film 500-nm thick deposited on it is used. To characterize and validate the fabricated coded apertures, a dual-metric method based on image processing techniques was developed. The method was used to optimize laser parameters, including the pulse power, the spot moving speed, and the pulse repetition rate. The coded aperture implemented with the parameter values determined was then used as the imaging device in the experimental stand and proved to form a high-contrast image. The double metric method allows one to optimize other laser parameters, along with the studied ones, for the given experimental conditions.
Different spatial alignment techniques for multimodal image fusion are presented in the paper. Main feature-based spatial alignment steps and operations as well as cross-correlation techniques are described. An experiment was carried out to compare spatial alignment methods. Experiment results are presented and conclusions are made. The text gives information about spatial alignment application for multimodal systems calibration.
This work discusses coded aperture functioning in the visible spectral range. A MURA coded aperture was implemented using laser ablation by evaporation of titanium film from a transparent substrate. The optimal laser parameters to make a high-contrast aperture are shown. The paper also present an algorithm based on periodic correlation which has been developed for image reconstruction. Experiments were carried out with the aperture of rank 37 with a minimal element of 130 μm. The images obtained during the experiment demonstrate the effectiveness of the proposed aperture implementation method and the developed image processing algorithm.
The currently existing incremental optical-electronic linear displacement encoders (OELDE) use raster conjugation, which allows for the measurement of linear motion with high accuracy by means of the conversion of optical signals in the opto-electronic path. In such devices, informative signals constantly undergo transformations associated with their processing. Variable environmental factors, especially temperature, have a harmful effect on signal conversion processes and cause additional error. The aim is to analyze the results of theoretical and experimental studies of the additional error from the effect of changes in ambient temperature on incremental OELDE’s. Analyzing the effect of temperature on the course of information transformation, it is possible to divide the main emerging partial components of the additional error into two groups: - errors due to changes in the relative spatial position of the elements of the OELDE; - errors due to changes in parameters and characteristics of elements of the OELDE.
A high-energy radiation imaging system is presented which is based on the scintillation method. To detect and visualize high-energy radiation, a SiPM array is used together with a CsI(Tl) scintillation crystal. At the current stage of development, gamma or X-ray sources are not used to verify the operation of the system and initiate scintillation. Instead of them, vacuum ultraviolet (VUV) radiation is used. The possibility of using a VUV lamp as a source of high-energy radiation has been proven computationally and experimentally. This allows eliminating the use of sources of gamma or X-ray radiation and special protective equipment at the initial stage of development. A coded aperture is used as an imaging device. It is made by laser evaporation of titanium sputtering from the surface of a transparent substrate. The results of this study show methods and materials which allow investigating the high-energy radiation imaging system at the initial stage without using sources of hazardous radiation.
In this work it is shown that high-intensity microprismatic tapes have a potential to be used as a good substrate for bright and cheap fiducial marks in machine vision metrology applications. The drawback of the tapes is that they have technological netting pattern distributed across the surface. The proposed image processing technique allows good suppression of the parasitic technological netting pattern by a harmonic mean image filtering followed by circle shape recovering based on Fourier descriptors. It was also shown that the combination can provide good results in mark position estimations. In experiments it was shown that subpixel accuracy of position estimation can be achieved after applying proposed image processing, while without filtering the error can exceed 4 pixels in some cases.
In this paper we show, how different optical elements affect the polarization state. We show it on the examples of elementary optical elements, such as refracting and reflecting surfaces and an anisotropic waveplate, and more complex elements: a plane-parallel plate, a Dove prism, a spherical lens, an image sensor. The method of considering the calculated influence on the example of Stokes polarimetry is also shown.
KEYWORDS: Probability theory, Light emitting diodes, Active optics, Error analysis, Control systems, Diodes, Computer simulations, Reliability, Buildings, Motion controllers, Image processing, Signal to noise ratio, Signal detection, Optoelectronics, Image analysis
The article is devoted to the optimization of optoelectronic systems of the spatial position of objects. Probabilistic
characteristics of the detection of an active structured mark on a random noisy background are investigated.
The developed computer model and the results of the study allow us to estimate the probabilistic characteristics of
detection of a complex structured mark on a random gradient background, and estimate the error of spatial coordinates.
The results of the study make it possible to improve the accuracy of measuring the coordinates of the object. Based on
the research recommendations are given on the choice of parameters of the optimal mark structure for use in opticalelectronic
systems for monitoring the spatial position of large-sized structures.
This article is devoted to consideration of the issues relating to digital images fusion of the multispectral optoelectronic systems. The images fusion formation methods and methods are studied. Theoretical analysis of the methods was completed in the course of the work, mathematical simulation model of the multispectral optoelectronic systems was developed. Effect of various factors on the result of fusion was demonstrated on the basis of the said model investigation. The paper also considers and suggests the objective assessment methods of the fusion image quality. The paper describes the mostly widely used from the above: the averaging method, the masking technique fusion, the interlacing fusion, fusion of images Fourier spectrum. The quality of the resulting image was assessed on the basis of the calculation of the cross entropy, brightness dispersion and excess of the Fourier spectrum function. Based on the research findings we can state that the images obtained by the mask technique methods, by averaging and the Fourier spectrum fusion methods have the highest information entropy. The best quality feature, in terms of the brightness dispersion and excess of the Fourier spectrum function, was demonstrated by the averaging method. The method allows reducing noise components of an image on the account of smoothing of its local brightness variations smoothing thus the contrast is improved.
The paper analyzes the construction matters and metrological parameters of the electrooptic converter to control linear displacements of the large structures of the buildings and facilities. The converter includes the base module, the processing module and a set of the reference marks. The base module is the main unit of the system, it includes the receiving optical system and the CMOS photodetector array that realizes the instrument coordinate system that controls the mark coordinates in the space. The methods of the frame-to-frame difference, adaptive threshold filtration, binarization and objects search by the tied areas to detect the marks against accidental contrast background is the basis of the algorithm. The entire algorithm is performed during one image reading stage and is based on the FPGA. The developed and manufactured converter experimental model was tested in laboratory conditions at the metrological bench at the distance between the base module and the mark 50±0.2 m. The static characteristic was read during the experiment of the reference mark displacement at the pitch of 5 mm in the horizontal and vertical directions for the displacement range 400 mm. The converter experimental model error not exceeding ±0.5 mm was obtained in the result of the experiment.
Energetic sensitivity of a system with optical equisignal zone is considered in the paper. Energetic sensitivity is a criterion for choosing components of such a system and determines its potential accuracy. The term of energetic sensitivity is revised for a spectrum and spectral response of the sensor is taken into account. New method of evaluating of the position of optical equisignal zone is proposed. The method is based on evaluation of the position on the CMOS array. Digital method of signal processing is compared to analog one. Digital method has some advantages over analog in functionality but still yield to analog in speed.
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