Matrix Photodetector Research Articles

Статистический анализ потенциала батиметрического лидара с времяпролетным матричным SPAD-фотоприемником

Статистический анализ потенциала батиметрического лидара с времяпролетным матричным SPAD-фотоприемником

Experimental study of the color separation system of a matrix photodetector

Experimental study of the color separation system of a matrix photodetector

Possibilities for Increasing the Signal-To-Noise Ratio in Technical Vision Systems of Robotic Complexes Using Laser Structured Lighting

The development of high-resolution machine vision systems with a long observation distance is an urgent task. The possibilities to increase the observation distance by increasing the signal-to-noise ratio (SNR) based on the use of the active parallax method are discussed in the article. The achievable observation distance in such systems is determined by the brightness of the illumination source and the ratio of the brightness of the illumination source to the brightness of the background illumination (the SNR for the photodetector pixel). The goal of the investigation: The article considers the possibility of further increasing the SNR in machine vision systems with laser structured lighting due to the use of pulsed or repetitively pulsed mode of the backlight laser in combination with a time-gated photodetector. This allows to realize a machine vision system with gating, which will provide an increase in the observation distance due to the time cutoff of the background component of the recorded image. In the current scientific literature, the data on machine vision systems with temporal gating of the photodetector device are not known. Methods: To consider the possibilities of increasing the SNR in vision systems, a numerical analysis by analytical formulas was used for the parameters and the operating conditions typical for robotic technical systems. The data on the number of solar photons reflected by the object and backscattering photons arising from scattering of the both solar and laser radiation were used to calculate the SNR in machine vision systems with a conventional-type matrix photodetector and with a time-gated photodetector. Results: The calculation analysis has shown that, the using of laser illumination repetitively pulsed mode and a gated photodetector device allows to increase significantly both the SNR and the observation distance. Practical significance: The proposed technical vision system implementation can improve the characteristics of robotic systems.

Enhanced Photocurrent in BiFeO3 Materials by Coupling Temperature and Thermo-Phototronic Effects for Self-Powered Ultraviolet Photodetector System.

Ferroelectric materials can be utilized for fabricating photodetectors because of the photovoltaic effect. Enhancing the photovoltaic performance of ferroelectric materials is still a challenge. Here, a self-powered ultraviolet (UV) photodetector is designed based on the ferroelectric BiFeO3 (BFO) material, exhibiting a high current/voltage response to 365 nm light in heating/cooling states. The photovoltaic performance of the BFO-based device can be well modulated by applying different temperature variations, where the output current and voltage can be enhanced by 60 and 75% in heating and cooling states, respectively. The enhancement mechanism of the photocurrent is associated with both temperature effect and thermo-phototronic effect in the photovoltaic process. Moreover, a 4 × 4 matrix photodetector array has been designed for detecting the 365 nm light distribution in the cooling state by utilizing photovoltage signals. This study clarifies the role of the temperature effect and the thermo-phototronic effect in the photovoltaic process of the BFO material and provides a feasible route for pushing forward practical applications of self-powered UV photodetectors.

Calibration of Matrix Photodetectors and Precision Positioning of Objects According to Raster Images

The problem of determining a small displacement of an object from a series of images in an interference microscope is studied. The extent of the effect of phase noise of the restoration of the coherent structure of a field is estimated. The effect of the heterogeneity of individual pixels of a matrix photodetector of a raster image is investigated.

Comparative analysis of mathematical models of the matrix photodetector used in digital holography

It is established, that in modern works on digital holography, three fundamentally different mathematical models of a matrix photodetector are used. Comparative analysis of these models, including analysis of the formula of each model and test calculations, has been conducted. The possibility of using these models to account for the influence of geometrical parameters of a matrix photodetector on the properties of recorded digital holograms is considered.

Experimental Study of the Hybrid Laser Radar

Objectives: The aim of this work was to perform experimental studies of hybrid laser radar as an intermediate option between the classical scanning pulsed laser radar and a system built in accordance with a 3D-Flash LADAR technology. Methods: The studies were performed on the ground optical track using modern equipment for the registration of measurement results. Modern methods of mathematical modeling were applied for data processing. Findings: Hybrid laser radar provided location frame frequency significantly greater than the frequency of the classical pulse radar, without the use of a matrix photodetector required for 3D-Flash LADAR. Frame frequency of 28 frames per second was obtained in the experimental settings with the view field of 20×20°. A signal/noise ratio was also determined imitating maximal operating range of 2 km on the ground track or of 5 km in space. Improvements: Hybrid laser radar can be used in robotic systems as a 3D technical vision system.

Electrical Properties of the V-Defects of Epitaxial HgCdTe

The manufacturing process of wide-band-gap matrix photodetector devices and miniaturization of their individual pixels gave rise to increased demands on the material quality and research methods. In the present paper we propose using the methods of atomic-force microscopy to study the local distribution of electrical properties of the V-defects that form in epitaxial films of HgCdTe during their growth process via molecular beam epitaxy. We demonstrate that a complex approach to studying the electrical properties of a predefined region of a V-defect allows one to obtain more detailed information on its properties. Using scanning spreading resistance microscopy, we show that, for a V-defect when the applied bias is increased, the surface area that participates in the process of charge carrier transfer also increases almost linearly. The presence of a potential barrier on the periphery of individual crystal grains that form the V-defect interferes with the flow of current and also affects the distribution of surface potential and capacitive contrast.

Development of analog-digital readout integrated circuits for infrared focal plane arrays

This paper describes the design of readout integrated circuits (ROICs) for hybrid infrared focal plane arrays (IR FPAs). This work contains the estimation of the noise equivalent temperature difference (NETD) of IR FPAs based on frame and row integration of pixel signals in the spectral ranges of 8 to 14 and 3 to 5 μm. This paper also describes the development of ROICs for IR FPAs created with the use of mercury—cadmium—telluride (MCT) photodiodes and quantum well infrared photodetectors (QWIPs). The designed ROICs ensure the use of matrix and linear photodetector chips, including those with increased dark currents, in order to produce IR FPAs with temperature resolution corresponding to the world level of array analogs.

Study of the Effect of Incorporation of CdS Nanoparticles on the Porous Silicon Photodetector

In this study, the influence of embedding cadmium sulfide nanoparticles, synthesised by a chemical method, on the performance of porous silicon matrix photodetectors was investigated. An anodization technique was used to fabricate porous silicon photodetectors at 16 mA/cm2 for 10 min.The characteristics of porous silicon and CdS nanoparticles were investigated by using x-ray diffraction XRD, atomic force microscopy AFM, scanning electron microscopy SEM, and energy dispersive x-ray EDX. Dark and illuminated current-voltage I-V characteristics and spectral responsivity of photodetectors were investigated before and after the incorporation of CdS nanoparticles. Considerable improvement was noticed in responsivity of the porous silicon photodetector after incorporating the CdS nanoparticles into the silicon matrix.

Исследование алгоритма высокоточного сопровождения зенитных управляемых ракет матричным фотоприемником по блику формирующей оптики системы самонаведения

In order to protect the aircraft from attacking surface-to-air missile with precision the algorithm of Activity-through the use of laser thermal imaging system with a receiver matrix type. As a discriminator considered algorithms assess the current position of the energy center of the image and the sum-difference signal processing, carrying out the measurement error angles between the direction of the surface-to-air missile and the optical axis of the matrix photodetector uneven coordinate sensitivity, noise immunity boosting algorithms. Developed a dynamic model of precision tracking, to evaluate the effectiveness of the formation at the entrance of the matrix image sensor in the form of an additive mixture of signal and noise.

Temperature dependence of diffusion length in MCT epitaxial layers

The temperature dependence of the minority charge carriers diffusion length in the active photosensitive layer of a matrix photodetector based on MCT heteroepitaxial structure grown by molecular beam epitaxy is studied.

Investigation of matrix photodetectors on structures with quantum wells in conditions of intensive optical lightning

Results of the investigation of degradation processes in matrix photodetectors on structures with quantum wells in the field of intensive laser radiation are presented. It is shown that the area joining the photodetector matrix crystal with the silicon crystal of a signal-processing integrated circuit plays an important role in these processes.

Construction of a multichannel filter for detecting point targets in the image formed by a matrix photodetector

A new approach is proposed to construct a multichannel filter for detecting small-size targets in images recorded by a matrix photodetector. For estimating the pulse response of each channel of the filter, the set of experimentally obtained images of targets having different locations with respect to photodetector cells is divided into several subsets, which are used as reference elements in calculating the pulse response of the filter. Experimental data are presented, which demonstrate appreciable reduction of the probability of missing the targets in images subjected to processing with a filter constructed by the proposed method.

Solution of the problem of calibrating the spatial distribution of photosensitivity of matrix photodetectors: Theory and experiment

A method of calibrating the spatial distribution of photosensitivity of matrix photodetectors without the use of reference optical radiation intensity distributions has been developed and experimentally verified. A scheme of the experimental setup implementing the method, an experimental procedure, and two modifications of the algorithm that reconstructs spatial distributions of photosensitivity using the measurement results have been developed. Experiments on calibrating the spatial distributions of photosensitivity of CCD matrices have been performed. It is shown that, using the presented method, calibration of the spatial distribution of photosensitivity of matrix photodetectors permits one to almost eliminate systematic error when detecting spatial distributions of the optical radiation intensity.

Calibration method for spatial distribution of photosensitivity of matrix photodetectors

We propose a calibration method for spatial distribution of photosensitivity of matrix radiation receivers. It is based on measurements of time-stable distributions of the light beam intensity at several different combinations of mutual positions of the beam and the radiation receiver. The scheme of the experiment was developed to realize this method, and the inverse problem of reconstruction of the spatial distribution of photosensitivity from the measurement results was solved. Numerical simulation of the experiment was used to study the features of the calibration algorithm. The spatial distributions of light sensitivity of the matrices, which work on the principles of charge-coupled device operation, were calibrated in an experiment.

Solar chromosphere in the D3 helium line from spectra of the eclipse of March 29, 2006

We present the processing results of slitless chromospheric spectra in a D3 helium line obtained during the solar eclipse of March 29, 2006. A “Cascade-Photometrics 650” CCD matrix photodetector with a rate of 16 frames/s was used for the observations. Altitude distribution of absolute brightness of the helium chromosphere has been mapped in a latitude interval 30 N-10 S on the western limb. A correlation between absolute brightness of the helium chromosphere and a solar cycle phase has been confirmed. It has been revealed that the altitude distribution of helium emission has one maximum at an altitude of approximately 2000 km. In the lower chromosphere, helium emission is undetectable. This confirms our assumption about absence of an additional maximum at 300 km in the D3 line brightness distribution in the chromosphere during sunspot maximum periods. The results also prove that X-ray coronal radiation with λ < 6 nm is the source of helium excitation in the lower chromosphere.

A 128 × 128 pixel ultraviolet photodetector based on a diamond sensor

A new 128 × 128 pixel matrix photodetector with a semiconductor diamond sensor is designed, fabricated, and studied. A 128 × 128 pixel ultraviolet image is detected experimentally.

Integration of heterospectral infrared images in the 3–5 and 8–14 μm bands in passive optoelectronic systems with matrix photodetectors

Basic results of the experimental investigation of the correlation between two-dimensional intensity distributions (in two different spectral bands: 3–5 and 8–14 μm) of aerial target and the background on heterospectral infrared (IR) images have been presented. The above images were obtained in the process of comparison tests of trial models of passive optoelectronic systems (OES) with matrix photodetectors (PD) mounted on the antenna of target-tracking radar station (TTRS). A technique for improving the quality of these images was also described. The specified technique was aimed at enhancing the ranges of target detection and recognition under condition of the integration of above images on the basis of the correlation revealed.

Thin-film PbSnTe:In/BaF2/CaF2/Si structures for monolithic matrix photodetectors operating in the far infrared range

We report for the first time on the creation of 288 × 2 matrix photodetectors with an element size of 25 × 25 μm based on PbSnTe:In/BaF2/CaF2/Si structures and present their threshold characteristics. The detection ability of about 90% elements ranges from 7.2 × 1012 to 8.7 × 1012 cm Hz0.5/W at T = 21.2 K. The proposed technology opens ways to the creation of monolithic matrix photodetectors operating in the far-IR range.