Image Intensifier Tube Research Articles

Лазерная оптико-телевизионная активно-импульсная система подводного видения

The article is devoted to the practical application of the active-pulse observation method to provide underwater vision in conditions of diffusing seawater. The laser optical-television active-pulse underwater vision system (APS UV) developed for the implementation of this method, based on synchronized pulsed laser illumination of objects of observation and video recording by a specially developed optical-television camera based on a highly efficient photodetector module with a sensitive structure «Third+ Generation Image Intensifier Tube with extended blue-green spectral region – Digital CMOS-matrix», provides the formation of video images of underwater objects in seawater with the determination of the range to them. A laser optical-television active-pulse underwater vision system (AIS PV) developed for the implementation of this method, based on synchronized pulsed laser illumination of underwater observation objects and video recording by a specially developed optical-television camera based on a highly efficient photodetector module with a sensitive structure “III+ generation electron-optical converter by – digital CMOS matrix”, which provides the formation of video images of underwater objects in seawater with the determination of the range to them. The article provides information on the physical prerequisites for the technical implementation of underwater vision in scattering seawater, as well as information on technical solutions for creating key elements of APS UV that can increase the range of vision by cutting off back scattering interference when observing in seawater. This advantage distinguishes APS UV from conventional optical television systems, in which back scattering is superimposed on the resulting image of the object, significantly reducing the range of vision and the quality of the resulting image. The results of the work performed are aimed at increasing the contrast of the image of the observed underwater object and, consequently, the range of vision of the APS UV. The article describes the developed model of the APS UV.

Objective method of measuring resolution of image intensifier tubes

Image intensifier tubes (IITs) are the most important modules of night vision devices used in huge numbers by military forces worldwide. Resolution is the most important parameter of IITs that presents information about ability of these devices to produce output images preserving information about details of the observed scenery. Despite its importance, it is still a common practice to measure resolution subjectively, by an observer looking at image of a resolution target created by a tested IIT. A series of attempts have been carried out to develop objective methods for accurate resolution measurement of IITs but with limited success. Accuracy of these methods varies depending on the tested IIT. This paper presents detailed analysis of proposed methods for objective resolution measurement. This analysis has shown that significant variability of accuracy of these methods is caused by one main drawback: the methods do not take into account influence of the spatial noise effect on human perception of image of the resolution target. Thus, an improved method taking into account spatial noise and its impact on target detection has been proposed. The method has been validated through experimental verification that shows accuracy improvements compared to other objective methods. This new approach improves accuracy of measurement of resolution of IITs to a level that can be accepted at professional test stations. In this way, this new method has potential to replace the standard subjective method to measure resolution of IITs and fix the biggest flaw of the standard test stations: measurement subjectivity.

AUTOMATED SYNTHESIS OF FAST LENSES FOR MODERN NIGHT VISION DEVICES

This article is devoted to research of the possibilities of automated design of fast and high-quality multi-lens objectives intended for use in night vision devices with modern image intensifier tubes of generation 4 and 4+, which have photocathodes with a diameter of up to 18 mm. Such image intensifier tubes are characterized by extended spectral sensitivity, high signal-to-noise ratio, and increased resolution. The computer program PODIL, developed earlier for the automated design of arbitrary optical systems, was applied to find out prescription data of fast lenses. For the parametric synthesis of optical systems, the modified evolutionary algorithm implemented in the program was used. The article presents the general methodology and results of automated parametric synthesis of a series of optical systems of objectives with different focal lengths, which contain from 7 to 9 lenses with spherical surfaces. The synthesized lenses provide angular field of view of 10°, 37° and 60° without any vignetting of axial and peripheral beams. The correspondent F numbers are 1.5, 1.33, and 1.4. The working spectral range of the designed lenses is determined by the spectral sensitivity of the photocathodes of the image intensifier tubes. In this research, it covers wavelengths from 0.45 to 0.9 μm. The longitudinal size of the designed optical systems (i.e. the distance from the first optical surface to the photocathode’s plane) is found within the range from 80 to 106 mm. The presented results of aberration analysis confirm the high image quality of the obtained optical systems. In particular, the maximum spatial frequencies of the evaluated polychromatic diffraction modulation transfer functions of the lenses over the entire field in both meridional and sagittal planes exceed 50 mm-1. The maximum values of relative distortion of the lenses are obtained within the range from 1% to 2%.

Static Mode Testing of S-20 Optical Streak Camera

The spectral response of the S-20 streak camera ranges from 350 to 850 nanometers. The streak camera consists of a streak tube and an image intensifier tube followed by a CCD camera. The optical streak camera can be operated in three modes viz. static mode, gated mode, and dynamic mode. In static mode, various electrodes are checked by applying suitable DC voltages For this purpose, a high-voltage biasing network is developed. Gated mode operation is introduced to improve signal-to-noise ratio. So, the Micro Channel Plate (MCP) of the image intensifier tube will be activated with the gated signal.

Subjective measurement of resolution of image intensifier tubes

Limiting resolution is traditionally defined as a spatial frequency of smallest resolvable element of a resolution target that can be distinguish by a human observer. This definition and measurement method have been criticized in a series of literature sources due to its subjectivity and low repeatability/accuracy. Such criticism looks reasonable as it is commonly known that results of measurement of resolution of the same tubes carried out by several test teams can differ significantly. This paper presents a detail analysis of classical subjective measurement method of limiting resolution of image intensifier tubes implemented by real test systems. The findings show that in spite of a common opinion, subjectivity of measurement is not the main reason for differences of test results carried out by different test teams. The main reasons are differences in performance of optics of test systems, use of resolution targets of different types and polarity, and inherent spatial non-uniformity of performance of image intensifier tubes. The paper also shows that due to spatial non-uniformity it is very difficult to design automatic test systems that could produce the same results as human observers using classical subjective measurement method.

An Investigation of Reading Thermal Images Processes by a Thermal Image Receiver Made in the Image Intensifier Tube Architecture

An Investigation of Reading Thermal Images Processes by a Thermal Image Receiver Made in the Image Intensifier Tube Architecture

The Thermal Image Receiver Realized in the Image Intensifier Tube Architecture

The Thermal Image Receiver Realized in the Image Intensifier Tube Architecture

Calculation Model of an Optical System for a Single-Channel Dual-Spectrum Receiver of an Image Intensifier Tube’s Architecture

Calculation Model of an Optical System for a Single-Channel Dual-Spectrum Receiver of an Image Intensifier Tube’s Architecture

Ultrafast optical gated image intensifier with a temporal resolution of 230 picosecond using uniform underlayer

An Au uniform photocathode underlayer is employed in this paper to obtain picosecond (ps) optical gating width for image intensifier tube. The transmittances and gating pulse transmission efficiencies of the underlayer with different thicknesses are tested and compared to determine the optimal thickness. An 18 mm diameter proximity focused microchannel plate image intensifier tube with S25 photocathode is fabricated using this uniform underlayer. The profile measurement shows the tube has an optical gating time as low as 230 ps full width at half maximum (FWHM) when gated with a 176 ps width gating pulse. The measured iris delay is between 83 ps and 108 ps, which approaches the theoretical limit of its kind.

An investigation of reading thermal images processes by a thermal image receiver made in the image intensifier tube architecture

The results of calculations of electric fields, potentials, and trajectories of photoelectrons calculations of single-channel dual-spectral thermal imager, implemented in the IIT architecture are presented. The values of the optimal potentials on the control electrodes (microchannel plate, reading electrode, and photocathode) that form a picture of the images of objects and ensure the correct reading of the potential relief from the surface of the sensor-converter pyroelectric film of the image thermal receiver under discussion are determined. Keywords: image intensifier tube, spontaneous polarization, a pyroelectric sensor, photocathode, photoelectronic emission, thermal object image receiver, secondary electron emission.

Calculation and optimization of the limiting characteristics of a single-channel dual-spectrum image receiver of objects emitting in the ultraviolet range

A single-channel, two-spectral image receiver of objects emitting in UV radiation, made in the image intensifier tube architecture, was proposed and investigated. With the help of the COMSOL Multiphysics software package, search optimal measurements of the potential on the elements of the image receiver (silicon membrane, germanium and diamond photocathode, MCP input and output sensors) were implemented, which provides the possibility of registering and presence of UV objects in relation to the terrain. Keywords: image intensifier tube, diamond photocathode, germanium photocathode, ultraviolet radiation, object imager, photoelectron emission, secondary electron emission.

Research on air tightness of image intensifier tube during laser sealing

采用高功率YAG激光焊接机对高性能三代像管管壳后端（4J34可伐合金）与荧光屏屏环（4J49可伐合金）进行封接试验。研究了激光功率、脉冲宽度对焊接接头成型及表面热扩散的影响规律。研究表明：4J34合金与4J49合金表面成型质量在设备最大工作电流100 A，激光功率195 W及脉宽1.7 ms时最好，相对于激光功率，脉冲宽度对焊缝熔宽和熔深的影响更加显著，接头焊接中心区硬化最为严重，其硬度最大，热影响区次之。

МикроРНК и эндокринная офтальмопатия, участие в глюкокортикоидном ответе

The accumulated clinical experience proves the existence of glucocorticoid-resistant forms of endocrine ophthalmopathy. It is assumed that epigenetic factors (miRNA) affect the pathogenesis of the disease and are involved in the formation of the glucocorticoid response. Purpose. To study the role of miRNA-146a and miRNA-155 in patients with clinical forms of endocrine ophthalmopathy and to assess their effect on the glucocorticoid response. Material and method: The study included 20 patients (40 orbits) with image intensifier tubes, treated with glucocorticoids (GC) with a negative result, mean age – 52.65 ± 12.6 years. The control group - 28 volunteers without autoimmune and tumor diseases, age 62.9 ± 7.54 years. The expression level of miRNA-155 and miRNA-146a was determined by real-time PCR. Results: The obtained data indicate an increase in the expression level of miRNA-146a and miRNA-155 in patients with clinical forms of endocrine ophthalmopathy at the stage of fibrosis (p <0.01). Conclusion: The obtained results of the functional activity of miRNA-146a and miRNA-155 confirm their participation in the pathogenesis of the development of edematous exophthalmos and endocrine myopathy by activating the fibroplastic process. Key words: endocrine ophthalmopathy, GC therapy, microRNA.

Analysis of the impact of light sources on the operational lifetime of Generation 3 and 3+ image intensifier tubes working as part of aviation night-vision goggles

The authors consider the problem of choosing light sources for helicopter equipment compatible with aviation night-vision goggles. A mathematical model for equivalent illuminance calculation in a photocathode plane created by helicopter cabin light sources is obtained. Based on this model and resource specifications of Generation 3 and $3+$ image intensifier tubes, we analyze the impact of the light environment created by helicopter light equipment and its impact on the operational resources of the image intensifier tubes depending on the applied light sources.

Image Processing Framework for Performance Enhancement of Low-Light Image Sensors

Night vision devices are used for capturing images under low light conditions ( $ lux), which are significantly different from images under standard illumination. The night vision devices based on image intensifier tube have power and cost advantages over other night vision devices, such as thermal imaging for short-range surveillance. However, these vision devices suffer from scintillation noise, which makes the resulting images noisy under very low light conditions. This paper presents a comprehensive methodology that uses a consolidated image processing module to improve the performance of low-light images acquired using image-intensifier-based night vision devices. The proposed module is a combination of a two-stage image processing framework. First, a spatio-temporal filter (based on wavelet and recursive frame averaging) is used to minimize inter-frame and intra-frame noise. Then, image enhancement is performed followed by residual noise reduction using a local spatial filter before applying image tone adjustment for display mapping. The results of the proposed module demonstrate performance enhancement of night vision devices under controlled simulated light conditions as well as field conditions. Objective and subjective analysis also reveals that the proposed module can effectively reduce noise and significantly improve visual image quality by 20–30%.

Active-pulse television measuring systems images space-time filtration by range

The paper proposes an approach for visualizing objects on images obtained with active-pulse television measuring systems (AP TMS) by range. The calculation of the AP TMS active vision area shape allows getting data of the light energy distribution inside the active vision area. To distinguish the object of interest on the video frame, an inter-frame difference of several frames obtained with different gating delays can be found. The equation of inter-frame difference for three frames is proposed. The difference simulation for three active vision areas was performed. To test the method of images space-time filtration by range, we used images obtained as a result of experimental studies conducted using large aerosol chamber of the V.E. Zuev Institute of Atmospheric Optics of Siberian Branch of the Russian Academy of Science (IAO SB RAS). In order to conduct the experiment video frames obtained under conditions of normal transparency of the propagation medium at different gating delays of the image intensifier tube (IIT) were taken. During the experiment, an image of the measuring table located at a distance of 15 m was distinguished, and the remaining objects located in the system’s field of view were successfully removed using space-time filtration. Removing of the “unwanted” information from images will increase the compression ratio and speed up the algorithms for further processing.The results obtained in this paper contribute to a more efficient use of the AP TMS for the purpose of detection and recognition of the objects under various conditions of visibility.

Использование интраоперационного компьютерного томографа с навигационной станцией при операциях на позвоночнике

The aim of the study: to analyze the results of using an intraoperative computed tomography scanner with a navigation station during spinal operations. Methods. The authors conducted a retrospective and prospective analysis of the results of 350 operations using the image intensifier tube, 390 operations with O arm and 11 operations with O arm and the Stealth-Station navigation station (Medtronic, USA). To the 350 patients operated on using the image intensifier, 1822 screws were implanted, on average 5.2 screws per operation. 117 (6.5%) screws were implanted incorrectly, of which a permissible or clinically insignificant malposition of the screw was noted in 90 (4.9%) patients. Incorrectly installed screws remaining in 27 (1.5%) patients required revision surgery. To 390 patients operated with O arm, 2477 screws were implanted, on average 6.3 screws during one operation. Incorrectly 33 (1.3%) screws were implanted, of which 25 screws were acceptable malposition. Invalid malposition of 8 (0.3%) screws was eliminated during the current operation. Results. Comparative studies of the total number of incorrectly implanted screws during operations using the image intensifier tube and O arm showed that they were more often observed when using the image intensifier tube (p <0.001) and there was no unacceptable malposition of the screws when performing the operation under O arm, since it was diagnosed in time during current operation and eliminated. A total of 66 screws were implanted in 11 patients operated using O arm and the Stealth-Station navigation station, an average of 6 screws during one operation. Inaccurate implantation of screws was not observed in any patient. Conclusions. O-arm with the Stealth-Station navigation station is the most modern method of controlling the correctness of spinal operations when anatomical landmarks are partially invisible - with open operations or invisible at all - with minimally invasive surgical interventions in real time.

Ультрафиолетовый фотоприемный модуль на основе электронно-оптического преобразователя с фотокатодом GaN/GaAlN на сапфире для применения в оптико-электронных комплексах космического базирования

Ультрафиолетовый фотоприемный модуль на основе электронно-оптического преобразователя с фотокатодом GaN/GaAlN на сапфире для применения в оптико-электронных комплексах космического базирования

Improvement of parameters X-ray television systems on the basis of electronic converters

Flat Panel Detectors (FPD) emerge as a next-generation digital x-ray technology. The numerous advantages of flat panel detectors over x-ray film, computed radiography image plates, and image-intensifier tubes are given. They include time efficiency through bypassing chemical processing and the ability to digitally transfer and enhance images. The most important parameters of different technologies are discussed. The comparison table of modern FPD is presented.Emergence and distribution of industrial television, creation of different types of vacuum transfer tubes, in particular for x-ray range, and then and their solid-state analogs promoted use and development the x-ray TV systems of methods of researches. In comparison with radiographic these methods have essential advantages and open essentially new opportunities of researches. With creation and mass introduction of modern computer facilities, in particular her attraction to processes of registration, visualization and processing of shadow x-ray images of objects. Now the special branch is put by x-ray TV systems of pulse action that are widely used in medicine, defectoscopy, military science and different technological processes. Thanks to a number of essential positive qualities (the small weight and dimensions, simplicity of a design, an opportunity of both the panoramic, and directed raying, the low power consumption and also an opportunity to control dynamic objects and processes) devices have received the greatest use in technology of nondestructive control of materials in non-stationary conditions.The device and the scheme of operation of the x-ray electron-optical converter with an axial arrangement of the receiver is considered. As the converter light signal matrixes on the basis of charge-coupled devices, and also CMOS sensors are used. Transformation of x-ray radiation to the image, available to the operator, takes place several stages. At each step of transformations primary information is distorted that leads to deterioration in the visual image. Key parameters of x-ray electron-optical converter are specified, shortcomings of this type of technologies are noted.By means of digital the x-ray TV systems of systems it is possible to receive images which quality is much higher qualities of x-ray films and computer radiography. As a result of the big relation signal/noise for digital detector system possible indication of defects, is less than the size of pixel. The sizes of solid-state detectors several times smaller for x-ray electron-optical converter. Besides they have no geometrical distortions and reflections. Other advantage of flat detectors is much faster processing of results at rather high quality of the image which gives a gain in time. The digital X-ray analysis allows to reduce a dose of x-ray radiation due to installation of an exposition at which the necessary noise level is supported.The development and improvement of technologies and technical means in the x-ray non-destructive control has taken the way of using highly stable sources of radiation, modern radiation converters, computer methods of their management, application of the newest methods of digital image processing and their analysis. There is an active transition of control systems with the use of radiation x-ray electron-optical converter to systems using multi-element transducers manufactured by microelectronics: amorphous selenium and amorphous silicon. The use of a television channel in such systems greatly expands the functionality of the equipment.Ref. 36, fig. 4, tabl. 3

The initial effects of hyperstereopsis on visual perception in helicopter pilots flying with see-through helmet-mounted displays

In see-through helmet-mounted displays (HMDs), image-intensifier tubes are located on the sides of the helmet. This HMD design increases the effective interpupillary distance and exposes the observer to hyperstereopsis. The modification of three-dimensional space perception by hyperstereopsis in laboratory studies is well known. Little is known, however, about its effects in real, operational conditions. The present study investigated the effects of hyperstereopsis on visual perception in helicopter pilots during the first flight of a night-flight training program using a see-through HMD. Fifteen pilots’ percepts of distance and height under hyperstereoscopic viewing were assessed using a double-distance estimation task in standard flight circuits. In addition, two questionnaires were used to characterize the perceptual effects induced by hyperstereoscopic viewing during the first night flight, and to determine whether any aftereffects were still present during the 24-h period following the flight. Height and distance estimation errors were observed. On average, pilots tended to underestimate the near plane relative to the farther plane in the double-distance estimation task; this is the inverse of what is commonly observed under natural viewing. We ascribed this effect to a non-linear decrease in the hyperstereopsis effect with viewing distance. Six pilots experienced sensory illusions resembling a distortion of apparent visual space: the impression of “sinking into a hole” when landing, of objects appearing closer than they actually were, and reduced in size. Four pilots cited landing as the most difficult situation encountered during the flight. Only minor complaints were reported for the 24-h period following the flight. The results of this field study represent a step towards characterizing the perceptual and operational impact of this display technology in helicopter pilots during initial exposure.