RU2589947C1 - Active-pulsed television night vision device - Google Patents

Abstract

FIELD: optics.

SUBSTANCE: invention relates to night vision devices. Device comprises monitoring unit, television channel, control and synchronisation unit, pulse infrared illuminator and frequency divider, delay conversion unit, two electromechanical drives, pumping current amplitude adjustment unit and series-connected natural illumination meter, signal conversion unit and frequency control unit.

EFFECT: high image quality of observed object.

1 cl, 1 dwg

Description

The present invention relates to the technique of night vision devices (NVD), intended for observation in low light conditions (twilight, night, etc.)

Known passive-active NVD, containing sequentially mounted on the optical axis of the lens, a replaceable filter, an electron-optical converter (image intensifier tube) and an eyepiece focused on the screen image intensifier tube. The composition of this NVD also includes an infrared (IR) illuminator containing a lens for generating output radiation focused on an IR emitter connected to a power supply. The IR emitter may be a lamp, IR LED or IR semiconductor laser. In the case of an IR emitter in the form of a lamp, a filter can be installed between the objective to form the output radiation and the IR emitter, which cuts off visible and ultraviolet radiation (1).

Such NVD can work in passive and active modes. The active mode was continuous in time and was used in cases where the level of natural night illumination (ENO) was low or had to work in complete darkness.

Serious drawbacks of this NVD were its inoperability in conditions of reduced transparency of the atmosphere (rain, snowfall, haze, etc.), as well as the inability to ensure duplication of information and transmission of the observed image remotely and to a personal computer. In addition, when operating in the active mode, backscattering radiation was superimposed on the image of the observed object and reduced its contrast up to the complete loss of visibility of the observed object. The NVD could not work under conditions of powerful light noise, did not provide a sufficiently accurate measurement of the distance to the object of observation, and did not allow observing low-contrast objects.

These disadvantages are largely eliminated in the well-known active-pulse (AI) television (TV) night vision device (AI TV NVD) containing a TV channel, the presence of which allows for duplication of information about the observation object and transmit the image remotely and to a personal computer. This AI PNV TV contains a monitoring unit, consisting of a first lens component of a transfer optics focused on its optical axis, a replaceable filter, a pulsed image intensifier tube and a first lens component of the transfer optics focused on its screen, a TV channel including a synchronizer and a second lens component of the transfer optics connected in series optically coupled to the first lens component of the transfer optics, a TV camera, on which the second lens component of the transfer optics, a video amplifier and a TV monitor are focused, and the outputs of the frame and internal synchronization clock of the same name are connected to the inputs of a TV camera, a video amplifier and a TV monitor. The PNV AI TV also includes a pulsed laser illuminator, consisting of a lens for generating output radiation focused on a pulsed laser semiconductor emitter connected to the first output of the pump unit, a control and synchronization unit containing a serially connected master pulse generator (ZG), the first input of which connected to the second output of the pumping unit of the pulsed laser illuminator, an adjustable delay unit (RHL) and a gate pulse shaper (FSI), the output of which is under it is connected to the gate input of the pulsed image intensifier tube of the monitoring unit, and a frequency division unit (BCH), the input of which is connected to the output of the horizontal synchronization of the TV channel synchro-generator, and the output to the second input of the ZGI of the control and synchronization unit. This AI TV NVD could operate in 3 modes: passive (pulsed laser illuminator turned off), active-continuous (illuminator turned on, but the control and synchronization unit is turned off and AI TV NVD works like a normal active NVD) and AI mode (illuminator and unit control and synchronization are turned on.) When operating in the AI mode, the ZGI of the control and synchronization unit is triggered by sync pulses from the second output of the pump unit of the pulsed laser illuminator, from the first output of which pulsed laser semiconductor is excited by current pulses vy emitter generating their peers for the duration of the pulses of infrared radiation. The lens for generating the output radiation of a pulsed laser illuminator collimates this IR radiation, generates the required illumination angle, and directs the IR radiation to the object of observation.

The IR radiation pulses reflected from the object of observation come into the lens of the observation unit, which forms the image of the object on the photocathode of the image intensifier tube operating in a pulsed mode. Before the arrival of pulses of infrared radiation on the photocathode of the image intensifier tube, its gate input is locked.

At the moment of arrival of the pulse reflected from the object of observation, the gate of the image intensifier tube opens for the duration of the strobe pulse, equal to or somewhat greater than the pulse duration of the IR radiation. To ensure such synchronous operation of the laser illuminator and the image intensifier tube, the clock pulses from the output of the control and synchronization block of the control unit are synchronized to the BRZ of this block, where they are delayed with respect to the clock pulses from the second output of the pump unit of the laser illuminator for a time equal to the distance from the infrared radiation emitter to object of observation and back. From the output of the BRZ block of the control and synchronization block, the sync pulse arrives at the FSI of this block, which creates gate voltage pulses, unlocks the gate input of the image intensifier tube, which amplifies the image in brightness and converts it into visible. The operator, smoothly adjusting the delay, can move in depth a narrow zone of the viewing space, determined by the duration of the strobe pulse, until the observed object falls within this zone. The image from the image intensifier screen is transferred using the transfer optics to the CCD matrix of the TV camera. A TV camera converts the image formed on the image intensifier tube into an electric video signal, which is amplified in a video amplifier and transmitted to a TV monitor, where it is converted into an optical image observed from an operator’s TV screen. The sync generator provides frame and line synchronization of the operation of the TV camera, video amplifier and TV monitor, as well as the synchronization of the ZGI operation, for which the line frequency signal of the TV channel sync generator is fed to the frequency division unit, which divides the line frequency to a level close to the frequency of the pulsed laser illuminator and multiple to her. This AI TV PNV, as the closest to the offer, is taken as a prototype. (2)

The prototype device provided a sufficiently high contrast in the image of the observed object due to:

- delayed clipping of backscattering radiation, which in conventional known NVDs operating in the active mode, is superimposed on the image of the observed object and reduces the contrast in its image with deteriorated and even normal transparency of the atmosphere;

- attenuation (equal to the duty cycle of the observation unit) of the radiation scattered in the atmosphere, determined by the level of natural illumination, which, when the known night vision devices operate in the passive mode under conditions of reduced atmospheric transparency, also sharply reduced the contrast in the image of the observed object;

- clipping the background behind the observation object due to the fact that the object is perceived within a very narrow depth of the viewing space, which allows you to observe low-contrast objects that are not visible in ordinary (known) passively active night vision devices, or even during the day in ordinary optical observation devices.

In addition, the AI TV PNV - prototype made it possible to accurately measure the distance to the object of observation by the amount of delay, since the image of the object is available for observation only at a certain amount of delay corresponding to the distance to the object. Moreover, the accuracy of measuring the range does not depend on the distance to the object, but is determined only by the duration of the strobe pulse and the backlight pulse.

Also, the prototype device excludes the possibility of issuing a false range value due to the reaction to random objects located between the observed object and the device (for example, tree branches, wires, etc.), the signal from which can significantly exceed the useful signal from the observed object, since all such false signals are cut off by a delay. The prototype device allows monitoring under conditions of powerful light interference, since when the observation unit operates in a pulsed mode, any long-term light interference (radiation from searchlights, headlights, fires of fires, explosions, etc.) is attenuated by a factor of one equal to the duty cycle of the device . Additional noise immunity is achieved by the use of a replaceable band-pass (or cut-off) filter in the observation unit with a passband corresponding to the working region of the spectrum of the laser illuminator.

However, the image quality obtained in the prototype device was insufficient.

This was due to the fact that when changing the distance to the object of observation, the lens of the observation unit remained unchanged its focus on the photocathode of the image intensifier tube. This naturally reduced image quality. The lens for generating the output radiation of the laser illuminator also kept its focus unchanged on the pulsed laser emitter and, accordingly, the illumination angle when changing the distance to the observation object. This led to unjustified energy losses and to a corresponding decrease in image quality at higher distances to the subject due to a lack, and at near ranges due to an excess of backlight brightness, which even leads to illumination of the image. At near ranges, the excess radiation power of the laser illuminator led to the same illumination. In addition, with an excessively high level of natural illumination at a given constant frequency of operation of the AI TV NVD, the image also flashed and, thereby, its quality decreased.

The proposed device solves the problem of improving the quality of the observed image.

To solve this problem, in the well-known AI TV PNV, comprising a monitoring unit, consisting of a first lens component of transfer optics focused on the screen of an optical axis of a lens, a replaceable filter, a pulsed image intensifier tube, and a TV channel including a synchronizer and a series-connected TV camera, on which the second lens component of the transfer optics is focused, optically coupled to the first lens component of the transfer optics, a video amplifier and a TV monitor, the outputs of the frame and horizontal sync onsync generator is connected respectively to the inputs of the same name as a TV camera, video amplifier and TV monitor, a pulsed IR illuminator, consisting of a pulsed IR emitter connected to the first output of the pump unit, and a lens for generating output radiation focused on the pulsed IR emitter, a control and synchronization unit, consisting from series-connected ZGI, the first input of which is connected to the second output of the pumping unit of a pulsed IR illuminator, BRZ and FSI, the output of which is connected to the input of the strobe of the image intensifier unit of the monitoring unit, and the frequency dividing unit, the input of which is connected to the horizontal synchronization output of the TV channel synchro-generator, and the output is connected to the second input of the control and synchronization block ZGI, a delay conversion unit (BPS) is introduced, the input of which is connected to the second output of the BRZ control unit and synchronization, two electromechanical drives, a unit for adjusting the amplitude of the pump current, the input of which is connected to the first output of the BPZ, and the output is connected to the input of the pumping unit of a pulsed IR illuminator, and connected in series natural light, signal conversion unit and frequency control unit, the output of which is connected to the third input of the ZGI of the control and synchronization unit, the second output of the BPZ connected through the first electromechanical drive to the lens barrel of the observation unit, and the third output through the second electromechanical drive to the frame the lens forming the output radiation of a pulsed IR illuminator.

The invention is illustrated in the drawing, which shows a block diagram of the proposed device.

The inventive AI TV PNV comprises a monitoring unit 1, consisting of a first mounted lens component 5 of the transfer optics 6 focused on the optical axis of the lens 2, a replaceable filter 3, a pulsed image intensifier 4, and a TV channel 7 including a second lens component 8 transfer optics 6, optically coupled to the first lens component 5 of transfer optics 6, a sync generator 9 and a series-connected TV camera 10, video amplifier 11 and TV monitor 12, to the frame and line synchronization inputs of which are connected respectively Significantly outputs of the synchro-generator 9.

The proposed AI TV PNV also contains a pulsed IR illuminator 13, consisting of a lens for generating output radiation 14 focused on a pulsed IR emitter 15 connected to the first output of the pump unit 16, a control and synchronization unit 17, including a series-connected ZGI 18, the first input of which is connected to the second output of the pumping unit 16 of the pulsed IR illuminator 13, BRZ 19 and FSI 20, the output of which is connected to the gating input of the image intensifier tube 4 of the monitoring unit 1, the frequency division unit 21, the input of which is connected to the output line synchronization generator 9 of the TV channel 7, and the output is with the second input of the ZGI 18 of the control and synchronization unit 17, as well as the newly introduced BPZ 22, the input of which is connected to the second output of the BRZ 19 of the control and synchronization unit 17, the first 23 and second 24 electromechanical drives , a unit for adjusting the amplitude of the pump current 25, the input of which is connected to the first output of the BPZ 22, and the output to the input of the pump unit 16 of the pulsed IR illuminator 13, and a series-connected meter of natural illumination 26, a signal conversion unit 27, and a control unit frequency 28, the output of which is connected to the third input of the ZGI 18 of the control and synchronization unit 17, and the second output of the BPZ 22 is connected through the first electromechanical drive 23 to the lens barrel 2 of the observation unit 1, and the third output through the second electromechanical drive 24 to the barrel the lens 14 of the formation of the output radiation of a pulsed IR illuminator 13.

The inventive AI TV PNV can operate in passive, active-continuous and active-pulse modes and works as follows.

When operating in passive mode, the replaceable filter 3 is removed from the path of the rays and the pulsed IR illuminator 13 and the control and synchronization unit 17 are turned off. Radiation determined by the level of natural night illumination (ENO) is reflected from the object of observation and the surrounding background and comes to the observation unit 1, the lens 2 of which forms an image of the object and background on the photocathode of the image intensifier tube 4. The image intensifier 4 converts the image into a visible one and enhances its brightness. From the image intensifier screen 4, the image is transferred using the transfer optics 6 to the CCD matrix of the TV camera 10 of the TV channel 7. The TV camera 10 generates an electric video signal that is amplified in the video amplifier 11 of the TV channel 7 and transmitted to the TV monitor 12 of this channel, where it is converted into a visible image observed from the screen of the TV monitor 12. The synchronizer 9 provides the frame and horizontal synchronization of the TV camera 10, video amplifier 11 and TV monitor 12.

When the AI TV PNV is operating in active-continuous mode, the pulsed IR illuminator 13 is turned on, the control and synchronization unit 17, both electromechanical actuators 23 and 24, BPZ 22 and the unit for adjusting the amplitude of the pump current 25 are switched off. Pump unit 16 of the pulsed IR illuminator 13 generates current pulses, which are pumped pulsed IR emitter 15, generating the corresponding pulses of infrared radiation. The lens 14 for generating the output radiation of a pulsed IR illuminator 13 collimates this radiation, forms the desired angle of illumination, and directs the radiation to the object of observation. Reflecting from the object of observation, radiation pulses arrive at the observation unit 1, the lens 2 of which forms an image of the observed object on the photocathode of the image intensifier tube 4. Image intensifier 4 converts the image into visible, enhances its brightness. Using transfer optics 6, the image from the screen of the image intensifier tube 4 is transmitted to the CCD matrix of the TV camera 10 of the TV channel 7. The TV camera 10 generates an electric video signal, which, after amplification in the video amplifier 11, is transmitted to the TV monitor 12, where it is converted into a visible image observed from the TV screen monitor 12. TV channel 7 synchronizer 9 provides frame and line synchronization of TV camera 10, video amplifier 11 and TV monitor 12.

When the AI TV PNV is operating in AI mode, all the elements and blocks included in the device are turned on. The pumping unit 16 of the pulsed IR illuminator 13 generates current pulses by which the pulsed IR emitter 15 is pumped, generating the corresponding IR pulses. The lens 14 for generating the output radiation of a pulsed IR illuminator 13 collimates this radiation, forms the desired angle of illumination, and directs the radiation to the object of observation. The radiation pulses reflected from the object of observation come to the observation unit 1, the lens 2 of which forms an image of the object on the photocathode of the image intensifier tube 4.

The replaceable filter 3 cuts off light interference acting in a wide spectral region. The image intensifier 4 operates in a pulsed mode. Before the radiation arrives at the photocathode of the image intensifier tube 4, its gating input is locked. At the moment of arrival of the radiation pulse reflected from the object of observation, the gate input of the image intensifier tube 4 opens for the duration of the strobe pulse, equal to or somewhat greater than the duration of the radiation pulse. To ensure the synchronous operation of the pulsed IR illuminator 13 and the EOF 4, the clock pulses from the output of the ZGI 18 are transmitted to the BRZ 19, where they are delayed with respect to the clock pulses from the first input of the ZGI 18 for a time equal to the passage by the radiation pulse of the distance from the AI TV PNV to the object of observation and vice versa. From the output of the BRZ 19, the clock pulse enters the FSI 20, which creates a gate voltage pulses, unlocking the gate input of the image intensifier 4. The latter amplifies the image in brightness and converts it into visible. The operator, smoothly adjusting the delay, can move in depth a narrow zone of the viewing space, determined by the duration of the strobe pulse, until the observed object falls within this zone. The image from the screen of the image intensifier tube 4 using the first 5 and second 8 lens components of the transfer optics 6 is transmitted to the CCD matrix of the TV camera 10 of the TV channel 7. The TV camera 10 converts the image into an electric video signal, which is amplified in the video amplifier 11 and transmitted to the TV monitor 12, where is converted into a visible image observed by the operator from the screen of the TV monitor 12. The sync generator 9 provides frame and line synchronization of the operation of the TV camera 10, video amplifier 11 and the TV monitor 12, as well as the synchronization of the operation of the PGI 18 of the control unit and the sync tions 17, which signal is a horizontal frequency clock 9 is supplied to the second input 18 via the DIG frequency dividing unit 21 that divides the frequency lines to a level close to the operating frequency of pulsed infrared illuminator 13 and fold it.

From the second output of the BRZ 19, the delay signal is supplied to the BPZ 22, where it is converted into an electrical signal that controls the operation of the first 23 and second 24 electromechanical drives.

The signal from the second output of the BPZ 22 is fed to the input of the first electromechanical drive 23 and adjusts the focus of the lens 2 of the observation unit 1 in accordance with the delay signal, i.e. in accordance with the distance to the object of observation. Due to this, the lens 2 is always precisely focused on the object of observation, at whatever distance from the AI TV NVD it is located, which improves the image quality in the entire working range of the ranges of the claimed device.

The signal from the third output of the BPZ 22 is fed to the input of the second electromechanical drive 24 and adjusts the focus of the lens 14 for generating the output radiation of the pulsed IR illuminator 13, forming the angle of illumination of the object in accordance with the delay signal, i.e. in accordance with the distance to the object. At the same time, the illumination angle of the pulsed IR illuminator 13 narrows at higher ranges, while expanding at close ranges. Due to this, at increased ranges, the energy intensity of the light of a pulsed IR illuminator 13 increases, respectively, the brightness of the observed image increases and, therefore, its quality; at short ranges, a large illumination angle allows you to cover the entire object of observation, which also positively affects the image quality of the observed object. It also allows you to reduce the excess brightness of the backlight and prevent image flare.

The signal from the first output of the BPZ 22 through the pump current amplitude control unit 25 is fed to the input of the pump unit 16 of the pulsed IR illuminator 13 and adjusts the pump current and, accordingly, the radiation power of the pulsed IR emitter 15 of the pulsed IR illuminator 13 in accordance with the delay signal, i.e. in accordance with the distance to the object. At near ranges, the pump current decreases, due to which the radiation power of the IR emitter 15 decreases. Correspondingly, the radiation power at the output of the IR illuminator 13 also decreases and excessive radiation power is not generated, which causes illumination of the image intensifier tube 4 of the observation unit 1. At higher ranges, the pump current in accordance with the signal the delay increases, which leads to an increase in the radiation power at the output of the IR illuminator 13 and allows to increase the brightness of the image, thereby improving the image quality of the object observation.

The measuring instrument of natural illumination 26 provides continuous measurement of the level of natural illumination and generates at the output an electrical signal corresponding to this level, fed to the input of the signal converting unit 27, where it is converted into a form that controls the operation of the operating frequency control unit 28 of the AI PNV TV operating frequency control. From the output of block 28, the signal is supplied to the third input of the ZGI 18 of the control and synchronization unit 17. At higher values of natural light, the frequency of the ZGI 18 decreases, while at lower values, it increases. As a result, the duty cycle of the AI TV NVD changes accordingly, i.e. the degree of its protection against light noise, the role of which, in this case, is played by the increased level of EHW (up to daylight). This eliminates the possibility of exposure to AI TV NVD with excess radiation from natural light and improves image quality.

Thus, the proposed construction of an AI TV PNV with the introduction of a BEP, two electromechanical drives, a unit for adjusting the amplitude of the pump current and a series-connected meter of natural illumination, a signal conversion unit and a frequency control unit made it possible to comprehensively improve the image quality of the observation object due to:

- providing operational focusing of the lens of the observation unit in accordance with the range at which the object of observation was located;

- providing operational adjustment of the angle of illumination of the object by a pulsed IR illuminator in accordance with the range at which the object of observation was located;

- providing operational adjustment of the power of the pulsed IR emitter in accordance with the range at which the object of observation was located;

- ensuring operational adjustment of the duty cycle of the AI TV PNV operation in accordance with a specific level of natural light.

A model of the proposed AI TV PNV was made and tested.

For the manufacture of the layout were used:

- as the lens of the observation unit, a lens lens with a focal length of 131 mm, a relative aperture of 1: 1 and a viewing angle of 4.1 °;

- as a replacement filter - a known cut-off filter based on cadmium telluride doped with zinc;

- Image intensifier tubes model EPM53G, OJSC "Cathode";

- transfer optics is made according to known optical schemes using known optical elements (see, for example, Special Technique, 2005, No. 3, p. 6-11);

- to build a television channel, a WATc model WAT 904 television camera was used, a video amplifier - UTS IRON, LOGIC, a television monitor model MDC 066 SKB "Dipol", the Republic of Belarus, a sync generator - Les DG-14B;

- a laser semiconductor emitter model L13, manufactured by Inject, was used in a pulsed IR illuminator, a Lazofor-2 lens with a focal length of 115 mm, a relative aperture of 1: 1.25 and an illumination angle of 1 ° 48 was used as an output radiation lens ′;

- the pumping unit of the pulsed IR illuminator, as well as the control and synchronization unit, were constructed according to well-known schemes (see, for example, Applied Physics, 2007, No. 5, pp. 127-130);

- to build a frequency division unit, the circuit according to US Pat. RF №2189694, publ. 2002, and for the delay conversion unit, the scheme according to US Pat. RF №2118847, publ. 1998;

- a light meter of model 1 PN-124 was used by the company Central Design Bureau Tochpribor, a signal conversion unit BPS-200Ех, BPS-200К-ЕХ, a frequency control unit RPU B7-2;

- used well-known electromechanical drives (see www.bergab / melektro.shtml);

- the unit for adjusting the amplitude of the pump current was also assembled based on well-known schemes (see www.technomag./edu/doc/373951/ html).

The tests showed that the proposed device can comprehensively improve the image quality of the observed object in the entire working range.

Information sources

1. Geykhman I.L., Volkov V.G. The basics of improving visibility in difficult conditions. M., LLC "Nedra-Business Center" 1999, p. 14, fig. one.

2. Geykhman I.L., Volkov V.G. The basics of improving visibility in difficult conditions. M., LLC "Nedra-Business Center" 1999, p. 61, fig. 26. (prototype).

Claims (1)

An active-pulsed night-vision television device comprising an observation unit, consisting of a series of lenses, a replaceable filter, an electron-optical converter and an electron-optical converter focused on the screen of the first lens component of the transfer optics, a television channel including a synchronizer and series-connected a television camera on which the second lens component of the transfer optics is focused, optically paired with the first lens a component of the transfer optics, a video amplifier and a television monitor, the frame and line synchronization outputs of the sync generator being connected respectively to the inputs of the television camera, video amplifier and a television monitor of the same name, a pulsed infrared illuminator consisting of a pulsed infrared emitter connected to the first output of the pump unit and an output forming lens radiation focused on a pulsed infrared emitter, control and synchronization unit, consisting of connected to the master pulse generator, the first input of which is connected to the second output of the pumping unit of the pulsed infrared illuminator, the adjustable delay unit and the gate generator, the output of which is connected to the gate of the electron-optical converter of the observation unit, the frequency division unit, the input of which is connected to the lowercase output synchronization of the synchronizer of the television channel, and the output to the second input of the master pulse generator of the control unit and synchronization II, characterized in that a delay conversion unit is introduced into it, the input of which is connected to the second output of the adjustable delay unit of the control and synchronization unit, two electromechanical drives, an amplitude control unit for the pump current, the input of which is connected to the first output of the delay conversion unit, and the output with the input of the pumping unit of a pulsed infrared illuminator, and a series-connected natural light meter, a signal conversion unit and a frequency control unit, the output of which is connected it is connected to the third input of the master pulse generator of the control and synchronization unit, the second output of the delay conversion unit being connected via the first electromechanical drive to the lens barrel of the observation unit, and the third output through the second electromechanical drive to the lens barrel of the output radiation of the pulsed infrared illuminator.

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