RU2785957C2 - Observation device-sight with built-in passive rangefinder - Google Patents

Abstract

FIELD: optoelectronic instrument making.

SUBSTANCE: invention relates to the field of optoelectronic instrument making and concerns an observation device-sight with a built-in passive rangefinder. The device contains two dichroic elements, a visual channel, and three digital channels – television, thermal-imaging, and passive rangefinder. The rangefinder channel is located under a head part of the device, and it contains a processor unit, a rangefinder lens, a flat diaphragm, a matrix photodetector, two AP-90 prisms, and two light filters. Input faces of AP-90 prisms are located along the course of a beam in front of one half of a light diameter of the rangefinder lens, optical axes of prisms coincide, hypotenuse faces of AP-90 prisms are parallel to each other, the flat diaphragm is located between the rangefinder lens and the matrix photodetector.

EFFECT: provision of a possibility of measurement of distances in a passive mode, a possibility of use of a rangefinder channel as a sighting thermal-imaging one with an increase of more than 8 times, maintaining simultaneous operation of all channels without mechanical switching, simplification of an optical tract, and provision of the accuracy of ranging of less than 10 m at a distance of 1000 m.

1 cl, 3 dwg, 3 tbl

Description

The present invention relates to the field of optoelectronic technology and can be used in the fire control system of armored vehicles.

Known observation device-sight with a built-in pulsed laser rangefinder (patent RU 2526230 C1, publ. 20.08.2014), containing three separate vertical channels - a single day channel, multiple day-night channel with switching visual observation to the image intensifier tube, and also the emitting channel of the laser rangefinder. The optical axis of the entrance pupil of the receiving channel of the laser rangefinder is aligned with the optical axis of the entrance pupil of the daytime single channel through the use of a dichroic element.

The daytime single channel includes protective glasses, a cube prism, an objective, a collective, an inclined plane-parallel dichroic plate, an inverting system, a rectangular prism, a plane-parallel plate and an eyepiece. The receiving channel of the laser rangefinder includes an objective and a single channel collective, a dichroic plate installed between the collective and the single channel wrapping system, which transmits the visible spectral range and reflects a wavelength of 1.54 μm, a matching optical system and a rangefinder photodetector.

The multiple day-night channel includes protective glasses, a second prism-cube, a lens, an I/O mechanism for an image intensifier tube or a matching optical component, an inverting system, two rectangular prisms, an inclined reflecting mirror, a plane-parallel plate, a movable and a fixed grid, and eyepiece. The radiating channel of the laser rangefinder contains two reflective mirrors that output laser radiation through the second prism-cube, while achieving a range measurement error of 10 m at distances from 1000 to 4000 m, typical for laser rangefinders.

The disadvantages of this device are the complexity of the execution of three separate optoelectronic channels, in one of which manual switching is carried out from the matching optical component when working during the day to the image intensifier tube when working at night, the need to use active illumination for the image image converter in case of insufficient illumination on the ground . The emitter of the laser range finder requires additional reflective mirrors in the emitting channel of the laser range finder, which complicates the optical path of the emitting channel. In addition, the mode of operation of the emitting channel of the laser rangefinder is active, which does not ensure the secrecy of measurements, it is easily detected by modern optoelectronic sensors with the determination of the exact coordinates of the place from which the measurement was made.

Known rangefinder sight TPD-2-49 (Ural Tank. Technical description and operating instructions (172M.TO). Book 1. Military publishing house of the USSR Ministry of Defense, Moscow, 1975, chapter 4.6), containing two parallel telescopic systems: left - aiming and right - rangefinder. The left telescopic system consists of a lens, a collective, an inverting system, a prism and an eyepiece. In the focal plane of the lens there is a reticle with aiming marks and a disk with distance marks and an index.

The right telescopic system consists of a lens, a double prism (biprism) in the focal plane of the lens, an inverting system, prisms and an eyepiece. The upper half of the lens receives a beam of rays entering through the prisms forming the right base branch with an internal base of 1500 mm, and the lower half of the lens receives a beam of rays entering through the compensator lenses, the prism and the main mirror, forming the left optical branch. The image from the focal plane of the lens is transferred by the inverting system and prisms to the focal plane of the eyepiece. In the focal plane of the eyepiece of the right telescopic system, an image is obtained, divided by a biprism edge into upper and lower halves, the images in which will be shifted relative to each other in proportion to the distance to this image. The alignment of images is carried out by moving the compensator lenses, which implements a passive method of distance measurement with median errors of distance measurement at distances from 1000 to 2000 m - 3%, from 2000 to 3000 m - 4%, from 3000 to 4000 m - 5%.

The disadvantages of this device are the presence of a large internal base (1500 mm), which is due to the properties of the eye and is a natural method to reduce the operator's subjective errors when combining images. Movable optical elements are used to superimpose images, which reduces reliability and complicates the design, and for work at night, the use of a second thermal imaging or television sight is required in case of insufficient illumination on the ground.

Known passive rangefinder Kovalev (Kovalev S.V., Shapovalov D.A. Passive rangefinder Kovalev. Geodesy and cartography, No. 3, 2021), containing two AR-90 prisms, a lens with a focusing lens, a flat aperture and one photodetector, while one of the prisms covers the lower half of the lens light diameter, the second - the upper half, the upper prism is shifted along the lens axis relative to the lower prism, forming an internal base of 25 mm, and a flat diaphragm is installed on the optical axis between the focusing lens of the lens and the photodetector, dividing it into two parts and separating the images from the upper and lower halves of the lens diameter. A flat diaphragm creates a visible border between two parts of the image of a vertical object - the upper and lower ones, on one photodetector, and the distance to the object is determined by the shift between the upper and lower parts of the images along the horizontal axis using software methods for coordinate measurements. The rangefinder has a small internal base (25 mm) in the absence of moving elements, and the theoretical range measurement error is 1.67 m at a distance of 1000 m.

The disadvantages of this rangefinder are the perpendicular arrangement of the axes of sight relative to the axis of the lens, which makes practical application difficult, as well as two constantly shifted (proportional to the distance) parts of the image of an object in the field of view on the photodetector - one in the upper half of the field of view, the other in the lower half, which is not allows for effective observation and aiming through it and requires the introduction of a second aiming channel in practical use. Also, there is no television and thermal imaging channels for working at night, which requires the use of an additional sight in case of insufficient illumination on the ground.

The closest in technical essence is an observation device-sight with combined optical axes of the entrance pupils of the working channels and with a built-in pulsed laser rangefinder (patent RU 2706391 C1, publ. 11/18/2019), containing a head part consisting of protective glass and a mirror element for vertical guidance, a visual optical channel containing a lens, an inverting system, a plane-parallel plate, a corrective lens, a movable and fixed grid and an eyepiece, a microdisplay and a second eyepiece, three dichroic elements, the first of which is installed after the head, reflecting the visible range and the short-wavelength part of the near-IR radiation and passing the long-wave part of the near-IR radiation and the thermal range of IR radiation. In the direction reflected from the first dichroic element, there is a visual optical channel, the wrapping system of which contains a BU-45° semi-pentaprism, the mirror plane of which is made in the form of a second dichroic element and is glued with an optical wedge, reflecting the visible part of the spectrum and passing the short-wave part of the near-IR radiation. In the reflected direction, a Schmidt prism with a BkR-45° roof, a plane-parallel plate, a corrective component, a movable and fixed grid and an eyepiece are installed in series, and in the transmitted direction there is a television channel containing a sequentially installed lens and a matrix television photodetector, while in the past through the first dichroic element direction is the third dichroic element that reflects the long-wavelength part of the near-IR radiation and transmits the thermal range of IR radiation. In the direction reflected from the third dichroic element, there is a receiving channel of the laser rangefinder, consisting of a lens and a photodetector, and in the direction passing through the third dichroic element, there is a thermal imaging channel containing a lens and a matrix thermal imaging photodetector installed in series. The optical axis of the emitter of the laser rangefinder is placed under the reflective surface of the vertical guidance element of the warhead, while achieving a range measurement error equal to 10 m at distances from 1000 to 4000 m.

The disadvantages of this device are the complexity of the execution of three separate optoelectronic channels containing three dichroic elements, one of which ensures the operability of the receiving channel of the laser rangefinder. There is also no digital channel with more than 5x magnification, which reduces detection capabilities. In addition, the mode of operation of the emitting channel of the laser rangefinder is active, which does not ensure the secrecy of measurements, it is easily detected by modern optoelectronic sensors with the determination of the exact coordinates of the place from which the measurement was made.

The objective of the present invention is to exclude the active mode when measuring range, to simplify the optical path with the provision of passive optoelectronic ranging, to reduce the internal base of the rangefinder while maintaining the overall dimensions of the head mirror and to ensure a range measurement accuracy of less than 10 m at a distance of 1000 m and less than 4% at a distance of 4000 m, providing a sighting television mode for the rangefinder channel with a magnification of more than 8 times, maintaining the simultaneous operation of all channels without mechanical switching.

The technical result, due to the task, is achieved by the fact that in the observation device-sight with a built-in passive rangefinder, containing a head part consisting of a protective glass and a mirror element for vertical guidance, a visual optical channel containing a lens, a wrapping system containing a semi-pentaprism BU- 45 and a Schmidt prism with a BkR-45 roof, a plane-parallel plate, a corrective component, a movable and fixed grid and an eyepiece, a microdisplay and a second eyepiece, two dichroic elements, the first of which is installed after the head part, reflecting the visible range and the short-wavelength part of the near-IR radiation and passing the thermal range of IR radiation to the thermal imaging channel containing a lens and a thermal imaging photodetector, the second one is applied to the mirror surface of the BU-45 semi-pentaprism, reflecting the visible range and passing the short-wave part of the near-IR radiation to the television channel containing an optical wedge, lens and bodies The revision photodetector, unlike the known one, contains a rangefinder channel located under the head of the device and containing a processor unit, a rangefinder lens, a flat diaphragm, a matrix photodetector, two AR-90 prisms, two light filters, while the input faces of the AR-90 prisms are located along the beam path in front of one half of the light diameter of the rangefinder lens, the optical axes of the prisms coincide, the hypotenuse faces of the AR-90 prisms are parallel to each other, the flat diaphragm is located between the rangefinder lens and the matrix photodetector, while the following relationships are fulfilled:

D _vis.ob. ≤B _pr ≤0.9⋅N spec _.

where: In _pr - the distance between the input optical axes of the AR-90 prisms;

D _vis.ob. - diameter of the entrance pupil of the lens of the visual channel;

H _mirror - the width of the mirror element of the head of the device;

L _diaphragm - the length of a flat diaphragm;

- задний вершинный отрезок объектива дальномера,

- rear vertex segment of the rangefinder lens,

and the range to the target is determined in the processor unit by the shift of one of the parts of the image on the matrix photodetector, and the rangefinding channel is the sighting channel when the image is formed in the processor unit on the microdisplay of the second eyepiece with a reverse program shift until both parts of the image coincide in real time.

Such an observation device-sight with a built-in passive rangefinder ensures the exclusion of the active mode when measuring the range, simplifies the optical path with the provision of passive optoelectronic ranging, reduces the internal base of the rangefinder while maintaining the overall dimensions of the head mirror and measurement accuracy of less than 10 m at a distance of 1000 m or less 4% at a distance of 4000 m, provides a sighting television mode for the rangefinder channel with a magnification of more than 8 times, maintains the simultaneous operation of all channels without mechanical switching.

The scheme of the observation device-sight with a built-in passive rangefinder is shown in figures 1, 2 and 3.

The observation device-sight with a built-in passive rangefinder contains a protective glass 1, a mirror element for vertical aiming 2, the first dichroic element 3, an optical channel lens 4, a semi-pentaprism 5 with a dichroic mirror surface (the second dichroic element), an optical wedge 9, a Schmidt prism with a roof 6, optical elements 7 (plane-parallel plate, corrective lens, movable and fixed grids), first eyepiece 8, TV channel lens 10, TV photodetector 11, thermal imaging lens 12, thermal imaging photodetector 13, rangefinder lens 14, flat diaphragm 15, matrix photodetector 16 , AR-90 prisms 17 and 18, light filters 19 and 20, processor unit 21, microdisplay 22 and second eyepiece 23.

The application option of the matrix photodetector 16 has the designation IMX327LQR, has a format of 1920×1080 pixels with the size of the sensitive area by HH=5.63 mm, by HH=3.167 mm, with a diagonal of 6.46 mm, with a pixel size of 2.932 μm.

The design parameters of the rangefinder lens option 14 of the observation device-sight with a built-in passive rangefinder are shown in Table 1.

The image quality of the rangefinder lens is corrected at a level close to the diffraction level - the contrast transfer coefficient for the axial point at the Nyquist frequency of 170 lines/mm (pixel size 2.932 μm) is ~0.35 at a diffraction level of ~0.37.

The principle of operation of the observation device-sight with a built-in passive rangefinder is as follows.

The radiation from the object passes through the protective glass 1 and the mirror element for vertical guidance - the head mirror 2, forming the optical axis "I". The first dichroic element 3 separates the light flux along the optical axis "I" in the spectrum, reflecting the visible range and the short-wave part of the near-IR radiation and passing the thermal range of the IR radiation.

In the direction reflected from the first dichroic element 3, there is a visual optical channel, the lens 4 of which builds an inverted image of the object in the plane of the grids. The turning system contains a semi-pentaprism BU-45° pos.5, the mirror plane of which is made in the form of a second dichroic element and glued to an optical wedge 9, reflecting the visible part of the spectrum and passing the short-wave part of the near-IR radiation. The visual channel continues along the beam in the reflected direction, where a Schmidt prism with a BkR-45° roof pos. 6, optical elements 7 (plane-parallel plate, corrective lens, movable and fixed grids) and the first eyepiece 8 are installed in series.

In the direction passed through the second dichroic element, there is a television channel containing sequentially installed lens 10, which focuses the image of an object in the short-wave part of the near-IR spectrum on a television photodetector 11.

In the direction passing through the first dichroic element 3, there is a thermal imaging channel containing sequentially installed lens 12, which focuses the image of an object in the thermal range of the IR spectrum onto a thermal imaging photodetector 13.

The use of two dichroic elements 3 and 5 in the observation device-sight with a built-in passive rangefinder simplifies the optical path of the device, allows you to combine the optical axes of the entrance pupils of the visual channel 4-8, the television channel 10-11 and the thermal imaging channel 12-13 on the same optical axis "I ". The optical axes "II" and "III" of the passive rangefinder are located parallel to the axis "I" directly under the reflective surface of the vertical guidance element 2 of the warhead, which ensures the simultaneous operation of all channels.

The location of the rangefinder channel under the head of the device allows you to place the internal base of the rangefinder, while the following relationship is fulfilled:

D _vis.ob. ≤B _pr ≤0.9⋅N spec _. ,

where: In _pr - the distance between the input optical axes of the AR-90 prisms;

D _vis.ob. - diameter of the entrance pupil of the lens of the visual channel;

N _mirror. - the width of the mirror element of the head of the device.

The implementation of this ratio allows you to get the internal base of the rangefinder "B _pr ", equal to 76 mm (in the embodiment) with a width of "H _mirror. » mirror element 2, equal to 110 mm and diameter «D _vis.ob. » the entrance pupil of the lens of the 4th visual channel, equal to 48 mm.

Rectangular prism 17 of type AR-90 has a leg size of 20 mm (prism height 10 mm), its entrance face is located in front of half of the entrance pupil of the lens. The input face of the rectangular prism 18 of type AR-90 has a leg size of 26 mm (prism height 16 mm) and is 53 mm away from the output face of the first prism, the optical axes of the prisms coincide, the hypotenuse faces of the prisms 17 and 18 are parallel to each other. The increased size of the prism 18 is due to its greater distance from the lens 14, which eliminates the vignetting of the angular field of view.

One half of the rangefinder lens 14 operates in the direct course of the rays and builds an image on one half of the matrix photodetector 16, forming a direct line of sight "II". The second half of the rangefinder lens 14 builds an image on the second half of the matrix photodetector 16 and works through two prisms 17 and 18 of the AP-90 type, which form the basic sighting axis "III". Removing the prism 18 from the prism 17 creates an internal base of the rangefinder "B _pr " - the distance between the sighting axis "II", formed by one half of the rangefinder lens 14, and the sighting axis "III", formed by prisms 17, 18 and the second half of the rangefinder lens 14.

A flat diaphragm 15 is installed between the rangefinder lens 14 and the photodetector 16, which separates the images from the direct and base sighting axes "II" and "III", creating a visible border on the matrix photodetector 16, dividing the image of a vertical object into two parts and preventing mutual illumination of the image parts of each other. otherwise, the following relation must be satisfied:

where: L _diaphragm - the length of the flat diaphragm;

- задний вершинный отрезок объектива дальномера,

- rear vertex segment of the rangefinder lens,

The fulfillment of this ratio ensures that parts of the image are shielded from mutual illumination.

Light filters 19 and 20 can be made of KS-10 or KS-11 glasses, they cut off the short-wavelength part of the spectrum, improving the operation of the rangefinder (sighting) channel in bad weather conditions (in the presence of haze, fog, etc.).

The mode of increased magnification of more than 8 times is ensured by the fact that the rangefinding channel is also a sighting television channel due to the fact that after determining the image shift on the matrix photodetector 16, the microprocessor unit 21 determines the range to the target by the known shift and transmits to the microdisplay 22 the image with the reverse software shift until the images match in real time (with a frame update time less than the time of inertia of vision, for example, every 20 ms). The increase in the television rangefinder (sight) channel can be determined by the known ratio:

where: F _about - the focal length of the rangefinder lens 14;

D _screen - microdisplay size 22 vertically;

D _f.pr. - the size of the matrix photodetector 16 vertically;

F _ok - focal length of the eyepiece 23.

With known data (F _about \u003d 83.9 mm, D _screen. \u003d 9.56 mm, D _f.pr. \u003d 5.63 mm, F _ok \u003d 15.67 mm), an increase in the rangefinder (sighting) channel when viewed through the eyepiece 22 will be ~ 9.09 times. The angular resolution limit will be ~7.2'', and the total field of view of the rangefinder (television sighting) channel will be 3.84°×2.16° (VL×GN).

The images constructed by the television, thermal imaging and rangefinding (sighting) channels are output by the processor unit 21 to the microdisplay 22 located in the front focal plane of the second eyepiece 23, in any sequence, including combining images. The optical axes of the first and second eyepieces are set parallel to each other at the average value of the base of the eyes of an adult, which makes it possible to observe simultaneously with two eyes, viewing visual and television/thermal imaging images simultaneously.

Range measurement is based on measuring the shift of one of the two parts of the image of the object "x" on the matrix photodetector 16 according to known formulas (Kovalev S.V., Shapovalov D.A. Kovalev passive rangefinder. Geodesy and cartography, No. 3, 2021) with known values internal base and focal length of the rangefinder lens 14:

where: F _about - the focal length of the rangefinder lens 14;

In _pr - the internal base of the rangefinder;

D _c - distance to the observed object.

The final formula for calculating the range and range measurement error will be as follows:

where: Δx is the error in measuring the shift "x" between parts of the image.

Range measurement error "ΔD _c " and the ability to work with a reduced internal base "In _pr " here largely depends on the accuracy of coordinate measurements "Δx".

The level of subpixel accuracy of coordinate measurements, equal to 0.001 of the pixel size of the photodetector, is used in the work (Kovalev S.V., Shapovalov D.A. Kovalev passive range finder. Geodesy and cartography, No. 3, 2021). To achieve this accuracy, special calibers or a geodetic staff with contrasting and clearly defined boundaries are used, as is required for geodetic measurements.

For arbitrary images of real scenes, subpixel accuracy levels of 0.01 of the photodetector pixel size have been achieved with digital ranging methods described in the work (Kozlov V.L., Vasilchuk A.S. Subpixel image processing for ranging based on a digital camera. Instruments and methods of measurement, No. 1(4), 2012). In the work (Kozlov V.L. Optimization of the size of the scanning window for measuring ranges from digital images. Journal of the Belarusian State University. Physics. No. 2, 2018), an error in measuring the coordinate in hundredths of a pixel was also achieved due to the implementation of a two-dimensional subpixel interpolation.

The range measurement error by a passive rangefinder with a known photodetector pixel size of 2.932 μm, with F _rev = 83.9 mm and internal base B _pr = 76 mm can be estimated with an image displacement measurement accuracy equal to 0.01 of the pixel size for one measurement. Then the accuracy of measuring the displacement in two dimensions (shift of two images) will be Δх=0.05864 µm and the following table of calculated values will be valid.

The calculations performed show the possibility of achieving an accuracy of measuring the distance to an object of less than 10 m at a distance of 1000 m and less than 4% at a distance of 4000 m.

The observation device-sight with a built-in passive rangefinder uses a rangefinder channel, which can also be a sighting television channel with a magnification of more than 8 times when compensating for the shift of image parts, while the technical parameters of the device will correspond to those given in Table 3.

As can be seen from the calculations, the observation device-sight with a built-in passive rangefinder makes it possible to exclude the active mode when measuring range, simplifies the optical path with the provision of passive optoelectronic ranging, reduces the internal base of the rangefinder while maintaining the overall dimensions of the head mirror and measurement accuracy of less than 10 m at a distance 1000 m and less than 4% at a distance of 4000 m, provides for the rangefinder channel a sighting television mode with a magnification of more than 8 times, maintains the simultaneous operation of all channels without mechanical switching.

Claims (9)

An observation device-sight with a built-in passive rangefinder, containing a head part consisting of a protective glass and a mirror element for vertical guidance, a visual optical channel containing a lens, a wrapping system containing a BU-45 semi-pentaprism and a Schmidt prism with a BkR-45 roof, a plane-parallel plate , a corrective component, a movable and a fixed grid and an eyepiece, a microdisplay and a second eyepiece, two dichroic elements, the first of which is installed after the head part, reflecting the visible range and the short-wave part of the near-IR radiation and passing the thermal range of the IR radiation to the thermal imaging channel containing the lens and thermal imaging photodetector, the second one is applied to the mirror surface of the BU-45 semi-pentaprism, reflecting the visible range and passing the short-wave part of the near-IR radiation to the television channel, containing an optical wedge, a lens and a television photodetector, characterized in that it contains a rangefinder channel located located under the head of the device and containing a processor unit, a rangefinder lens, a flat diaphragm, a matrix photodetector, two AR-90 prisms, two light filters, while the entrance faces of the AR-90 prisms are located along the beam in front of one half of the light diameter of the rangefinder lens, optical axes the prisms coincide, the hypotenuse faces of the AR-90 prisms are parallel to each other, the flat diaphragm is located between the rangefinder lens and the matrix photodetector, while the following relations are fulfilled: D _vis.ob. ≤B _pr ≤0.9⋅N spec _.

, where: In _pr - the distance between the input optical axes of the AR-90 prisms; D _vis.ob. - diameter of the entrance pupil of the lens of the visual channel; H _mirror - the width of the mirror element of the head of the device; L _diaphragm - the length of a flat diaphragm;

- rear vertex segment of the rangefinder lens, and the range to the target is determined in the processor unit by the shift of one of the parts of the image on the matrix photodetector, and the rangefinding channel is the sighting channel when the image is formed in the processor unit on the microdisplay of the second eyepiece with a reverse program shift until both parts of the image coincide in real time.

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