RU2646436C2 - Single-pupilary multispectral optical system with built-in laser ranger - Google Patents

Abstract

FIELD: measuring equipment.

SUBSTANCE: single-pupillary multispectral optical system with built-in laser ranger contains a common input channel, a spectro-dividing plate reflecting the spectral range of optical channel and transmitting the spectral range of thermal imaging channel. Wherein, reflected channel is made televisional of two components between which the second spectro-dividing plate is installed, reflecting spectral range of television channel and bypassing the spectral range of range channel that contains the flat mirror with axial hole located at an angle to the optical axis, performing apertural division for the branches of light-sensitive detector and semiconductor of laser emitter.

EFFECT: simplification of design, providing the possibility of measuring range.

2 cl, 2 dwg, 2 tbl

Description

The patented single-pupil multispectral optical system with an integrated laser range finder can be used for heat and television devices and sights with a range measurement function used in a wide variety of operating conditions.

A known optical system of a single-pupil sight with a laser range finder (patent RU 2560347 C1, publ. 08/20/2015), containing visual and range finder channels of the sight with a common input optics containing a spectro-dividing cube, forming a channel of the built-in laser range finder, containing a negative lens, quarter-wave phase plate, a polarizing splitter branching a rangefinder channel into a radiating and receiving part, each of which contains focusing lenses.

The disadvantages of this optical system are the impossibility of night observation and the complexity of the execution of the range-finding channel of the sight.

The closest in technical essence is a single-pupil multispectral optical system with an integrated laser range finder (patent RU 2581763 C2, publ. 04/20/2016) containing a common input channel, a spectrodividing plate reflecting the spectral range of the television channel and transmitting the spectral range of the thermal imaging channel, two optical channels for each of the spectral ranges, and the reflected television channel is made two-component, between the components of which there is a spectrodividing a cube that transmits the spectral range of the television channel and reflects the wavelength of the rangefinder channel containing the collimating two-component optics, a quarter-wave phase plate, a polarizing splitter branching the rangefinder channel into the emitting and receiving parts, each of which contains a two-component pairing lens.

The disadvantage of this optical system is the complexity of the television and rangefinder channels of the sight.

The objective of the present invention is to reduce the number of optical components and simplify the multispectral optical system while maintaining the quality of the optical image and the ability to measure range through a single input optics of the optical system.

The technical result due to the task is achieved by the fact that in a single-pupil multispectral optical system with a built-in laser range finder containing a common input channel, a spectrodividing plate that transmits the spectral range of the thermal imaging channel and reflects the spectral ranges of the rangefinder and television channels, of which the television channel is made of two-component, and between its components a spectrum splitter is installed, in contrast to the known, between the components of a television of the second channel, a second spectrodividing plate is installed, which reflects the spectral range of the television channel and transmits a rangefinder channel containing a flat mirror with an axial hole, located at an angle to the optical axis, and two branches - a photodetector and a semiconductor laser emitter, optically coupled to the first component of the television channel, this holds the following relationship:

d _li <d _fp ≤10⋅d _li

α _pzo ≥α _cn2 ,

where d _fp - the size of the sensitive area of the photodetector of the range finder;

_{whether l} is the maximum size of the emitting area of the laser diode of the range finder;

α _PZO - the angle of inclination of a flat mirror with an axial hole to the optical axis;

α _sp2 - the angle of inclination of the second spectrodividing plate to the optical axis.

Such an optical system reduces the number of optical components and simplifies the multispectral optical system while maintaining the quality of the optical image and the ability to measure range through a single input optics of the optical system.

The essence of the invention according to the second embodiment is that in a single-pupil multispectral optical system with an integrated laser range finder, in contrast to the known one, one of the branches of the laser range finder contains a flat reflecting mirror located at an angle to the optical axis.

Such an optical system reduces the overall dimensions of the branches of the laser rangefinder.

The optical scheme of a single-pupil multispectral optical system with an integrated laser range finder according to option 1 is shown in figure 1.

A single-pupil multispectral optical system with an integrated laser range finder contains a common input channel consisting of a meniscus lens 1 and a spectrodividing plate 2 with a dichroic coating, passing one spectral range (for example, 8–14 μm) and reflecting other spectral ranges (for example, 0.6 ÷ 0.95 μm and 1.5 ÷ 1.6 μm).

The optical channel in the direction passing through the dividing plate 2 with a dichroic coating consists of a positive lens 3 and a positive lens 4, a protective glass 5 and a photodetector 6.

The optical channel in the direction reflected from the dichroic coated plate 2 contains a negative lens 7, a positive lens 8 and a second dividing spectrometric plate 9 with a dichroic coating that transmits one spectral range (e.g., 1.5-1.6 μm) and reflects a different spectral range ( e.g. 0.6 ÷ 0.95 μm).

The optical channel in the direction reflected from the second dividing plate 9 with a dichroic coating consists of a positive lens 10, a negative lens 11, a positive lens 12, a negative lens 13, a protective glass 14 and a television photodetector 15.

The optical channel in the direction passing through the second spectro-dividing plate 9 with a dichroic coating consists of a flat mirror 16 with an axial hole located at an angle to the optical axis, a photodetector 17 and a semiconductor laser emitter 18.

The design parameters of the optical system embodiment are shown in table 1.

The parameters of this embodiment of the optical system for the optical channel of the spectral range (8.0 ÷ 13.5) μm:

The parameters of this embodiment of the optical system for the optical channel of the spectral range (0.6 ÷ 0.95) μm:

- estimated wavelength 0.7 microns; - working spectral range (0.6 ÷ 0.95) μm; - focal length 45.0 mm; - linear field of view 16.0 mm; - relative hole 1: 1.28

The parameters of this embodiment of the optical system for a rangefinder channel at a wavelength of a laser diode of 1.54 μm:

- estimated wavelength 1.54 microns; - focal length 119.4 mm; - diameter of the entrance pupil 35.0 mm; - equivalent diameter of the entrance pupil 24 mm (radiation); 24.5 mm (f / p); - equivalent relative aperture 1: 4.8; - aperture angle 0 ÷ 11.5 ° (radiation); 11.5 ÷ 16.7 ° mm (f / p);

- the option assumes the same equivalent focal length for the radiating and receiving branches of the rangefinder channel. The choice of another value of the equivalent focal length is carried out by recalculating the values of R13, R14, R15, R16.

The optical scheme of a single-pupil multispectral optical system with an integrated laser range finder according to the second embodiment is shown in figure 2.

Here, a flat mirror 19 is introduced into the rangefinder channel, breaking the optical axis of the radiating branch of the rangefinder. The design parameters of the second embodiment of the optical system are shown in table 2.

The principle of operation of a single-pupil multispectral optical system with an integrated laser range finder is as follows.

The first component 1, made in the form of a meniscus, in combination with the second component 2, made in the form of a dividing plate with a dichroic coating on the first surface, is a single input window for four channels - thermal, television, emitting rangefinder and receiving rangefinder, operating in different spectral ranges.

The optical channel in the direction passing through the dichroic coated plate 2 contains two components 3 and 4, made in the form of positive meniscus lenses, which ensures the necessary correction of aberrations on the photosensitive area 6 of the photodetector with protective glass 5 in the spectral range (8.0 ÷ 13.5 ) μm.

The television channel in the direction reflected from the dichroic coated plate 2 is two-component, the first component of which consists of a two-lens power part 7 and 8, which creates the necessary optical power for both television and rangefinder channels, the second component of the television channel consists of a four-lens field aberration compensator 10, 11, 12 and 13, compensating for the curvature of the image surface in the spectral range (0.6 ÷ 0.95) μm.

Between the two components of the television channel reflected from the plate 2, a second spectro-dividing plate 9 is installed, which reflects the spectral range of the television channel (0.6 ÷ 0.95) μm and transmits the spectral range of the range-finding channel (1.5 ÷ 1.6) μm, which contains a flat a mirror 16 with an axial hole, located at an angle to the optical axis, and which carries out aperture separation, passing through the axial hole the central part of the entrance pupil for the range finder emitter 18 and reflecting the annular external entrance zone th pupil of the photodetector 17 EDM, with the following relations:

d _li <d _fp ≤10⋅d _li

α _pzo ≥α _cn2 ,

where d _fp - the size of the sensitive area of the photodetector of the range finder;

_{whether l} is the maximum size of the emitting area of the laser diode of the range finder;

α _PZO - the angle of inclination of a flat mirror with an axial hole to the optical axis;

α _sp2 - the angle of inclination of the second spectrodividing plate to the optical axis.

The fulfillment of these relations ensures a guaranteed excess of the field of view of the photodetector 17 over the angular divergence of the beam from the emitter 18 and minimization of the overall dimensions of the receiving branch of the laser range finder.

The principle of operation of a single-pupil multispectral optical system with an integrated laser range finder according to the second embodiment is that one of the branches of the laser range finder, for example, radiating, contains a flat reflecting mirror 19, located at an angle to the optical axis, thereby minimizing the overall dimensions of the radiating branch of the laser range finder .

In the radiating branch of the rangefinder channel, the maximum value of the scattering circle is ~ 83.92 μm, which gives an increase in the image of the radiation spot on the target from ~ 1.5 m to ~ 2.2 m at a distance to the target of 1000 meters, which is quite acceptable for range measurements.

In the receiving branch of the rangefinder channel, the maximum value of the scattering circle is ~ 195 μm, which for a photodetector with a sensitive area of 0.35 mm ensures normal reception quality of the reflected signal.

For observation channels, we set the quality criterion - the value of the polychromatic contrast transfer coefficient (CPC) and take into account:

- the thickness of the protective glass of the photodetectors 5 and 15, equal to 1.0 mm;

- spectral efficiency according to wavelengths taking into account the sensitivity of the photodetector and the light transmission of the lens - 1.0 at a wavelength of 0.6 μm, 1.0 at a wavelength of 0.7 μm, 0.8 at a wavelength of 0.8 μm, 0.3 at a wavelength of 0.9 μm and 0.15 at a wavelength of 0.95 μm (for a television channel), 1.0 at wavelengths of 8.0 μm, 10.6 μm and 13.5 μm (for a thermal imaging channel);

- spatial frequency ~ 50 lin / mm (Nyquist frequency for the photodetector (0.6 ÷ 0.95) μm with a sensitive element size equal to 9.7 μm);

- spatial frequency ~ 30 lin / mm (Nyquist frequency for the photodetector (8.0 ÷ 13.5) μm with a sensitive element size equal to 17 μm).

We obtain the following calculated values of the qualitative characteristics of the optical system:

For a television channel:

- for a point on the axis PDA _M = 48%

- for the field point 5.0 mm from the center Images PDA _M = 35% PDA _C = 42% - for a field point of 7.75 mm from the center Images PDA _M = 26% PDA _C = 35%

For thermal imaging channel:

- for a point on the axis PDA _M = 48% PDA _C = 51% - for a field point 4.0 mm from the center Images PDA _M = 33% PDA _C = 47% - for a field point of 6.8 mm from the center Images PDA _M = 31% PDA _C = 50%

As can be seen from the calculations, the optical system, with its simplicity of design, provides good image quality for single-pupil optoelectronic devices using: a high-resolution television channel (format of at least 1280 × 1024 pixels) with a CCD matrix of the spectral range (0.6 ÷ 0 , 95) microns with a pixel size of 9.7 microns; - high resolution thermal imaging channel (at least 640 × 480 pixels) with a microbolometric matrix of the spectral range (8.0 ÷ 13.5) microns with a pixel size of 17 microns; - built-in channel of a laser range finder.

Claims (8)

1. A single-pupil multispectral optical system with an integrated laser range finder, containing a common input channel, a spectrodividing plate that transmits the spectral range of the thermal imaging channel and reflects the spectral ranges of the rangefinder and television channels, of which the television channel is made two-component, and a spectrodivider is installed between its components, characterized in that between the components of the television channel there is a second spectrodividing plate reflecting the spectral the first range of the television channel and the transmission rangefinder channel, containing a flat mirror with an axial hole, located at an angle to the optical axis, and two branches - a photodetector and a semiconductor laser emitter, optically coupled to the first component of the television channel, the following relationships are true: d _li <d _fp ≤10⋅d _li α _pzo ≥α _cn2 , where d _fp - the size of the sensitive area of the photodetector of the range finder; _{whether l} is the maximum size of the emitting area of the laser diode of the range finder; α _PZO - the angle of inclination of a flat mirror with an axial hole to the optical axis; α _sp2 - the angle of inclination of the second spectrodividing plate to the optical axis. 2. A single pupil multispectral optical system with an integrated laser range finder according to claim 1, characterized in that one of the branches of the laser range finder contains a flat reflecting mirror located at an angle to the optical axis.

Images