CN111983590B - Dual-wavelength staring type imaging optical receiving system - Google Patents

Abstract

The invention relates to a dual-wavelength staring type imaging optical receiving system, which belongs to the technical field of laser imaging radar systems. The system includes: a common aperture receiving optical system, a beam splitting prism, a 1064 nm optical receiving branch and a 532 nm optical receiving branch, the common aperture receiving optical system, the beam splitting prism and the 1064 nm optical receiving branch are coaxially arranged, and the 532 nm optical receiving branch is arranged coaxially. The receiving end of the receiving branch is facing the reflected light path of the beam splitting prism. The dual-wavelength staring imaging optical receiving system designed by the invention can not only realize highly reliable target recognition and detection by utilizing the dual-spectral reflection characteristics of echoes, but also has a small size, a large field of view, and high real-time performance, which is a large field of view for a small platform. Laser imaging applications provide effective technical solutions.

Description

A dual-wavelength staring imaging optical receiving system

technical field

The invention relates to a dual-wavelength staring type imaging optical receiving system, which belongs to the technical field of laser imaging radar systems.

Background technique

With the development of laser active imaging technology, the light source has gradually developed from a single wavelength to multiple wavelengths, and the detector has developed from a single pixel to an area array. Using multi-spectral information can improve the reliability of target recognition and parameter estimation, and can reduce the requirements for the correction effect of echo information intensity; the use of area array detectors can expand the transient field of view and shorten the imaging time. To achieve long-distance detection, multi-wavelength detection devices require higher laser energy and more types of detectors to adapt to laser emission and detection in different wavelength bands, which leads to an increase in the size and weight of the laser, an increase in the design complexity of the laser emission system, and an increase in detection and detection. The increase in the volume of the optical system makes the multi-wavelength detection scheme insufficient in the application potential of small platforms.

In order to adapt to the detection of small platforms, it is proposed to use dual wavelengths for target detection. Compared with multi-wavelength detection, dual-wavelength detection reduces the system volume and the difficulty of optical design. At present, the application of dual-wavelength lidar in atmospheric monitoring and atmospheric composition analysis is relatively mature. In recent years, dual-wavelength lidar has gradually developed into target detection and imaging-based target parameter estimation. The use of dual-wavelength detection can achieve effective parameter estimation and reduce the accuracy requirements of echo intensity information correction, and is widely used in the field of earth observation. For example, the effective distinction between branches and trunks in forests, and the estimation of vegetation moisture content have been fully demonstrated. In the future, dual-wavelength imaging lidar has considerable application potential in the field of target recognition, such as improving target contrast, target recognition based on reflection spectral characteristics, etc.

Most of the currently used dual-wavelength lidars are scanning imaging schemes, and there are few staring imaging schemes. And because it is not a common aperture receiver, it is necessary to use two lasers to output two-band lasers, which leads to the problems of large laser volume, large scanning volume, high time synchronization requirements of scanning mirrors, long imaging time and imaging distortion.

SUMMARY OF THE INVENTION

The purpose of the present invention is to propose a dual-wavelength staring imaging optical receiving system to solve the problems existing in the existing dual-wavelength laser radar.

A dual-wavelength staring type imaging optical receiving system, the system comprises: a common aperture receiving optical system, a beam splitter prism, a 1064nm optical receiving branch and a 532nm optical receiving branch, the common aperture receiving optical system, the beam splitting prism and the 1064nm optical receiving branch The receiving branch is arranged coaxially, and the receiving end of the 532 nm optical receiving branch is facing the reflected light path of the beam splitting prism.

Further, the common aperture receiving optical system includes three optical lenses arranged coaxially.

Further, the beam splitting prism is used to transmit the 1064 nm wavelength light to the 1064 nm optical receiving branch, and reflect the 532 nm wavelength light to the 532 nm optical receiving branch, and the beam splitting prism is a 40×40 mm cube beam splitting prism.

Further, the 1064nm optical receiving branch includes a 1064nm band narrowband filter, a 1064nm optical path iris, a 1064nm optical path diaphragm motor, three optical lenses and a Gm-APD, the 1064nm band narrowband filter, The 1064nm optical path iris, three optical lenses and Gm-APD are arranged in order from near to far relative to the transmission side of the beam splitting prism, and the 1064nm optical path diaphragm motor is installed on the 1064nm optical path variable diaphragm , used to adjust the size of the iris diaphragm of the 1064nm optical path.

Further, the aperture of the 1064nm optical path variable diaphragm is 0.8mm˜15mm, and the aperture of the 1064nm band narrow-band filter is 25mm.

Further, the resolution of the Gm-APD is 64×64, and the size of the focal plane is 3.2mm×3.2mm.

Further, the 532nm optical receiving branch includes a 532nm optical path variable diaphragm, a 532nm wavelength band narrowband filter, a 532nm optical path right-angle reflective prism, an ICCD, a 532nm optical path diaphragm motor, a first optical lens and a second optical lens, The 532nm optical path variable diaphragm, the first optical lens, the 532nm band narrow-band filter, the second optical lens and the 532nm optical path right-angle reflective prism are arranged in order from near to far relative to the reflection side of the beam splitting prism, and the ICCD The diaphragm motor of the 532nm optical path is installed on the 532nm optical path variable diaphragm, and is used to adjust the size of the 532nm optical path variable diaphragm.

Further, the 532nm optical path right angle reflecting prism is a 30×30mm right angle prism, the aperture of the 532nm optical path variable diaphragm is 0.8mm˜25mm, and the aperture of the 532nm band narrow-band filter is 30mm.

Further, the ICCD includes a photocathode, a first high-voltage region, a microchannel plate, a second high-voltage region, a phosphor screen, an optical transducer and a CCD, the photocathode, the first high-voltage region, the microchannel plate, and the second high-voltage region. , a fluorescent screen, an optical converter and a CCD are connected in sequence, wherein the distance between the output surface of the microchannel plate and the input surface of the optical converter is less than 1mm, and the output surface of the optical converter and the CCD focal plane detector are The focal plane distance is less than 1mm.

Further, the resolution of the ICCD is 960×720, and the size of the focal plane is Ф15mm.

The main advantages of the present invention are: the dual-wavelength staring imaging optical receiving system designed by the present invention can not only realize highly reliable target recognition and detection by utilizing the dual-spectral reflection characteristics of echoes, but also the system is small in size, large in field of view, and high in real-time performance. , providing an effective technical solution for the application of small platform and large field of view laser imaging.

Description of drawings

1 is a cross-sectional view of a dual-wavelength staring imaging optical receiving system of the present invention;

Fig. 2 is three views of a dual-wavelength staring imaging optical receiving system of the present invention, wherein Fig. 2(a) is a front view; Fig. 2(b) is a side view; Fig. 2(c) is a top view;

FIG. 3 is a schematic structural diagram of an ICCD;

FIG. 4 is a physical diagram of a dual-wavelength staring imaging optical receiving system of the present invention.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

1, 2 and 4, a dual-wavelength staring type imaging optical receiving system, the system includes: a common aperture receiving optical system, a beam splitting prism 1, a 1064 nm optical receiving branch and a 532 nm optical receiving branch, The common aperture receiving optical system, the beam splitting prism 1 and the 1064 nm optical receiving branch are coaxially arranged, and the receiving end of the 532 nm optical receiving branch is facing the reflected light path of the beam splitting prism 1 .

Specifically, the present invention selects the common aperture optical receiving scheme, mainly considering that after the spectral detection and receiving, the spatial registration can be realized with high precision, and at the same time, compared with the separate independent system, the difficulty of coaxial adjustment is reduced, but the difficulty of optical design is increased. , the number of lenses will increase.

The optical design of the receiving optical system is carried out, and the detection and reception of dual-wavelength light waves are realized by using common aperture and light-splitting technology. The transmission wavelength of the spectroscope is 1064nm, the reflection wavelength is 532nm, and the spectral efficiency can be greater than 90%.

The receiving optical field angle is 5°, the 1064nm band is detected by 64×64Gm-APD, and the 532nm band is detected by 960×720ICCD. The size of the focal plane is 3.2mm×3.2mm. According to this parameter, the designed optical focal length is f=195mm@532nm, f=52mm@1064nm. Taking into account the light-gathering and receiving ability of the optical system, the F-numbers of the dual-channel are 2.5 and 1.5, respectively. The designed optical system is shown in Figure 1.

The 1064nm/532nm dual optical path staring imaging optical receiving system works in the atmospheric window, which can meet the needs of dual wavelength detection with large field of view, long distance and real-time performance, and the two wavelength bands can use the same laser output, which greatly reduces the volume of the laser emission system.

Under the constraints of miniaturized volume, the spatial layout of the beam splitter prism, polarizer, diaphragm, diaphragm motor, and detector of the entire optical receiving system is perfectly optimized, which is suitable for small platform laser active imaging applications.

Referring to FIG. 1 , the co-aperture receiving optical system includes three optical lenses arranged coaxially.

Referring to FIG. 1 , the beam splitting prism 1 is used to transmit the 1064 nm wavelength light to the 1064 nm optical receiving branch and reflect the 532 nm wavelength light to the 532 nm optical receiving branch, and the beam splitting prism 1 is a 40×40mm cube Beam splitting prism.

Referring to FIG. 1, the 1064nm optical receiving branch includes a 1064nm band narrowband filter 2, a 1064nm optical path variable diaphragm 3, a 1064nm optical path diaphragm motor 4, three optical lenses and a Gm-APD5. The narrow band filter 2, 1064nm optical path variable diaphragm 3, three optical lenses and Gm-APD5 are arranged in order from near to far relative to the transmission side of the beam splitter 1, and the diaphragm motor 4 for the 1064 nm optical path is installed On the 1064 nm optical path variable diaphragm 3 , it is used to adjust the size of the 1064 nm optical path variable diaphragm 3 .

The aperture of the 1064 nm optical path variable diaphragm 3 is 0.8 mm˜15 mm, and the aperture of the 1064 nm wavelength band narrow-band filter 2 is 25 mm.

The resolution of the Gm-APD5 is 64×64, and the focal plane size is 3.2mm×3.2mm@1064nm.

Specifically, the design imaging evaluation analysis of the 1064 nm optical branch is performed, as shown in FIG. 4 . The evaluation results show that the imaging quality of this band is good, the distortion is less than 2%, and the comprehensive imaging quality meets the design requirements.

Referring to Figure 1, the 532nm optical receiving branch includes a 532nm optical path variable aperture 6, a 532nm band narrow-band filter 7, a 532nm optical path right-angle reflecting prism 8, an ICCD9, a 532nm optical path diaphragm motor 10, a first optical Lens and second optical lens, the reflection of the 532nm optical path variable diaphragm 6, the first optical lens, the 532nm band narrow-band filter 7, the second optical lens and the 532nm optical path right angle reflecting prism 8 relative to the beam splitting prism 1 The sides are arranged in order from near to far, the ICCD 9 is arranged on the reflection side of the 532 nm optical path right-angle reflecting prism 8, and the 532 nm optical path diaphragm motor 10 is installed on the 532 nm optical path variable diaphragm 6 for adjustment. The size of the 532nm optical path variable diaphragm 6.

The 532nm optical path right angle reflecting prism 8 is a 30×30mm right angle prism, the aperture of the 532nm optical path variable diaphragm 6 is 0.8mm˜25mm, and the aperture of the 532nm band narrow-band filter 7 is 30mm.

Specifically, the design imaging evaluation analysis is performed on the 532nm optical branch. The evaluation results show that the imaging quality of this band is good, the distortion is less than 2%, and the comprehensive imaging quality meets the design requirements.

The 532nm and 1064nm optical paths use variable diaphragms to eliminate stray light in the lens barrel and can adjust the echo intensity and contrast according to the echo light characteristics of the actual scene. The structure uses a stepping motor controlled by the host computer to adjust the diaphragm size is adjusted. The overall structure volume is 898.5cm ³ , and the weight can be optimized to 2.44kg.

Referring to FIG. 3 , the ICCD9 includes a photocathode, a first high-voltage region, a microchannel plate, a second high-voltage region, a phosphor screen, an optical transducer and a CCD. The photocathode, the first high-voltage region, the microchannel plate, the first high-voltage region, the The two high-voltage areas, the fluorescent screen, the optical converter and the CCD are connected in sequence, wherein the distance between the output surface of the microchannel plate and the input surface of the optical converter is less than 1 mm, and the output surface of the optical converter and the CCD focus The focal plane distance of the flat detector is less than 1mm.

The resolution of the ICCD9 is 960×720, and the size of the focal plane is Ф15mm.

Specifically, the single-photon detection efficiency adopted by Gm-APD can reach 15%. The main structure of the distance gate detector ICCD is shown in Figure 3. The distance between the output surface of the ICCD microchannel plate and the input surface of the optical converter is less than 1mm, and the distance between the output surface of the optical converter and the focal plane of the CCD focal plane detector is also It is less than 1mm, making the whole device compact, with high coupling efficiency and high imaging quality.

The sensitivity of the photocathode is about 5×10 ⁴ A/W; the gain of the microchannel plate is 10 ⁶ , the dynamic range is more than 2 orders of magnitude, and the gain can reach 1×10 ⁶ lm/m ² /lx; the phosphor screen adopts high-performance phosphor to respond The speed is fast, about 300ns; the transmittance of the optical converter reaches 60%, the fiber core diameter is 6μm, and the resolution can reach 55 line pairs; the CCD quantum efficiency is 60%, and 56 times gain adjustment can be realized. ICCD can achieve high-speed, high-sensitivity echo detection. Gm-APD and ICCD two detectors can guarantee 25Hz real-time imaging.

The optical system of the present invention realizes high imaging quality detection of dual-band 5° field of view through optical design optimization, and the two bands are detected by high-sensitivity ICCD and Gm-APD respectively, which can reduce the impact on laser emission energy under the constraint of detection performance. need.

The invention is used for the laser imaging radar system for detection by the dual-wavelength area array, and the target recognition rate and the reliability of parameter estimation can be improved by using the dual-wavelength echo information. The technical scheme of common aperture receiving and beam splitting prism in the system is adopted, and the overall device layout and volume are optimized under the premise of ensuring the detection performance, which reduces the volume of the system and improves the integration degree of the system, which miniaturizes the dual-wavelength imaging detection system Provide technical solutions. This device can be used in laser imaging detection solutions for small-volume platform applications.

Claims (5)

1. A dual wavelength staring type imaging optical receiving system, characterized in that the system comprises: the device comprises a common-caliber receiving optical system, a beam splitter prism (1), a 1064nm optical receiving branch and a 532nm optical receiving branch, wherein the common-caliber receiving optical system, the beam splitter prism (1) and the 1064nm optical receiving branch are coaxially arranged, a receiving end of the 532nm optical receiving branch is over against a reflection light path of the beam splitter prism (1),

the 1064nm optical receiving branch comprises a 1064nm waveband narrow-band filter (2), a 1064nm optical path variable diaphragm (3), a diaphragm motor (4) of a 1064nm optical path, three optical lenses and a Gm-APD (5), the 1064nm waveband narrow-band filter (2), the 1064nm optical path variable diaphragm (3), the three optical lenses and the Gm-APD (5) are sequentially arranged from near to far relative to the transmission side of the beam splitter prism (1), and the diaphragm motor (4) of the 1064nm optical path is installed on the 1064nm optical path variable diaphragm (3) and used for adjusting the size of the 1064nm optical path variable diaphragm (3);

the 532nm optical receiving branch comprises a 532nm optical path variable diaphragm (6), a 532nm waveband narrowband filter (7), a 532nm optical path right-angle reflecting prism (8), an ICCD (9), a diaphragm motor (10) of a 532nm optical path, a first optical lens and a second optical lens, the 532nm optical path variable diaphragm (6), the first optical lens, the 532nm waveband narrowband filter (7), the second optical lens and the 532nm optical path right-angle reflecting prism (8) are sequentially arranged from near to far relative to the reflecting side of the beam splitter prism (1), the ICCD (9) is arranged at the reflecting side of the 532nm optical path right-angle reflecting prism (8), the 532nm optical path diaphragm motor (10) is arranged on the 532nm optical path variable diaphragm (6) and is used for adjusting the size of the 532nm optical path variable diaphragm (6),

the beam splitter prism (1) is used for transmitting 1064nm wavelength light to the 1064nm optical receiving branch and reflecting 532nm wavelength light to the 532nm optical receiving branch, and the beam splitter prism (1) is a cube beam splitter prism with the size of 40 x 40 mm;

the aperture of the 1064nm optical path variable diaphragm (3) is 0.8-15 mm, and the aperture of the 1064nm waveband narrow-band filter (2) is 25 mm;

the 532nm optical path right-angle reflecting prism (8) is a 30 x 30mm right-angle prism, the aperture of the 532nm optical path variable diaphragm (6) is 0.8 mm-25 mm, and the aperture of the 532nm waveband narrowband filter (7) is 30 mm.

2. The dual wavelength staring imaging optical receiver system as claimed in claim 1, wherein said common aperture receiver optical system includes three coaxially aligned optical lenses.

3. The dual wavelength staring imaging optical receiving system as claimed in claim 1, wherein the Gm-APD (5) has a resolution of 64 x 64 and a focal plane size of 3.2mm x 3.2 mm.

4. The dual wavelength staring imaging optical receiving system according to claim 1, wherein the ICCD (9) comprises a photocathode, a first high-voltage region, a microchannel plate, a second high-voltage region, a fluorescent screen, an optical transducer and a CCD, the photocathode, the first high-voltage region, the microchannel plate, the second high-voltage region, the fluorescent screen, the optical transducer and the CCD being connected in series, wherein the distance between the output surface of the microchannel plate and the input surface of the optical transducer is less than 1mm, and the distance between the output surface of the optical transducer and the focal plane of the CCD focal plane detector is less than 1 mm.

5. A dual wavelength staring type imaging optical receiving system according to claim 4, wherein the resolution of said ICCD (9) is 960 x 720 and the focal size is Φ 15 mm.

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