RU2809468C1 - Laser location system - Google Patents

Abstract

FIELD: optical equipment.

SUBSTANCE: optical ranging systems that provide detection of an object in the space surrounding the installation site of a laser ranging system, obtaining information about the shape of its surface, if necessary, its visualization, and object recognition. A laser ranging system implements a scheme for multichannel recording of signal envelopes generated when a probing laser pulse is scattered by various parts of the surface of an object, which may be located in any locatable region of space around the laser ranging system. Synchronous registration of counts, envelopes of multiple signals, simultaneously recorded by an array of photodetectors, makes it possible to reconstruct the irradiated part of the object’s surface and carry out its recognition.

EFFECT: ability to change spatial resolution, which makes it possible to perform a high-resolution reconstruction of the surface of a located object located at an arbitrary distance from it.

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Description

The invention relates to optical ranging - systems that provide detection of an object in the space surrounding the installation site of a laser ranging system, obtaining information about the shape of its surface, if necessary, its visualization and object recognition.

A location system is known (patent RU 2612874 [1]), designed to scan the surrounding space, detect objects and determine their position in space. Its disadvantage is the use of the same optical system to form a beam of probing laser radiation and form the field of view of the radiation receiver, which inevitably leads to partial illumination of the receiver by probing radiation, as a result of which the sensitivity of the receiver decreases over a certain time interval and deteriorates at distances corresponding to this time object detection characteristics. The closest to the claimed technical solution is a location system (patent RU 2660390 [2]), containing a pulsed laser, an output optical system of a transmitting channel, a photodetector device, a single-axis scanning device, an optical lens of a photodetector device, an array of photodetectors, a fiber-optic bundle and a computing device , connected to them via a fiber optic harness).

The disadvantage of this technical solution is the limited range resolution, which does not allow determining the characteristic features of the object’s surface - it is known that the envelope of the recorded radiation pulse is related to its shape of the located object and its orientation in space, so its analysis allows for recognition of the located object [3].

The tasks to be solved by the claimed invention are: reducing the size of the region of space in which the characteristics of object detection deteriorate; reconstruction of the surface of the detected object; providing object detection in three-dimensional (3D) space around the laser ranging system.

The introduction into the system (Fig. 1) of units for recording samples of the envelopes of recorded pulses - long-range portraits with high spatial resolution - makes it possible to synthesize a 3D image of the located volume [3], and if there is an object within its limits, to reconstruct its surface. The result of such reconstruction is presented in Fig. 2. The introduction of optical elements into the location system that change the focal values of the optical systems of the transmitting and receiving channels makes it possible to change its spatial resolution, which makes it possible to reconstruct with high resolution the surface of the located object located at an arbitrary distance from the location system. In this case, the distance to the object is determined by a computing device, which, in accordance with it, ensures a change in the focal lengths of the optical systems of the receiving and transmitting channels, while simultaneously ensuring the matching of the cross-sectional dimensions of the laser beam of the transmitting channel and the set of fields of view that record the radiation of photodetectors scattered by the object.

The introduction of a system of flat mirrors that change the position of the laser beam and the fields of view of the radiation of photodetectors that register the radiation scattered by an object makes it possible to scan space and register long-range portraits with high spatial resolution in the vertical plane, and due to synchronized rotations of the entire laser ranging system, to ensure scanning of part of the entire surrounding space or its selected area.

The achieved technical result consists in providing high temporal resolution of synchronized samples of the envelopes of the recorded radiation pulses in each channel of the photodetector.

The range of a laser location system can be increased by using a laser radiation amplifier based on active laser mirrors as part of the transmitting channel [4].

The set of essential features characterizing the essence of the claimed invention is not known from the prior art, which allows us to conclude that the invention meets the “Novelty” criterion.

The essence of the claimed invention is not obvious to a specialist from the known level of technology, because it does not reveal the above influence on the resulting technical result - a new property of an object - a set of features that distinguish the claimed invention from the prototype, which allows us to conclude that it meets the criterion of "Inventive Step".

The set of essential features that characterize the essence of the invention, in principle, can be repeatedly used to implement a laser ranging system to obtain a technical result consisting in reducing the size of the area of space in which the characteristics of object detection deteriorate; reconstruction of the surface of the detected object; and detection of an object in the space around the laser location system, which determines the achievement of the task, which allows us to conclude that the invention meets the criterion of “Industrial applicability”.

In fig. Figure 1 shows a functional diagram of the laser ranging system:

1 - pulse laser;

2 - optical system of the transmitting channel;

3 - photodetector device for recording a laser radiation pulse;

4 - optical system of the receiving channel;

5 - fiber optic bundle;

6 - array of photodetectors;

7 - computing device;

8 - drive for moving the transmitting and receiving channels in the horizontal plane;

9 - drive of the scanning system operating in the vertical plane;

10 - optical elements that provide a change in the focal length of the optical system of the transmitting channel;

11 - optical elements that provide a change in the focal length of the optical system of the receiving channel;

12 - drive of the focusing elements of the optical system of the transmitting channel;

13 - drive of the focusing elements of the optical system of the receiving channel;

14 - array of photodetectors with analog-to-digital converters;

15 - scanning system operating in a vertical plane;

16 - multi-pass laser amplifier with a mirror active optical system.

The cross section of the probing laser beam is indicated by a dash-dotted line, and the fields of view of the photodiodes are indicated by continuous lines.

In fig. Figure 2 shows the result of reconstructing the surface of a detected object.

The radiation of a pulsed laser (1) enters the input of the optical system of the transmitting channel (2), the moving elements (10) of which, moved by the drive (12), provide a change in its focal length and thereby ensure a change in the cross-sectional dimensions of the laser beam in the vicinity where there may be an object. The direction of propagation of laser radiation pulses and the position in space of the field of view of the optical system of the receiving channel (4) is set by the position of flat mirrors (15) - the executive element of the scanning system operating in the vertical plane. Optical elements that provide a change in the focal length of the optical system of the receiving channel (11) are moved by a drive (13). The position of this drive, which determines the focus size of the optical system of the receiving channel (4), as well as the position of the drive (12) matched with it in terms of the focus size of the optical system of the transmitting channel (2), are set by the computing device (7). Its inputs receive signals from the outputs of an array of photodetectors with analog-to-digital converters (14), the input of each of which is connected to the corresponding output of the array of photodetectors (6). Each photodetector of this array receives part of the radiation, the spatial distribution of which in the focal plane of the optical system of the receiving channel (11) forms an image of the located part of space, and if an object is located in it, its image. A fiber optic bundle (5) is used to transmit radiation from each image area to the corresponding photodetector. The computing device analyzes the set of registered signals, based on the results of which it makes a decision about detecting or not detecting an object, and if the object is detected, determines the distance to it, in accordance with the obtained distance value (or according to operator commands) adjusts the position of the drives (12 ) and (13), and also performs 3D reconstruction of the located part of the space and/or recognition of an object detected in this part. Information data can be transmitted to the operator, for example, via a radio channel built into the computing device. The same communication channel can be used to transmit operator commands to the computing device. The drive for moving the transmitting and receiving channels in the horizontal plane (8) ensures rotation of the carrier platform of the location system relative to the carrier. The photodetector device for recording the laser radiation pulse (3), connected to the computing device (7), ensures synchronization of the time of radiation of the laser pulse and the moment of the start of recording the scattered pulse counts. The computing device (7) also ensures synchronization of the operation of the drives (8) and (9) to ensure scanning in the space of the laser ranging system. The use of a multi-pass laser radiation amplifier with a mirror active optical system (16) included in the optical circuit between the pulse laser (1) and the input of the optical system of the transmitting channel (2) as part of the laser ranging system will increase its range without significantly increasing the divergence of the laser radiation beam.

With regard to the duration of the laser pulse, it has been established [5, 6] that reliable recognition of an object is possible if this value does not exceed 10% of the time interval of propagation of the radiation pulse along the surface of the object in the direction in which this time is minimal.

References:

1. RF Patent No. 2612874. Pulse laser ranging system. Issued on November 12, 2015. Publ. 03/13/2017, bulletin. No. 8.

2. RF patent No. 2660390. Pulse laser ranging system. Issued 06/15/2017. Publ. 07/06/2018, bulletin. No. 19.

3. Bury E.V. Synthesis of an object recognition system based on the shape of the laser pulse envelope during pulse-periodic location // Quantum Electronics, 1988. - T. 25, No. 5. pp. 471-475.

4. RF Patent No. 2583105. Multi-pass laser amplifier with a mirror active optical system. Issued 02/17/2014. Publ. 05/10/2016, bulletin. No. 13.

5. Baulin F.B., Bury E.V. Methods for generating feature vectors for recognizing objects from long-range portraits in pulsed laser ranging // Computer Optics, 2021. - T. 45, No. 6. - pp. 934 - 941.

6. Bury E.V. Pulsed laser ranging: physical and information bases of new opportunities. M.: Nauka, 2020. - 431 p.

Claims (3)

1. Laser ranging system containing: pulsed laser; optical system of the transmitting channel; transmitting channel clock signal generator; optical system of the receiving channel; photodetector matrix; computing device; a scanning device for positioning the fields of optical systems in a vertical plane, as well as a fiber-optic bundle, the fibers of which, on one side, face the ends of the corresponding photodetectors of the photodetector array, and on the other side, the ends of the fibers of the bundle face the output of the optical system of the receiving channel and are located in its focal plane , wherein the synchronization signal former of the transmitting channel, optically connected to the laser, is connected to the synchronization input of the computing device, characterized in that the system additionally includes: a device for positioning the elements of the transmitting and receiving channels in the horizontal plane, optical elements that change the focus values of the optical systems of the transmitting and receiving channels , providing their movement are electromechanical drives and high-speed analog-to-digital converters (ADC), and the output of each photodetector of the photodetector matrix is connected to the input of the corresponding ADC, the outputs of these ADCs are connected to the inputs of a computing device, the outputs of which are connected to electromechanical drives and positioning optical systems. 2. Laser location system according to claim 1, characterized in that scanning of space is carried out due to a synchronous change in the spatial position of the beam of laser beams and fields of view of photodetectors, carried out in the vertical plane by rotating flat mirrors with an appropriate drive, and in the horizontal plane - due to rotation the entire laser ranging system by another drive, each of the drives being connected to a computing device. 3. Laser location system according to claims. 1 and 2, characterized in that at the output of the pulsed laser there is a laser amplifier based on active optical mirrors, which ensures the formation of a beam of high-intensity laser beams with low divergence.

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