KR102644619B1 - LIDAR device using reflective beam expander - Google Patents

Abstract

It relates to a LiDAR device using a reflective beam expander that can manufacture the LiDAR device in a small size and realize the stability of laser beam alignment, including a transmitter that expands the laser beam and transmits it to the air, and a laser beam transmitted from the transmitter into the air. A receiving unit including a receiving telescope and a receiving optical system that receives and detects a beam scattered by air molecules or aerosols, wherein the transmitting unit generates and outputs the laser beam, and a laser beam generator that generates and outputs the laser beam. By providing a configuration with a single reflective beam expander that reflects and expands the plurality of laser wavelengths output from the generator, miniaturization of the LiDAR device and simplification of parts can be realized.

Description

LIDAR device using reflective beam expander}

The present invention relates to a LiDAR device using a reflective beam expander, and in particular, to a LiDAR device using a reflective beam expander that can manufacture the LiDAR device in a small size and realize the stability of laser beam alignment.

LIDAR (Light Detection And Ranging) irradiates the wavelength of a laser beam (transmitted beam) into the atmosphere and collects the scattered light (received beam) scattered by air molecules or aerosols in the atmosphere through a telescope and optical sensor to provide physical It is a device that observes phosphorus characteristics. A LiDAR device using such LiDAR is a device that fires pulsed laser light into the atmosphere and uses its reflector or scatterer to measure distance or atmospheric phenomena, and is also called a laser radar.

LiDAR devices currently in use have to enlarge the laser beam as much as possible and irradiate it into the air to prevent the laser beam from spreading. This is because the larger the magnification value, the smaller the divergence angle of the laser beam.

Therefore, in order to reduce the laser beam divergence angle, a refractive beam expander (lens type) is used to reduce the laser beam divergence angle and irradiate it into the air.

The divergence angle of a laser is a very important variable when sending a laser to a long distance. Generally, when a laser beam is irradiated into the atmosphere, a divergence angle of the beam is created due to changes in the temperature or refractive index of the atmosphere, and the size is about 10 mrad. It becomes.

This value becomes a factor in determining the minimum field of view (FOV) of the LiDAR, which is the scanning range, when designing LiDAR. Generally, the laser divergence angle is within about 1 mrad, and when enlarged using a refractive beam expander device, the divergence angle is reduced by the magnification, so in order to radiate a laser beam to a long distance, the beam is enlarged and sent.

An example of such LiDAR technology is disclosed in Documents 1 to 3 below.

For example, Patent Document 1 below describes a LiDAR optical device that provides sensing light to a scanner of a LiDAR system, a light source that outputs sensing light with a preset wavelength, and is arranged to form a preset first angle with the horizontal plane, A mirror that reflects the sensing light to the scanner of the LiDAR system, an angle adjustment unit that adjusts the angle formed by the mirror with the horizontal plane, and has a preset size, and is installed outside the LiDAR system even while the LiDAR system is operating. A light detection unit that receives reflected light reflected from a hole and a target provided on one side of the housing and enters from the scanner of the LiDAR system and converts it into an electrical signal so that the angle formed by the mirror with the horizontal plane can be adjusted using the angle adjustment unit. A lidar optical device comprising:

In addition, Patent Document 2 below discloses a beam expansion unit that reduces the divergence angle for the laser emitted from the laser unit, an etalon that transmits the laser with the reduced divergence angle, irradiating the transmitted laser to a target object, and the target object. Disclosed is a Doppler LiDAR device including a transceiver that receives a backscattered signal backscattered from and a processor that measures wind field characteristics using a first scattered signal that passes through the etalon among the backscattered signals. there is.

Meanwhile, Patent Document 3 below discloses a reflective mirror disposed at a first angle with the horizontal plane and having a reflective surface, a light source that outputs a pulse laser along a light transmission path formed at a distance from the upper end of the reflective mirror, and the pulse. A single lens transmitting and receiving light that generates a collimated beam or divergence beam so that the laser progresses to the measurement target, receives the light reflected from the measurement target, and transmits it to the reflecting surface. A scanning lidar is disclosed that is disposed to face the light and includes a light detection unit that converts light reflected from the reflective surface into an electrical signal, and a scattering prevention unit disposed between the light source and the light detection unit.

Republic of Korea Patent Publication No. 10-1814129 (registered on December 26, 2017) Republic of Korea Patent Publication No. 10-1282494 (registered on June 28, 2013) Republic of Korea Patent Publication No. 10-2235710 (registered on March 29, 2021)

Patent Document 1 as described above discloses a technology that allows precise adjustment of the scanning area by adjusting the angle at which the sensing light is irradiated even when the LiDAR system is in operation, but a motor unit for controlling the rotation of the mirror unit is provided in the device. There was a problem that miniaturization could not be achieved.

In addition, in Patent Document 2, a structure is provided to transmit a laser that has passed through the etalon to the target object so that wind field characteristics can be easily measured. However, in Patent Document 2, the first beam splitter and the second beam splitter are also applied. , it was difficult to manufacture a LIDAR device in a small size, and problems with beam alignment occurred.

Meanwhile, in the technology disclosed in Patent Document 3, a single-lens optical system structure was proposed to solve the problem of multiple alignment points, but since a rotating mirror is applied, the problem is that miniaturization of the device cannot be achieved as in Patent Document 1. There was.

As described above, in the case of LiDAR devices according to conventional technology, when more than one laser wavelength is irradiated into the air, a plurality of refractive beam expanders are needed depending on the laser wavelength, which makes it difficult to manufacture the LiDAR device in a small size. . In addition, since multiple refractive beam expanders must be used, various optical components are used, and the large number of optical components causes a decrease in the laser beam output, and causes a problem in which the beam alignment is distorted due to a sensitive reaction to the beam alignment. did.

In addition, since the LiDAR device must collect a laser beam with a single telescope, the laser must be irradiated through the same optical axis. However, when using multiple refractive beam expanders, there was a problem in that the beams had to be ultimately combined into the same optical axis.

The purpose of the present invention is to solve the problems described above, and to provide a reflective beam that can provide stability in laser beam alignment by minimizing other additional optical devices by expanding a plurality of laser wavelengths with a single optical device. It provides a LiDAR device using an enlarger.

Another object of the present invention is to use a reflective beam expander that does not require other optical components to match the optical axes and can realize simplification of device components by using a single reflective beam expander even for multiple laser wavelengths since there is no chromatic aberration. It provides a LiDAR device.

Another object of the present invention is to provide a lidar device using a reflective beam expander that can realize miniaturization of the device by minimizing additional optical devices.

Another object of the present invention is to provide a LiDAR device using a reflective beam expander that can easily operate the device by simplifying parts.

In order to achieve the above object, a lidar device using a reflective beam expander according to the present invention includes a transmitter that expands a laser beam and transmits it toward the atmosphere, and a laser beam transmitted from the transmitter into the atmosphere by target air molecules or aerosols. It includes a receiver having a receiving telescope that receives and detects a scattered beam, and a receiving optical system, wherein the transmitter includes a laser beam generator that generates and outputs the laser beam, and a plurality of laser wavelengths output from the laser beam generator. It is characterized by having a single reflective beam expander that reflects and expands.

In addition, in the lidar device according to the present invention, the reflective beam expander is characterized by reflecting and expanding a wavelength of 250 nm to 2 μm.

In addition, in the lidar device according to the present invention, the reflective beam expander includes a main body, the main body is provided on one side of the main body, and a device that reflects and expands a plurality of laser wavelengths generated from the laser beam generator. 1. It is characterized by comprising a reflector and a second reflector provided on the other side of the main body, which receives a plurality of laser wavelengths expanded by the first reflector and transmits them to the atmosphere.

In addition, in the lidar device according to the present invention, the first reflector and the second reflector each include a spherical mirror coated with aluminum and are respectively fitted into the main body.

In addition, in the LiDAR device according to the present invention, the first reflector has the function of a concave mirror, and the second reflector has the function of a convex mirror.

In addition, in the lidar device according to the present invention, the radius of curvature of the first reflector is formed to be smaller than the radius of curvature of the second reflector.

As described above, according to the lidar device using the reflective beam expander according to the present invention, the plurality of laser wavelengths output from the laser beam generator are reflected and expanded in the transmitter that expands the laser beam and transmits it in the air direction. By providing a beam expander as a single part, miniaturization of the LiDAR device and simplification of parts can be realized.

In addition, according to the lidar device using a reflective beam expander according to the present invention, the first reflector and the second reflector are each provided with a spherical mirror coated with aluminum, thereby achieving the effect of reducing the weight of the device.

In addition, according to the lidar device using a reflective beam expander according to the present invention, the laser beam generator and the first reflector that reflects and expands the laser beam are provided on the same axis, which provides the effect of providing stability in laser beam alignment. is obtained.

In addition, according to the lidar device using a reflective beam expander according to the present invention, the effect of easily realizing the operation of the device is obtained by providing a reflective beam expander that reflects and expands the laser wavelength as a single component. .

1 is a diagram showing the configuration of a general refractive beam expander LiDAR device;
Figure 2 is a diagram showing the configuration of a lidar device using a reflective beam expander according to the present invention;
Figure 3 is a diagram showing the configuration of the reflective beam expander shown in Figure 2;
FIG. 4 is a diagram for explaining the functions of the first and second reflectors shown in FIG. 3;
Figure 5 is a graph for explaining the reflectance in the first reflector and the second reflector.

The above and other objects and new features of the present invention will become more clear by the description of this specification and the accompanying drawings.

First, the configuration of the LiDAR device applied to the present invention will be described with reference to FIG. 1. Figure 1 is a diagram showing the configuration of a general refractive beam expander LiDAR device.

As shown in FIG. 1, a typical LiDAR device consists of a transmitter 10 that transmits a laser toward a target 20 in the air and a receiver 30 that receives a laser beam scattered in the air. In the transmitter 10, the beam irradiated from the laser is separated through a beam splitter, which is an optical component, wavelength 1 passes through the beam splitter and enters the refractive beam expander 2, and wavelength 2 reflected by the beam splitter is separated using a mirror. It is incident on refractive beam expander 1 and reflected by another mirror, so that the paths of the two wavelength beams match in the final color selection mirror. Beams of wavelengths 1 and 2 matched by the color selection mirror are irradiated to the target 20 in the air.

In addition, for example, the signal scattered and reflected from the target 20, which is ultrafine dust in the air, is collected by the receiving telescope 31 of the receiving unit 30, and the collected signal is collected by the photodetector, which is the receiving optical system 32. Through detection and signal processing, various information such as spatial distribution, amount, and type of pollutants can be obtained.

However, since the LiDAR device shown in FIG. 1 uses a beam splitter, multiple beam expanders, multiple mirrors, and color selection mirrors, it is difficult to miniaturize the device and there is also the problem of having to combine beams along the same optical axis.

The present invention was made to solve the problems described above, and was designed to provide stability of laser beam alignment by minimizing optical devices.

Hereinafter, embodiments according to the present invention will be described with reference to the drawings.

In addition, in the description of the embodiment, the same components as those in FIG. 1 are assigned the same numbers and repeated descriptions thereof are omitted.

Figure 2 is a diagram showing the configuration of a lidar device using a reflective beam expander according to the present invention, and Figure 3 is a diagram showing the configuration of the reflective beam expander shown in Figure 2.

As shown in FIG. 2, the LiDAR device according to the present invention includes a transmitter 100 that enlarges a laser beam and transmits it in the air direction, and a laser beam transmitted from the transmitter 100 into the air is transmitted to the air target 20. It includes a receiving unit 30 including a receiving telescope 31 and a receiving optical system 32 that receives and detects beams scattered by molecules or aerosols.

In addition, in the LiDAR device according to the present invention, it is detected through the photodetector of the receiving optical system 32 and stored as a storage medium, and the stored signals are analyzed to determine the spatial distribution, amount, and distribution of particulate pollutants located at a specific altitude in the atmosphere. It may include a data processing device that acquires various information such as type, and a display device that displays the state of air pollution according to the processed data. In addition, data processing in the data processing device is performed using a deep learning method, and the display device displays not only ultrafine dust or fine dust emission information, but also small spherical particles (artificial origin) as qualitative information such as type of fine dust particle. pollutants: sulfate, black carbon, etc., which are more harmful to the human body), large non-spherical particles (yellow dust, flying dust, pollen, etc.) information can be displayed.

As shown in FIG. 2, the transmitter 100 includes a laser beam generator 110 that generates and outputs a laser beam, and a laser beam generator 110 that reflects and expands a plurality of laser wavelengths output from the laser beam generator 110. It is provided with a reflective beam expander (120). That is, in the present invention, the functions of a beam splitter, multiple beam expanders, multiple mirrors, and color selection mirrors as shown in FIG. 1 are realized by a single reflective beam expander 120 without the need for other optical components, By realizing simplification of parts, miniaturization of the LiDAR device can be realized.

The laser beam generator 110 uses a microchip laser as a light source and can output a wavelength of 250 nm to 2 μm. For example, the laser beam generator 110 may output a laser having a wavelength of at least one of 1064 nm, 532 nm, or 355 nm to be transmitted to the atmosphere.

As shown in FIGS. 2 and 3, the reflective beam expander 120 includes a main body 121, the main body 121 is provided on one side of the main body, and the laser beam generator 110 A first reflector 122 is provided on the other side of the main body to reflect and expand a plurality of laser wavelengths generated from the main body, and receives the plurality of laser wavelengths expanded from the first reflector 122 and transmits them to the atmosphere. It includes a second reflector 123. That is, the main body 121 is made of aluminum and has an approximate "〔" shape, and the first reflector 122 and the second reflector 123 each have the shape of a spherical mirror coated with aluminum. In addition, in the above description, the main body 121 is made of aluminum, but it is not limited thereto and may be made of other metal or plastic materials. In addition, the first reflector 122 and the second reflector 123 may also be made of concave mirror and convex mirror materials used in general lidar devices instead of aluminum-coated spherical mirrors.

As shown in FIG. 2, the first reflector 122 and the second reflector 123 are inclined at about 45 degrees in the horizontal direction with respect to the laser beam generated by the laser beam generator 110. ) is installed. The first reflector 122 and the second reflector 123 may be configured to fit into the main body 121.

As shown in FIG. 3, the first reflection unit 122 is provided on the same axis as the laser beam generator 110, and the first and second wavelengths output from the laser beam generator 110 ( It has the function of a concave mirror to magnify and reflect each laser beam, and the second reflector 123 is located on a different axis from the laser beam generator 110 at a predetermined distance from the first reflector 122. It is provided opposite the first reflector 122 and has the function of a convex mirror to transmit the first and second wavelengths magnified by the first reflector 122 into the air. Therefore, as indicated by the arrow in FIG. 3, the first and second wavelengths output from the laser beam generator 110 are expanded in the direction of the mounting position of the laser beam generator 110 and transmitted into the air.

In addition, in the reflective beam expander 120, as shown in FIG. 4, the radius of curvature of the first reflector 122 is the radius of curvature of the second reflector 123 so that the laser beam is expanded and transmitted. It is formed smaller. FIG. 4 is a diagram for explaining the functions of the first and second reflectors shown in FIG. 3.

Meanwhile, in the reflective beam expander 120 according to the present invention, as shown in FIG. 5, the reflectance of the first reflector 122 and the second reflector 123 is provided to be the same. Figure 5 is a graph for explaining the reflectance in the first reflector and the second reflector.

The laser beam emitted into the atmosphere through the second reflector 123 causes scattering when it encounters particulate air pollutants such as yellow dust, pollen, and ultrafine dust present in the atmosphere, and the backscattered light among them is transmitted to the receiver (30). ) is collected through a receiving telescope (31)), and the collected signals are detected through a receiving optical system (32) equipped with a photodetector and stored as a storage medium, and the stored signals are used in a deep learning technique in a data processing device. It is analyzed through , and the analysis results can be displayed on the display device as various information such as spatial distribution, amount, and type of particulate pollutants located at a specific altitude in the atmosphere.

As described above, in the lidar device according to the present invention, the reflective beam expander 120 is manufactured in an ultra-light form through optimization and performance improvement of the signal acquisition module and internal optical devices, and can be mass-produced at low cost, not only in the fixed type but also in the fixed type. It can be manufactured in a form that can be mounted on a mobile vehicle. In addition, it can be configured to measure horizontal as well as vertical distribution, with a fine dust vertical distribution of approximately 4 km (high accuracy within 3 km) and horizontal distribution within a 4 km radius with a resolution of 10 m intervals in a 360° direction. By measuring the distribution of ultrafine dust in minutes, information on the distribution of ultrafine dust around buildings such as buildings or schools or industrial complexes can be displayed on a display device in real time.

In other words, the LiDAR device using the reflective beam expander 120 applied to the present invention does not require other optical components to match the optical axis compared to the refractive beam expander LiDAR device shown in FIG. 1, and there is no chromatic aberration. Multiple laser wavelengths can also be expanded using a single reflective beam expander device. Specifically, the refractive beam expander LiDAR device requires a plurality of refractive beam expanders when there are multiple laser wavelengths, and various optical components are required to match the optical path, which causes a problem of optical alignment, but the present invention Reflective beam expander lidar devices according to can ensure stability by simplifying parts and minimizing optical devices.

Although the invention made by the present inventor has been described in detail according to the above-mentioned embodiments, the present invention is not limited to the above-described embodiments and can of course be changed in various ways without departing from the gist of the invention.

By using a LiDAR device using a reflective beam expander according to the present invention, miniaturization of the LiDAR device and simplification of parts can be realized.

100: Transmitting unit
120: Reflective beam expander
122: first reflection unit
123: second reflection unit

Claims (6)

A transmitter that expands the laser beam and transmits it to the atmosphere,
A receiving unit including a receiving telescope and a receiving optical system that receives and detects a beam scattered by air molecules or aerosols that target the laser beam transmitted from the transmitting unit into the atmosphere,
The transmitting unit includes a laser beam generator that generates and outputs the laser beam, and a reflective beam expander that reflects and expands a plurality of laser wavelengths output from the laser beam generator,
The reflective beam expander includes a main body,
The main body includes a first reflector provided on one side of the main body, which reflects and enlarges a plurality of laser wavelengths generated from the laser beam generator, and a plurality of laser wavelengths provided on the other side of the main body and expanded from the first reflector. It includes a second reflector that receives the laser wavelengths and transmits them to the atmosphere,
The first reflector is provided on the same axis as the laser beam generator,
The second reflector is provided at a predetermined distance from the first reflector and faces the first reflector on a different axis from the laser beam generator,
The LiDAR device is characterized in that the first reflector has the function of a concave mirror, and the second reflector has the function of a convex mirror. In paragraph 1:
The reflective beam expander is a lidar device characterized in that it reflects and expands a wavelength of 250nm to 2㎛. delete In paragraph 1:
The first reflector and the second reflector each include a spherical mirror coated with aluminum and are respectively fitted into the main body. delete In paragraph 1:
A lidar device, characterized in that the radius of curvature of the first reflector is formed to be smaller than the radius of curvature of the second reflector.

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