KR102385020B1 - Optical system for lidar system - Google Patents

Abstract

The present invention relates to an optical system for a laser scanning system that can be manufactured in a compact structure with a small volume and reduced manufacturing cost by having a very simple optical structure.
An optical system for a laser scanning system according to the present invention includes a reflective mirror, a light emitting part disposed in contact with or adjacent to one surface of the reflective mirror, a light receiving part disposed opposite to the other surface of the reflective mirror, and the reflective mirror and the light emission It includes a driving unit for rotating and driving the unit together, the reflective mirror has at least one light transmitting window formed at a position spaced a predetermined distance from the center, and the other surface reflects the light emitted by the light emitting unit and reflected on the object A reflective surface is formed, and the light emitting unit includes at least one laser light source disposed at a position corresponding to the at least one window, and the laser light emitted from the laser light source is emitted to the outside through the window and reflected on the object. The laser light is reflected toward the light receiving unit by the reflective surface.

Description

Optical system for laser scanning system {OPTICAL SYSTEM FOR LIDAR SYSTEM}

The present invention relates to an optical system for a laser scanning system. More specifically, for a laser scanning system that does not complicate the optical system structure even with multi-channels, and can use a low-power laser light source by maximizing high intensity reflected light, thereby reducing manufacturing cost and realizing a compact laser scanning system. It's about optics.

A laser scanning system called LIDAR (Light Detection And Ranging) or LADAR (Laser Detection And Ranging) emits pulsed laser light toward a target and then returns the reflected light to the target with a photo detector (Photo Detector). ) and converts it into an electrical signal, it is a system that can calculate the distance to the target, the moving speed of the target, and a 3D stereoscopic image.

The laser scanning system is widely applied in various fields such as sensors for detecting obstacles in front of robots and unmanned vehicles, radar guns for speed measurement, aerial geo-mapping devices, 3D ground surveys, and underwater scanning.

In general, such a laser scanning system includes a light source device for generating pulsed laser light, light transmitting and receiving means for emitting the pulsed laser light and receiving reflected light of the emitted pulsed laser light, and rotating the pulsed laser light to scan the pulsed laser light at a predetermined angle and a control device for controlling the light source device, the light transmitting/receiving means, and the driving device.

However, in the case of a conventional laser scanning system, in order to obtain a wide-angle scan angle of 180° or more and multi-channel data, a structure in which both the light source device and the optical transmission/reception means are driven by a driving device is often used. As the number of parts increases, a large-capacity rotary motor is required, which increases the weight and volume of the scanning system.

In addition, in the case of a laser scanning system in which a light transmitting unit emitting pulsed laser light and a light receiving unit receiving reflected light are operated separately from each other, there is a problem in that the overall volume is increased and the optical system is complicated.

In order to solve this problem, when the light transmitting unit and the light receiving unit are coaxially arranged (the light transmitting unit and the light receiving unit are sequentially formed on an axis extending in one direction), the light transmitting unit is usually transmitted through the center of the light receiving unit. At this time, interference occurs in the central portion of the light receiving unit, so that the region with the strongest intensity of reflected light is not received by the light receiving unit, so that the receiving intensity of the reflected light is lowered, making remote sensing difficult.

Although remote sensing may be performed through a method of increasing the optical output of the optical transmitter, this problem greatly increases the manufacturing cost of the laser scanning system, thereby hindering commercialization in various fields. If the area of the light receiving unit is increased by another method, the volume of the laser scanning system becomes large, so that a compact configuration becomes difficult.

Republic of Korea Patent Publication No. 2014-0025041

The present invention is to solve the problems of the prior art described above, and the object of the present invention is to facilitate wide-angle scanning of 180° or more, and the optical system structure is not complicated even if the laser light source is multi-channel with 2 or more, and reflected light with high intensity is produced. An object of the present invention is to provide an optical system for a laser scanning system that can be utilized to the fullest, thereby reducing manufacturing cost and realizing a compact laser scanning system.

In order to solve the above problems, the present invention provides a reflective mirror, a light emitting part disposed in contact with or adjacent to one surface of the reflective mirror, a light receiving part disposed opposite to the other surface of the reflective mirror, and the reflective mirror and the light emitting part It includes a driving unit for rotating and driving together, the reflection mirror has at least one light transmitting window formed at a position spaced a predetermined distance from the center, and the other surface reflects the light emitted by the light emitting unit and reflected on the object A slope is formed, and the light emitting unit includes at least one laser light source disposed at a position corresponding to the at least one light transmission window, and the laser light emitted from the laser light source is emitted to the outside through the light transmission window and an object Provided is an optical system for a laser scanning system in which the laser light reflected by the reflective surface is reflected toward the light receiving unit.

In this way, the laser light is directly emitted to the outside without going through a separate mirror through the light emitting unit coupled to one surface of the reflective mirror, and the reflected light enters the light receiving unit through the reflective mirror, eliminating the need for a complicated mirror structure. The volume can be reduced because the light emitted from the light emitting unit is reflected and the central part, which has the strongest intensity among the reflected light incident on the reflection mirror, can be reflected to the light receiving unit without interference, so that sufficient resolution can be obtained even if the output of the laser light source is low. . In addition, in the above structure, since the light receiving unit is not driven by the driving unit, the output of the driving unit can be reduced compared to the method of driving the light receiving unit together. Accordingly, it is possible to manufacture a compact laser scanning system having a smaller volume and easier operation than in the related art.

In addition, in the optical system for a laser scanning system according to the present invention, preferably, two or more of the light transmitting window and the laser light source are disposed, and may be disposed at equal intervals along the circumferential direction, respectively.

In the case of a multi-channel configuration using two or more laser light sources, it is advantageous for light control to arrange each laser light source at equal intervals. In addition, since the present invention has a structure in which laser light is emitted directly from the light emitting unit attached to the reflection mirror, the number of laser light sources is simply increased without changing the mirror structure, so that the structure is very simple even with a multi-channel structure. This makes it easy to design in response to a change in the number of channels.

In addition, in the optical system for a laser scanning system according to the present invention, the window may be formed at a position spaced apart from the center of the reflection mirror by at least 1/2 of a radius.

In order to fully utilize the central region of the light receiving unit having the strongest intensity of reflected light reflected by an object, the window is preferably formed at a position more than 1/2 of a radius from the center of the reflection mirror, and 3/4 or more It is more preferable to be formed at a distant position.

In addition, in the optical system for a laser scanning system according to the present invention, the driving unit includes a hollow shaft motor, and power and control signals to the light emitting unit are provided through a rotary connector fastened to the hollow portion of the hollow shaft motor. can be

Through this, power and control signals can be provided to the laser light source directly attached to the reflective mirror while rotating the light emitting unit and the reflective mirror, thereby facilitating wide-angle scanning.

In addition, in the optical system for a laser scanning system according to the present invention, the light emitting unit may include two or more laser light sources, and each of the lights emitted from the two or more laser light sources may be emitted at different angles.

In this way, when implemented as a multi-channel having two or more laser light sources, the resolution of the point cloud data can be increased, and when the emission angle of each light source is different, a vertical scan as well as a 360° orientation becomes possible, Three-dimensional three-dimensional data can be obtained.

In addition, in the optical system for a laser scanning system according to the present invention, the light receiving unit may include a focusing lens for focusing the light reflected from the reflective surface, and a light processing unit for generating an electrical signal from the light focused from the focusing lens. there is.

In the optical system for a laser scanning system according to the present invention, only a laser light emitting unit composed of a single channel (or multiple channels) and a light receiving reflective mirror are located within the rotation shaft of the motor, and a light receiving unit, a motor driving unit, a sensor control unit, etc. The core components of the scanning sensor can be configured to be fixed to the outside of the rotating shaft.

This provides only the power required for driving the laser light emitting unit and the multi-channel light emission control signal line through the rotary connector located at the center of the rotary motor, and by configuring the laser light emitting unit at a predetermined fixed angle, the sensor can be configured into multiple channels. Also, by rotating it horizontally, it is possible to implement a laser scanning system of a compact size that can scan a wide angle of 180° or more.

In addition, in the optical system for a laser scanning system according to the present invention, light is emitted through a light emitting unit that is attached to one side of the reflection mirror and directly emits pulsed laser light through a window formed in the reflection mirror, so that a separate mirror is used for light emission It is not necessary, and the structure is very simple even if it is a single channel as well as a multi-channel.

In addition, since the window of the reflective mirror emitting pulsed laser light is formed at a location away from the center by a predetermined distance, the reflected light from the center having high intensity can be utilized to the maximum.

In addition, the light emitting unit, the reflecting mirror, and the light receiving unit are sequentially arranged along one direction, and the driving unit is configured to drive only the light emitting unit and the reflecting mirror except for the light receiving unit. can be used

In addition, according to an embodiment of the present invention, using a hollow shaft motor and a rotary connector, power and control signals are provided to rotate the light emitting unit and the reflecting mirror, so 360° rotation is easy and wide-angle scanning is easy .

Through the above configuration and features, the optical system for a laser scanning system according to the present invention is easy to manufacture and enables a compact laser scanning system to be implemented while reducing manufacturing cost.

1 is a cross-sectional view of a laser scanning system including an optical system according to an embodiment of the present invention.
2 is a plan view of a light emitting unit constituting an optical system according to an embodiment of the present invention.
3 is a plan view of a reflection mirror constituting an optical system according to an embodiment of the present invention.
4 is a schematic diagram illustrating a process of processing reflected light entering a light receiving unit constituting a laser scanning system including an optical system according to an embodiment of the present invention.
5 is a graph illustrating a process of scanning through an optical system according to an embodiment of the present invention.

Hereinafter, the present invention will be described in detail based on preferred embodiments of the present invention with reference to the accompanying drawings.

In addition, the terms or words used in the present specification and claims should not be construed in their ordinary and dictionary meanings, and the inventors may appropriately define the concept of terms to describe their invention in the best way. Based on the principle that there is, it should be interpreted as meaning and concept consistent with the technical idea of the present invention. Accordingly, the embodiments described in this specification and the configurations shown in the drawings are only preferred embodiments of the present invention, and do not represent all of the technical spirit of the present invention, so various equivalents that can be substituted for them at the time of the present application and modifications, and the scope of the present invention is not limited to the embodiments described below.

The optical system for a laser scanning system according to the present invention includes a light emitting unit 100 emitting a large amount of laser light, a reflection mirror 200 for reflecting the reflected light reflected by the laser light by an object in a predetermined direction, and the reflection mirror It comprises a light receiving unit 300 for generating an electric signal by receiving the light reflected by 200 , and a driving unit 400 for rotationally driving the light emitting unit 100 and the reflecting mirror 300 . In addition, the laser scanning system further includes a control unit 500 for controlling the components of the optical system, and a cover 600 for protecting the reflection mirror 200 .

The light emitting unit 100 is for emitting pulsed laser light for obtaining a 3D image to the outside through point cloud data obtained by measuring the distance to the object, and includes a plurality of laser light sources 110 and a plurality of laser light sources ( 110) and a disk-shaped case 120 for accommodating it.

As shown in FIG. 1 , the light emitting unit 100 is bonded at a predetermined distance to the opposite surface of the reflective surface 210 that can reflect light from the reflective mirror 200 (the space to arrange the light emitting unit) If insufficient) or directly connected to the arrangement.

In addition, the light emitting unit 100 may be formed of one laser light source, but is preferably formed of multiple channels (ie, two or more laser light sources) in order to obtain a high-resolution stereoscopic image. At this time, as shown in FIG. 2 , a plurality of laser light sources may be arranged at equal intervals along the circumferential direction of the disk-shaped case 120 . In addition, one end of the rod-shaped connecting part 130 extending long in the longitudinal direction to receive the driving force from the driving part 400 is fixed to both sides of the case 120 .

In the embodiment of the present invention, a total of eight laser light sources are applied, but the number of laser light sources may be variously adjusted according to the performance required for the laser scanning system. The emission angles of the pulsed laser light emitted from the eight laser light sources may be adjusted differently. When the laser light source is mounted on the disc-shaped case 120, the emission angle is different through a method of varying the fixing angle to the fastener of the case 120 molded to maintain a predetermined angle set differently from each other. maintain. As shown in FIG. 2 , for example, with respect to the horizontal centerline of the case 120 , 0°, +2°, +4°, +6°, +5°, 3°, -2°, - It can be emitted from each laser light source at an inclined angle of 3°. In this way, by varying the emission angle of each laser light source, it is possible to scan in the vertical direction.

In addition, in the embodiment of the present invention, the laser light source is disposed at a position about 4/5 of a radius away from the center of the reflective mirror 200 to which the laser light source is bonded, but the position of the laser light source may be variously adjusted.

Meanwhile, a collimator (not shown) for making the emitted pulsed laser light into a focused light may be disposed in each of the laser light sources, and the collimator is an FAC (Fast Axis Collimator) disposed adjacent to the emission part of the laser light source. and SAC (Slow Axis Collimaotr) placed after FAC. Through such collimation, the shape of the light emitted from the laser light source can be made into an approximately rectangular focused light shape.

The reflective mirror 200 has a circular disk shape and is inclined at a predetermined angle, a reflective surface 210 is formed on the upper surface of the drawing, and is located about 4/5 of a radius from the center along the circumferential direction, etc. Eight light-transmitting windows 220 made of substantially rectangular-shaped through-holes or holes covered with a light-transmitting material (eg, glass, transparent plastic, etc.) are formed at intervals.

On the opposite surface of the reflective surface 210 of the reflective mirror, the light oscillated from the laser light source 110 passes through the collimator and is emitted directly through the reflective mirror 200 without passing through a separate mirror. The light emitting unit 100 is fixedly arranged so that the collimator is adjacent to the light transmitting window 220 so that the light emitting unit 100 is adjacent to the light transmitting window 220 .

Through such a structure, an optical system such as a reflection mirror for emitting pulsed laser light in a target direction can be eliminated. In particular, in the case of a multi-channel structure using two or more laser light sources, the related optical system becomes complicated and it is difficult to synchronize and control the pulsed laser light. In the embodiment of the present invention, the pulsed laser light is transmitted through the reflection mirror 200 Since a method of direct emitting through the window 220 is used, there is an advantage in that a complicated optical system is not required even with multi-channels, and synchronization control between multi-channel sources is simplified.

The light receiving unit 300 receives the reflected light from which the pulsed laser light emitted through the light emitting unit 100 is reflected by an external object, and includes at least one light focusing lens 310 , and the light The light focused from the focusing lens 310 is converted into an electrical signal through the optical signal processor 320 to form a three-dimensional image.

As shown in FIG. 4 , the optical signal processor 320 removes a component below a specific frequency or a component above a specific frequency, respectively, in order to minimize the influence of an external signal, such as sunlight, not emitted laser light. a band-pass filter, an array-type photodiode that converts the light passing through the band-pass filter into an electrical signal, and an amplifier that amplifies the electrical signal of the photodiode; a peak detector to detect, an analog-to-digital converter (ADC) for obtaining the intensity of reflected light from the detection signal of the peak detector, a time discriminator for determining an input time of reflected light from the signal amplified through the amplifier, and the time discriminator It includes TDC (time-digital converter) that measures the difference between pulsed laser light output time and reflected laser input time from the information of the device.

The driving unit 400 is a device for rotating and driving the light emitting unit 100 and the reflection mirror 300 to scan at a predetermined angle, for example, 90°, 180°, 270°, 360°. A power source 410 , a motor 420 , and a rotary connector 430 for transmitting power and a control signal to the rotating light emitting unit 100 are included.

The power source 410, as shown in FIG. 1, is installed in the case and receives an external power source (eg, 24V power), and a main control power supply for supplying power to various devices operated by electricity; and a high voltage converter for providing high voltage power to the laser light source 110 .

In the embodiment of the present invention, a hollow shaft motor is used as the motor 420 , but the present invention is not limited thereto. A rotary connector 430 is disposed inside the hollow shaft motor. In addition, one end of a connection part 230 connected to the reflective mirror 200 is fixed to the motor 420 in a rotating body. The rotatable connector 430 is to provide power and a control signal to the rotating laser light source 110 driven by the motor 420 .

The control unit 500 is provided with a control circuit for controlling various configurations of the laser scanning system and a 3D image data processing module. The control unit 500 includes a first control unit 510 for controlling the motor 420 and the light emitting unit 100 , and a second control unit 520 for controlling the power source 410 and the light receiving unit 300 . is made including

The first control unit 510 is disposed between the power source 410 and the motor 420, and a high-performance controller ( (not shown) and an encoder counter 511 are mounted and wiring is formed so as to electrically configure a circuit.

In addition, the second control unit 520 is attached to the cover 600 on which the window is not formed, and generates and provides a signal for controlling the light receiving unit 300 .

On the other hand, in the embodiment of the present invention, the first control unit 510 and the second control unit 520 are separately arranged, but when the 360 degree scan becomes difficult by the second control unit 520, the second control unit 520 is It may be integrated into the first control unit 510 to be integrally configured.

As shown in FIG. 1 , the cover 600 is made of synthetic resin or metal in the form of a tube, and one side emits pulsed laser light generated by the laser light source 110 and receives the reflected light. A window 610 for this is formed. In the case of the optical system for a laser scanning system according to the present invention, since the position at which the laser light is emitted and the position at which the laser light is received are the same, only one window is formed in the cover 210 without forming windows for emitting light and for receiving light, respectively.

The window 610 may be formed according to a scanning angle. For example, when a 180 degree scan is required, a window is formed about half of the entire perimeter, and when a 360 degree scan is required, a window can be formed around the entire perimeter.

Next, the operation of the 3D scanning system including the optical system as described above will be described in detail.

Power is supplied through the power source 410 , and operating power and control signals are provided to the laser light source 110 and the motor 420 by a control circuit provided in the control unit 500 .

Accordingly, when the motor 420 is driven, the reflection mirror 200 and the light emitting unit 100 connected to the reflection mirror 200 are rotationally driven together by the connection unit 130 connected to the motor 420 . In addition, the rotary connector 430 is rotationally driven. However, the light receiving unit 300 is not coupled to the rotation of the cover 600 , and thus is not rotationally driven. Accordingly, the number of parts to be rotated by the motor 420 can be reduced, so that a low-output motor can be used compared to the related art.

At the same time, when a pulse laser is generated from the laser light source 110, the generated pulse laser is focused through the collimator 120, passes through the light transmission window 220 formed in the reflection mirror 200, and the cover ( It is emitted to the outside through the window 610 formed in the 600).

At this time, if the emission order of the laser light source 110 with respect to time is changed, 3D stereoscopic scanning is performed in the form shown in FIG. 5 . The emission angle of each laser light source can be variously adjusted according to the type of point cloud data required for the scanning system.

When the pulsed laser emitted in this way reaches an external object and is reflected, the reflected pulse laser enters the scanning system through the window 610 formed on the cover 600, and the reflected pulse laser enters the reflective lens 200 ) is reflected by the reflective surface 210 and sent to the light receiving unit 300 .

The reflected pulse lasers incident on the light receiving unit 300 are collected by the focusing lens 310 and sent to the light processor 320 . In the light processor 320, the received pulse laser removes a component below a specific frequency or a component above a specific frequency through a band-pass filter, and converts the light passing through the band-pass filter into an electrical signal through a photodiode, , the converted electrical signal is amplified through an amplifier, a specific peak is detected from the amplified electrical signal through a peak detector, and then the intensity of the pulse laser reflected from the detection signal is obtained using the ADC, and at the same time a time discriminator and TDC The time of the reflected light is obtained from the signal amplified through , and point cloud data is generated. The point cloud data generated in this way is provided to an arithmetic device for forming a 3D image.

100: light emitting part
200: reflective lens
300: light receiving unit
400: driving unit
500: control
600: cover

Claims (6)

reflective mirrors,
a light emitting part disposed in contact with or adjacent to one surface of the reflective mirror;
a light receiving unit disposed to face the other surface of the reflective mirror;
A driving unit for rotating and driving the reflection mirror and the light emitting unit together,
Two or more light transmitting windows are formed in the reflective mirror at a position spaced apart from the center by a predetermined distance, and a reflective surface for reflecting the light emitted by the light emitting unit and reflected on the object is formed on the other surface,
The light emitting unit includes two or more laser light sources disposed at positions corresponding to the two or more light transmitting windows,
The laser light emitted from the laser light source is emitted to the outside through the light transmission window, and the laser light reflected on the object is reflected toward the light receiving unit by the reflective surface,
The two or more light transmission windows and the laser light source are arranged at a predetermined distance along the circumferential direction,
The two or more light transmitting windows are formed at a location more than 1/2 of a radius from the center of the reflection mirror,
The two or more laser light sources are emitted in a different emission order, an optical system for a laser scanning system. According to claim 1,
The two or more light transmission windows and the laser light source are respectively arranged at equal intervals along the circumferential direction, an optical system for a laser scanning system. delete The method of claim 1,
The two or more laser light sources are emitted at different angles, an optical system for a laser scanning system. According to claim 1,
The driving unit includes a hollow shaft motor,
Power and control signals to the light emitting unit are provided through a rotary connector fastened to the hollow portion of the hollow shaft motor, an optical system for a laser scanning system. According to claim 1,
The optical system for a laser scanning system, wherein the light receiving unit includes a focusing lens for focusing the light reflected from the reflective surface, and a light processing unit for generating an electric signal from the light focused from the focusing lens.

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