WO2023048691A1

WO2023048691A1 - Fast and high-resolution lidar with multiaxis and multi- surface polygon scanner

Info

Publication number: WO2023048691A1
Application number: PCT/TR2022/051037
Authority: WO
Inventors: Emre YÜCE; Umut TAYLAN
Original assignee: Orta Dogu Teknik Universitesi
Priority date: 2021-09-27
Filing date: 2022-09-26
Publication date: 2023-03-30

Abstract

The invention relates to a LIDAR device that can scan with a single structure in both vertical and horizontal planes. The invention is characterized in that it comprises at least one light source (110) sending the beam to scan the scanned area (130), at least one multi-surface scanner (100) enabling the transmission of the incident beams (101) sent from the said light source (110) to the scanned area (130) and at least one reflective optical component (140) placed at different angles on each surface of the said multi-surface scanner (100), at least one detector component (111) enabling the detection of the reflected beams (102) from the scanned area (130) and calculating the flight time of the beam sent, at least one control unit (150) to control the said light source (110), the multi-surface scanner (100) and the detector component (111) and connected to them by at least one signal/data transmission line (151), at least one rotating system (120) to move the said multi-surface scanner (100) circularly to different points of the space, and at least one linear movement system (121) to move the said multi-surface scanner (100) to axially in a direction different from the rotational axis.

Description

FAST AND HIGH-RESOLUTION LIDAR WITH MULTIAXIS AND MULTI¬

SURFACE POLYGON SCANNER

TECHNICAL FIELD

The invention generally relates to a LIDAR device that scans with an optomechanical system with a single structure in both vertical and horizontal planes.

STATE OF THE ART

LIDAR works with the logic of detecting the return time of the beams sent with various 3- dimensional scanning systems through sensors. Today, as automation becomes more and more important day by day, the importance of LIDAR systems is increasing and many different systems and designs are being developed and used. Examples of technologies using LIDAR systems include robotics, remote detector systems, unmanned aerial and land vehicles, navigation, 3-dimensional scanning and mapping systems.

There are different types of LIDARs in use today. These LIDAR types can be divided into two main branches with and without scanning. Scanless LIDAR systems are also called flash LIDAR systems. Scanning systems are also divided into mechanical and non-mechanical LIDARs. Non-mechanical scanning LIDARs are generated by an optical phase array. Mechanical scanning LIDAR systems can be classified as the micro-electro-mechanical system (MEMS) LIDAR and optomechanical scanning systems.

The entire area to be displayed in flash LIDARs is illuminated and the photodetectors, which are arranged in a series, operate by calculating the flight time of the beams reflected from each point in the illuminated area. Due to the illumination made in this way, the photodetector array can only collect a small fraction of the beams sent. This results in flash LIDARs having a low signal/noise ratio, a reduced maximum measurable distance, and a high power light source requirement. The resolution in these systems depends on the size and density of the detector array. These situations make the production of a high resolution system difficult and increase its cost. In optical phased array LIDARs, spatial scanning is done by working on the same principle as a phased array radar. The optical phase modulators in the system control the phase delays of the beams coming from the light source and control the waveform. The directions of the beams can be controlled by controlling the wavefront shape. These systems can be scanned without a mechanical system by controlling the waveform. The problems of optical phase array LIDARs are that the maximum angle that can be scanned is low, the optical power is low for practical use and the cost is high because they are high technology products.

MEMS-based LIDARs, one of the mechanical LIDAR types, operate on the principle that one or more micro mirrors scan at a certain angle with a laser beam. These mirrors usually scan with the controlled variation of the applied voltage and variation of the inclination angle of the micro mirror. Their production is costly as they require photo -lithographic processes. In addition, MEMS LIDARs modulate the pixels to make a scan. Since the number of pixels that are closed in this modulation is high, only a small part of the light is used, which causes the measurable distance to decrease.

LIDAR with optomechanical scanning, which is one of the other mechanical LIDAR types, is the LIDAR type with the highest utilization rate. They have scanning systems in which optical elements such as mirrors and prisms are used for the directional control of the beams. Wide scan angles, long range and high scan speeds are advantages of optomechanical scanning LIDARs. Despite these features, optomechanical scanning LIDARs weigh heavily, and those with these high features can cost tens of thousands of dollars. Furthermore, although they may have a scanning angle of 360 degrees in the horizontal plane, their resolution in the vertical plane depends on the number of mirrors used. Increasing the resolution in the vertical plane makes the use of the produced system difficult and causes an increase in its cost.

In the Korean patent application numbered KR 20190130495 A, which is in the present art, reflective elements placed in a polygonal structure as beam reflective elements are mentioned. The insertion angles of the reflecting elements are the same and it has been explained that the polygon structure scans in the horizontal plane. For scanning in the vertical plane, another reflective element is mentioned separately from the polygon structure. This patent structure mentioned above does not solve other problems in the prior art. In the US patent application numbered US 20200025888A, which is in the state of the art, lasers called VCSEL are arranged in a way to form sequences in horizontal and vertical planes as light sources, and it is mentioned that they are designed to send continuous wave laser beams from the vertical cavities they have. In addition, the directing of the beams is done with 2-dimensional nanopillar structures placed on a meta-surface, and it has been mentioned that polygon mirrors can be used to recheck the direction of the beams after nanopillars. In addition, in the said invention, meta-surface and VCSEL lasers should be produced by lithographic methods. The said patent does not solve other problems in the prior art.

In the US patent application numbered US 20190265336A1, which is in the state of the art, a structure with two separate reflective elements is disclosed. The movement in the vertical plane is provided by the one-step movement of the mirror galvanometer. In addition, the angles of the reflecting elements are the same and the polygon can only scan in the horizontal plane. In order to scan in the vertical plane, separate from the polygon structure, the movement of the reflective element controlled by the mirror galvanometer and beam orientation are needed. In addition, the light reflecting element in the patent in question consists of a single polygon structure. This patent application does not solve other problems in the prior art.

As a result, improvements are made in LIDAR systems, therefore, there is a need for new structures that will eliminate the disadvantages mentioned above and bring solutions to existing systems.

THE OBJECT OF THE INVENTION

The present invention relates to the LIDAR system that meets the above-mentioned needs and eliminates all disadvantages and provides some additional advantages.

The main object of the invention is to provide a LIDAR device that scans with an optomechanical system with a single structure in both vertical and horizontal planes.

An object of the invention is to provide rapid scanning of the area where the light is desired to be scanned and directing the light at the same time at high resolution. Another object of the invention is to provide high resolution spatial scanning in both horizontal and vertical axis with a polygon by placing the optical guiding elements used in the polygons at different angles.

Another object of the invention is to ensure that spatial scanning can be performed at high speed with a system that can simultaneously make linear and circular movements.

Another object of the invention is to develop a system that can scan at high resolution using a multilayer polygon.

Another object of the invention is to provide a system that will increase the resolution by increasing the number of light-guide optical elements on the polygon.

Another object of the invention is to provide a system that can be easily produced with a 3- dimensional printer or CNC, in contrast to LIDAR systems that require high technology and production capacities such as systems that use optical phase sequence technology or without the need for cleanrooms and high-cost equipment to be used in MEMS-based LIDAR systems.

The structural and characteristic features and all the advantages of the invention will be understood more clearly by reference to the following figures and the detailed description thereof. Therefore, the evaluation should be made by taking into consideration these figures and detailed descriptions.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention should be evaluated together with the figures explained below to be understood together with its embodiments and additional elements in the best way.

Figure 1 Light-guiding element with different angled surfaces

Figure 2 Guiding the beams from the light source to two different lines in the target area with mirrors positioned at different angles Figure 3 Angled mirror guiding the light to the desired region by the circular and linear moving polygons

Figure 4 Guiding the circular and linear multi-surface scanner in sequence to the target area

Figure 5 Scanning in the horizontal plane with the circular movement of the multi-surface scanner

Figure 6 Sending light to different locations in the target area when it moves downward by the linear/circular movement of the multi-surface scanner

Figure 7 Using lenses before to focus and after the scanner system to collimate light for reducing the area of the mirrors (light guiding elements))

Figure 8 Block diagram of the system of the invention

REFERENCE NUMBERS

1-42. Mirror

100. Multi-surface scanner

101. Incident beam

102. Reflected beam

110. Light source

111. Detector component

120. Rotating system

121. Linear movement system

130. Scanned area

140. Reflective optical component

150. Control unit

151. Signal/Data transmission line

DETAILED DESCRIPTION OF THE INVENTION In this detailed description, preferred embodiments of the beam guidance and rangefinder device of the invention are merely explained for a better understanding of the subject of the invention and without any limiting effect.

Figure 1 shows the light directing component with different angled surfaces. This versatile and multi-layered beam guide performs biaxial scanning with circular and linear movement mechanisms.

Figure 2 shows that the beams (101) coming from the light source (110) are directed to two different lines in the target area with mirrors positioned at different angles. The scanning process between the columns is performed by rotating the reflective optical component (140).

Figure 3 shows the orientation of the light to different points in the target area with the angle of the mirrors (1-42) on the multi-surface scanner (100).

Figure 4 shows the sequential light guidance of the multi-surface and layered reflective element that can move circularly and linearly to the target area. The angle of the mirror (1) on the reflective optical component (140) is positioned in a way that it will cast light to the line where area numbered 1 is located in the target area. Scanning is performed in 2 dimensions with the circular and linear movement of the reflective optical component (140). The third- dimensional image is obtained by measuring the flight time.

Figure 5 illustrates the horizontal scanning with the circular movement of the multi-surface scanner (100). It is possible to send light to different locations in the target area with the circular movement of the multi-surface scanner (100).

Figure 6 illustrates sending light to different locations in the target area when it moves downward by the linear/circular movement of the multi-surface scanner (100). High resolution is obtained by the linear and circular movement of the multi-surface scanner (100). It is possible to increase the scan resolution by increasing the number of surfaces.

Figure 7 shows the focusing of the light on the reflective optical component (140) with the lenses used before and after the multi-surface scanner (100) and their collimation afterward. It is possible to use smaller-sized mirrors in this way. Figure 8 shows the block diagram of the system.

A multi-surface scanner (100) is a reflective optical system formed by placing reflective optical components (140) at different angles on each surface. The light beam coming out of the light source (110) is called the light (101). The light (101) from the light source (110) falls into the area where the scanning is desired with the beam (102) reflected from the multisurface scanner (100). The light source (110) can be a wide or narrow band operating, wavelength tunable and constant wavelength pulsed laser, continuous laser, LED or fluorescent lamp, supercontinuum light source.

The detector component (111) may be one or more photodiodes, phototransistors, thermal sensors or single-photon detectors, etc.

The rotating system (120) is a system that enables the multi-surface scanner (100) to move in a circular movement. The linear movement system (121) is a system that allows the multisurface scanner (100) to make the linear movement. The scanned area (130) shows the area to be viewed or perceived. The reflective optical component (140) is a light-reflecting component located on the multi-surface scanner (100). The reflective optical component (140) is a multi-axial polygonal mirror with multiple surfaces. The control unit (150) enables the control of the light source (110), the multi-surface scanner (100), and the detector component (111). There is a signal/data transmission line (150) connecting the control unit (150) to the light source (110), the detector component (111), the rotating system (120) and the linear movement system (121), and transmitting the obtained data to the control unit (150).

As can be seen in detail in Figure 4, the beams emitted from the light source (110) are sent onto the reflective optical component (140) in the multi-surface scanner (100). The incident beams (101) falling on the reflective optical component (140) reflect the incident beam (101) relative to the positions and angles of the reflecting optical component (140). The reflected beam (102) of the reflecting optical component (140) is sent to the scanned area (130) where spatial scanning is desired. The beams (102) reflected from the obstacle or object in the area are detected by the detector component (111). The multi-surface scanner (100) rotates with the rotating system (120) which provides circular movement. When the rotation takes place, the beams (101) from the light source (110) come onto the other reflective optical components (140) and are sent through these elements to different points in space. The beams bouncing back from the object or obstacles in the scanned area (130) are detected by the detector component (111) and the flight time of the transmitted beam is calculated. With the linear movement system (121), the multi-surface scanner (100) also moves linearly on an axis different from the rotation axis. With this movement, scanning is also performed with the other polygons in the system.

Calculation of the flight time of the beam, the control of the light source (110), the multisurface scanner (100), and the detector component (111) is performed by the control unit (150). The control unit (150) is connected to the light source (110), the rotating system (120), the linear movement system (121), and the detector component (111) by the signal/data transmission line (151). Controls and necessary calculations are provided by the data transmitted from this line.

Each surface of the polygons has versatile reflective optical components (140) placed at different angles. The number of reflective optical components (140) in the system can be adjusted. Likewise, the number of light sources (110) used may be increased. Accordingly, the number of detector components (111) may also be increased. The light source (110) may be a wavelength tunable and constant wavelength pulsed laser, continuous laser, LED, or fluorescent, super-continuous light source operating in a wide or narrow bandwidth. The detector components (111) may be avalanche photodiodes, photocells, single -photon detectors, thermal sensors, and/or another type of photodiode. Camera sensors such as CCD, CMOS, and EMCCD are also suitable for use.

The LIDAR systems based on the calculation of the flight times of the beams consist of the multi-surface scanner (100), the multidirectional reflective optical components (140), the rotating system (120), the linear movement system (121), the detector component (111), the light source (110), and the control unit (150). The multi-surface scanner (100) consists of reflective optical components (140) on it. The reflective optical component (140) is based on the principle that the light changes direction with the orientations or designs of the elements on the multi-surface scanner (100). The reflective optical components (140) may consist of mirrors. These mirrors can consist of micro -mirrors, concave mirrors, convex mirrors, and binary optical mirrors. The reflective optical component (140) may be a polygon consisting of one and/or more structural components. The number of reflective optical components (140) may be increased or decreased with respect to the desired scan resolution. The light source (110) may consist of multiple lasers. The detector component (111) may consist of avalanche photodiode, positive, semiconductor, and negative diodes. The detector component (111) may consist of a single detector or multiple detectors. The detector component (111) may consist of avalanche photodiodes. The photodiodes mentioned may be in the form of a focal plane array. The detector component (111) may be electrically or optically connected to the data circuits.

The light source (110) can be a wide or narrow band operating, wavelength tunable or constant wavelength pulsed laser, continuous laser, LED or fluorescent lamp, supercontinuum light source. The specified lasers may be pulsed, wavelength tunable or constant wavelength lasers. The light source (110) may be integrated with its drivers, control unit circuit, optical amplifiers, optical sensors, sensor electronics, power regulating electronics, control electronics, data converter electronics, and processors in the form of one or more light sources, either monolithic or hybrid. The said integration can be made into a module or with multiple modules. The said integration may be monolithic or hybrid.

The rotating system (120) and the linear movement system (121) may consist of the step motor, servomotor, brushless DC motor, DC motor with reducer, or DC motor without the reducer. The rotating system (120) and the linear movement system (121) can be controlled by the control unit (150).

The 3 dimensional LIDAR system, which is based on the flight time calculation of the beams, can be connected with a global positioning system sensor, global positioning system satellite sensor, inertial measurement unit, rotary encoder, visible video camera, infrared video camera, radar, ultrasonic sensor, embedded processor, ethernet control unit, cell modem, wireless controls, data recorder, human machine interface, power supply, coating, wiring and holder devices, in a way that it is connected to at least one or more modules. The system mentioned herein may be in the form of multiple combinations of all the elements mentioned. The said video camera may be integrated on the same printed circuit together with or separately from the light source (110). The said components are connected in a monolithic or hybrid manner with at least one or more lasers, laser drives, laser control unit, optical amplifiers, optical sensors, sensor electronics, power control electronics, control electronics, data converter electronics, and data processing electronics.

Claims

CLAIMS A LIDAR device capable of scanning with a single structure in both vertical and horizontal planes, characterized in that it comprises:

- At least one light source (110) that sends the light beam to scan the scanned area (130),

- At least one multi-surface scanner (100) providing the transmission of the incident beams (101) sent from the said light source (110) to the scanned area (130) and at least one reflective optical component (140) placed at different angles on each surface of the said multi-surface scanner (100),

- At least one detector component (111) which detects the beams (102) reflected from the scanned area (130) and calculates the flight time of the sent beam,

- At least one control unit (150) which controls the light source (110), the multisurface scanner (100), and the detector component (111) and is connected to them by at least one signal/data transmission line (151),

- At least one rotating system (120) that sends beams to different points in space by allowing the said multi-surface scanner (100) to move circularly,

- At least one linear movement system (121) to move the multi-surface scanner (100) linearly on an axis other than the rotational axis.

2. A LIDAR device according to claim 1, characterized in that the said light source (110) comprises a laser or continuous laser or LED or fluorescent or super- continuous light source that operates in a wide or narrow bandwidth, the wavelength of which can be scanned and is pulsed at a constant wavelength. A LIDAR device according to claim 1, characterized in that the said detector component (111) comprises avalanche photodiodes, photocells, one or more photodiodes, phototransistors, single-photon detectors, thermal detectors, and/or another type of photodiode. A LIDAR device according to claim 1, characterized in that the said reflective optical component (140) comprises of at least one mirror (1-42) in the form of a polygon with multiple axes and surfaces. A LIDAR device according to claim 4, characterized in that the said mirrors (1-42) comprise of micro mirror, concave, convex, or binary optical mirrors. A LIDAR device according to claim 1, characterized in that the said rotating system (120) comprises of step motor, servo motor, brushless DC motor, DC motor with reducer, or DC motor without the reducer. A LIDAR device according to claim 1, characterized in that the said linear movement system (121) comprises of step motor, servo motor, brushless DC motor, DC motor with reducer, or DC motor without the reducer. A LIDAR device according to claim 1, characterized in that it may comprise of at least one lens used before and after the multi-surface scanner (100), which allows the light to focus on the reflective optical component (140) and then be collected again.