Rotating mirror angle calibration device and calibration method

Abstract

The invention discloses a rotating mirror angle calibration device which comprises at least one light source, a motor, a motor driver, an angle sensor, a light spot position detection unit and a main control processing unit. Wherein light rays emitted by the light source are reflected to the light spot detection unit through the reflecting surface of the rotating mirror, and projection light spots received by the light spot detection unit are processed by the main control processing unit to obtain the direction angle of the light rays reflected by the reflecting surface. According to the optical lever principle, a light beam is emitted to the reflecting surface of the rotating mirror, the light beam is projected to the light spot position detection unit through a light path with a certain length, the angle of the reflecting surface is obtained by detecting the central position of a light spot, and the angle calibration precision is improved; in addition, a detection light path and rotating mirror control are integrated into one detection device, off-line detection of the rotating mirror can be achieved, rotating mirror calibration and system equipment calibration are separated, and calibration efficiency is improved.

Description

Technical Field

[0001] The present application belongs to the field of laser scanning technology, and in particular relates to a rotating mirror angle calibration device and a rotating mirror angle calibration method. Background Art

[0002] An optical scanning mirror is an optical element used to change the direction of light beam propagation and realize the function of light beam scanning. It is usually a rotating mirror with multiple reflective surfaces, which is driven to rotate by a motor or other driving device. When the light beam is irradiated on the reflective surface of the mirror, the direction of the reflected light beam will change continuously as the mirror rotates, thereby realizing scanning of a certain area. Optical scanning mirrors are widely used in laser printing, laser radar, optical detection and other equipment. For example, in laser printing equipment, the optical scanning mirror is used to reflect the laser beam to the surface of the drum, and realizes line-by-line scanning of the drum through rapid rotation, thereby converting the digital information in the computer into an electrostatic latent image on the drum. In a rotating mirror laser radar, the measuring laser is incident on the scanning mirror, and the object in front is quickly scanned horizontally as the mirror rotates, which can effectively expand the laser radar scanning field of view.

[0003] In the above-mentioned rotating mirror equipment, the rotating mirror scanning system is usually composed of a multi-faceted reflector, a motor, an angle sensor, a control system, and a beam transceiver; wherein the angle sensor feeds back the rotation angle of the rotating mirror in real time, and the control system controls the laser transceiver to transmit or receive laser signals according to the angle fed back by the angle sensor. In the mass production process, there are manufacturing tolerances in the production and bonding of the lenses, and there are also certain assembly tolerances between the angle sensor and the zero position of the rotating mirror. The above manufacturing tolerances and assembly tolerances will cause the optical paths of the two adjacent rotating mirror reflection surfaces to not completely overlap, reducing the scanning repeatability and accuracy. Therefore, in order for the rotating mirror scanning equipment to work properly, the rotating mirror angle should be calibrated before leaving the factory.

[0004] The contents of the rotating mirror angle calibration include: the incident light zero angle of each reflective surface, the pitch deviation angle, and the zero-degree deviation angle between the angle sensor and the rotating mirror. In the existing manufacturing process, measurement means are often added during the assembly process to reduce the above-mentioned manufacturing tolerance and assembly tolerance, so as to achieve the purpose of not requiring calibration, but this will reduce production efficiency. Or after assembling the entire set of rotating mirror scanning devices and other devices into a complete set of equipment, the system calibration is performed. The disadvantage is that the system needs to be recalibrated after replacing the rotating mirror module, which reduces reusability. Summary of the invention

[0005] On this basis, the present invention proposes a rotating mirror angle calibration device and calibration method, and the specific technical scheme is as follows.

[0006] A rotating mirror angle calibration device, used for calibrating the initial reflected light direction angle of each reflecting surface of the rotating mirror; the rotating mirror comprises N reflecting surfaces, N is a natural number greater than 3; characterized in that it comprises at least one light source, a motor and a motor driver, an angle sensor, a light spot position detection unit and a main control processing unit; The main control processing unit sends a control signal to the motor driver to drive the motor to rotate to a specified angle or at a specified speed; the angle sensor is fixed on the motor to output the rotation angle of the rotating mirror in real time; The light emitted by the light source is reflected by the reflection surface of the rotating mirror to the light spot detection unit, and the projection light spot received by the light spot detection unit is processed by the main control processing unit to obtain the initial reflection light direction angle of the current reflection surface of the rotating mirror.

[0007] Preferably, the light spot detection unit includes a projection screen and a camera aimed at the projection screen; the light emitted by the light source is reflected onto the projection screen by the rotating mirror, and a light spot image is obtained by photographing the camera, and the light spot image is processed by the main control processing unit to obtain an initial reflected light direction angle of the current reflection surface of the rotating mirror.

[0008] Preferably, the light spot detection unit includes a four-quadrant photodetector and a signal processing device; the light emitted by the light source is reflected onto the four-quadrant photodetector via the reflective surface of the rotating mirror, and is converted into an offset signal of the projected light spot relative to the center of the four-quadrant photodetector after being processed by the signal processing device. The offset signal is sent to the main control processing unit for processing to obtain the initial reflected light direction angle of the current reflective surface of the rotating mirror. Preferably, the motor further comprises a power-off non-volatile memory, the initial reflected light direction angle of each reflective surface of the rotating mirror is written into the non-volatile memory, and the power-off non-volatile memory is an EEPROM or a flash chip.

[0009] Preferably, the angle sensor is a magnetic grating angle encoder or a grating encoder.

[0010] Preferably, the angle resolution of the angle sensor should be better than 0.01° Preferably, the light source is a single-point laser light source or a cross-line light source in the visible light band.

[0011] Preferably, the rotating mirror angle calibration device further comprises a housing, and the light source, the motor driver, the light spot position detection unit and the main control processing unit are installed in the housing.

[0012] A method for calibrating a rotating mirror angle, using the rotating mirror angle calibration device as described above, comprises the following steps: Step 1, the main control processing unit controls the motor to rotate the rotating mirror to a default starting angle of the first reflective surface, and the main control processing unit controls the light source to emit a light beam, and the light beam is reflected by the first reflective surface of the rotating mirror to the projection screen; Step 2, the camera collects the spot image on the projection screen and sends it to the main control processing unit, and obtains the initial reflected light direction angle of the first reflection surface of the rotating mirror after image processing; Step 3, the main control processing unit controls the motor to rotate the rotating mirror to the default starting angle of the second reflecting surface, and the main control processing unit controls the light source to emit a light beam, and the light beam is reflected onto the projection screen through the second reflecting surface of the rotating mirror; the camera collects the light spot image on the projection screen, and adjusts the starting light emitting angle of the second reflecting surface through the main control processing unit, so that the light spot position on the projection screen coincides with the light spot position of the light beam reflected from the first reflecting surface to the projection screen, and records the rotation angle of the angle sensor at this time, which is marked as the initial reflected light direction angle corresponding to the second reflecting surface; Step 4, repeat the same operation as that on the second reflective surface in step 3 for the third to Nth reflective surfaces of the rotating mirror, so that the light spot positions of the light beam reflected by all reflective surfaces on the projection screen coincide with each other, and obtain the initial reflected light direction angle of each reflective surface of the rotating mirror through the angle sensor.

[0013] A method for calibrating a rotating mirror angle, using the rotating mirror angle calibration device as described above, comprises the following steps: Step 1, the main control processing unit controls the motor to rotate the rotating mirror to a default starting angle of the first reflective surface, and the main control processing unit controls the light source to emit a light beam, and the light beam is reflected by the first reflective surface of the rotating mirror and then projected onto the four-quadrant photoelectric sensor, forming a projection light spot on the four-quadrant photoelectric sensor; Step 2, the four-quadrant photoelectric detector outputs the center coordinate position of the light spot and sends it to the main control processing unit, which converts the center coordinate position of the projected light spot into the initial reflected light direction angle of the first reflecting surface; Step 3, the main control processing unit controls the motor to rotate the rotating mirror to the default starting angle of the second reflecting surface, and the main control processing unit controls the light source to emit a light beam, and the light beam is reflected by the second reflecting surface of the rotating mirror and then projected onto the four-quadrant photoelectric sensor, forming a projection light spot on the four-quadrant photoelectric sensor; adjusting the starting light emitting angle of the second reflecting surface so that the position of the projection light spot on the four-quadrant photoelectric sensor coincides with the position of the projection light spot on the first reflecting surface, and recording the rotation angle of the angle sensor at this time, which is marked as the initial reflected light direction angle corresponding to the second reflecting surface; Step 4, repeat the same operation as that on the second reflective surface in step 3 for the third to Nth reflective surfaces of the rotating mirror, so that the positions of the projected light spots reflected by all reflective surfaces to the four-quadrant photoelectric sensor coincide with each other, and obtain the initial reflected light direction angle of each reflective surface of the rotating mirror through the angle sensor.

[0014] The rotating mirror angle calibration device and calibration method provided by the present invention have the following technical effects: 1) The present invention uses the principle of optical lever to incident a beam of light onto the reflective surface of the rotating mirror, and projects it onto the light spot position detection unit through a certain length of optical path. The angle of the reflective surface is obtained by detecting the center position of the light spot, thereby improving the accuracy of angle calibration; 2) The present invention integrates the detection optical path and the rotating mirror control into a detection device, which can realize the offline detection of the rotating mirror, separate the rotating mirror calibration and the system equipment calibration, and improve the calibration efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The accompanying drawings are used to provide further understanding of the present application and constitute a part of the specification. They are used to explain the present application together with the embodiments of the present application and do not constitute a limitation of the present application.

[0016] Figure 1 A system diagram of the rotating mirror calibration device provided in Example 1 of the present application; Figure 2 A structural diagram of the rotating mirror calibration device provided in Example 1 of the present application; Figure 3 An optical path diagram of the rotating mirror calibration device provided in Example 1 of the present application; Figure 4 This is a structural diagram of the rotating mirror calibration device provided in Example 2 of the present application.

[0017] Among them, 101. rotating mirror, 201. projection screen, 301. light source, 401. light beam, 501. motor, 601. camera, 701. main control processing unit, 801. four-quadrant photoelectric sensor, 901. zero degree mark of rotating mirror, 1001. light spot position detection unit; S1. first reflection surface, S2. second reflection surface, S3. third reflection surface, S4. fourth reflection surface. DETAILED DESCRIPTION

[0018] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0019] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicating orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0020] Example 1 This embodiment provides a rotating mirror angle calibration device and a calibration method thereof.

[0021] Rotating mirror angle calibration device Figure 1 , Figure 2 As shown, it includes at least one light source 301, a rotating mirror 101, a motor 501 and a motor driver (not shown in the figure) for driving the rotating mirror to rotate, an angle sensor for feeding back the angle of the rotating mirror (the angle sensor is hidden in the rotating mirror 101 and not shown in the figure), a main control processing unit 701, and a light spot position detection unit. The rotating mirror 101 includes a plurality of reflection surfaces S1-S4, and the light spot position detection unit 1001 includes a projection screen 201 and a camera 601.

[0022] In this embodiment, the rotating mirror 101 is fixed on the outer rotor of the motor 501 and rotates together with the outer rotor of the motor 501. The main control processing unit 701 sends a control signal to the motor driver to drive the motor 501 to rotate to a specified angle or at a specified speed. The angle sensor is fixed to one end of the motor 501 and outputs the current angle of the rotating mirror 101 in real time.

[0023] The light source 301 emits a light beam 401, which is reflected by the reflection surface of the rotating mirror 101 onto the projection screen 201 to form a projection spot. The camera 601 is aimed at the projection screen 201 to capture a light spot image. The position and angle between the light source 301 and the rotating mirror 101 are fixed, and the position of the projection spot on the projection screen 201 depends on the rotation angle of the rotating mirror 101. The light spot image captured by the camera 601 is calculated by the main control processing unit 701 to obtain the position of the projection spot on the projection screen 201, and the angle of the rotating mirror 101 at this time can be inferred.

[0024] Preferably, in this example, the angle sensor is a magnetic grating angle encoder or a grating encoder. Further, the angle resolution of the angle sensor should be better than 0.01°.

[0025] Preferably, in this embodiment, the light source is a single-point laser light source or a cross light source in the visible light band, so as to more accurately extract the center position of the light spot.

[0026] Preferably, the rotating mirror calibration device of this embodiment further includes a housing, in which the motor driver, the projection screen 201, the camera 601, the light source 301 and the main control processing unit 701 are installed, so as to shield the interference of ambient light.

[0027] The specific optical path and method of the rotating mirror calibration device of this embodiment for detecting the direction angle of the initial reflected light of each reflecting surface of the rotating mirror are as follows.

[0028] like Figure 3 As shown, the rotating mirror 101 may have multiple reflective surfaces, and four reflective surfaces are used as an example, which are marked as reflective surfaces S1, S2, S3, and S4 respectively. The rotating mirror 101 rotates counterclockwise around its central axis. The small black square between the reflective surfaces S1 and S4 is the zero-degree mark 901 of the rotating mirror, corresponding to the zero-degree signal of the angle sensor; the arrow indicates the zero-degree indication direction of the rotating mirror 101, and the angle between the arrow and the horizontal right direction is recorded as the rotation angle of the rotating mirror. Figure 3 In the figure, the light beam emitted by the light source 301 is vertically upward, and after being reflected by the reflection surface S1 of the rotating mirror 101, it is projected onto the projection screen of the light spot detection unit.

[0029] Ideally, when the rotation angle of the rotating mirror 101 is 0 degrees, the reflected light 401 is emitted in the horizontal right direction. When there is a manufacturing error in the reflective surface S1, the reflected light 401 will deviate from the ideal position. By detecting the position of the projected light spot on the projection screen 201, the offset angle of the reflective surface S1, that is, the initial reflected light direction angle, can be calculated. Similarly, the above principle can be used to detect the initial reflected light direction angle of each reflective surface, that is, calibration data.

[0030] On this basis, preferably, in this embodiment, the motor 501 of the rotating mirror calibration device also includes a power-off non-volatile memory in which the initial reflected light direction angle corresponding to each reflective surface is written. After the rotating mirror 101 and the motor 501 are installed and integrated into the system device, the system device reads the initial reflected light direction angle on the power-off non-volatile memory and recalibrates the initial light-emitting moment so that the emission spots of all reflective surfaces on the rotating mirror 101 overlap. Preferably, the power-off non-volatile memory can be an EEPROM or a flash chip for storing calibration data.

[0031] Therefore, the method of calibrating each reflective surface of the rotating mirror using the rotation calibration device of this embodiment includes: Step 1, the main control processing unit 701 controls the motor 501 to rotate the rotating mirror 101 to the default starting angle of the first reflection surface S1, and the main control processing unit 701 controls the light source 301 to emit the light beam 401, and the light beam is reflected by the first reflection surface S1 of the rotating mirror 101 to the projection screen; Step 2, the camera 601 collects the spot image on the projection screen 201 and sends it to the main control processing unit 701 to calculate the initial reflected light direction angle of the first reflection surface S1 of the rotating mirror 101; Step 3, the main control processing unit 701 controls the motor 501 to rotate the rotating mirror to the default starting angle of the second reflecting surface S2, and the main control processing unit 701 controls the light source 301 to emit the light beam 401, and the light beam 401 is reflected onto the projection screen through the second reflecting surface S2 of the rotating mirror 101; the camera 601 collects the light spot image on the projection screen, and adjusts the starting light-emitting angle of the second reflecting surface S2 through the main control unit 701, so that the light spot position on the projection screen S2 coincides with the light spot position of the light beam reflected by the first reflecting surface S1 to the projection screen, and records the rotation angle of the angle sensor at this time, which is marked as the initial reflected light direction angle corresponding to the second reflecting surface S2.

[0032] Step 4, repeat the same operation as that on the second reflecting surface in step 3 for the 3rd to 4th reflecting surfaces of the rotating mirror, so that the positions of the light spots reflected by all reflecting surfaces on the projection screen coincide with each other, and obtain the initial reflected light direction angle of each reflecting surface of the rotating mirror, i.e., calibration data, through the angle sensor.

[0033] Preferably, the step calibration method may further include step 5, writing the initial reflected light direction angle corresponding to each reflective surface into the power-off non-volatile memory of the motor 501. After the rotating mirror 101 and the motor 501 are installed and integrated into the system device, the system device reads the calibration data on the power-off non-volatile memory to recalibrate the initial light emission time so that the emission spots of all reflective surfaces on the rotating mirror overlap.

[0034] Example 2 This embodiment provides a rotating mirror angle calibration device and a calibration method thereof.

[0035] Rotating mirror angle calibration device Figure 4 As shown, it includes at least one light source 301, a rotating mirror 101, a motor 501 and a motor driver (not shown in the figure) for driving the rotating mirror to rotate, an angle sensor for feeding back the angle of the rotating mirror (the angle sensor is hidden in the rotating mirror 101 and not shown in the figure), a main control processing unit 701, and a light spot position detection unit. The rotating mirror 101 includes multiple reflection surfaces, and the light spot position detection unit includes a four-quadrant photoelectric sensor 801 and a signal processing device.

[0036] In this embodiment, the rotating mirror 101 is fixed on the outer rotor of the motor 501 and rotates together with the outer rotor of the motor 501. The main control processing unit 701 sends a control signal to the motor driver to drive the motor 501 to rotate to a specified angle or at a specified speed. The angle sensor is fixed to one end of the motor 501 and outputs the rotation angle of the lower reflective surface of the rotating mirror in real time.

[0037] The light source 301 emits a light beam 401, which is reflected by the reflection surface of the rotating mirror 101 onto the four-quadrant detector 801 to form a projection light spot. The position and angle between the light source 301 and the rotating mirror 101 are fixed, and the position of the projection light spot on the four-quadrant detector 801 depends on the rotation angle of the rotating mirror 101. The signal processing device calculates the center coordinate position of the projection light spot relative to the four-quadrant detector 801, and the center coordinate position is sent to the main control processing unit 701 for processing to obtain the angle data of the current reflection surface of the rotating mirror 101 and the calibration data.

[0038] Preferably, in this embodiment, the angle sensor is a magnetic grating angle encoder or a grating encoder. Further, the angle resolution of the angle sensor should be better than 0.01°.

[0039] Preferably, in this embodiment, the light source is a single-point laser light source or a cross light source in the visible light band, so as to more accurately extract the center position of the light spot.

[0040] Preferably, the rotating mirror calibration device of this embodiment further includes a housing, in which the motor driver, the four-quadrant detector 801, the signal processing device, the light source 301 and the main control processing unit 701 are installed, so as to shield the interference of ambient light.

[0041] Preferably, in this embodiment, the motor 501 of the rotating mirror calibration device also includes a power-off non-volatile memory into which the calibration data corresponding to each reflective surface is written. After the rotating mirror 101 and the motor 501 are installed and integrated into the system device, the system device reads the calibration data on the power-off non-volatile memory to recalibrate the initial light-emitting moment so that the emission spots of all reflective surfaces on the rotating mirror 101 overlap. Preferably, the power-off non-volatile memory can be an EEPROM or a flash chip for storing calibration data.

[0042] Therefore, the method for calibrating each reflective surface of the rotating mirror 101 using the rotating mirror calibration device of this embodiment includes: Step 1, the main control processing unit 701 controls the motor 501 to rotate the rotating mirror 101 to the default starting angle of the first reflection surface S1, and the main control processing unit 701 controls the light source 301 to emit the light beam 401, and the light beam is reflected by the first reflection surface S1 of the rotating mirror 101 to the four-quadrant detector 801; Step 2, the signal processing device calculates the center coordinate position of the projected light spot relative to the four-quadrant detector 801, and the center coordinate position is sent to the main control processing unit 701 for processing to obtain the initial reflected light direction angle of the current reflecting surface of the rotating mirror 101; Step 3, the main control processing unit 701 controls the motor 501 to rotate the rotating mirror to the default starting angle of the second reflecting surface S2, and the main control processing unit 701 controls the light source 301 to emit the light beam 401, and the light beam 401 is reflected by the second reflecting surface S2 of the rotating mirror 101 to the four-quadrant detector 801; the main control processing unit 701 adjusts the starting light-emitting angle of the second reflecting surface S2 so that the light spot position on the four-quadrant detector 801 coincides with the light spot position of the light beam reflected by the first reflecting surface S1 to the four-quadrant detector 801, and records the rotation angle of the angle sensor at this time, which is marked as the initial reflected light direction angle corresponding to the second reflecting surface S2.

[0043] Step 4, repeat the same operation as that on the second reflecting surface in step 3 for the 3rd to 4th reflecting surfaces of the rotating mirror, so that the light spot positions of the light beams reflected by all reflecting surfaces on the four-quadrant detector 801 coincide with each other, and obtain the initial reflected light direction angle of each reflecting surface of the rotating mirror, i.e., the calibration data, through the angle sensor.

[0044] Preferably, the step calibration method may further include step 5, writing the calibration data corresponding to each reflective surface into the power-off non-volatile memory of the motor 501. After the rotating mirror 101 and the motor 501 are installed and integrated into the system device, the system device reads the calibration data in the power-off non-volatile memory to recalibrate the initial light emission time so that the emission spots of all reflective surfaces on the rotating mirror overlap.

[0045] Although the embodiments of the present application have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present application, and that the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A rotating mirror angle calibration device, used for calibrating the initial reflected light direction angle of each reflecting surface of the rotating mirror; the rotating mirror comprises N reflecting surfaces, N is a natural number greater than 3; characterized in that, It includes at least one light source, a motor and a motor driver, an angle sensor, a light spot position detection unit and a main control processing unit; The main control processing unit sends a control signal to the motor driver to drive the motor to rotate to a specified angle or at a specified speed; the angle sensor is fixed on the motor to output the rotation angle of the rotating mirror in real time; The light emitted by the light source is reflected by the reflection surface of the rotating mirror to the light spot detection unit, and the projection light spot received by the light spot detection unit is processed by the main control processing unit to obtain the initial reflection light direction angle of the current reflection surface of the rotating mirror.

2. A rotating mirror angle calibration device as claimed in claim 1, characterized in that: The light spot detection unit includes a projection screen and a camera aimed at the projection screen for shooting; the light emitted by the light source is reflected onto the projection screen by the rotating mirror, and a light spot image is obtained by shooting with the camera. The light spot image is processed by the main control processing unit to obtain an initial reflected light direction angle of the current reflection surface of the rotating mirror.

3. The rotating mirror angle calibration device according to claim 1, characterized in that: The light spot detection unit includes a four-quadrant photodetector and a signal processing device; the light emitted by the light source is reflected onto the four-quadrant photodetector via the reflective surface of the rotating mirror, and is converted into an offset signal of the projected light spot relative to the center of the four-quadrant photodetector after being processed by the signal processing device. The offset signal is sent to the main control processing unit for processing to obtain the initial reflected light direction angle of the current reflective surface of the rotating mirror.

4. The rotating mirror angle calibration device according to claim 1, characterized in that: The motor further comprises a power-off non-volatile memory, and the initial reflected light direction angle of each reflecting surface of the rotating mirror is written into the non-volatile memory, and the power-off non-volatile memory is an EEPROM or a flash chip.

5. The rotating mirror angle calibration device according to claim 1, characterized in that: The angle sensor is a magnetic grating angle encoder or a grating encoder.

6. A rotating mirror angle calibration device as claimed in claim 5, characterized in that: The angle resolution of the angle sensor should be better than 0.01°.

7. The rotating mirror angle calibration device according to claim 1, characterized in that: The light source is a single-point laser light source or a cross-line light source in the visible light band.

8. The rotating mirror angle calibration device according to claim 1, characterized in that: The rotating mirror angle calibration device also includes a housing, in which the light source, the motor driver, the light spot position detection unit and the main control processing unit are installed.

9. A method for calibrating a rotating mirror angle, characterized in that: The application of the rotating mirror angle calibration device as claimed in claim 2 comprises the following steps: Step 1, the main control processing unit controls the motor to rotate the rotating mirror to a default starting angle of the first reflective surface, and the main control processing unit controls the light source to emit a light beam, and the light beam is reflected by the first reflective surface of the rotating mirror to the projection screen; Step 2, the camera collects the spot image on the projection screen and sends it to the main control processing unit, and obtains the initial reflected light direction angle of the first reflection surface of the rotating mirror after image processing; Step 3, the main control processing unit controls the motor to rotate the rotating mirror to the default starting angle of the second reflecting surface, and the main control processing unit controls the light source to emit a light beam, and the light beam is reflected onto the projection screen through the second reflecting surface of the rotating mirror; the camera collects the light spot image on the projection screen, and adjusts the starting light emitting angle of the second reflecting surface through the main control processing unit, so that the light spot position on the projection screen coincides with the light spot position of the light beam reflected from the first reflecting surface to the projection screen, and records the rotation angle of the angle sensor at this time, which is marked as the initial reflected light direction angle corresponding to the second reflecting surface; Step 4, repeat the same operation as that on the second reflective surface in step 3 for the third to Nth reflective surfaces of the rotating mirror, so that the light spot positions of the light beam reflected by all reflective surfaces on the projection screen coincide with each other, and obtain the initial reflected light direction angle of each reflective surface of the rotating mirror through the angle sensor.

10. A method for calibrating a rotating mirror angle, characterized in that: The application of the rotating mirror angle calibration device as claimed in claim 3 comprises the following steps: Step 1, the main control processing unit controls the motor to rotate the rotating mirror to a default starting angle of the first reflective surface, and the main control processing unit controls the light source to emit a light beam, and the light beam is reflected by the first reflective surface of the rotating mirror and then projected onto the four-quadrant photoelectric sensor, forming a projection light spot on the four-quadrant photoelectric sensor; Step 2, the four-quadrant photoelectric detector outputs the center coordinate position of the light spot and sends it to the main control processing unit, which converts the center coordinate position of the projected light spot into the initial reflected light direction angle of the first reflecting surface; Step 3, the main control processing unit controls the motor to rotate the rotating mirror to the default starting angle of the second reflecting surface, and the main control processing unit controls the light source to emit a light beam, and the light beam is reflected by the second reflecting surface of the rotating mirror and then projected onto the four-quadrant photoelectric sensor, forming a projection light spot on the four-quadrant photoelectric sensor; adjusting the starting light emitting angle of the second reflecting surface so that the position of the projection light spot on the four-quadrant photoelectric sensor coincides with the position of the projection light spot on the first reflecting surface, and recording the rotation angle of the angle sensor at this time, which is marked as the initial reflected light direction angle corresponding to the second reflecting surface; Step 4, repeat the same operation as that on the second reflective surface in step 3 for the third to Nth reflective surfaces of the rotating mirror, so that the positions of the projected light spots reflected by all reflective surfaces to the four-quadrant photoelectric sensor coincide with each other, and obtain the initial reflected light direction angle of each reflective surface of the rotating mirror through the angle sensor.

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