Optical detection device

Abstract

The invention discloses an optical detection device, which comprises a rotating platform capable of performing horizontal azimuth angle rotation around a central shaft, and a detection unit arranged on a fulcrum and capable of performing vertical pitch angle deflection around the fulcrum, and the detection unit comprises an active detection unit and a passive detection unit which are coaxially arranged with the same aperture, and the common light path part is also provided with an image rotation compensation assembly. The image rotation compensation assembly comprises a first wedge-shaped mirror and a second wedge-shaped mirror which can be independently controlled to rotate. When the rotating platform rotates, the passive detection unit realizes image stabilization by setting the two wedge-shaped mirrors to rotate with opposite phases and the same speed value. And when the rotating platform does not rotate, the active detection unit sets different relative speeds and directions through the two wedge-shaped mirrors to realize scanning detection of an external space.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical detection, and in particular relates to an optical detection device. Background Art

[0002] A search revealed a May 2015 article in the Infrared and Laser literature titled "Research on Image Motion Compensation Using a Rotating Dual Wedge" describing a method for image motion compensation using dual wedge mirrors. However, the control principle described in the article, "Design of a Rotating Dual Wedge Image Motion Compensation System," is as follows: During the exposure time, a speed control module is used to ensure that the angular deflection rate of the wedge is consistent with the instantaneous rotational speed of the turntable. However, calculations and verification by the inventors have shown that image motion compensation cannot be achieved if the angular deflection rate of the wedge is consistent with the instantaneous rotational speed of the turntable. Furthermore, due to the "slow-fast-slow" nature of dual wedge mirror compensation, localized image smearing can occur in many cases. Therefore, this method requires necessary improvements for certain precision detection applications.

[0003] The information disclosed in this background technology section is only intended to enhance understanding of the overall background of the invention and should not be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art. Summary of the Invention

[0004] The object of the present invention is to provide a device for detecting foreign matter on a planar surface, thereby solving the problem of how an image rotation compensation component works in passive and active detection respectively to achieve image stabilization and laser scanning.

[0005] To achieve the above object, the present invention provides an optical detection device, comprising: a rotating platform, arranged outside the detection area and driven by an azimuth motor to perform horizontal azimuth rotation around a central axis; The detection unit includes a passive detection unit and an active detection unit, which is fixed at the pitch fulcrum of the rotating platform and driven by the pitch motor to achieve pitch deflection; the passive detection unit includes at least one detection imaging camera, and the active detection unit includes a laser emitting component and a laser receiving camera; a synthesizer mirror configured to synthesize the wavelengths of the optical paths of the passive detection unit and the active detection unit to form a common aperture detection optical path; An image rotation compensation assembly is provided between the synthesizer and the external light, and includes coaxial wedge mirrors 1 and 2, wherein the offset between the central axis of the rotation axis of the wedge mirrors 1 and 2 and the center line of the imaging light path is less than 5 mm; When the passive detection unit is working, the rotating platform drives the detection unit to rotate horizontally, and the wedge mirror-1 and wedge mirror-2 rotate in opposite directions at the same speed value ω, and the following parameter relationship is satisfied: In the 180° rotation compensation range: angular velocity ω = ω1*π / γ, and wedge angle α satisfies 4α = 2θ = γ; In the 90° rotation compensation range: angular velocity ω = ω1*π / γ, and wedge angle α satisfies 2α = θ = γ; Where: ω1 is the angular velocity of the rotating platform, γ is the image shift angle caused by the rotating platform during the exposure time t2 of the imaging camera; When the active detection unit is working, the wedge mirror-1 and the wedge mirror-2 operate at independent angular velocities ω2, ω3 and rotation directions, so that the laser output by the laser emitting assembly forms a maximum 2α angle scan to the outside, and the laser receiving camera receives the target reflection signal.

[0006] With this arrangement, since the output light spot of each rotating wedge mirror satisfies the motion law of the sine function or the cosine function, the rotation of the wedge mirror in opposite directions causes the synthesized light beam to reciprocate only in one axial direction. Therefore, within the above-mentioned 180° interval, the light spot has a "slow-fast-slow" movement law on the Y-axis. Therefore, although the reciprocating motion of the light beam can compensate for image shift, there is still the possibility that the change in speed will cause inconsistency in the image compensation speed and produce local image tailing.

[0007] If a 90° segment (fast moving interval) is used for compensation, the possibility of image tailing can be reduced.

[0008] The above Y-axis is a description of a direction, the purpose of which is to clearly describe the movement law of the light spot.

[0009] Preferably, in the above technical solution, the image rotation compensation component further includes: The motor and transmission pair driving wedge mirror-1 and wedge mirror-2; An angle sensor is provided on the rotation axis of the wedge mirror or the motor shaft; In the initial state, the maximum thickness points A of the two wedge-shaped mirrors are located in the same plane-1. Plane-1 contains the central axis of the wedge-shaped mirror rotation axis and the Y axis perpendicularly intersecting at point O, and is parallel to the azimuth rotation plane of the rotating platform. The motor drives the two wedge-shaped mirrors to rotate in opposite directions at the same angular velocity ω through the transmission pair, so that the light beam produces a compensatory displacement along the Y-axis in plane-1.

[0010] Preferably, in the above technical solution, the maximum beam tilt angle θ of the two wedge-shaped mirrors is max =2α, the maximum compensation angle is 4α, where α is the wedge angle of a single wedge mirror.

[0011] Preferably, in the above technical solution, the angle sensor generates a synchronization pulse when the wedge mirror rotates to the initial point, triggering the following operations: When using the 180° compensation interval, the initial point is the moment when point A leaves plane -1; When using the 90° compensation interval, the initial point is the moment when point A rotates to ±45°; The synchronous pulse triggers the light source emitter to start emitting light for a duration of t1, and starts the imaging camera exposure for a duration of t2≤t1.

[0012] Preferably, in the above technical solution, the transmission pair is a gear set or a pulley mechanism.

[0013] Preferably, in the above technical solution, when the active detection unit is working, the deflection angles of wedge mirror-1 and wedge mirror-2 satisfy: Bevel angle = α sin(ω2 t+φ)+α sin(ω3 t+ψ), where α is the slope of the wedge mirror, ω2 and ω3 are angular velocities, and φ and ψ are initial phases; When ω2≠ω3, the laser scanning trajectory is lotus-shaped, the scanning density is determined by ω2 / ω3, and the time to complete a circle of scanning is determined by the smaller value of ω2 and ω3.

[0014] Compared with the prior art, the present invention has the following beneficial effects: The image motion compensation problem existing in the existing technical solutions for optical detection is improved, and the frequency of low-speed compensation of the mechanical deflection mirror is greatly increased, thereby realizing a solution of using continuous rotational motion for compensation instead of a solution of using intermittent deflection motion for compensation, improving the imaging quality, meeting the image stabilization requirements of 20HZ-300HZ frame rate cameras, and reducing the cost of using fast-reflection mirrors.

[0015] The deficiencies of the technical solutions for double wedge mirror compensation in the literature were corrected, and the relationship between the angular velocity of the wedge mirror and the angular velocity of the rotating platform, as well as the relationship between the maximum compensation angle and the wedge angle, were redefined, making high-speed compensation possible.

[0016] Further computational verification of the shortcomings of dual wedge mirror compensation revealed the "slow-fast-slow" motion pattern of the light spot on the Y-axis within the 180° compensation range, revealing the possibility of localized image smearing caused by inconsistent image compensation speeds. The team proposed a technical solution to reduce image smear by using a 90° segment (the fast motion range) for compensation. This solution not only resolves image smearing and improves image quality, but also increases the compensation frequency, thereby improving the camera's frame rate and enabling higher-precision and faster detection.

[0017] The detection area is scanned in an arc shape by continuously rotating the rotating platform. The imaging camera can complete the scanning of the entire arc scanning area with one field of view and aperture setting. During this period, the double wedge mirror rotates at high speed to complete image motion compensation. It is fast and efficient, and is suitable for applications where high detection speed is required.

[0018] The rotating platform is used to enter the device for detecting idle areas, adjust the field of view angle and aperture of the imaging camera, and the size of the emission beam of the emitting light source, and divide the adjustment time and the detection time. This fully utilizes the advantage of the continuous rotation of the rotating platform, so that there is no need to adjust the camera during detection, and no targets are detected during adjustment, which improves work efficiency and avoids a series of problems caused by the intermittent operation of the rotating platform, such as shortened mechanical life, mechanical vibration damage to the detection unit, and long start / pause time.

[0019] By utilizing the high-speed rotation of the double wedge mirror, the laser of the laser active detection unit is scanned by the double wedge mirror, and dual detection (passive detection and active detection) can be achieved by sharing one double wedge mirror, thereby reducing the size of the device, simplifying the structure of the device, reducing design difficulty and reducing processing costs.

[0020] A double wedge mirror unit has two functions: one is the image rotation compensation function during passive camera detection, and the other is the scanning function during active detection, thereby making multi-target detection possible during active detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a structural diagram; Figure 2 for Figure 1 Side view of Figure 3 Schematic diagram of image compensation using a 180° rotation interval of a wedge mirror; Figure 4 Schematic diagram of image compensation using a 90° rotation interval of a wedge mirror; Figure 5 and Figure 6 Schematic diagram of the rotating platform rotating so that the image moves on the target surface; Figure 7 and Figure 8 This is a schematic diagram of the image moving on the target surface when the rotation compensation component is not working; Figure 9 This is a schematic diagram of the image being stationary on the target surface when the rotation compensation component is working; Figure 10 and Figure 11 is a schematic diagram of an image rotation compensation component as a scanning unit; Figure 12 and Figure 13 Schematic diagram of an image rotation compensation component used as a scanning unit to form a laser scanning line. DETAILED DESCRIPTION

[0022] The specific embodiments of the present invention are described in detail below, but it should be understood that the protection scope of the present invention is not limited by the specific embodiments.

[0023] Unless expressly stated otherwise, throughout the specification and claims, the term "comprise" or variations such as "include" or "comprising", etc., will be understood to include the stated elements or components but not to exclude other elements or other components.

[0024] Example 1

[0025] An optical detection device, comprising: The rotating platform is set outside the detection area and is driven by the azimuth motor to rotate horizontally around the central axis; The detection unit includes a passive detection unit and an active detection unit, which are rotatably fixed at the pitch fulcrum of the rotating platform and driven by the pitch motor to achieve pitch deflection; the passive detection unit includes at least one detection imaging camera, and the active detection unit includes a laser emitting component and a laser receiving camera; The synthesizer mirror synthesizes the corresponding wavelengths of the passive detection unit and the active detection unit to form a common aperture for external detection; An image rotation compensation assembly is provided between the synthesizer and the external light, and includes wedge mirror 1 and wedge mirror 2, wherein the offset between the central axis of the rotation axis of wedge mirror 1 and wedge mirror 2 and the center line of the imaging light path is less than 5 mm; When the passive detection unit is working, the rotating platform drives the detection unit to rotate in the horizontal azimuth. Wedge mirror-1 and wedge mirror-2 rotate in opposite phases and have the same rotation speed value ω. The two wedge mirrors satisfy the following parameter relationship: When using the 180° rotation compensation interval: angular velocity ω = ω1*π / γ, and the wedge angle α satisfies 4α = 2θ = γ; When a 90° rotation compensation interval is used: the angular velocity ω = ω1 * π / γ, and the wedge angle α satisfies: 2α = θ = γ; where: ω is the angular velocity of the two wedge mirrors, ω1 is the angular velocity of the rotating platform, and γ is the image shift angle caused by the rotating platform within the imaging camera exposure time t2.

[0026] In this way, the imaging camera image of the passive detection unit is stabilized.

[0027] When the active detection unit is working, the wedge mirror-1 and wedge mirror-2 of the image rotation compensation component form a double wedge mirror scanning unit with independent rotation speed ω2, ω3 and rotation direction settings, so as to realize the scanning of the laser emitted by the laser emitting component to the outside at different angles up to 2*α. The wedge mirror-1 and wedge mirror-2 rotate continuously to make the output laser scan outward, and at the same time, the laser receiving camera receives the reflected signal of the target in the scanning area.

[0028] In this way, the active detection unit can scan and image the outside.

[0029] The image rotation compensation component also includes: Wedge mirror-1 and wedge mirror-2 and corresponding drive motors are connected to the transmission pair; Angle sensor, arranged at the rotation transmission shaft of the two wedge-shaped mirrors or the motor shaft; When the passive detection unit is operating, the initial setting is such that point A of the two wedge-shaped mirrors lies within the same plane-1. This plane-1 contains the central axis of the wedge-shaped mirror's rotation axis and the Y axis, which intersects this central axis at point o and is perpendicular to it. Point A is the point of maximum wedge thickness. This plane-1 is parallel to the azimuth rotation plane of the rotating platform.

[0030] The driving motor drives the two wedge-shaped mirrors to rotate in opposite directions at the same angular velocity ω through the transmission pair, so that the light beam produces a compensating displacement along the Y-axis in plane-1.

[0031] The maximum beam tilt angle θ of the two wedge mirrors max =2α, the maximum compensation angle is 4α, where α is the wedge angle of a single wedge mirror.

[0032] The angle sensor generates a synchronization pulse when the wedge mirror rotates to the initial point. This pulse simultaneously triggers: when the initial point is the moment when point A leaves plane -1, the 180° rotation compensation interval is set; or when the initial point is the moment when point A leaves plane -1 and rotates to ±45°, the 90° rotation compensation interval is set; the light source emitter is started and the light emission lasts for t1; and the imaging camera is started, with an exposure time of t2 ≤ t1.

[0033] The transmission pair adopts a gear set or a pulley mechanism.

[0034] When the active detection unit is working, the wedge mirror-1 and wedge mirror-2 of the image rotation compensation component have their own independent rotation speed ω2, ω3 and rotation direction settings, so that the laser emitted by the laser emitting component is deflected to the outside at different angles of up to 2α, and at the same time, the laser receiving camera receives the reflected signal of the target within the scanning range.

[0035] The two coaxial wedge-shaped lenses are wedge-shaped mirror-1 and wedge-shaped mirror-2, which are driven by two motors respectively. The two motors use different scanning speed combinations to adjust the beam output angle. The angle is α* sin(ω2* t+φ)+α* sin(ω3* t+ψ), where α is the slope of wedge mirror 1 and wedge mirror 2, ω2 is the angular velocity of wedge mirror 1, ω3 is the angular velocity of wedge mirror 2, φ is the position of wedge mirror 1 at time 0, ψ is the position of wedge mirror 2 at time 0, and t is the time variable; if ω2 is not equal to ω3, the trajectory density of the scanning line depends on the size of ω2 / ω3, and the time to complete a circle of lotus-shaped trajectory depends on the smaller value of the speed ω2 and ω3, thus forming a lotus-shaped trajectory.

[0036] In this way, the active detection unit can scan and image the outside.

[0037] The foregoing descriptions of specific exemplary embodiments of the present invention are for purposes of illustration and description. These descriptions are not intended to limit the invention to the precise forms disclosed, and it is apparent that many variations and modifications are possible in light of the foregoing teachings. The exemplary embodiments have been selected and described for the purpose of explaining the specific principles of the invention and their practical application, thereby enabling those skilled in the art to realize and utilize a variety of exemplary embodiments of the invention and various options and modifications. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. An optical detection device, characterized in that: include: a rotating platform, arranged outside the detection area and driven by an azimuth motor to perform horizontal azimuth rotation around a central axis; The detection unit includes a passive detection unit and an active detection unit, which is fixed at the pitch fulcrum of the rotating platform and driven by the pitch motor to achieve pitch deflection; the passive detection unit includes at least one detection imaging camera, and the active detection unit includes a laser emitting assembly and a laser receiving camera; a synthesizer mirror configured to synthesize the wavelengths of the optical paths of the passive detection unit and the active detection unit to form a common aperture detection optical path; An image rotation compensation assembly is provided between the synthesizer and the external light, and includes coaxial wedge mirrors 1 and 2, wherein the offset between the central axis of the rotation axis of the wedge mirrors 1 and 2 and the center line of the imaging light path is less than 5 mm; When the passive detection unit is working, the rotating platform drives the detection unit to rotate horizontally, and the wedge mirror-1 and wedge mirror-2 rotate in opposite directions at the same speed value ω, and the following parameter relationship is satisfied: In the 180° rotation compensation range: angular velocity ω = ω1*π / γ, and wedge angle α satisfies 4α = 2θ = γ; In the 90° rotation compensation range: angular velocity ω = ω1*π / γ, and wedge angle α satisfies 2α = θ = γ; Where: ω1 is the angular velocity of the rotating platform, γ is the image shift angle caused by the rotating platform during the exposure time t2 of the imaging camera; When the active detection unit is working, the wedge mirror-1 and the wedge mirror-2 operate at independent angular velocities ω2, ω3 and rotation directions, so that the laser output by the laser emitting assembly forms a maximum 2α angle scan to the outside, and the laser receiving camera receives the target reflection signal.

2. The device according to claim 1, characterized in that: The image rotation compensation component further includes: The motor and transmission pair driving wedge mirror-1 and wedge mirror-2; An angle sensor is provided on the rotation axis of the wedge mirror or the motor shaft; In the initial state, the maximum thickness points A of the two wedge-shaped mirrors are located in the same plane-1. The plane-1 includes the central axis of the wedge-shaped mirror rotation axis and the Y axis perpendicularly intersecting at point O, and is parallel to the azimuth rotation plane of the rotating platform. The motor drives the two wedge-shaped mirrors to rotate in opposite directions at the same angular velocity ω through the transmission pair, so that the light beam generates a compensatory displacement along the Y-axis in plane-1.

3. The device according to claim 2, characterized in that: The maximum beam tilt angle θ of the two wedge-shaped mirrors max =2α, the maximum compensation angle is 4α, where α is the wedge angle of a single wedge mirror.

4. The device according to claim 1, characterized in that: The angle sensor generates a synchronization pulse when the wedge mirror rotates to the initial point, triggering the following operations: When using the 180° compensation interval, the initial point is the moment when point A leaves plane -1; When using the 90° compensation interval, the initial point is the moment when point A rotates to ±45°; The synchronous pulse triggers the light source emitter to start emitting light for a duration of t1, and starts the imaging camera exposure for a duration of t2≤t1.

5. The device according to claim 2, characterized in that: The transmission pair is a gear set or a pulley mechanism.

6. The device according to claim 1, characterized in that: When the active detection unit is working, the deflection angles of the wedge mirror-1 and the wedge mirror-2 satisfy: Bevel angle = α sin(ω2 t+φ)+α sin(ω3 t+ψ), where α is the slope of the wedge mirror, ω2 and ω3 are the rotation angular velocities of wedge mirror-1 and wedge mirror-2 respectively, and φ and ψ are the initial phases; When ω2≠ω3, the laser scanning trajectory is lotus-shaped, the scanning density is determined by ω2 / ω3, and the time to complete a circle of scanning is determined by the smaller value of ω2 and ω3.

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