CN217543378U - Prism for scanning and prism scanning device - Google Patents

Abstract

The utility model relates to a prism for scanning and a prism scanning device, wherein the prism is provided with a rotating shaft and a top surface and a bottom surface which are parallel to each other, and the rotating shaft penetrates through the top surface and the bottom surface and is respectively vertical to the top surface and the bottom surface; the top surface and the bottom surface are respectively polygonal, the number of the edges of the top surface is the same as that of the edges of the bottom surface, and the edges of the top surface and the edges of the bottom surface are arranged in parallel in a one-to-one correspondence manner; the plane formed by connecting adjacent vertexes between the top surface and the bottom surface is used as the working surface of the prism, and the included angle beta between the working surface and the rotating shaft is more than 0 degree and less than beta and less than 90 degrees. Compared with a tower mirror scanning mode, when the areas of the working surfaces are the same, the scanning prism provided by the utility model has small volume, weight and rotational inertia and more excellent power consumption; the laser foot point track projected on the target through the scanning prism is parabolic, so that the scanning mode can more easily acquire point cloud data of a vertical facade; and the prism has a larger field angle than the tower mirror, and can improve the acquisition efficiency.

Description

Prism for scanning and prism scanning device

Technical Field

The utility model relates to a laser radar scanning technical field, concretely relates to prism and prism scanning device for scanning.

Background

The field angle of the line scanning type laser radar is generally 360 degrees, when the line scanning type laser radar is applied to an airborne scene for carrying out pipeline inspection, corridor inspection, electric power line inspection and other strip-shaped target surveying and mapping, as a detection target is only located in a fan-shaped area on the side or below the laser radar, most scanning lines are wasted, and meanwhile, the scanning lines in a target area are sparse. In view of the situation, in recent years, various laser radar scanning modes adaptive to airborne application are proposed, and the scanning field of view of the laser radar is compressed to a proper angle from 360 degrees, so that the number of scanning lines of a central field of view is increased, and the scanning efficiency and the point cloud density of a target area are improved. In the prior art, the tower mirror scanning scheme is most widely applied.

The technical principle of the tower mirror scanning scheme is shown in figure 1. The tower mirror is driven by the motor to rotate at a high speed, and the working surface of the tower mirror is a plurality of inclined planes distributed along the circumferential direction. The emergent laser is reflected on the working surface, and the light path is deflected to point to the target direction. After a complete working surface sweeps the emergent light, the scanning track of the laser foot point on the target is a straight line perpendicular to the advancing direction. However, the tower mirror scanning scheme has the following problems: firstly, because the tower mirror has a plurality of working faces, and included angles exist between the working faces and the mounting face as well as between the working faces and the rotating shaft, the tower mirror belongs to a special-shaped structure, and the tower mirror is large in processing and manufacturing difficulty and high in processing cost. Secondly, under the same clear aperture, the size, the weight and the rotational inertia of the tower mirror are larger, so that the size, the weight and the power consumption of the whole laser radar are increased; thirdly, the angle of view of the scanning of the tower mirror is relatively small, resulting in low efficiency of the scanning operation: taking the four-working-surface tower mirror shown in fig. 2 as an example, when one of the working surfaces completely passes through the emergent light, the computer simulation can obtain the angle of view scanned by the tower mirror as: and 83.6 degrees.

SUMMERY OF THE UTILITY MODEL

The utility model provides a prism for scanning and a prism scanning device, aiming at the technical problems existing in the prior art, compared with a tower mirror scanning mode, when the working surface areas are the same, the volume, the weight and the rotational inertia of the scanning prism are small, and the volume, the weight and the power consumption of the whole product are more excellent; the laser foot point track projected on the target through the scanning prism is in a parabola shape, so that the scanning mode can more easily acquire point cloud data of a vertical facade; and the prism has a larger field angle than the tower mirror, and can improve the acquisition efficiency.

The utility model provides an above-mentioned technical problem's technical scheme as follows:

as a first aspect of the present invention, the present invention provides a prism for scanning, wherein the prism is provided with a rotation axis and a top surface and a bottom surface parallel to each other, and the rotation axis runs through the top surface and the bottom surface and is perpendicular to the top surface and the bottom surface respectively; the top surface and the bottom surface are respectively polygonal, the number of the edges of the top surface is the same as that of the edges of the bottom surface, and the edges of the top surface and the edges of the bottom surface are arranged in parallel in a one-to-one correspondence manner; the plane formed by connecting adjacent vertexes between the top surface and the bottom surface is used as the working surface of the prism, and the included angle beta between the working surface and the rotating shaft is more than 0 degree and less than beta and less than 90 degrees.

On the basis of the technical scheme, the utility model discloses can also do following improvement.

Preferably, the rotation axis passes through the geometric center of the top and bottom surfaces.

Preferably, the longer side of the top surface is parallel to the shorter side of the bottom surface, the shorter side of the top surface is parallel to the longer side of the bottom surface, and the working surface is trapezoidal.

Preferably, the top surface and the bottom surface are respectively rectangular, the long sides of the top surface are equal to the long sides of the bottom surface in size, and the short sides of the top surface are equal to the short sides of the bottom surface in size.

Preferably, the number n of the working faces is more than or equal to 4.

Preferably, a reflective film is disposed on the working surface.

As a third aspect of the present invention, the utility model also provides a prism scanning device, including foretell prism for scanning, still include light source, driving motor and mounting base, light source and driving motor are fixed respectively and are set up on mounting base, the rotation axis of prism and driving motor's the coaxial setting of rotor and fixed connection, the light source sets up towards the working face of prism, and the contained angle alpha scope of the optical axis of light source and rotation axis is 0 to be less than or equal to alpha and is less than or equal to 90.

As a third aspect of the present invention, the utility model also provides a prism scanning device, including foretell prism for scanning, still include light source, driving motor, speculum and mounting base, light source, speculum and driving motor are fixed respectively and are set up on mounting base, the rotation axis of prism and driving motor's the coaxial setting of rotor and fixed connection, the plane of reflection of speculum is faced the light source and the working face of prism sets up, the emergent light of light source is through the working face of the directional prism behind the speculum reflection, the optical axis of light source is less than or equal to alpha and is less than or equal to 90 with the contained angle alpha scope of rotation axis for 0.

The utility model has the advantages that: 1. in the scheme of the utility model, the laser foot point track projected on the target by the scanning prism is in a parabola shape, so that the scanning mode can more easily acquire the point cloud data of the vertical face; 2. compared with a tower mirror scanning scheme, when the areas of the working surfaces are the same, the scanning prism has small volume, weight and rotational inertia, and the whole scanning device has better volume, weight and power consumption; 3. under the condition of ensuring the optimal volume and weight of the scanning assembly, the scanning prism has a larger field angle, and the acquisition efficiency can be improved.

Drawings

FIG. 1 is a schematic diagram of a tower mirror scanning architecture;

FIG. 2 is a schematic view of the field angle of the tower mirror scan;

fig. 3 is a schematic structural view of the scanning prism of the present invention, wherein (a) is a front view and (b) is a perspective view;

fig. 4 is a schematic view of a specialized scanning prism structure of the present invention, wherein (a) is a front view and (b) is a three-dimensional view;

fig. 5 is a schematic view of two symmetrical working surfaces of the specialized scanning prism of the present invention;

FIG. 6 shows the emergent light path of working surfaces A and B when the included angle between the rotation axis and the optical axis is 45 degrees;

FIG. 7 shows the light path emitted from the working surfaces C and D when the included angle between the rotation axis and the optical axis is 45 degrees;

FIG. 8 is a trace line of the laser foot point when the included angle between the rotation axis and the optical axis is 45 degrees;

fig. 9 shows the light path of the working surfaces a and B when the included angle between the rotation axis and the optical axis is 90 ° in the present invention;

FIG. 10 shows the light path emitted from the working surfaces C and D when the included angle between the rotation axis and the optical axis is 90 degrees;

FIG. 11 is a trace of the laser foot point when the included angle between the rotation axis and the optical axis is 90 degrees;

fig. 12 shows the angle of view of the working surfaces a and B when the included angle between the rotation axis and the optical axis is 45 ° in the present invention;

fig. 13 is a view angle of the C and D working surfaces when the included angle between the rotation axis and the optical axis is 45 ° in the present invention;

fig. 14 is a schematic view of the angle of view reached by the prism rotation when the included angle between the rotation axis and the optical axis is 90 ° in the present invention;

fig. 15 is a schematic structural view of a special-shaped hexagonal prism according to a second embodiment of the present invention;

fig. 16 is a schematic diagram of an emergent light path of a prism when an included angle between the rotation axis and the optical axis is 0 ° in the fourth embodiment of the present invention.

In the drawings, the reference numbers indicate the following list of parts:

1. target, 2, prism, 3, working surface, 4, rotation axis, 5, system base, 6, light source, 7 and reflector.

Detailed Description

The principles and features of the present invention are described below in conjunction with the following drawings, the examples given are only intended to illustrate the present invention and are not intended to limit the scope of the present invention.

The first embodiment is as follows:

as shown in fig. 3, the present embodiment provides a prism for scanning, in which a rotation axis and a top surface and a bottom surface parallel to each other are disposed on the prism, and the rotation axis penetrates through the top surface and the bottom surface and is perpendicular to the top surface and the bottom surface respectively; the top surface and the bottom surface are respectively polygonal, the number of the edges of the top surface is the same as that of the edges of the bottom surface, and the edges of the top surface and the edges of the bottom surface are arranged in parallel in a one-to-one correspondence manner; the plane formed by connecting adjacent vertexes between the top surface and the bottom surface is used as the working surface of the prism, the range of the included angle beta between the working surface and the rotating shaft is more than 0 degree and less than 90 degrees, and the included angle beta between the working surface and the rotating shaft can be adjusted by adjusting the side length ratio of the top surface to the bottom surface.

When the prism of the embodiment is used for scanning, laser emitted by the light source is emitted to the working surface of the prism, the prism rotates around the rotating shaft at a high speed, the laser is reflected to the target object through the reflection action of the working surface, and the photodetector of the scanning device receives the reflected light of the target object, so that the target object is scanned.

Preferably, the rotation axis passes through the geometric centers of the top and bottom surfaces. Of course, the axis of rotation may not be located at the geometric center of the top and bottom surfaces. When the prism is used for scanning, the rotating shaft is positioned at the geometric center of the top surface and the bottom surface, so that the rotating inertia of the prism in the rotating process is smaller, and the operation is more stable.

Preferably, the longer side of the top surface is parallel to the shorter side of the bottom surface, the shorter side of the top surface is parallel to the longer side of the bottom surface, and the working surface is trapezoidal. The edges of the top surface and the edges of the bottom surface are parallel in a one-to-one correspondence manner, so that a plane for reflecting scanning laser is formed, and the plane serves as a working surface. Because the sizes of the parallel sides on the top surface and the bottom surface are different, the formed working surface is trapezoidal. In order to enhance the reflection effect of the prism on the laser, a reflection film is arranged on the working surface.

The structural form, the operating state at each angle and the viewing angle analysis principle of the prism in the present embodiment will now be described with reference to the drawings.

1. Structural form of prism

The structure of the scanning prism of the present embodiment is shown in fig. 3, in which (a) is a front view of the prism, and (b) is a perspective view of the prism. The scanning prism is a special-shaped quadrangular prism, the top surface and the bottom surface of the scanning prism are rectangular, the top surface and the bottom surface are parallel to each other, and four side surfaces of the scanning prism form four continuous trapezoidal working surfaces together. The short side of the top surface rectangle is a1, and the long side of the top surface rectangle is b1; the bottom rectangle has a short side a2 and a long side b2. The top surface short side a1 is parallel to the bottom surface long side b2, and the top surface long side b1 is parallel to the bottom surface short side a 2. c is the rotation axis of the scanning prism.

For convenience of discussion and calculation below, the scanning prism is further specialized in terms of structural configuration and dimensions, such that:

1. the size of the long side b1 of the rectangle on the top surface of the scanning prism is equal to that of the long side b2 of the rectangle on the bottom surface;

2. the short side a1 of the top surface rectangle of the scanning prism is equal to the short side a2 of the bottom surface rectangle in size;

3. the geometric centers (intersections of diagonal lines) of the top surface rectangle and the bottom surface rectangle are both located on the rotation axis c.

The structure of the specialized scanning prism is shown in fig. 4, wherein (a) is a front view of the prism, and (b) is a perspective view of the prism.

Under the above dimensional constraints, the 4 working faces of the scanning prism are composed of two sets of mutually symmetrical faces, as shown in fig. 5. As shown in fig. 5, the a-plane and the B-plane are a set of symmetric planes, the C-plane and the D-plane are a set of symmetric planes, and the included angle β between each working plane of the prism and the rotation axis is equal to make the angle 5 °.

2. Analysis of the angle between the optical axis and the prism rotation axis

In this embodiment, the range of the included angle α between the optical axis of the laser output from the light source and the rotation axis c of the prism may be: alpha is more than or equal to 0 degree and less than or equal to 90 degrees. The following describes the layout relationship between the light emitted from the light source and the prism, and the scanning foot point locus in the layout relationship, taking 45 ° and 90 ° as examples.

1. The included angle between the rotating shaft of the scanning prism and the emergent optical axis is 45 DEG

When the included angle between the rotation axis of the scanning prism and the exit optical axis is 45 °, the exit optical path is shown in fig. 6 and 7, where fig. 6 is the exit optical path of the working surfaces a and B, and fig. 7 is the exit optical path of the working surfaces C and D. Wherein, 1 is a target object; 2 is a scanning prism assembly; 3 is the working surface of the prism; 4 is a prism rotating shaft; 5 is a system base which is a rigid support structure of the system optical device; and 6, a light source, wherein laser emitted by the light source is reflected by the working surface of the scanning prism and then leaves the system to point to the target to be detected.

Through computer simulation, when an included angle between an optical axis and a rotating shaft of the scanning prism is 45 degrees, the scanning prism rotates for a circle, and foot point tracks of laser on a plane target are two parabolas. The two parabolas are respectively symmetrical left and right and are uniformly distributed, and the figure 8 shows. When the equipment advances along with a carrier (such as an unmanned aerial vehicle), the scanning mode is easier to acquire point cloud data of a vertical facade compared with a tower mirror scanning scheme, and the track effect is suitable for serving as airborne laser point cloud data.

The coordinate system in fig. 8 is defined as: the emitting direction of the light source is coincident with the negative direction of the Y axis, and the point O is the projection of the intersection point of the optical axis and the rotating shaft to the target plane. For convenient display, the tracing point is thinned, and a sampling point is given every 5 degrees of rotation of the scanning prism and is bounded by +/-35 degrees. And (4) placing the parabolas of the two track points in the same coordinate system to give the coordinates of the track points.

The distance from the light source to the target plane is set to be 100 meters, and the X, Y coordinate values of the tracing points of the working surfaces A and B and the working surfaces C and D of the prism are given in table 1.

TABLE 1

2. The included angle between the rotary shaft of the scanning prism and the emergent optical axis is 90 DEG

When the included angle between the rotating shaft of the scanning prism and the emergent optical axis is 90 degrees, the emergent light path of the working surfaces A and B is shown in 9,C and the emergent light path of the working surface D is shown in fig. 10. Wherein, 1 is a target object; 2 is a scanning prism assembly; 3 is the working surface of the scanning prism; 4 is the rotating shaft of the scanning prism; 5 is a system base, which is a rigid support structure of the system optical device; and 6, a light source, wherein laser emitted by the light source is reflected by the working surface of the scanning prism and then leaves the system to point to the measured target.

Through computer simulation, when an included angle between a rotating shaft of the scanning prism and an emergent optical axis is 90 degrees, the scanning prism rotates for a circle, and foot point tracks of laser on the ground are two symmetrical parabolas with opposite opening directions. The two parabolas are respectively symmetrical left and right and are uniformly distributed, as shown in figure 11.

The coordinate system in fig. 11 is defined as: the light source is vertical to the XY plane, the rotating shaft of the scanning prism is coincident with the Y axis, and the point O is the intersection point of the optical axis and the target plane. For convenient display, the tracing point is thinned, and a sampling point is given every 5 degrees of rotation of the scanning prism and is bounded by +/-30 degrees. And (4) placing the parabolas of the two track points under the origin of coordinates of the same coordinate system, and giving coordinate values of the track points.

The distance from the light source to the target plane is set to be 100 meters, and the X, Y coordinate values of the trace points of the working surfaces A and B and the working surfaces C and D are given in table 2.

TABLE 2

3. Analysis of field angle of a scanning prism

The foregoing describes the foot point trajectory of the laser on the planar target when the angle between the rotation axis of the scanning prism and the optical axis is 45 ° and 90 °, and the scanning field angles in these two states are analyzed below.

When the included angle between the rotating shaft of the scanning prism and the emergent optical axis is 45 degrees, two reflected lights appear successively after the prism reflection when the emergent light of the light source is successively tangent with the edges at the left side and the right side of the same working surface of the scanning prism. At this time, when looking at the emergent light direction, the included angle between the two reflected lights is the angle of view. As shown in fig. 12 and 13. Fig. 12 shows the viewing angles of the working surfaces a and B, and fig. 13 shows the viewing angles of the working surfaces C and D. When the angle between the rotation axis of the scanning prism and the exit optical axis is 90 °, the angle of view is as shown in fig. 14.

As can be seen from fig. 12 and 13, the angle of view when the angle between the rotation axis of the scanning prism and the exit optical axis is 45 ° is: 96 degrees and 117.4 degrees. As can be seen from fig. 14, the angle of view when the angle between the rotation axis of the scanning prism and the exit optical axis is 90 ° is: 151.6. Comparing the angle of view of the tower mirror scanning in fig. 2, it can be seen that the angle of view of the scanning prism in the present solution is larger than that in the tower mirror scanning solution under the same number of working surfaces.

In summary, compared with the tower mirror scanning scheme, the scheme has the following advantages:

1. the laser foot point track projected on the target by the scanning prism is parabolic, so that the scanning mode can more easily acquire point cloud data of a vertical facade.

2. When the areas of the working surfaces are the same, the scanning prism has small volume, weight and rotational inertia, and the volume, weight and power consumption of the whole product are better;

3. under the condition of ensuring the optimal volume and weight of the scanning assembly, the scanning prism has a larger field angle, and the acquisition efficiency can be improved.

Example two:

in this embodiment, as shown in fig. 15 (a) and (b), the prism in this embodiment has a special-shaped hexagonal prism structure, the top surface and the bottom surface are respectively hexagonal, at least one of the hexagonal shapes is an irregular hexagonal shape, six sides of the top surface and six sides of the bottom surface are parallel to each other in a one-to-one correspondence manner, and six side planes of the top surface and the six sides of the bottom surface form six continuous trapezoidal working surfaces together. Compared with the tower mirror scanning scheme with six working surfaces, the embodiment also has the following advantages: the laser foot point tracks projected onto the target are parabolic, and because the included angle beta between each working surface and the rotating shaft is possibly different, the laser foot point tracks projected onto the target by the working surfaces with different included angles beta are parabolic with different radians, and compared with the linear foot point tracks presented by the tower mirror, the scanning mode of the scheme is easier to acquire point cloud data of a vertical facade; when the areas of the working surfaces are the same, the scanning prism has small volume, weight and rotational inertia, and the volume, weight and power consumption of the whole product are better; the field angle of the scanning prism is larger, and the acquisition efficiency can be improved.

Likewise, as a further extension, the prism working faces can also be provided in other numbers, such as five, seven … …, etc.

Example three:

on the basis of the prism structure and the principle of the first embodiment or the second embodiment, the embodiment provides a prism scanning device, which comprises the prism for scanning, and further comprises a light source, a driving motor and a mounting base, wherein the light source and the driving motor are respectively and fixedly arranged on the mounting base, a rotating shaft of the prism is coaxially arranged with a rotor of the driving motor and fixedly connected with the rotor, the light source is arranged towards a working surface of the prism, and the included angle alpha between the optical axis of the light source and the rotating shaft is not less than 0 degree and not more than 90 degrees.

The light source is used for providing scanning laser, and driving motor is used for driving the prism to carry out high-speed rotation, and the mounting base is used for providing mechanism support for light source, driving motor.

Example four:

on the basis of the third embodiment, this embodiment still provides another prism scanning device, including aforementioned prism for the scanning, still include light source, driving motor, speculum and mounting base, light source, speculum and driving motor are fixed the setting respectively on mounting base, the rotation axis of prism and driving motor's the coaxial setting of rotor and through system base fixed connection, the plane of reflection of speculum is faced the light source and the working face setting of prism, emergent light (pulse laser) that the light source sent points to the working face of prism after the speculum reflects, reachs the measured target thing after scanning prism reflects once more. The included angle alpha between the optical axis of the light source and the rotating shaft is between 0 degree and 90 degrees. Fig. 16 shows an example of a usage scenario of the scanning device, where in fig. 16, 1 is a target; 2 is a scanning prism assembly; 3 is the working surface of the prism; 4 is a prism rotating shaft; a system base is a rigid supporting structure of a system optical device (prism) and is used for mounting the prism on a rotor of a driving motor; 6 is a light source for providing pulsed laser for scanning; the reflector 7 is used for reflecting the laser emitted by the light source 6 to the working surface of the scanning prism through the reflector 7, and the laser leaves the system after being reflected by the working surface of the prism and points to the measured target 1.

In this embodiment, as shown in fig. 16, the rotation axis of the scanning prism and the exit optical axis may be arranged in parallel, that is, an included angle between the rotation axis of the prism and the optical axis is set to be 0 °, a reflecting mirror is arranged in front of the light source, the pulse laser emitted from the light source reaches the scanning prism after passing through the reflecting mirror, and reaches the target object to be measured after being reflected again by the scanning prism. The arrangement of the mirror may further adjust the angle α between the optical axis of the light source and the rotational axis of the prism, for example by extending the angle α to 0 °. The arrangement of the reflector can also flexibly adjust the incident angle between the laser optical axis and the working surface on the premise of not changing the inherent structure of the laser scanning system.

The above description is only for the preferred embodiment of the present invention, and is not intended to limit the present invention, and any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention should be included within the protection scope of the present invention.

Claims (8)

1. A prism for scanning is characterized in that a rotating shaft, a top surface and a bottom surface which are parallel to each other are arranged on the prism, and the rotating shaft penetrates through the top surface and the bottom surface and is respectively vertical to the top surface and the bottom surface; the top surface and the bottom surface are respectively polygonal, the number of the edges of the top surface is the same as that of the edges of the bottom surface, and the edges of the top surface and the edges of the bottom surface are arranged in parallel in a one-to-one correspondence manner; the plane formed by connecting adjacent vertexes between the top surface and the bottom surface is used as the working surface of the prism, and the included angle beta between the working surface and the rotating shaft is more than 0 degree and less than beta and less than 90 degrees.

2. A prism for scanning according to claim 1, wherein said rotation axis passes through the geometric centers of said top and bottom surfaces.

3. A scanning prism according to claim 1 or 2, wherein the longer side of the top surface is parallel to the shorter side of the base surface, the shorter side of the top surface is parallel to the longer side of the base surface, and the working surface is trapezoidal.

4. The prism for scanning according to claim 3, wherein the top surface and the bottom surface are rectangular, the long sides of the top surface and the bottom surface have the same size, and the short sides of the top surface and the bottom surface have the same size.

5. A prism for scanning as claimed in claim 1 or 2, characterized in that the number n of working faces is 4 or more.

6. A prism for scanning according to claim 1, wherein a reflective film is provided on the working surface.

7. A prism scanning device, comprising the prism for scanning according to any one of claims 1 to 6, further comprising a light source, a driving motor and a mounting base, wherein the light source and the driving motor are respectively and fixedly arranged on the mounting base, the rotating shaft of the prism is coaxially arranged with and fixedly connected with the rotor of the driving motor, the light source is arranged towards the working surface of the prism, and the included angle α between the optical axis of the light source and the rotating shaft is between 0 ° and 90 °.

8. A prism scanning device, comprising the prism for scanning as claimed in any one of claims 1 to 6, further comprising a light source, a driving motor, a reflector and a mounting base, wherein the light source, the reflector and the driving motor are respectively and fixedly arranged on the mounting base, the rotation axis of the prism is coaxially arranged with and fixedly connected to the rotor of the driving motor, the reflection surface of the reflector faces the light source and the working surface of the prism, the emergent light of the light source is reflected by the reflector and directed to the working surface of the prism, and the included angle α between the optical axis of the light source and the rotation axis is in the range of 0 ° < α > to 90 °.

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