Optical shaping module and optical shaping device

Abstract

The invention provides an optical shaping module and an optical shaping device, and relates to the technical field of optical shaping, the optical shaping module comprises a first collimation module and a rotational symmetry module, the first collimation module collimates a light beam emitted by a light source in a first direction; the rotational symmetry module has a rotational symmetry structure based on a main optical axis of a light beam emitted by the light source so as to eliminate residual aberration of the first collimation module and realize beam expansion and target focal length of the light beam. Preliminary collimation in the first direction is carried out by adopting the first collimation module, and then residual aberration of the first collimation module is eliminated through the rotational symmetry module with a rotational symmetry structure based on a main optical axis of a light beam emitted by the light source, so that the system can eliminate coma and compress a divergence angle to a theoretical limit. The first collimation module eliminates divergence in the first direction and is insensitive to coma, so that the coma of the system can be ignored; at the moment, the rotational symmetry module is located in parallel light beams, the requirement for the position precision of the rotational symmetry module is not high, coma is easy to eliminate, and the divergence angle is compressed.

Description

Technical Field

[0001] The present application relates to the technical field of optical shaping, and in particular to an optical shaping module and an optical shaping device. Background Art

[0002] In laser shaping systems, fast axis collimators are often used to perform fast axis collimation on edge-emitting laser diodes. In actual engineering, due to the existence of aberrations such as coma, the divergence angle of the system cannot reach the theoretical limit.

[0003] To solve this problem, the common practice is to use a combination of several lenses, but the disadvantage is that there are very strict requirements for the positioning accuracy of each lens. The high requirements for lens positioning increase the cost of the product because they lead to the need for expensive lens barrels and / or active calibration. In addition, the use of spherical lenses is also limited because coma will occur when the emitter width is large enough. Summary of the invention

[0004] The purpose of the embodiments of the present application is to provide an optical shaping module and an optical shaping device, which can reduce the system coma, compress the system divergence angle to the theoretical limit, and are easy to implement.

[0005] According to one aspect of an embodiment of the present application, an optical shaping module is provided, comprising a first collimation module and a rotationally symmetric module, wherein the first collimation module collimates the light beam emitted by a light source in a first direction; the rotationally symmetric module has a rotationally symmetric structural setting based on the main optical axis of the light beam emitted by the light source, so as to eliminate the residual aberration of the first collimation module and realize the beam expansion and target focal length of the light beam.

[0006] Optionally, the first collimating module comprises a cylindrical lens or a cylindrical lens group.

[0007] Optionally, the rotationally symmetric module includes a rotationally symmetric lens or a rotationally symmetric lens group.

[0008] Optionally, the optical shaping module further includes a turning module, and the turning module at least includes a reflector or a cross mirror to deflect the optical path of the light beam.

[0009] Optionally, the optical shaping module further includes a diffuser disposed on the main optical axis, and the diffuser is used to diffuse and homogenize the light beam in a first direction.

[0010] Optionally, the optical shaping module further includes a second collimation module disposed on the main optical axis, and the second collimation module is used to collimate the light beam in a second direction, and the second direction is perpendicular to the first direction.

[0011] Optionally, the optical shaping module further includes a scanning mirror disposed on the main optical axis, wherein the scanning mirror deflects the light beam in the second direction and is configured to scan the incident light beam in the second direction to expand the field of view.

[0012] Optionally, the optical shaping module further includes a Kepler telescope, and the Kepler telescope includes a first lens and a second lens arranged in sequence.

[0013] Optionally, the turning module is arranged between the first lens and the second lens.

[0014] Another aspect of an embodiment of the present application provides an optical shaping device, comprising: a light source, and the above-mentioned optical shaping module arranged on the light path of light emitted by the light source.

[0015] The optical shaping module and optical shaping device provided by the embodiment of the present application, the light beam emitted by the light source passes through the first collimation module and the rotational symmetric module in sequence, the rotational symmetric module has a rotational symmetric structure based on the main optical axis of the light beam emitted by the light source, the light beam completes the collimation of the first direction of the light beam when passing through the first collimation module, and the light beam eliminates the residual aberration of the first collimation module when passing through the rotational symmetric module; the present application adopts the first collimation module to perform preliminary collimation in the first direction, and then eliminates the residual aberration of the first collimation module through the rotational symmetric module having a rotational symmetric structure based on the main optical axis of the light beam emitted by the light source, so that the system can eliminate coma and compress the divergence angle to the theoretical limit. In addition, since the first collimation module eliminates the divergence in the first direction, it is insensitive to coma, so that the coma of the system can be ignored; at this time, the rotational symmetric module is located in a parallel (first direction) light beam, the position accuracy of the rotational symmetric module is not required to be high, and the use restrictions are small, so that the optical shaping module is easy to achieve the purpose of eliminating coma and compressing the divergence angle. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments of the present application will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 is a schematic diagram of the structure of the optical shaping module provided in this embodiment;

[0018] Figure 2 is a light source diagram of the optical shaping module provided in this embodiment;

[0019] Figure 3 is an energy distribution diagram of the optical shaping module provided in this embodiment;

[0020] Figure 4 is a field distribution diagram of the scanning mirror of the optical shaping module provided in this embodiment;

[0021] Figure 5 It is the energy distribution diagram of the system when the line light source and FAC are combined.

[0022] Icon: 100 - light source; 101 - first collimation module; 102 - rotational symmetry module; 103 - second collimation module; 104 - diffuser; 105 - first lens; 106 - turning module; 107 - second lens; 108 - scanning mirror; F1 - first direction; F2 - second direction. DETAILED DESCRIPTION

[0023] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application.

[0024] In the description of this application, it should be noted that the terms "inside", "outside", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the application is usually placed when in use, which is only for the convenience of describing this application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0025] It should also be noted that, unless otherwise clearly specified and limited, the terms "disposed" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0026] In the prior art, FAC (Fast Axis Collimation) is often used in a standard way to perform fast axis collimation on edge-emitting laser diodes. One of the main problems here is cross aberration; the effect of the slow axis input angle on the fast axis output angle.

[0027] The optical focal length of a lens multiplied by the divergence angle remains constant, that is, the BPP (Beam Parameter Product) is conserved. BPP = ω0Xθ, ω0 is the beam waist radius (proportional to the focal length), and θ is the far-field divergence angle. BPP can be intuitively calculated using the beam waist size and the far-field divergence angle.

[0028] However, in actual engineering, due to the existence of aberrations such as coma, the divergence angle cannot reach the theoretical limit. For example, the design goal is a focal length of 18mm and a divergence angle of 0.5°. Assuming that the focal length of a FAC (Fast Axis Collimation) cylindrical lens is 18mm, the divergence angle after passing through it is theoretically 0.5°, but in fact, due to the existence of aberrations, the divergence angle after compression by the FAC cylindrical lens is 20%-30% higher than the theoretical limit, which is 0.6°-0.7°, and cannot reach the 0.5° target.

[0029] The existing technology usually uses a combination of several lenses to solve the above problems, but its disadvantage is that it has very strict requirements on the positioning accuracy of each lens. The high requirements for lens positioning increase the cost of the product because they lead to the need for expensive lens barrels and / or active calibration. In addition, the use of spherical lenses is also limited because coma will occur when the transmitter width is large enough.

[0030] In view of this, an embodiment of the present application provides an optical shaping module that can reduce the system coma and compress the system divergence angle to the theoretical limit, and is easy to implement, has low requirements on the positioning accuracy of optical parts, and has few usage restrictions.

[0031] For details, please refer to Figure 1 As shown, the optical shaping module provided by the embodiment of the present application includes a first collimation module 101 and a rotationally symmetric module 102, wherein the first collimation module 101 collimates the light beam emitted by the light source 100 in a first direction F1; the rotationally symmetric module 102 has a rotationally symmetric structure arrangement based on the main optical axis of the light beam emitted by the light source 100, so as to eliminate the residual aberration of the first collimation module 101 and realize the beam expansion and target focal length.

[0032] The first collimation module 101 and the rotationally symmetric module 102 are sequentially arranged on the optical path of the light source 100, and the light beam emitted by the light source 100 passes through the first collimation module 101 and the rotationally symmetric module 102 in sequence; when the light beam passes through the first collimation module 101, the first collimation module 101 collimates the light beam in the first direction F1, and when the light beam passes through the rotationally symmetric module 102, the rotationally symmetric module 102 has a rotationally symmetric structure based on the main optical axis of the light beam emitted by the light source 100, thereby eliminating the residual aberration of the first collimation module 101.

[0033] For the light source 100, in one implementation of the present application, the light source 100 may be a linear light source 100; in addition, the light source 100 is all light sources 100 having fast and slow axis directions, and the divergence angles of the fast axis and slow axis directions of the light source 100 are different, the divergence angle in the fast axis direction is large, and the divergence angle in the slow axis direction is small.

[0034] The first collimation module 101 collimates the light beam in a first direction F1, and the first direction F1 can be a fast axis or a slow axis. The first direction F1 is determined according to which direction of the field of view is to be adopted. For example, if the system ultimately focuses on the field of view in the fast axis direction, the first direction F1 is the fast axis, and the same is true for the slow axis, which will not be elaborated.

[0035] In one embodiment of the present application, Figure 1 As shown, the first collimation module 101 and the rotationally symmetric module 102 are sequentially arranged in the fast axis direction of the light source 100, and the first direction F1 is the fast axis direction; at this time, the first collimation module 101 collimates the light beam in the fast axis direction, and the rotationally symmetric module 102 is axially symmetric along the fast axis direction to eliminate the residual aberration of the first collimation module 101.

[0036] As for coma, since the first collimator module 101 eliminates the divergence in the fast axis direction, the first collimator module 101 is insensitive to coma, so the system coma is not prominent and can be ignored. In this case, the position accuracy requirement of the rotational symmetry module 102 is not so strict, because the rotational symmetry module 102 is located in a parallel (fast axis direction) beam.

[0037] Therefore, in the optical shaping module provided by the embodiment of the present application, the light beam emitted by the light source passes through the first collimation module 101 and the rotationally symmetric module 102 in sequence, and the rotationally symmetric module 102 has a rotationally symmetric structure based on the main optical axis of the light beam emitted by the light source 100. When the light beam passes through the first collimation module 101, the collimation of the first direction F1 of the light beam is completed, and when the light beam passes through the rotationally symmetric module 102, the residual aberration of the first collimation module 101 is eliminated; the present application adopts the first collimation module 101 to perform preliminary collimation in the first direction F1, and then eliminates the residual aberration of the first collimation module 101 through the rotationally symmetric module 102 having a rotationally symmetric structure based on the main optical axis of the light beam emitted by the light source 100, so that the system can eliminate coma and compress the divergence angle to the theoretical limit. Moreover, since the first collimation module 101 eliminates the divergence in the first direction F1 and is insensitive to coma, the coma of the system can be ignored; at this time, the rotational symmetric module 102 is located in a parallel (first direction F1) light beam, the requirements for the position accuracy of the rotational symmetric module 102 are not high, and the usage restrictions are small, so that the optical shaping module can easily achieve the purpose of eliminating coma and compressing the divergence angle.

[0038] Further, the sum of the focal length of the first collimating module 101 and the focal length of the rotationally symmetric module 102 is equal to the target focal length.

[0039] In the present application, the first collimator module 101 has a short focal length, the focal length of the first collimator module 101 is smaller than the target focal length, the sum of the focal length of the first collimator module 101 and the focal length of the rotationally symmetric module 102 is equal to the target focal length, and by way of example, the target focal length may be 18 mm; in this way, placing an axially symmetric rotationally symmetric module 102 behind the first collimator module 101 with a short focal length can eliminate coma and compress the divergence angle to the theoretical limit of 0.5°.

[0040] Optionally, the first collimating module 101 includes a cylindrical lens or a cylindrical lens group.

[0041] For example, a cylindrical lens may be used for collimation, and the cylindrical lens is cylindrical in the first direction F1, so that collimation in the first direction F1 can be achieved. Of course, collimation can also be achieved by a cylindrical lens group formed by multiple cylindrical lenses.

[0042] Furthermore, the rotationally symmetric module 102 includes a rotationally symmetric lens or a rotationally symmetric lens group.

[0043] For example, the rotationally symmetric lens may be a rotationally symmetric telescope in a second direction F2 perpendicular to the first direction F1, and its light incident surface is a concave surface and its light emitting surface is a convex surface.

[0044] The rotationally symmetric lens is a meniscus telescope, which is axially symmetric along the first direction F1 , and in the second direction F2 , its light incident surface is concave toward the side away from the light source 100 , and its light emitting surface is convex toward the side away from the light source 100 .

[0045] A rotationally symmetric lens group formed by a plurality of rotationally symmetric lenses can also realize the function of a single rotationally symmetric lens, and the effect is better.

[0046] By combining the first collimating module 101 and the rotationally symmetric module 102, the purpose of eliminating coma and compressing the divergence angle is achieved.

[0047] On this basis, the optical shaping module further includes a second collimating module 103 disposed on the main optical axis. The second collimating module 103 is used to collimate the light beam in a second direction F2, and the second direction F2 is perpendicular to the first direction F1.

[0048] After passing through the rotational symmetric module 102 , the light beam is further collimated in a second direction F2 by the second collimating module 103 . The second direction F2 is perpendicular to the first direction F1 . For example, when the first direction F1 is a fast axis, the second direction F2 is a slow axis, and vice versa.

[0049] In one achievable manner of the present application, the second collimating module 103 includes a cylindrical lens or a cylindrical lens group, and the cylindrical lens is cylindrical in the second direction F2.

[0050] The cylindrical lens has a cylindrical surface in the second direction F2, and can collimate the light beam in the second direction F2. Figure 1 For example, the light incident surface of the second collimating module 103 in the slow axis direction is cylindrical, and the light emitting surface is flat, so as to achieve collimation of the light beam in the slow axis direction.

[0051] In addition, the optical shaping module further includes a diffuser 104 disposed on the main optical axis, and the diffuser 104 is used to diffuse and homogenize the light beam in the first direction F1.

[0052] In one embodiment of the present application, the diffuser 104 can be used in a system such as LiDAR. Figure 1 After passing through the diffuser 104, the light beam forms a sufficiently large angular divergence.

[0053] A shaping module is disposed on the light-emitting side of the diffuser 104 to shape the light beam so that the diffuser 104 generates a real far field.

[0054] After the light beam passes through the diffuser 104, a far field is generated in the second direction F2. Since the far field of the diffuser 104 cannot be distorted, an imaging lens cannot be used, and the imaging lens will distort the field angle. The present application shapes the light beam by setting a shaping module, so that after the light beam passes through the diffuser 104 and the shaping module, the far field in the second direction F2 is not distorted or twisted.

[0055] In one example, the shaping module includes a Kepler telescope, which is mainly used to ensure that the radiation passing through the diffuser 104 is reflected by the scanning mirror 108 (which is as small as possible) with minimal aperture loss. The Kepler telescope is a type of refracting telescope, which images upside down, left and right, but can be designed with a larger field of view; the Kepler telescope includes a first lens 105 and a second lens 107 arranged in sequence, and the light beam passes through the first lens 105 and the second lens 107 in sequence, which can fold the optical axis twice while forming an upright image, thereby greatly reducing the size and weight of the telescope.

[0056] The optical shaping module further includes a scanning mirror 108 disposed on the main optical axis. The scanning mirror 108 deflects the light beam in the second direction F2 and is used to scan the incident light beam in the second direction F2 to expand the field of view.

[0057] As mentioned above, the diffuser 104 can make the light beam form a sufficiently large angular divergence. The optical shaping module of the present application also ensures that the radiation passing through the diffuser 104 is reflected by the scanning mirror 108 (the size is as small as possible), and the aperture loss is minimized; when the size of the light beam at the output end is the same as the size of the light beam at the input end, the aperture loss is minimized. For example, the scanning mirror 108 is a rotating mirror, which performs scanning by rotating.

[0058] Since the far field of the diffuser 104 cannot be distorted, an imaging lens cannot be used, and in this case the usual solution is to place the rotating mirror as close as possible to the diffuser 104. However, in this case, the distribution of the light turns out to be asymmetric around the rotation axis of the rotating mirror, that is, the beam size at the output will be different from that at the input (as a rule, it will be larger). This means that either aperture losses must be allowed or a larger rotating mirror must be used.

[0059] In order to solve this problem, the present application adopts a Kepler telescope with a pair of cross mirrors, which are located between the first lens 105 and the second lens 107 to change the direction of the light path; the cross mirror (turning module) can be located between the first lens 105 and the second lens 107, and of course can also be located at other positions where the light path needs to be changed, and the present application does not make specific restrictions on this.

[0060] The scanning mirror 108 is an additional element used to minimize the module size and rotate the light beam 90° around the optical axis, which has the effect of expanding the field of view by scanning the light spot. As is always the case in engineering practice, the selected layout is the result of a compromise: introducing additional optical elements to optimize the operation of the rotating mirror and minimize the losses, or not introducing additional optical elements, giving priority to minimizing the cost and size of the module. The present application can avoid aperture losses and minimize the size of the scanning mirror 108 through the Kepler telescope.

[0061] Figure 1 In FIG. 1 , the scanning mirror 108 deflects the light beam in the fast axis direction, showing two positions with scanning angles of +60° / -60°, and the field of view of the scanning spot formed by the scanning mirror 108 is expanded.

[0062] It should be added that the entire optical path can change the direction of the optical path through the turning module 106. The turning module 106 includes at least a reflector or a cross mirror. The cross mirror is equivalent to a reflector to deflect the optical path of the light beam. At this time, the turning module 106 is set at any position of the optical path, so that the optical path of the light beam changes after passing through the turning module 106, so as to meet the needs of scenes of different sizes.

[0063] For example, the present application Figure 1 In the figure, the turning module 106 is a cross mirror, which is arranged between the first lens 105 and the second lens 107. After the light beam emitted by the light source 100 reaches the cross mirror in the vertical direction, the light beam is deflected by 90° (with an arrow dotted line) by the cross mirror. After passing through the cross mirror, the light beam enters the second lens 107 in the horizontal direction and then passes through the scanning mirror 108 to emit a scanning spot. In this way, the vertical dimension is shortened to adapt to the required scene.

[0064] In summary, the optical shaping module of the present application adopts a first collimation module 101 and a rotationally symmetric module 102. The first collimation module 101 is used to preliminarily collimate the first direction F1 beam of the incident light; the rotationally symmetric module 102 is used to eliminate the residual aberration caused by the first collimation module 101, further expand the beam and compress the divergence angle of the first direction F1, so that the divergence angle of the first direction F1 reaches the theoretical limit value; at the same time, the rotationally symmetric module 102 is insensitive to position settings. Compared with using a single fast-axis cylindrical fast-axis collimating lens, at the same target focal length, the divergence angle that can be achieved by the present application is smaller, and the rotationally symmetric module 102 is insensitive to position, the installation accuracy requirement is not high, and the product cost is low.

[0065] The embodiment of the present application further discloses an optical shaping device, including a light source 100, and an optical shaping module as described above, which is arranged on the light path of the light source 100.

[0066] The light source 100 may be a laser source; further, the light source 100 may be Figure 2 Linear light source in .

[0067] The following uses light source 100 as Figure 2 Take the line light source in as an example, Figure 5 The energy distribution diagram of the system when the line light source and FAC are combined is shown; when the line light source, FAC and rotationally symmetric lens of the present application are combined, the energy distribution is as follows Figure 3 As shown by Figure 3 and Figure 5 By comparison, it can be seen that the combination of the first collimation module 101 and the rotational symmetry module 102 of the present application is Figure 5 Compared with a single FAC lens, the present application provides a narrower contrast distribution. In other words, the module of the present application has no additional tolerance requirements, has low requirements on the positioning accuracy of each optical element in the module, and is easier to achieve the purpose of eliminating coma and compressing the divergence angle.

[0068] For information on the transmission of radiation from the diffuser 104 to the scanning mirror 108, please refer to Figure 4 , in the field distribution on the scanning mirror 108, Za is the input plane, Zb is the output plane, and Zo is the axis rotation plane; the strong fluctuation (Zo) in the rotation axis plane shows the output lens array of the diffuser 104. The system provides aberration-free transmission from the diffuser 104 plane to the reflection plane of the scanning mirror 108. In this case, the input and output distributions are close to each other. This condition makes it possible to choose a minimum size scanning mirror 108 and minimize the aperture loss of the light beam. And because of the use of a telecentric optical system from the diffuser 104 to the scanning mirror 108, the occurrence of system angular distortion is also excluded.

[0069] The optical shaping device has the same structure and beneficial effects as the optical shaping module in the aforementioned embodiment. The structure and beneficial effects of the optical shaping module have been described in detail in the aforementioned embodiment and will not be repeated here.

[0070] The above are only embodiments of the present application and are not intended to limit the scope of protection of the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the scope of protection of the present application.

Claims

1. An optical shaping module, characterized in that: include: A first collimation module and a rotationally symmetric module, wherein the first collimation module collimates the light beam emitted by the light source in a first direction; the rotationally symmetric module has a rotationally symmetric structure based on the main optical axis of the light beam emitted by the light source to eliminate the residual aberration of the first collimation module and achieve beam expansion and target focal length of the light beam.

2. The optical shaping module according to claim 1, characterized in that: The first collimating module includes a cylindrical lens or a cylindrical lens group.

3. The optical shaping module according to claim 1, characterized in that: The rotationally symmetric module comprises a rotationally symmetric lens or a rotationally symmetric lens group.

4. The optical shaping module according to claim 1, characterized in that: The optical shaping module also includes a turning module, and the turning module at least includes a reflecting mirror or a cross mirror to deflect the optical path of the light beam.

5. The optical shaping module according to claim 1, characterized in that: The optical shaping module also includes a diffuser arranged on the main optical axis, and the diffuser is used to diffuse and homogenize the light beam in a first direction.

6. The optical shaping module according to any one of claims 1 to 5, characterized in that: The optical shaping module also includes a second collimating module disposed on the main optical axis, and the second collimating module is used to collimate the light beam in a second direction, and the second direction is perpendicular to the first direction.

7. The optical shaping module according to claim 6, characterized in that: The optical shaping module also includes a scanning mirror arranged on the main optical axis, and the scanning mirror deflects the light beam in the second direction, and is used to scan the incident light beam in the second direction to expand the field of view.

8. The optical shaping module according to claim 4, characterized in that: The optical shaping module also includes a Kepler telescope, and the Kepler telescope includes a first lens and a second lens arranged in sequence.

9. The optical shaping module according to claim 8, characterized in that: The turning module is arranged between the first lens and the second lens.

10. An optical shaping device, characterized in that: It comprises a light source and an optical shaping module according to any one of claims 1 to 9 arranged on the light path of the light source.

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