Optical system, lidar sensor and method for manufacturing an optical system

Abstract

This invention relates to an optical system, a lidar sensor having such an optical system, and a method for manufacturing the optical system. The optical system includes: a light source (10), a substrate holder (20) having a first fastening region (22) and a second fastening region (24), and an optical unit (30) having a third fastening region (32) and a fourth fastening region (34). The optical unit (30) is fastened to the substrate holder (20) along a joining direction (40) transverse to, and particularly perpendicular to, the orientation of the fastening regions (22, 24, 32, 34), such that the first fastening region (22) is connected to the third fastening region (32) and the second fastening region (34). Region (24) is bonded to the fourth fastening region (34), the light source (10) is fastened in a predefined position and relative to the base holder (20) in a predefined orientation, the third fastening region (32) and the fourth fastening region (34) are disposed on the optical unit (30) spaced apart from each other along the joining direction (40) between the optical unit (30) and the base holder (20), and the optical unit (30) is configured to influence the light beam emitted by the light source (10) toward the optical unit (30).

Description

Technical Field

[0001] The present invention relates to an optical system, a lidar sensor including such an optical system, and a method for manufacturing the optical system. Background Technology

[0002] Laser radiation is typically shaped using cylindrical lenses to achieve appropriate illumination (e.g., laser beams) even with varying laser emitter geometries. Simple optics for generating laser beams can be composed, for example, of cylindrical lenses that collimate the laser beam in a spatial direction (e.g., horizontal) and do not affect the beam in a spatial direction perpendicular to it (e.g., vertical). Due to collimation in one spatial direction and divergence in the spatial direction perpendicular to it, a laser beam is formed even with a small distance to the optical system. Therefore, the cylindrical lens can be moved in the non-collimated spatial direction without affecting the beamforming of the laser beam. To achieve the required collimation, the optics must be positioned as accurately as possible at a distance from the laser source equal to the focal length of the optics. Here, two typical bonding geometries are used in the prior art. In the case of axial bonding, the optics are bonded to a retainer along the beam propagation axis. In the case of lateral bonding, the optics are bonded to the space between the retainer and the opposing side.

[0003] DE102008027721A1 describes an optical system with a device for compensating for thermal effects, wherein the device for compensating for thermal effects works in conjunction with a carrier assembly. The mechanism for compensating for thermal effects is based on a reference to the coefficients of thermal expansion of the different materials involved in the construction of the carrier assembly, so as to convert temperature changes into mechanical regulating movements.

[0004] DE102015208276B4 describes a lens module for an imaging instrument having a lens arrangement including a first lens and a second lens, and a retainer, wherein a first adhesive is disposed between a surface of the first lens and the retainer, and a second adhesive is disposed between another surface of the first lens and the retainer, such that the effects of changes in the refractive indices of the first and second lenses due to changes in the temperature of the lens arrangement on the focal length of the lens arrangement and the effects of deformation of the first lens due to changes in the temperature of the lens arrangement on the focal length of the lens arrangement cancel each other out. Summary of the Invention

[0005] According to a first aspect of the invention, an optical system is proposed, comprising a light source, a substrate holder having a first fastening region and a second fastening region, and an optical unit having a third fastening region and a fourth fastening region. Essentially, any light source having any wavelength range (e.g., for generating visible light, infrared light, or near-infrared light) can be considered as the light source, but in particular, a laser light source such as a laser diode, for example, the light source of a lidar sensor. The substrate holder is made of, for example, metal and / or plastic and / or glass and / or materials different from them, and is constructed, for example, in the form of a hollow cuboid (e.g., in the form of a shell), in the form of a transparent volume, in the form of a frame, or in a form different from them. The optical unit is fastened to the substrate holder along a joining direction transverse to, and especially perpendicular to, the orientation of the fastening regions, such that the first fastening region is bonded to the third fastening region and the second fastening region is bonded to the fourth fastening region.

[0006] Advantageously, in the optical system according to the invention, the arrangement order of the first fastening region, the third fastening region, and the adhesive therebetween between the substrate retainer and the optical unit in the bonding direction is the same as the arrangement order of the second fastening region, the fourth fastening region, and the adhesive therebetween in the bonding direction. This provides the advantage that possible length changes of the adhesive in the bonding direction or opposite to the bonding direction (e.g., caused by aging and / or environmental influences such as temperature fluctuations and / or humidity fluctuations) affect both types of adhesion in the same direction, thus preventing tensile or compressive stress from being generated on the adhesive, even though the optical unit thus moves relative to the light source in the bonding direction or opposite to the bonding direction. Accordingly, such length changes of the adhesive in the optical system according to the invention do not lead to potential tearing of the adhesive, thereby providing particularly high reliability in the existing optical system.

[0007] The light source is secured in a predefined position and with a predefined orientation relative to the substrate holder. This securing is preferably based on the substrate holder and the light source being arranged on a common substrate, such as a base, which can be made of any material and, in particular, printed circuit board material. The light source is arranged outside and / or inside the substrate holder, wherein the substrate holder in all cases has open and / or light-guiding portions, so that light generated by the light source can be emitted toward the optical unit on the side of the substrate holder secured to the optical unit. It should be noted in this case that the light source can be pre-assembled integrally with the substrate holder or can be configured itself as the substrate holder.

[0008] Furthermore, the third and fourth fastening regions are spaced apart from each other on the optical unit in the joining direction between the optical unit and the substrate holder. Preferably, the third and fourth fastening regions are located at corresponding opposite edges of the optical unit, and the different arrangement of the corresponding fastening regions will be explained in more detail below in conjunction with a description of an advantageous configuration for the current optical system.

[0009] The optical unit is configured to influence the light beam emitted from the light source in the direction toward the optical unit. In order to influence the light beam, the optical unit is preferably an optical unit for beam shaping (e.g., a collimating lens, etc.), or alternatively or additionally an optical unit for beam deflection (e.g., a plane mirror, a beam splitter, etc.) and / or an optical unit for beam filtering (e.g., a polarizing filter, a gray filter, etc.).

[0010] Another advantage of existing optical systems is that greater flexibility is achieved in selecting appropriate adhesives to fasten the optical units to the substrate holder, since stress in the adhesive area is avoided by the present invention, and adhesives with more unfavorable expansion characteristics and / or higher elasticity and / or stronger shrinkage during hardening, etc., can also be used, thereby resulting in cost advantages through the selection of adhesives.

[0011] The dependent claims describe preferred extensions of the invention.

[0012] According to an advantageous configuration, the optical unit has a lens or lens system, on which an optical device holder is preferably pre-assembled, wherein a third and / or fourth fastening region is provided on the optical device holder. The optical device holder is made of, for example, metal and / or plastic and is connected to the lens or lens system material in a locking and / or form-locking and / or force-locking manner. When using a lens system, in addition to providing a fastening function for the optical unit on the base holder, the optical device holder also advantageously enables the fastening function between the respective lenses of the optical unit. Here, it is possible to arrange individual lenses in the direction of the optical path and / or transverse to the direction of the optical path by means of the optical device holder.

[0013] Particularly advantageously, the lens or lens system includes a cylindrical lens (convex, concave, or biconvex), which is preferably arranged in the optical path of the optical system such that it collimates the light generated by the light source in one spatial direction (e.g., in a horizontal illumination direction), while the light remains substantially unaffected in a spatial direction perpendicular to it. Alternatively or additionally, the lens or lens system includes symmetrical optical elements, particularly spherical lenses and / or microlens arrays, especially cylindrical microlens arrays.

[0014] Preferably, the optical unit has at least one fastening plate that covers the substrate holder in the engagement direction and includes a third or fourth fastening region. Here, the fastening plate is either part of the optical device holder or an additional component fastened to the lens or lens system and / or the optical device holder. Such a fastening plate particularly offers advantages in terms of the ease of design of the substrate holder and / or the optical system and / or in the simplified assembly of the corresponding components.

[0015] In an advantageous configuration, a third and / or fourth fastening region is disposed within a corresponding gap in the optical unit, wherein the gap extends completely through the optical unit, allowing a protruding portion of the substrate holder (e.g., a tab) to pass through the gap for bonding with the optical unit within the gap. This provides in particular the advantage that the optical unit must have only one element for beam manipulation and does not require additional optical device holders. However, a combination of this current configuration of the optical unit and additional optical device holders is also clearly feasible.

[0016] Particularly advantageously, the corresponding materials used to manufacture the substrate retainer and the optical unit have a substantially uniform coefficient of thermal expansion. In this way, particularly low stress is generated in the bonded area because the thermally determined expansion of the substrate retainer and the optical unit exerts a uniform effect in the bonding direction or in the opposite direction to the bonding direction and thus compensates for each other in terms of their effect on the adhesive.

[0017] Particularly preferably, the optical unit produces collimation in a predefined spatial direction, wherein the arrangement of the bonding direction and thus the corresponding fastening regions is determined such that the effect of the movement of the optical unit relative to the light source along the bonding direction on the collimation is minimized. In embodiments where a cylindrical lens is used in the optical unit, the cylindrical lens is correspondingly fastened such that the third and fourth fastening regions are arranged spaced apart from each other in the direction of the curvature axis of the cylindrical lens. Changes in the length of the adhesive thus cause movement of the cylindrical lens in the direction of the curvature axis, thereby keeping the distance between the cylindrical lens and the light source and thus the beam effects caused by the cylindrical lens substantially unaffected.

[0018] According to a second aspect of the invention, a lidar sensor is provided comprising a transmitting unit having an optical system as described above. The lidar sensor is, for example, a point scanner, a line scanner, or a flash lidar sensor. Preferably, the lidar sensor is an environmental sensor for a transport vehicle, wherein the transport vehicle is, for example, a road vehicle (e.g., a motorcycle, passenger car, transport vehicle, truck), a rail vehicle, or an aircraft / aircraft and / or a watercraft, without limiting the lidar sensor to applications limited to transport vehicles only. The features, combinations of features, and the resulting advantages clearly correspond to those implemented in combination with the first-mentioned aspects of the invention, so that reference is made to the above embodiments to avoid repetition.

[0019] According to a third aspect of the invention, a method for manufacturing an optical system is provided. In a first step of the method according to the invention, a light source and a substrate holder are used, wherein the light source is fastened at a predetermined position and relative to the substrate holder in a predetermined orientation. In a second step of the method according to the invention, an adhesive is applied to a first fastening region of the substrate holder and / or a third fastening region of the optical unit, and to a second fastening region of the optical unit and / or a fourth fastening region of the optical unit, wherein the third and fourth fastening regions are spaced apart from each other on the optical unit between the optical unit and the substrate holder in the bonding direction. The application of the adhesive is preferably performed mechanically by means of an assembly device. In a third step of the method according to the invention, the optical unit is fastened to the substrate holder along a bonding direction transverse to, and especially perpendicular to, the orientation of the fastening regions, such that the first fastening region is bonded to the third fastening region and the second fastening region is bonded to the fourth fastening region, wherein the optical unit is configured to influence a light beam emitted by the light source toward the optical unit. Preferably, the optical unit is also fastened mechanically by means of an assembly device, wherein the optical unit is moved close to the substrate retainer along the joining direction and / or transverse to the joining direction during the fastening process.

[0020] Particularly advantageously, the step of fastening the optical unit to the substrate holder includes coarse positioning and coarse orientation of the optical unit relative to the light source, wherein the fastening area of ​​the substrate holder is not yet in contact with the corresponding fastening area in the optical unit by adhesive during this step. This provides the particular advantage that the optical unit can be brought very close to its target position without unintentionally dispersing the applied adhesive in this state, which could lead to inaccurate adhesive dispersion and thus potentially unreliable adhesion. Furthermore, the positioning of the optical unit close to the target position is achieved in this state, allowing for a coarse inspection of the arrangement of the optical unit relative to the light source (e.g., by means of optical measurements based on the light from the light source and / or by moving it to a predefined position). In a subsequent step, the optical unit and the substrate holder are combined in the engagement direction, such that the corresponding fastening area of ​​the substrate holder comes into contact with the corresponding fastening area in the optical unit by adhesive. In this state, it is now advantageously possible to perform fine positioning and fine orientation of the optical unit relative to the light source by means of optical measurements. After fine positioning and fine orientation are completed, the optical unit is held in its target position relative to the light source for an extended period of time by means of an assembly device, where it is calibrated to such a degree, until the adhesive hardens in the final process step. Depending on the type of adhesive used and / or the time requirements of the manufacturing method described above, hardening is carried out by waiting for a predefined hardening time to pass and / or by means of an activation treatment, such as heat treatment and / or ultraviolet irradiation treatment. Attached Figure Description

[0021] Embodiments of the present invention will then be described in detail with reference to the accompanying drawings. Herein lies:

[0022] Figure 1a A schematic side view of the optical system according to the invention in the first embodiment;

[0023] Figure 1b A schematic top view of the optical system according to the invention in the first embodiment;

[0024] Figure 2a A three-dimensional front view of a cylindrical lens of the optical system according to the present invention in the second embodiment;

[0025] Figure 2b A schematic side view of the optical system in the second embodiment; and

[0026] Figure 3 A schematic radiation diagram of a lidar sensor according to the present invention. Detailed Implementation

[0027] Figure 1a A schematic side view of the optical system according to the invention, according to a first embodiment, is shown. The optical system includes a substrate holder 20, which is made of plastic and is hollow internally, so that a light beam entering from the side can exit unaffected through the substrate holder 20 on the opposite side. Here, such a light beam is a laser generated by means of a laser diode 10, which is fastened in a predetermined position and with a predetermined orientation relative to the substrate holder 20. Furthermore, the substrate holder 20 has a first fastening region 22 and a second fastening region 24. Additionally, the optical system includes an optical unit 30 having a third fastening region 32 and a fourth fastening region 34. The optical unit 30 consists of a cylindrical lens 36 and an arcuate optical device holder 38 bonded to it perpendicularly to the cylindrical lens 36. The optical unit 30 is fastened to the base retainer 20 along a bonding direction 40 perpendicular to the fastening regions 22, 24, 32, 34, so that the first fastening region 22 and the third fastening region 32, and the second fastening region 24 and the fourth fastening region 34 are bonded together by means of adhesive 50.

[0028] Furthermore, the optical unit 30 is configured to collimate the laser generated by the laser diode 10 in the horizontal direction and allow it to pass unaffected in the vertical direction. This means that possible changes in the length of the adhesive 50 have no or only negligible impact on the collimation function of the cylindrical lens 36.

[0029] In the manufacturing process of such an optical system, the optical unit 30 is preferably first brought close to the substrate holder 20 by means of an assembly device, such that the adhesive 50 applied to the first fastening region 22 and the second fastening region 24 is just not yet in contact with the optical unit 30. In this state, the optical unit 30 is then first roughly positioned and roughly oriented relative to the laser diode 10. Next, the optical unit 30 is lowered along the bonding direction 40 onto the adhesive 50 applied to the substrate holder 20, so that the fastening regions 22, 32 and fastening regions 24, 34 are in contact with each other by the adhesive 50. The subsequent fine positioning and fine orientation of the optical unit 30 relative to the laser diode 10 is then performed by means of an assembly device along the bonding direction 40 and / or transverse to the bonding direction 40 (that is, in the direction of the optical path of the optical system).

[0030] Figure 1bA schematic top view of the optical system according to the invention in the first embodiment is shown. From the top view, it can be seen that the laser generated by the laser diode 10 is collimated in the horizontal direction by means of the cylindrical lens 36, which is shown in dashed lines (because it is covered by the optical device holder 38 of the optical unit 30 in the top view).

[0031] Figure 2a A perspective front view of the cylindrical lens 36 of the optical system according to the invention in a second embodiment is shown. In this embodiment, the optical unit 30 consists only of the cylindrical lens 36 itself and therefore does not have an optical switch 38. Instead of securing the cylindrical lens 36 to the substrate holder 20, a gap 60 is provided in the cylindrical lens 36, which, in this view, extends completely through the cylindrical lens 36 from front to back.

[0032] Figure 2b A schematic side view of the optical system in the second embodiment is shown. To avoid repetition, only the differences between the second and first embodiments will be described below. Here, the substrate holder 20 has a tab 80 in the upper region, the size of which is smaller than the cross-sectional area of ​​the clearance 60 in the front view by a predetermined value. In this way, the clearance 60 of the cylindrical lens 36 can be first guided perpendicularly to the bonding direction 40 through the tab 80, and then the cylindrical lens 36 can be lowered along the bonding direction 40 onto the corresponding adhesive 50, so that the cylindrical lens 36 is form-locked to the substrate holder 20 not only at its lower end but also in the region of the clearance 60 by means of the adhesive 50.

[0033] Figure 3 A schematic top view of a lidar sensor 70 according to the present invention is shown. The lidar sensor 70 includes the optical system according to the present invention described above, which comprises a substrate holder 20, a light source 10 disposed herein within the substrate holder 20, and an optical unit 30, wherein the optical unit 30 has a cylindrical lens 36 and an optical device holder 38. Laser light collimated by the cylindrical lens 36 passes through the protective glass 75 of the lidar sensor 70 and illuminates the environment of the lidar sensor 70.

Claims

1. An optical system comprising: • Light source (10) • A base retainer (20) having a first fastening region (22) and a second fastening region (24), and • An optical unit (30) having a third fastening region (32) and a fourth fastening region (34). in, • The optical unit (30) is fastened to the base holder (20) along a bonding direction (40) transverse to the orientation of the fastening regions (22, 24, 32, 34), thereby bonding the first fastening region (22) to the third fastening region (32) and the second fastening region (24) to the fourth fastening region (34). The light source (10) is fastened at a predefined position and relative to the base holder (20) in a predefined orientation. The third fastening region (32) and the fourth fastening region (34) are disposed on the optical unit (30) spaced apart from each other along the joining direction (40) between the optical unit (30) and the substrate holder (20), and • The optical unit (30) is configured to influence the light beam emitted by the light source (10) in the direction toward the optical unit (30).

2. The optical system according to claim 1, wherein, The optical unit (30) is fastened to the base retainer (20) along a bonding direction (40) perpendicular to the orientation of the fastening regions (22, 24, 32, 34).

3. The optical system according to claim 1, wherein, The optical unit (30) has a lens (36) or a lens system on which an optical device holder (38) is pre-assembled, wherein the third fastening region (32) and / or the fourth fastening region (34) are disposed on the optical device holder (38).

4. The optical system according to claim 3, wherein, The lens (36) or the lens system includes • Cylindrical lenses, and / or • Symmetrical optical devices, and / or • Microlens arrays, especially cylindrical microlens arrays.

5. The optical system according to claim 4, wherein, The symmetrical optical device is a spherical lens.

6. The optical system according to any one of claims 1 to 5, wherein, The optical unit (30) has at least one fastening plate that covers the substrate retainer (20) along the engagement direction (40), and the fastening plate includes the third fastening region (32) or the fourth fastening region (34).

7. The optical system according to any one of claims 1 to 5, wherein, The third fastening region (32) and / or the fourth fastening region (34) are disposed in the corresponding gaps (60) of the optical unit (30).

8. The optical system according to any one of claims 1 to 5, wherein, The corresponding materials used to manufacture the substrate retainer (20) and the optical unit (30) have substantially uniform coefficients of thermal expansion.

9. The optical system according to any one of claims 1 to 5, wherein, The optical unit (20) produces collimation in a predefined spatial direction, wherein the arrangement of the engagement direction (40) and thus the corresponding fastening regions (22, 24, 32, 24) is determined such that the effect of the movement of the optical unit (30) relative to the light source (10) along the engagement direction (40) on the collimation is minimized.

10. A lidar sensor (70) comprising a transmitting unit having an optical system according to any one of claims 1 to 9.

11. A method for manufacturing an optical system, comprising the following steps: • Using a (100) light source (10) and a substrate holder (20), wherein, The light source (10) is fastened at a predefined position and relative to the base holder (20) in a predefined orientation. • Apply adhesive (50) to On the first fastening region (22) of the substrate retainer (20) and / or the third fastening region (32) of the optical unit (30) of the optical system, and On the second fastening region (24) of the substrate retainer (20) and / or the fourth fastening region (34) of the optical unit (30), The third fastening region (32) and the fourth fastening region (34) are disposed on the optical unit (30) spaced apart from each other along the joining direction (40) between the optical unit (30) and the substrate holder (20), and • The optical unit (30) is fastened (300) to the base holder (20) along a bonding direction (40) oriented transversely to the fastening regions (22, 24, 32, 34), thereby bonding the first fastening region (22) with the third fastening region (32), the second fastening region (24), and the fourth fastening region (34), wherein the optical unit (30) is configured to influence the light beam emitted by the light source (10) toward the optical unit (30).

12. The method according to claim 11, wherein, The optical unit (30) is fastened (300) to the base holder (20) along a bonding direction (40) perpendicular to the orientation of the fastening regions (22, 24, 32, 34).

13. The method according to claim 11, wherein, The steps for securing the optical unit (30) to the substrate holder (20) include: • The optical unit (30) is roughly positioned and roughly oriented relative to the light source (10), wherein the fastening areas (22, 24) of the substrate holder (20) are not yet in contact with the corresponding fastening areas (32, 34) of the optical unit (30) by the adhesive (50) during this step. • The optical unit (30) and the substrate holder (20) are combined along the joining direction (40) such that the corresponding fastening areas (22, 24) of the substrate holder (20) come into contact with the corresponding fastening areas (32, 34) of the optical unit (30) via the adhesive (50). • By means of optical measurement, the optical unit (30) is precisely positioned and oriented relative to the light source (10), and • Harden the adhesive (50).

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