Electromagnetic wave irradiation device

Abstract

This electromagnetic wave irradiation device is provided with: an irradiation unit (31) that irradiates electromagnetic waves; a lens group into which the electromagnetic waves are incident; and a changing unit that changes the irradiation direction of the electromagnetic waves that have passed through the lens group. The lens group includes a first anamorphic lens (41) configured so that the power thereof in a first direction perpendicular to the optical axis of the electromagnetic waves is greater than the power in a second direction perpendicular to the optical axis and the first direction. The spread angle of the electromagnetic waves in the first direction is greater than the spread angle in the second direction.

Description

Electromagnetic wave irradiation device CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority from Japanese Patent Application No. 2023-193097 (filed November 13, 2023), the entire disclosure of which is incorporated herein by reference.

[0002] The present disclosure relates to an electromagnetic wave irradiation device.

[0003] In recent years, devices have been developed that obtain information about surrounding objects, etc. from the results of detecting electromagnetic waves. For example, Patent Document 1 discloses a LIDAR (Light Detection and Ranging) system that includes a collimator lens that converts laser light into parallel light and a prism that emits the laser light incident on a first surface from a second surface.

[0004] Japanese Patent Application Laid-Open No. 2022-059924

[0005] (1) An electromagnetic wave irradiation device according to an embodiment of the present disclosure includes: an irradiation unit that irradiates electromagnetic waves; a lens group that receives the electromagnetic waves; and a change unit that changes the irradiation direction of the electromagnetic waves that have passed through the lens group, wherein the lens group includes a first anamorphic lens having a power of the electromagnetic waves in a first direction perpendicular to an optical axis that is greater than a power of the electromagnetic waves in a second direction perpendicular to the optical axis and the first direction, and the spread angle of the electromagnetic waves in the first direction is greater than the spread angle in the second direction.

[0006] (2) As an embodiment of the present disclosure, in (1), the lens group further includes a second anamorphic lens whose power in the first direction is smaller than the power in the second direction.

[0007] (3) As an embodiment of the present disclosure, in (2), the power of the first anamorphic lens in the first direction is greater than the power of the second anamorphic lens in the second direction.

[0008] (4) As an embodiment of the present disclosure, in (2) or (3), the first anamorphic lens emits the electromagnetic waves incident from the irradiation unit, and the second anamorphic lens receives the electromagnetic waves from the first anamorphic lens and emits them toward the modification unit.

[0009] (5) As an embodiment of the present disclosure, in any one of (2) to (4), the second anamorphic lens forms an exit pupil on the modified portion.

[0010] (6) As an embodiment of the present disclosure, in any one of (2) to (5), the lens group includes a collimator lens that is rotationally symmetric with respect to the optical axis.

[0011] (7) As an embodiment of the present disclosure, in any one of (1) to (6), the irradiation unit is a multi-channel laser diode in which a plurality of light-emitting regions are arranged in the second direction.

[0012] (8) As an embodiment of the present disclosure, in any one of (1) to (7), the changer includes a MEMS mirror capable of changing the irradiation direction of the electromagnetic wave at least along the first direction.

[0013] (9) As an embodiment of the present disclosure, in any one of (2) to (6), the first anamorphic lens has zero power in the second direction, and the second anamorphic lens has zero power in the first direction.

[0014] (10) As an embodiment of the present disclosure, in (6), the lens group is configured from, in order from the irradiation unit side, the first anamorphic lens, the collimator lens, and the second anamorphic lens.

[0015] (11) As an embodiment of the present disclosure, in (6), the first anamorphic lens, the second anamorphic lens, and the collimator lens include aspheric surfaces.

[0016] (12) As one embodiment of the present disclosure, in (6), the first anamorphic lens, the second anamorphic lens, and the collimator lens each have one of an object-side surface and an image-side surface that is flat, and the other is a convex surface.

[0017] (13) As an embodiment of the present disclosure, in (12), the first anamorphic lens is integrated with the collimator lens.

[0018] Fig. 1 is a diagram showing a schematic configuration of an electromagnetic wave irradiation device according to an embodiment of the present disclosure. Fig. 2A is a partially enlarged view of the electromagnetic wave irradiation device, showing the schematic configuration as viewed from one direction. Fig. 2B is a partially enlarged view of the electromagnetic wave irradiation device, showing the schematic configuration as viewed from another direction. Fig. 3 is a diagram showing an example configuration of an irradiation unit. Fig. 4A is a diagram explaining the spread angle of an electromagnetic wave. Fig. 4B is a diagram explaining the spread angle of an electromagnetic wave. Fig. 5 is a diagram for explaining detection of electromagnetic waves including reflected waves.

[0019] An electromagnetic wave irradiation device according to an embodiment of the present disclosure will be described below with reference to the drawings. In each drawing, identical or corresponding parts are designated by the same reference numerals. In the description of this embodiment, the description of identical or corresponding parts will be omitted or simplified as appropriate.

[0020] FIG. 1 is a diagram showing a schematic configuration of an electromagnetic wave irradiation device according to this embodiment. The electromagnetic wave irradiation device includes an irradiation unit 31, a lens group, and a change unit. The lens group is an irradiation optical system of the electromagnetic wave irradiation device and includes a first anamorphic lens 41 and a second anamorphic lens 42. The lens group may include a collimator lens 43. The lens group may further include a combining unit 40. The change unit includes a scanning unit 50. The change unit may further include a wave guide unit 60, a mirror 61, and an emission unit 70. The configuration of the electromagnetic wave irradiation device shown in FIG. 1 is an example. The electromagnetic wave irradiation device may include all of the functional units shown in FIG. 1, may include functional units other than those shown in FIG. 1, or may not include some of the functional units shown in FIG. 1.

[0021] Here, for convenience of explanation, the functional units are shown sufficiently spaced apart from one another. In the actual configuration of the electromagnetic wave irradiation device, the functional units constituting the electromagnetic wave irradiation device may be more densely packed than the state shown in Fig. 1. For example, the functional units may be arranged so that the electromagnetic wave irradiation device is configured to be small enough to fit within an area of ​​several centimeters square.

[0022] The electromagnetic wave irradiation device can irradiate electromagnetic waves and output the irradiated electromagnetic waves while changing the irradiation direction. At least a portion of the electromagnetic waves whose irradiation direction has been changed by the electromagnetic wave irradiation device may be reflected by a predetermined target (such as an object). The electromagnetic waves reflected by the predetermined target (such as an object) (reflected waves) may be detected and used for distance measurement. In this embodiment, the electromagnetic wave irradiation device is used as part of a LIDAR device that irradiates electromagnetic waves that are laser light and measures the distance to, the shape of, and the like of a predetermined target based on the reflected waves.

[0023] FIG. 5 is a diagram illustrating detection of electromagnetic waves including reflected waves. For example, the LIDAR device may include an electromagnetic wave irradiation device, an incident unit 15, a separation unit 16, an image sensor 17, a switching unit 18, a post-stage optical system 19, and a photodiode 20. In the example of FIG. 5 , electromagnetic waves irradiated from the electromagnetic wave irradiation device are incident as irradiated waves on a region R in space where a predetermined object exists, within a range in which the LIDAR device can irradiate irradiated waves. The irradiated waves are, for example, infrared rays. Electromagnetic waves including reflected waves, which are irradiated by a predetermined object existing in region R, are incident on the incident unit 15 of the LIDAR device. The electromagnetic waves including reflected waves may include not only infrared rays but also visible light, which is external light reflected by a predetermined object existing in region R. The separation unit 16 separates visible light from the electromagnetic waves including reflected waves, and the separated visible light is detected by the image sensor 17. The separation unit 16 also separates infrared light from the electromagnetic waves including reflected waves. The separated infrared light is reflected by the switching unit 18, passes through a post-stage optical system 19, and is detected by a photodiode 20. As the irradiation direction of the irradiation wave changes (deflection, optical scanning), the area R in space where the irradiation wave is incident changes. Furthermore, the LIDAR device uses the detected reflected wave to calculate the distance to a predetermined object, for example, using a ToF method.

[0024] Referring again to FIG. 1 , the components of the electromagnetic wave irradiation device will be described. The irradiation unit 31 irradiates electromagnetic waves. In this embodiment, the irradiation unit 31 irradiates infrared rays as electromagnetic waves for scanning a predetermined object. However, the electromagnetic waves irradiated by the irradiation unit 31 are not limited to infrared rays. In this embodiment, the irradiation unit 31 is configured to include a semiconductor laser (light-emitting region 310 in FIG. 3 ) that functions as a laser utilizing semiconductor recombination light emission. However, the irradiation unit 31 may be configured to include a laser light source other than a semiconductor laser. The irradiation unit 31 may irradiate, for example, pulsed electromagnetic waves.

[0025] FIG. 3 is a diagram showing an example of the configuration of the irradiation unit 31, showing an enlarged view of the irradiation surface. In this embodiment, multiple light-emitting regions 310 are arranged in an array on the irradiation surface of the irradiation unit 31. That is, the irradiation unit 31 has a multi-channel laser diode configuration in which multiple light-emitting regions are arranged in the x-axis direction. Here, the light-emitting region 310 may be a single laser diode, and the irradiation unit 31 may be composed of multiple laser diodes. Hereinafter, the x-axis direction may be referred to as the array direction or the second direction. In the example of FIG. 3, three light-emitting regions 310 are arranged in the array direction, but the number of light-emitting regions 310 is not limited to three. Each of the multiple light-emitting regions 310 has a light-emitting region with a length L1 in the array direction. In addition, the length of the non-light-emitting region between the light-emitting regions 310 is L2. The irradiation surface of the irradiation unit 31 is generally elongated in the array direction, with L2 being greater than L1. The lower view of FIG. 3 also shows an enlarged view of the light-emitting region 310. To increase the amount of light, the light-emitting region 310 may have a multi-layer structure. In the example of Figure 3, a configuration having three layers in the y-axis direction perpendicular to the x-axis direction is shown, but the number of layers in the light-emitting region 310 is not limited to three. Hereinafter, the y-axis direction may be referred to as the layer direction or the first direction. In addition, the same x-y coordinate system as in Figure 3 may be used in other drawings to explain the positional relationship of the components of the electromagnetic wave irradiation device.

[0026] In the irradiation unit 31, in which multiple light-emitting regions 310 are arranged in an array, the spread of electromagnetic waves (infrared rays in this embodiment) varies depending on the direction. FIGS. 4A and 4B are diagrams illustrating the spread angle of the electromagnetic waves. As described above, the light-emitting region 310 has a multilayer structure. As shown in FIG. 4A , the length (thickness) of one of the light-emitting layers is short. Therefore, the spread angle of the electromagnetic waves in the y-axis direction (layer direction) is large. Here, the spread angle indicates the spread of the irradiated electromagnetic waves as an angle relative to the case where the waves travel in a straight line (in a direction perpendicular to the x-axis and y-axis directions). In contrast, the length of the light-emitting region 310 in the x-axis direction (array direction) is longer than the length (thickness) of one of the light-emitting layers. Therefore, the spread angle of the electromagnetic waves in the x-axis direction (array direction) is narrow. The lens group onto which the electromagnetic waves irradiated from the irradiation unit 31 are incident is preferably configured to reduce light loss in accordance with the difference in the spread angle of the electromagnetic waves depending on the direction. The electromagnetic wave irradiation device according to this embodiment has a lens group configured as described below, which can reduce optical loss and increase the laser light density, and can be used in a LIDAR device to improve distance measurement accuracy.

[0027] 2A is an enlarged view of a portion including a lens group of the electromagnetic wave irradiation device, showing the schematic configuration when viewed in the positive direction of the x-axis. FIG. 2B is an enlarged view of a portion including a lens group of the electromagnetic wave irradiation device, showing the schematic configuration when viewed in the negative direction of the y-axis. In FIGS. 2A and 2B, thin solid lines indicate electromagnetic waves that are irradiated from the irradiation unit 31, pass through the lens group, and are refracted, etc., before reaching the scanning unit 50. In FIG. 2B, the irradiation unit 31 has multiple light-emitting regions 310 in the x-axis direction (array direction), and electromagnetic waves are irradiated from each light-emitting region 310.

[0028] The lens group includes at least a first anamorphic lens 41 and a second anamorphic lens 42. The first anamorphic lens 41 is disposed closer to the irradiation unit 31 than the second anamorphic lens 42. For example, the first anamorphic lens 41 may be configured to emit electromagnetic waves incident from the irradiation unit 31, and the second anamorphic lens 42 may be configured to receive electromagnetic waves from the first anamorphic lens 41 and emit them toward the modification unit. Anamorphic lenses have different powers depending on the direction. Here, the power in a certain direction is the refractive power that refracts electromagnetic waves in that direction.

[0029] 2A and 2B, the y-axis direction (layer direction) is referred to as the first direction, and the x-axis direction (array direction) is referred to as the second direction. As described above, the light-emitting region 310 of the irradiation unit 31 has a large spread angle in the first direction and a small spread angle in the second direction. That is, the spread angle of the electromagnetic wave in the first direction is larger than the spread angle in the second direction. If the electromagnetic wave continues to travel with a large spread angle, the amount of light that does not reach the scanning unit 50 (loss) increases. Therefore, with respect to the first direction, it is preferable to correct the propagation direction of the electromagnetic wave at a position close to the irradiation unit 31. The first anamorphic lens 41 has a power greater in the first direction perpendicular to the optical axis of the electromagnetic wave than in the second direction perpendicular to the optical axis and the first direction. Therefore, by arranging the first anamorphic lens 41 closer to the irradiation unit 31, light loss can be reduced.

[0030] The second anamorphic lens 42 has a symmetrical structure to the first anamorphic lens 41 so as to form an exit pupil on the scanning unit 50. That is, the power of the second anamorphic lens 42 in the first direction is smaller than the power in the second direction. Here, the power of the first anamorphic lens 41 in the first direction and the power of the second anamorphic lens 42 in the second direction may be determined based on, for example, the difference between the spread angle of the electromagnetic wave in the first direction and the spread angle in the second direction. Here, the power of the first anamorphic lens 41 in the first direction may be set to be larger than the power of the second anamorphic lens 42 in the second direction. In this case, the beam diameter in the scanning unit 50 is reduced, thereby suppressing interference. Here, interference refers to the superposition of the electromagnetic wave traveling from the second anamorphic lens 42 to the scanning unit 50 and the electromagnetic wave whose traveling direction has been changed by the scanning unit 50.

[0031] The first anamorphic lens 41 may have zero power in the second direction, and the second anamorphic lens 42 may have zero power in the first direction. In this case, the design of the first anamorphic lens 41 and the second anamorphic lens 42 becomes easier, and installation accuracy can be improved.

[0032] 2A and 2B , the lens group may further include a collimator lens 43 that is rotationally symmetric with respect to the optical axis. The inclusion of the collimator lens 43 in the lens group suppresses the occurrence of aberrations. In this case, the lens group may be configured such that a first anamorphic lens 41, a collimator lens 43, and a second anamorphic lens 42 are arranged in this order from the irradiation unit 31 side. Furthermore, the first anamorphic lens 41, the second anamorphic lens 42, and the collimator lens 43 may each include an aspherical surface. In this case, the effect of reducing light loss can be further improved compared to when the lens group is configured with spherical lenses.

[0033] Furthermore, each of the first anamorphic lens 41, the second anamorphic lens 42, and the collimator lens 43 may have one of its object-side and image-side surfaces flat and the other convex. In this case, the first anamorphic lens 41, the second anamorphic lens 42, and the collimator lens 43 can be easily designed and installation accuracy can be improved. Furthermore, the first anamorphic lens 41 and the collimator lens 43 can be integrated, for example, by bonding flat surfaces together. In this case, installation accuracy can be further improved.

[0034] 2A and 2B , the lens group may further include a combining unit 40. The combining unit 40 outputs two electromagnetic waves input from different directions in a predetermined direction. The combining unit 40 may output the combined electromagnetic wave toward the scanning unit 50. The combining unit 40 may be, for example, a prism or a cold mirror, but may have any configuration as long as it can combine two electromagnetic waves and output them in a predetermined direction.

[0035] 1 again, the configuration of the modification unit will be described below. The modification unit deflects and scans the electromagnetic wave that has passed through the lens group. As described above, the modification unit includes at least the scanning unit 50, but may also include a waveguide unit 60, a mirror 61, and an emission unit 70, as in this embodiment.

[0036] The scanning unit 50 may be configured to include, for example, a reflective mirror that deflects the incident electromagnetic wave. The reflective mirror of the scanning unit 50 may be, for example, a MEMS (Micro Electro Mechanical Systems) mirror, a polygon mirror, or a galvanometer mirror. In this embodiment, the scanning unit 50 is a MEMS mirror that can change the irradiation position of the electromagnetic wave at least in a first direction (that can change the irradiation direction of the electromagnetic wave at least along the first direction).

[0037] The scanning unit 50 has a rotation axis and rotates around the rotation axis. Here, the rotation does not necessarily have to be an orbital motion, but may be, for example, a swinging motion. The scanning unit 50 may deflect incident electromagnetic waves by the rotational motion toward, for example, the waveguide unit 60.

[0038] The waveguide 60 reflects or passes the incident electromagnetic wave. When the incident electromagnetic wave is an electromagnetic wave combined by the combiner 40, the waveguide 60 may have a function of separating the electromagnetic wave. For example, when an electromagnetic wave formed by combining visible light and infrared light is incident on the waveguide 60, the waveguide 60 may reflect the visible light and pass the infrared light. The waveguide 60 may be configured to include, for example, a cold mirror.

[0039] The mirror 61 is a member that adjusts the optical path so that the electromagnetic wave from the waveguide 60 that becomes the above-mentioned irradiation wave is directed toward the emission section 70. The changing section may be configured without the mirror 61. In this case, the waveguide 60 is disposed relative to the emission section 70 so that the electromagnetic wave from the waveguide 60 is directed directly toward the emission section 70.

[0040] The emission unit 70 is scanned by the scanning unit 50 and emits electromagnetic waves that become the above-mentioned irradiation waves from the electromagnetic wave emission device. Specifically, the emission unit 70 may emit infrared rays that are scanned by the scanning unit 50. The emission unit 70 may be made of, for example, glass or acrylic so as to allow infrared rays to pass through.

[0041] As described above, the electromagnetic wave irradiation device according to this embodiment can reduce optical loss and improve distance measurement accuracy by using the above-described lens group configuration.

[0042] Although the embodiments of the present disclosure have been described based on the drawings and examples, it should be noted that those skilled in the art would easily be able to make various modifications or alterations based on the present disclosure. Therefore, it should be noted that these modifications and alterations are included within the scope of the present disclosure. For example, the functions included in each component or step can be rearranged so as not to cause logical inconsistencies, and multiple components or steps can be combined or divided into one. The embodiments of the present disclosure can also be realized as a program executed by a processor included in an apparatus or a storage medium on which a program is recorded. It should be understood that these are also included within the scope of the present disclosure.

[0043] REFERENCE SIGNS LIST 15 Incident section 16 Separation section 17 Image sensor 18 Switching section 19 Post-stage optical system 20 Photodiode 31 Irradiation section 40 Combining section 41 First anamorphic lens 42 Second anamorphic lens 43 Collimator lens 50 Scanning section 60 Waveguide section 61 Mirror 70 Emitter section 310 Light-emitting region

Claims

1. An irradiation unit that emits electromagnetic waves, The lens group into which the electromagnetic waves are incident, It includes a changing unit that changes the irradiation direction of the electromagnetic waves that have passed through the lens group, The aforementioned lens group is The system includes a first anamorphic lens in which the power in a first direction perpendicular to the optical axis of the electromagnetic wave is greater than the power in a second direction perpendicular to the optical axis and the first direction. An electromagnetic wave irradiation device wherein the spread angle of the electromagnetic wave in the first direction is greater than the spread angle in the second direction.

2. The aforementioned lens group is The electromagnetic wave irradiation device according to claim 1, further comprising a second anamorphic lens having a power in the first direction less than the power in the second direction.

3. The electromagnetic wave irradiation device according to claim 2, wherein the power of the first anamorphic lens in the first direction is greater than the power of the second anamorphic lens in the second direction.

4. The electromagnetic wave irradiation device according to claim 2 or 3, wherein the first anamorphic lens emits the electromagnetic waves from the incident irradiation section, and the second anamorphic lens receives the electromagnetic waves from the first anamorphic lens and emits them toward the modification section.

5. The electromagnetic wave irradiation device according to claim 2, wherein the second anamorphic lens forms an exit pupil on the modified portion.

6. The electromagnetic wave irradiation device according to claim 2 or 3, wherein the lens group includes a collimator lens that is rotationally symmetric with respect to the optical axis.

7. The electromagnetic wave irradiation device according to claim 2 or 3, wherein the irradiation unit is a multi-channel laser diode having a plurality of light-emitting regions arranged in the second direction.

8. The electromagnetic wave irradiation device according to claim 2 or 3, wherein the modified part includes a MEMS mirror capable of changing the irradiation direction of the electromagnetic wave along at least the first direction.

9. The first anamorphic lens has zero power in the second direction. The electromagnetic wave irradiation device according to claim 2 or 3, wherein the second anamorphic lens has zero power in the first direction.

10. The electromagnetic wave irradiation device according to claim 6, wherein the lens group comprises, in order from the side of the irradiation unit, the first anamorphic lens, the collimator lens, and the second anamorphic lens.

11. The electromagnetic wave irradiation device according to claim 6, wherein the first anamorphic lens, the second anamorphic lens, and the collimator lens include an aspherical surface.

12. The electromagnetic wave irradiation device according to claim 6, wherein each of the first anamorphic lens, the second anamorphic lens, and the collimator lens has one of its object-side and image-side surfaces being flat and the other being convex.

13. The electromagnetic wave irradiation device according to claim 12, wherein the first anamorphic lens is integrated with the collimator lens.