JP2022043268A - Irradiation apparatus and light receiving apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an irradiation apparatus that can expand an irradiation range of an electromagnetic wave and a light receiving apparatus that can suitably expand a light reception range.

SOLUTION: A light measuring apparatus 100 comprises: a light source unit 1; an MEMS mirror device 20 having an MEMS mirror 2; an optical member 3; a light receiving unit 4; and a control unit 5. The optical member 3 emits emission light Lt incident from the MEMS mirror 2 to the outside of the measuring apparatus 100, and makes return light Lr reflected on a measurement object OB incident on the MEMS mirror 2. The optical member 3 has a transmittance angle dependent filter 9. The transmittance angle dependent filter 9 reflects the emission light Lt and the return light Lr toward the MEMS mirror 2 to cause the MEMS mirror 2 to reflect the emission light Lt and the return light Lr multiple times, thereby increasing the apparent tilt angle of the MEMS mirror 2.

SELECTED DRAWING: Figure 3

COPYRIGHT: (C)2022,JPO&INPIT

Description

The present invention relates to reception and irradiation of electromagnetic waves.

Conventionally, a measuring device such as a lidar (LIDAR: Laser Illuminated Detection and Ranging, Laser Imaging Detection and Ranging or LiDAR: Light Detection and Ranging) using a laser beam which is an electromagnetic wave is known. For example, Patent Document 1 discloses a rider using a MEMS (Micro Electro Electro Mechanical Systems) mirror.

Japanese Unexamined Patent Publication No. 2016-184018

Generally, when a wobbling type MEMS mirror is applied to a rider that scans in the horizontal direction, an optical system that is a rotation target is used to convert the emitted light in the horizontal direction, so that the light receiving element is directed from the outside world. The optical system that collects the incident light has a problem that the pupil magnification in the sagittal direction becomes small.

As an example of the problem to be solved by the present invention, the above-mentioned one can be mentioned. An object of the present invention is to provide an irradiation device capable of expanding the irradiation range of electromagnetic waves and a receiving device capable of suitably expanding the light receiving range.

The invention according to the claim is an irradiation device that irradiates an electromagnetic wave irradiated by an irradiation unit in a predetermined direction, and shakes the filter unit and the frame portion that transmit the electromagnetic waves emitted by the irradiation unit. The filter unit includes a first reflection unit that moves and reflects the electromagnetic wave transmitted by the filter unit as a first reflected wave, and the filter unit is provided with the filter unit to the first reflection unit of the electromagnetic wave transmitted through the filter unit. The first reflected wave is reflected by the first reflecting portion so as to be incident on the first reflecting portion at an angle larger than the incident angle, and the first reflecting portion is reflected by the filter portion. The reflected wave is reflected as a second reflected wave transmitted through the filter unit.

Further, the invention according to the claim is a receiving device in which an electromagnetic wave emitted by an irradiation unit receives a reflected wave reflected by an object, and is shaken with respect to a filter unit and a frame portion that transmit the reflected wave. It is provided with a first reflecting unit that moves and reflects the reflected wave transmitted by the filter unit as a first reflected wave, and the filter unit is directed to the first reflecting unit of the electromagnetic wave transmitted through the filter unit. The first reflected wave is reflected on the first reflecting portion so as to be incident on the first reflecting portion at an angle smaller than the incident angle of the above, and the first reflecting portion is reflected by the filter portion. 1 The reflected wave is reflected as a second reflected wave that passes through the filter unit and is incident on the receiving unit.

The schematic configuration of the irradiation apparatus which concerns on 1st Example is shown. It is a figure which showed the operating range of the MEMS mirror roughly. It is a figure explaining the optical action of the transmittance angle dependent filter. It is a graph which shows the characteristic of the transmittance based on the incident angle of the transmittance angle dependent filter. It is a figure which showed the optical action of the transmittance angle-dependent filter when it is reflected three times by a MEMS mirror. A schematic configuration of the receiving device according to the second embodiment is shown. It is a figure which showed the optical action of the transmittance angle-dependent filter when it is reflected three times by a MEMS mirror. The schematic configuration of the measuring apparatus which concerns on 3rd Embodiment is shown. It is a top view which showed the configuration example of the MEMS mirror device. An example of the configuration of the optical member is shown.

In a preferred embodiment of the present invention, the irradiation device irradiates the electromagnetic waves irradiated by the irradiation unit in a predetermined direction with respect to the filter unit and the frame portion that transmit the electromagnetic waves emitted by the irradiation unit. It is provided with a first reflecting unit that swings and reflects the electromagnetic wave transmitted by the filter unit as a first reflected wave, and the filter unit is directed to the first reflecting unit of the electromagnetic wave transmitted through the filter unit. The first reflected wave is reflected by the first reflecting portion so as to be incident on the first reflecting portion at an angle larger than the incident angle of the above, and the first reflecting portion is reflected by the filter portion. 1 The reflected wave is reflected as a second reflected wave transmitted through the filter unit. According to this aspect, even when the tilt angle of the first reflecting portion is limited, the irradiation device preferably increases the tilt angle of the first reflecting portion in appearance to expand the irradiation range of the electromagnetic wave. Can be done.

In one aspect of the irradiation device, the filter unit is an optical member having a transmittance angle dependence. According to this aspect, the filter unit transmits the electromagnetic wave irradiated by the irradiation unit, reflects the first reflected wave to the first reflection unit, and transmits the second reflected wave to the outside. Can be done.

In another aspect of the irradiation device, the filter unit reflects an electromagnetic wave whose angle of incidence on the filter unit is from a first angle to a second angle larger than the first angle, and the incident angle is increased. The electromagnetic wave transmitted by the third angle or less, which is less than the first angle, or the fourth angle or more, which is larger than the second angle, is irradiated by the irradiation unit, and the incident angle is the third angle or less. The incident angle of the first reflected wave is an angle from the first angle to the second angle, and the incident angle of the second reflected wave is equal to or larger than the fourth angle. Since the filter unit has such an angle dependence of the transmittance, the first reflected wave is reflected by the first reflecting unit and the second reflected wave is transmitted while transmitting the electromagnetic wave irradiated by the irradiation unit. It can be transmitted and ejected to the outside.

In another aspect of the irradiation device, the first reflective portion has a tilt angle with respect to the frame portion within a predetermined angle range, and the tilt angle becomes an arbitrary angle within the predetermined angle range. The filter unit reflects the first reflected wave to the first reflecting unit, and the first reflecting unit reflects the first reflected wave reflected by the filter unit as the second reflected wave. According to this aspect, the irradiation device preferably expands the scanning angle (vertical viewing angle) in the vertical direction when the tilt angle of the first reflecting portion is modulated to scan in the direction perpendicular to the main scanning direction. Can be done.

In another aspect of the irradiation device, the first reflecting portion is tilted with respect to the filter portion. As a result, the filter unit reflects the first reflected wave to the first reflection unit so that the electromagnetic wave transmitted through the filter unit is incident on the first reflection unit at an angle larger than the angle of incidence on the first reflection unit. Is possible. Preferably, the filter portion is provided in parallel with the frame portion. Since the first reflecting portion swings with respect to the frame portion, the first reflecting portion is suitably tilted with respect to the filter portion according to this embodiment.

In another aspect of the irradiation device, the first reflecting unit re-reflects the first reflected wave reflected by the filter unit as the first reflected wave, and then the first reflected wave is used as the second reflected wave. It is reflected by the filter unit as a reflected wave. According to this aspect, the irradiation device can greatly increase the tilt angle of the first reflective portion in appearance. For example, when the first reflection unit rereflects the first reflected wave reflected by the filter unit once, the inclination angle of the first reflection unit as it looks is set to the inclination angle of the first reflection unit when the filter unit is not arranged. The tilt angle of can be doubled. That is, if the number of times of rereflection is increased, the tilt angle of the apparent first reflecting portion can be doubled, tripled, and so on.

In another embodiment of the present invention, the electromagnetic wave irradiated by the irradiation unit is a receiving device that receives the reflected wave reflected by the object, and swings with respect to the filter unit and the frame unit that transmit the reflected wave. The filter unit includes a first reflection unit that reflects the reflected wave transmitted by the filter unit as a first reflected wave, and the filter unit transfers the electromagnetic wave transmitted through the filter unit to the first reflection unit. The first reflected wave is reflected by the first reflecting portion so as to be incident on the first reflecting portion at an angle smaller than the incident angle, and the first reflecting portion is reflected by the filter portion. The reflected wave is reflected as a second reflected wave that passes through the filter unit and is incident on the receiving unit. According to this aspect, in the receiving device, even if the reflected wave incident on the first reflecting portion cannot be directly reflected by the light receiving portion due to the limitation of the tilt angle of the first reflecting portion, the receiving device can receive the reflected wave through the filter portion. Can be suitably guided to.

Hereinafter, preferred first to third embodiments of the present invention will be described with reference to the drawings. Hereinafter, both "irradiation" and "emission" refer to the output of light, and in the explanation premised on the existence of an object to which light hits, such as a reflecting part or an object, "irradiation" and light are used. In the explanation that does not presuppose (not be aware of) the existence of the object to which is hit, "injection" is used for convenience in the following explanation.

<First Example>
FIG. 1 shows a schematic configuration of the irradiation device 10 according to the first embodiment. The irradiation device 10 emits a laser beam (also referred to as “injection light Lt”) which is an electromagnetic wave (for example, an infrared ray having a wavelength of 905 nm) to the outside world. The irradiation device 10 mainly includes a light source unit 1 that emits emitted light Lt, a MEMS mirror 2, and a transmittance angle-dependent filter 9.

After that, the direction in which the emitted light Lt emitted from the light source unit 1 is incident on the MEMS mirror 2 (that is, the normal direction when the MEMS mirror 2 is not tilted) is the "z-axis direction", and the direction perpendicular to the z-axis. Are defined as "x-axis direction" and "y-axis direction", respectively, and each of these positive directions is defined as shown in the figure. FIG. 1 shows an xz cross section of the irradiation device 10, and the MEMS mirror 2 is tilted about the y-axis by a tilt angle “ψ”. The tilt angle ψ is equal to the angle formed by the normal direction of the MEMS mirror 2 with respect to the z-axis. The two-dot chain line in FIG. 1 indicates the normal direction of the MEMS mirror 2.

The MEMS mirror 2 swings with respect to a frame portion (not shown) to reflect the laser light incident from the light source unit 1 toward the transmittance angle-dependent filter 9, and the light reflected by the transmittance angle-dependent filter 9. Is reflected again and reflected toward the outside world. The MEMS mirror 2 is, for example, an electrostatically driven mirror, and is a wobbling type mirror whose operation is controlled by a control unit (not shown). The MEMS mirror 2 is an example of the "first reflecting unit" in the present invention.

The transmittance angle-dependent filter 9 is placed so as to face the reflection surface of the MEMS mirror 2 and parallel to the xy plane (that is, the frame portion of the MEMS mirror 2 (not shown)), and the light incident on the MEMS mirror 2 and the light It is provided on the optical path of the light reflected by the MEMS mirror 2. The transmittance angle-dependent filter 9 is a filter in which the transmittance of the light changes depending on the incident angle of the light. In the example of FIG. 1, the transmittance angle-dependent filter 9 transmits the emitted light Lt emitted from the light source unit 1, then reflects the emitted light Lt reflected by the MEMS mirror 2, and is rereflected by the MEMS mirror 2. The emitted light Lt is transmitted. The transmittance angle-dependent filter 9 may be provided, for example, in place of the window plate of the MEMS mirror 2. The transmittance angle-dependent filter 9 is an example of the "filter unit" in the present invention.

FIG. 2 is a diagram schematically showing the operating range of the MEMS mirror 2. In the example of FIG. 2, the MEMS mirror 2 rotates about the z-axis while the tilt angle ψ keeps the angle “ψ ₀ ” as shown by the arrow 90. Further, preferably, the tilt angle ψ of the MEMS mirror 2 can be modulated by an angle “Δψ” about the angle ψ ₀ . In this case, the following equation (1) holds for the tilt angle ψ of the MEMS mirror 2.
ψ ₀ － Δ ψ ≦ ψ ≦ ψ ₀ + Δψ (1)
In general, it is difficult to set the angle ψ ₀ and the angle Δψ to be large angles due to the manufacturing method and the like. Then, in this embodiment, the apparent (apparent) tilt angle of the wobbling type MEMS mirror 2 in which the tilt angle is limited by providing the transmittance angle-dependent filter 9 at a position facing the reflection surface of the MEMS mirror 2. Increase ψ and preferably increase the scanning angle.

FIG. 3 is a diagram illustrating the optical action of the transmittance angle-dependent filter 9 shown in FIG. First, the emitted light Lt is incident on the transmittance angle-dependent filter 9 perpendicularly (that is, due to an incident angle of 0 °) along the z-axis, passes through the transmittance angle-dependent filter 9, and then tilts the MEMS mirror 2. It is incident on the MEMS mirror 2 with an incident angle ψ equal to the angle ψ. After that, the emitted light Lt is reflected by the MEMS mirror 2 to be incident on the transmittance angle-dependent filter 9 by the incident angle 2 ψ, and is reflected by the transmittance angle-dependent filter 9 to be re-incidented to the MEMS mirror 2. Then, the emitted light Lt re-incidents into the MEMS mirror 2 is reflected by the MEMS mirror 2 and then is incident on the transmittance angle-dependent filter 9 by the incident angle 4 ψ and passes through the transmittance angle-dependent filter 9. The emission light Lt first reflected by the MEMS mirror 2 is an example of the "first reflected wave" in the present invention, and the emission light Lt reflected last (second time) by the MEMS mirror 2 is the present invention. This is an example of the "second reflected wave" in.

As described above, in the example of FIG. 3, the transmittance angle-dependent filter 9 transmits light having an incident angle of 0 ° and an incident angle of 4 ψ with a high transmittance close to 100%, and transmits light having an incident angle of 2 ψ to 0%. It has an incident angle dependence of the transmittance such that it is reflected by the transmittance close to. This dependence on the angle of incidence will be described later with reference to FIG.

Further, in the example of FIG. 3, the angle formed by the reflected light when the MEMS mirror 2 first reflects the emitted light Lt is "2ψ", whereas the MEMS mirror 2 reflects the emitted light Lt for the second time. The angle formed by the reflected light (that is, the emitted light Lt emitted to the outside world) when reflected on the z-axis is doubled to "4ψ". As described above, by providing the transmittance angle-dependent filter 9, the irradiation device 10 has the same angle as when the tilt angle ψ of the MEMS mirror 2 is doubled as compared with the configuration without the transmittance angle-dependent filter 9. Can emit the emission light Lt. Therefore, according to the irradiation device 10 according to the present embodiment, the apparent (apparent) tilt angle ψ of the wobbling type MEMS mirror 2 having a generally limited tilt angle is increased, and the scanning angle is suitably expanded. be able to.

Further, when the tilt angle of the MEMS mirror 2 is expressed by the equation (1), the irradiation device 10 causes the emitted light Lt emitted to the outside world to be “± 4Δψ” with respect to the z-axis at an inclination angle of 4 ψ ₀ . It is possible to modulate with. If the irradiation device 10 is not provided with the transmittance angle-dependent filter 9, the irradiation device 10 modulates the emitted light Lt emitted to the outside world by “± 2Δψ” with respect to the z-axis at an inclination angle of 2 ψ ₀ . It will be. Therefore, by providing the transmittance angle-dependent filter 9, the irradiation device 10 substantially doubles the modulation angle, and preferably has a vertical viewing angle which is a scanning angle perpendicular to the horizontal direction (that is, the main scanning direction). It can also be doubled.

Next, the incident angle dependence of the transmittance of the transmittance angle dependent filter 9 will be described with reference to FIG.

FIG. 4 is a graph showing the characteristics of the transmittance based on the incident angle of the transmittance angle-dependent filter 9. In the example of FIG. 4, the band having an incident angle of 0 ° to 3 ° and an incident angle of 43 ° to 69 ° has a transmittance of about 100% (here, 98% or more) (also referred to as a “transmission band”). .). On the other hand, in the band having an incident angle of 21 ° to 35 °, the transmittance is about 0% (here, 2% or less) (also referred to as “reflection band”). In the reflection band, if the absorption of the filter 9 itself such as the dielectric multilayer film can be ignored, “reflectance = 1-transmittance”, so that the reflectance is about 100% in the reflection band.

For example, when the transmittance angle-dependent filter 9 has the characteristics shown in FIG. 4, and the angle ψ ₀ is “14 °” and the angle Δψ is “3 °”, “22” is based on the equation (1). “° ≦ 2 ψ ≦ 34 °” and “44 ° ≦ 4 ψ ≦ 68 °” are established. Therefore, in this case, the transmittance angle-dependent filter 9 transmits light having an incident angle of 0 ° and an incident angle of 4 ψ with a transmittance close to 100%, and reflects light having an incident angle of 2 ψ with a transmittance close to 0%. Therefore, it is possible to suitably realize the optical action shown in FIGS. 1 and 3.

The theoretical upper limit of the angle Δψ is set so that the transmission band and the reflection band shown in FIG. 4 do not overlap.
Δψ <ψ ₀ / (2N-1)
Must be.

Further, in order to manufacture the transmittance angle-dependent filter 9 having less ripple in the graph showing the relationship between the transmittance and the incident angle, the transmittance angle-dependent filter 9 is, for example, a lugate type filter or an adjustment of the film thickness of each layer. It is preferable that the film is composed of a dielectric multilayer film formed by the film.

The incident angle of 21 ° in FIG. 4 is an example of the “first angle” in the present invention, and the incident angle of 35 ° is an example of the “second angle” in the present invention. Further, the incident angle of 3 ° is an example of the "third angle" in the present invention, and the incident angle of 43 ° is an example of the "fourth angle" in the present invention.

In the examples of FIGS. 1 and 3, the transmittance angle-dependent filter 9 is configured to reflect the emitted light Lt to the MEMS mirror 2 twice. Instead of this, the transmittance angle-dependent filter 9 may be configured to reflect the emitted light Lt to the MEMS mirror 2 three times or more.

That is, the transmittance angle-dependent filter 9 reflects the laser beam from the light source unit 1 N times (N is an integer of 3 or more) to generate the emitted light Lt having an angle formed with the z-axis of "2ψ · N". It is ejected to the outside of the irradiation device 10.

FIG. 5 is a diagram showing the optical action of the transmittance angle-dependent filter 9 when “N = 3”. In the example of FIG. 5, the transmittance angle-dependent filter 9 transmits light having an incident angle of 0 ° and an incident angle of 6 ψ with a transmittance close to 100%, and transmits light having incident angles 2 ψ and 4 ψ near 0%. It has an incident angle dependence of the transmittance that is reflected by the rate. When the MEMS mirror 2 first reflects the emitted light Lt, the angle formed by the reflected light with the z-axis is 2ψ, whereas the MEMS mirror 2 reflects the emitted light Lt last (that is, the third time). The angle formed by the reflected light (that is, the emitted light Lt emitted to the outside world) with the z-axis is "6ψ". The first and second emitted light Lt reflected by the MEMS mirror 2 is an example of the "first reflected wave" in the present invention, and the last emitted light Lt reflected by the MEMS mirror 2 is the present invention. This is an example of the "second reflected wave".

As described above, according to the example of FIG. 5, the transmittance angle-dependent filter 9 can triple the apparent tilt angle of the MEMS mirror 2 and preferably increase the scanning angle. In reality, the emitted light Lt has a luminous flux diameter of a predetermined length, and the entire or most of the luminous flux of the emitted light Lt reflected by the transmittance angle-dependent filter 9 needs to be incident on the MEMS mirror 2. On the other hand, the larger the number of reflections N on the MEMS mirror 2, the wider the irradiation range of the emitted light Lt irradiated on the MEMS mirror 2. Therefore, in consideration of the limitation of the size of the MEMS mirror 2, in reality, "N ≦ 3" is preferable.

As described above, the irradiation device 10 according to the present embodiment irradiates the emitted light Lt, which is an electromagnetic wave emitted by the light source unit 1, in a predetermined direction, and is emitted by the light source unit 1. It includes a transmittance angle-dependent filter 9 that transmits the emitted light Lt, and a MEMS mirror 2 that reflects the emitted light Lt transmitted by the transmittance angle-dependent filter 9 as a first reflected wave. Then, the transmittance angle-dependent filter 9 makes the first reflected wave MEMS so that the emitted light Lt transmitted through the transmittance angle-dependent filter 9 is incident on the MEMS mirror 2 at an angle larger than the angle of incidence on the MEMS mirror 2. Reflected by the mirror 2, the MEMS mirror 2 reflects the first reflected wave reflected by the transmittance angle-dependent filter 9 as the second reflected wave transmitted through the transmittance angle-dependent filter 9. As a result, the irradiation device 10 can increase the apparent tilt angle of the wobbling type MEMS mirror 2 having a limited tilt angle, and can suitably increase the scanning angle.

<Second Example>
FIG. 6 shows a schematic configuration of the receiving device 11 according to the second embodiment. The second embodiment is an example in which the transmittance angle-dependent filter 9 included in the irradiation device 10 of the first embodiment is applied to the laser receiving optical system, and the receiving device 11 according to the second embodiment is from a light source (not shown). The emitted laser light receives the light reflected by an object in the outside world (also referred to as "return light Lr"). The receiving device 11 shown in FIG. 6 includes a MEMS mirror 2, a light receiving unit 4 such as an avalanche photodiode, and a transmittance angle-dependent filter 9. In the second embodiment, the z-axis is the direction in which the return light Lr incident on the light receiving unit 4 is emitted from the MEMS mirror 2.

Here, the MEMS mirror 2 is a wobbling (swinging) type mirror in which the inclination (that is, the angle of optical scanning) changes within a predetermined range, similar to the MEMS mirror 2 of the irradiation device 10 shown in FIGS. 1 to 3. Is. Further, the transmittance angle-dependent filter 9 is placed in a state of facing the reflection surface of the MEMS mirror 2 and parallel to the xy plane, as in the first embodiment, and the return light Lr and the return light Lr incident on the MEMS mirror 2 are mounted. It is provided on the optical path of the return light Lr that reflects the MEMS mirror 2. The transmittance angle-dependent filter 9 has an incident angle dependence of the transmittance, transmits the return light Lr incident from the outside world, and then reflects the return light Lr reflected by the MEMS mirror 2, and the MEMS mirror. By transmitting the return light Lr rereflected by 2, the return light Lr is guided to the light receiving unit 4.

In the example of FIG. 6, first, the return light Lr is incident on the transmittance angle-dependent filter 9 by the incident angle 4 ψ, passes through the transmittance angle-dependent filter 9, and then is incident on the MEMS mirror 2 by the incident angle 4 ψ. After that, the return light Lr is reflected by the MEMS mirror 2 and is incident on the transmittance angle-dependent filter 9 by the incident angle 2ψ. Then, the return light Lr is reflected again by the transmittance angle-dependent filter 9 and is re-incidented into the MEMS mirror 2 by the incident angle 2 ψ, and then is reflected by the MEMS mirror 2 and is reflected by the MEMS mirror 2 and is reflected by the incident angle 0 ° to be reflected by the transmittance angle-dependent filter. It enters the light receiving unit 4 by incident on the light 9 and passing through the transmittance angle-dependent filter 9. The return light Lr first reflected by the MEMS mirror 2 is an example of the "first reflected wave" in the present invention, and the return light Lr reflected last (second time) by the MEMS mirror 2 is the present invention. This is an example of the "second reflected wave" in.

As described above, in the example of FIG. 6, the transmittance angle-dependent filter 9 transmits light having an incident angle of 0 ° and an incident angle of 4ψ with a transmittance close to 100%, as in the example of FIG. 1 of the first embodiment. Moreover, it has an incident angle dependence of the transmittance such that light having an incident angle of 2ψ is reflected by a transmittance close to 0%. Therefore, the transmittance angle-dependent filter 9 may have, for example, the incident angle dependence of the transmittance as shown in FIG.

Then, according to the receiving device 11 according to the second embodiment, the apparent tilt angle of the wobbling type MEMS mirror 2 having a limitation on the tilt angle ψ can be increased. Further, in general, the larger the apparent tilt angle ψ, the larger the pupil magnification in the sagittal direction. Further, according to the configuration of the receiving device 11 according to the present embodiment, since the apparent tilt angle can be expanded, the mirror diameter of the apparent MEMS mirror 2 can be expanded and the received light amount can be suitably increased.

The transmittance angle-dependent filter 9 used in the receiving device 11 reflects light incident from the outside onto the MEMS mirror 2 three or more times, like the transmittance angle-dependent filter 9 used in the irradiation device 10 of the first embodiment. (That is, the number of reflections N on the MEMS mirror 2 may be 3 or more).

FIG. 7 is a diagram showing the optical action of the transmittance angle-dependent filter 9 in which “N = 3”. In the example of FIG. 7, the transmittance angle-dependent filter 9 transmits light having an incident angle of 0 ° and an incident angle of 6 ψ with a transmittance close to 100%, and transmits light having incident angles 2 ψ and 4 ψ near 0%. It has an incident angle dependence of the transmittance that is reflected by the rate. Then, according to this example, the receiving device 11 can preferably guide the return light Lr incident on the MEMS mirror 2 at the incident angle 6ψ to the light receiving unit 4. The return light Lr reflected first and second by the MEMS mirror 2 is an example of the "first reflected wave" in the present invention, and the return light Lr finally reflected by the MEMS mirror 2 is in the present invention. This is an example of the "second reflected wave".

As described above, according to the example of FIG. 7, the transmittance angle-dependent filter 9 triples the apparent tilt angle of the MEMS mirror 2, enlarges the mirror diameter of the apparent MEMS mirror 2, and makes the received light amount suitable. Can be increased. As in the first embodiment, in order to enter the light receiving portion 4 without missing a part of the luminous flux of the return light Lr, “N ≦ 3” is practically preferable.

As described above, the receiving device 11 according to the second embodiment is a receiving device that receives the return light Lr reflected by the object, and has a transmittance angle-dependent filter 9 that transmits the return light Lr and a transmittance. A MEMS mirror 2 that reflects the return light Lr transmitted by the angle-dependent filter 9 as a first reflected wave is provided. Then, the transmittance angle-dependent filter 9 makes the first reflected wave MEMS so that the return light Lr transmitted through the transmittance angle-dependent filter 9 is incident on the MEMS mirror 2 at an angle smaller than the angle of incidence on the MEMS mirror 2. Reflected by the mirror 2, the MEMS mirror 2 reflects the first reflected wave reflected by the transmittance angle-dependent filter 9 as the second reflected wave transmitted through the transmittance angle-dependent filter 9 and incident on the light receiving unit 4. .. As a result, the receiving device 11 can increase the apparent tilt angle of the wobbling type MEMS mirror 2 having a limited tilt angle ψ.

<Third Example>
The third embodiment shows an example in which the irradiation device 10 of the first embodiment and the receiving device 11 of the second embodiment are applied to the rider.

FIG. 8 shows a schematic configuration of the measuring device 100 according to the third embodiment. The measuring device 100 emits infrared rays (for example, wavelength 905 nm) emission light Lt which is an electromagnetic wave to the measurement object OB, receives the return light Lr, and measures the distance to the measurement object OB. The measuring device 100 is, for example, a rider mounted on a vehicle and having a measurement range within a predetermined distance from the vehicle. As shown in the figure, the measuring device 100 includes a light source unit 1, a MEMS mirror device 20 having a MEMS mirror 2, an optical member 3, a light receiving unit 4, and a control unit 5.

The light source unit 1 emits infrared emission light Lt toward the MEMS mirror 2 of the MEMS mirror device 20. The light receiving unit 4 generates a detection signal corresponding to the amount of the received return light Lr and sends it to the control unit 5.

The MEMS mirror device 20 has a MEMS mirror 2 and reflects the emitted light Lt incident from the light source unit 1 toward the optical member 3. Further, the MEMS mirror device 20 reflects the return light Lr incident from the optical member 3 toward the light receiving unit 4. The MEMS mirror device 20 reflects the emitted light Lt in a range of 360 degrees in the horizontal direction, for example.

The optical member 3 emits the emitted light Lt incident from the MEMS mirror 2 to the outside of the measuring device 100, and causes the return light Lr reflected by the object to be measured OB to be incident on the MEMS mirror 2. Further, the optical member 3 has the transmittance angle-dependent filter 9 described in the first and second embodiments. The transmittance angle-dependent filter 9 reflects the emitted light Lt and the return light Lr toward the MEMS mirror 2, thereby reflecting the emitted light Lt and the return light Lr a plurality of times by the MEMS mirror 2, respectively, and the appearance of the MEMS mirror 2. Increase the tilt angle of.

The control unit 5 controls the emission of the emitted light Lt from the light source unit 1 and processes the detection signal supplied from the light receiving unit 4 to calculate the distance to the measurement target OB. Further, the control unit 5 transmits a control signal regarding the inclination of the MEMS mirror 2 to the MEMS mirror 2, so that the irradiation direction of the emitted light Lt is gradually changed by the MEMS mirror 2.

FIG. 9 is a top view showing a configuration example of the MEMS mirror device 20. As shown in FIG. 9, the MEMS mirror device 20 mainly includes a MEMS mirror 2, a frame portion 12, a fixed frame 13, magnets 14A to 14D, X-axis torsion bars 15A and 15B, and a Y-axis torsion bar. It has 16A and 16B and strain gauges 17V and 17H.

The fixed frame 13 is a structure for supporting the frame portion 12, and is formed of a metal material or a semiconductor material such as silicon. The fixed frame 13 has a frame shape having a gap inside. The frame portion 12 has a frame shape having a gap inside. The frame portion 12 is connected to the fixed frame 13 via the X-axis torsion bars 15A and 15B, and is free to swing (rotate) with respect to the fixed frame 13 with the X-axis torsion bars 15A and 15B as rotation axes. .. The fixed portion 11 and the frame portion 12 are examples of the “frame portion” in the present invention. The MEMS mirror 2 is swingable with respect to the frame portion 12 with the Y-axis torsion bars 16A and 16B as rotation axes. A convex pattern is formed on the surfaces of the fixed frame 13 and the frame portion 12, and the wiring pattern extending from the fixed frame 13 via the X-axis torsion bars 15A and 15B follows the frame shape of the frame portion 12. A coil 18 is formed on the surface of the frame portion 12. The magnets 14A to 14D are arranged around the frame portion 12 and generate a horizontal (H) direction and a vertical (V) direction magnetic field in the region where the coil 18 formed in the frame portion 12 exists. Further, a strain gauge 17V is provided near the X-axis torsion bar 15B, and a strain gauge 17H is provided near the Y-axis torsion bar 16B. The strain gauge 17V is a sensor that detects the position of the MEMS mirror 2 in the vertical (V) direction, and outputs a voltage corresponding to the twist amount and the twist direction of the X-axis torsion bar 15B. The strain gauge 17H is a sensor that detects the position of the MEMS mirror 2 in the horizontal (H) direction, and outputs a voltage corresponding to the twist amount and the twist direction of the Y-axis torsion bar 16B.

FIG. 10 shows a configuration example of the optical member 3. The optical member 3 shown in FIG. 10 has an optical circulator 7, an omnidirectional lens 8, and a transmittance angle-dependent filter 9.

The optical circulator 7 converts the emitted light Lt emitted by the light source unit 1 into parallel light and emits it toward the MEMS mirror 2 existing in the negative direction of the z-axis, and also condenses the return light Lr reflected by the MEMS mirror 2. It leads to the light receiving unit 4 existing in the positive direction of the z-axis.

The omnidirectional lens 8 has a shape that is rotationally symmetric with respect to the z-axis, converts the field of view of the emitted light Lt reflected by the MEMS mirror 2 into the horizontal direction of 360 degrees, and the return light Lr incident from the horizontal direction of 360 degrees. Is incident on the MEMS mirror 2. Further, in the omnidirectional lens 8, for example, a hole is formed in the center along the z-axis, and the emitted light Lt emitted from the optical circulator 7 toward the MEMS mirror 2 is guided to the MEMS mirror 2 through the hole, and at the same time, the MEMS. The return light Lr reflected by the mirror 2 is guided to the optical circulator 7 through the hole.

The transmission angle-dependent filter 9 is mounted in a state parallel to the MEMS mirror device 20, and is on the optical path of the emission light Lt and the return light Lr incident on the MEMS mirror 2, and is reflected by the MEMS mirror 2. It is provided on the optical path of Lt and the return light Lr. The transmittance angle-dependent filter 9 has an incident angle dependence of the transmittance, transmits the emission light Lt emitted from the light source unit 1, and transmits 1 or the emission light Lt reflected by the MEMS mirror 2. After being reflected a plurality of times, the emitted light Lt having an incident angle of a predetermined angle or more is transmitted and guided to the omnidirectional lens 8. Similarly, the transmittance angle-dependent filter 9 transmits the return light Lr incident from the omnidirectional lens 8 and reflects the return light Lr reflected by the MEMS mirror 2 one or more times, and then the incident angle is equal to or less than a predetermined angle. The returned light Lr is transmitted and guided to the light receiving unit 4.

Then, according to the configuration of the measuring device 100 having the optical member 3 and the transmittance angle-dependent filter 9 shown in FIG. 10, the same effect as that the tilt angle ψ of the MEMS mirror 2 is multiplied can be obtained, and all of them can be obtained. It is possible to increase the pupil magnification in the sagittal direction of the azimuth lens. As a result, in the light receiving system, the light receiving portion can receive the return light having a larger diameter, and in the emitting system, the laser light having a larger diameter can be emitted to the outside. Further, as compared with the configuration in which the MEMS mirror 2 is used alone without using the transmittance angle-dependent filter 9, the amount of light received by the light receiving unit 4 is suitably increased, and the emitted light emitted from the measuring device 100 is emitted. It is possible to reduce the spread angle of Lt and increase the angular resolution of measurement.

The configuration of the optical member 3 may be any optical system that converts the field of view horizontally, and is not limited to the configuration shown in FIG. For example, the optical member 3 may be composed of a reflection / refraction element or a single mirror. Further, the transmittance angle-dependent filter 9 applied to the optical member 3 is not limited to the one configured to reflect the emitted light Lt and the return light Lr twice by the MEMS mirror 2, respectively, as shown in FIGS. 5 and 7. As shown, the MEMS mirror 2 may be configured to reflect the emission light Lt and the return light Lr three or more times, respectively.

Generally, when a wobbling type MEMS mirror is applied to a rider that scans horizontally as described above, since a rotationally symmetric optical system is usually used, incident light from the outside world is collected toward a light receiving element. The optical system has a smaller pupil magnification in the sagittal direction. Since the optically invariant is generally stored in this rotationally symmetric optical system, it is generally derived that the sagittal pupil magnification is sin2ψ times when the mechanical tilt angle of the MEMS is set to ψ. Further, since the tilt angle of the MEMS mirror is generally as small as about 15 ° or less, the sagittal pupil magnification becomes a value smaller than 1, and the amount of received light reflected from the target also decreases accordingly.

Therefore, by adopting the above-described configuration, it is possible to substantially increase the optical tilt angle ψ of the reflected light in the MEMS mirror, and it is possible to increase the pupil magnification. This makes it possible to increase the amount of light received from the lidar's target. Further, as shown in the equation (1), when the tilt angle ψ can be modulated by the angle Δψ from the angle ψ ₀ , the modulation angle can also be doubled and is perpendicular to the horizontal direction (that is, the main scanning direction). The scanning angle (vertical viewing angle) in any direction can be preferably doubled.

Further, in the first to third embodiments, the transmittance angle-dependent filter 9 may be provided in place of the window plate of the MEMS mirror 2, and therefore, as compared with the case where an optical element such as a mirror or a lens is inserted. , The increase in the number of parts is preferably suppressed. Further, by using the transmittance angle-dependent filter 9, it is possible to suppress an increase in the material cost at the time of mass production, save space, and the like, and it is not necessary to arrange and fix the optical system with high accuracy. It becomes.

1 Light source unit 2 MEMS mirror 3 Optical member 4 Light receiving unit 5 Control unit 9 Transmittance angle-dependent filter OB Measurement target 100 Measuring device

Claims (1)

An irradiation device that irradiates an electromagnetic wave emitted by an irradiation unit in a predetermined direction.
A filter unit that transmits electromagnetic waves emitted by the irradiation unit,
A first reflecting portion that swings with respect to the frame portion and reflects the electromagnetic wave transmitted by the filter portion as a first reflected wave.
Equipped with
The filter unit transfers the first reflected wave to the first reflection unit so that the electromagnetic wave transmitted through the filter unit is incident on the first reflection unit at an angle larger than the angle of incidence on the first reflection unit. Irradiation device that reflects on.

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