WO2016067359A1

WO2016067359A1 - Laser doppler sensor

Info

Publication number: WO2016067359A1
Application number: PCT/JP2014/078589
Authority: WO
Inventors: 義博市川; 渉小野寺; 加藤　哲也
Original assignee: パイオニア株式会社
Priority date: 2014-10-28
Filing date: 2014-10-28
Publication date: 2016-05-06
Also published as: JPWO2016067359A1; JP6347848B2

Abstract

This laser Doppler sensor is provided with a light emitting part (221) for emitting a laser beam onto an object (500), and a translucent member (240) covering the light emitting part and having a transparent surface (241) through which the laser beam passes. The transparent surface of the translucent member is disposed in an inclined manner with respect to an emission light path of the laser beam. Thereby, a light path of a return beam (RB) reflected at a cover part can be shifted from a light path of an emission beam (LB), and as a result, destabilization of the light emitting part because of light interference can be prevented.

Description

Laser Doppler sensor

The present invention relates to a technical field of a laser Doppler sensor that detects various kinds of information related to an object by irradiating the object with light.

As this type of device, for example, there is known a device that obtains information about a living body such as blood flow and pulse wave by irradiating the living body with light and detecting light reflected or transmitted by the living body. . In such an apparatus, there is a possibility that light interference occurs due to light returning to the laser light source due to scattering after irradiation or the like (hereinafter referred to as “return light” as appropriate), resulting in instability of the laser light source. is there. For this reason, for example, Patent Document 1 proposes a technique of reducing the return light by providing a light shielding structure (pinhole) in the cover portion of the laser light source.

JP 2007-175416 A

However, in the apparatus described in Patent Document 1 described above, since there is return light generated by reflection at the cover portion (that is, a member through which the laser light is transmitted), the laser light source is sufficiently destabilized. Can not be suppressed. In addition, since the amount of light that can be irradiated is reduced by the light shielding structure, it is required to increase the output of the laser light source in order to obtain the same amount of light as that without the light shielding structure. Furthermore, an increase in cost due to the formation of the light shielding structure is inevitable.

Examples of problems to be solved by the present invention include the above. An object of the present invention is to provide a laser Doppler sensor capable of effectively suppressing instability of a laser light source with a relatively simple configuration.

A laser Doppler sensor for solving the above-described problems includes: a light emitting unit that irradiates a target with laser light; and a translucent member that covers the light emitting unit and has a transmission surface through which the laser light is transmitted. The transmission surface is arranged to be inclined with respect to the irradiation light path of the laser beam.

It is a perspective view which shows the whole structure of the laser Doppler sensor which concerns on 1st Example. It is sectional drawing which shows the structure of the sensor part which concerns on 1st Example. It is sectional drawing which shows the optical path of the emitted light and return light in a sensor part. It is sectional drawing which shows the structure of the sensor part which concerns on the comparative example which concerns on 1st Example. It is sectional drawing which shows the structure of the sensor part which concerns on a 1st modification. It is sectional drawing which shows the structure of the sensor part which concerns on a 2nd modification. It is sectional drawing which shows the structure of the sensor part which concerns on a 3rd modification. It is sectional drawing which shows the structure of the sensor part which concerns on a 4th modification. It is sectional drawing which shows the structure of the sensor part which concerns on a 5th modification. It is sectional drawing which shows the structure of the sensor part which concerns on a 6th modification. It is sectional drawing which shows the structure of the sensor part which concerns on a 7th modification. It is sectional drawing which shows the structure of the sensor part which concerns on an 8th modification. It is a perspective view which shows the whole structure of the laser Doppler sensor which concerns on 2nd Example. It is sectional drawing which shows the structure of the sensor part which concerns on 2nd Example.

<1>
The laser Doppler sensor according to the present embodiment includes a light emitting unit that irradiates an object with laser light, and a translucent member that covers the light emitting unit and has a transmission surface through which the laser light is transmitted. Are inclined with respect to the irradiation light path of the laser beam.

According to the laser Doppler sensor of the present embodiment, during the operation, the object is irradiated with laser light from a light emitting unit configured as a semiconductor laser, for example. The irradiated laser light is scattered on the object. If this scattered light is received, a signal indicating information about the object can be generated therefrom, and for example, a blood flow velocity or a pulse wave of a living body that is the object can be detected.

The light emitted from the light emitting part is transmitted through a transmissive member provided so as to cover the light emitting part before being irradiated onto the object. Note that “covering” here does not mean that the transparent member completely covers the periphery of the light emitting portion, but is provided so as to cover the range through which the irradiated laser light passes. It is the purpose. Therefore, the transmissive member may be provided as a mold that covers a light source that is an example of a light emitting unit, or may be provided as a cover member or a window positioned outside the mold. The transmissive member has a transmissive surface configured to include a highly transmissive member such as glass, and the light emitted from the light emitting unit is transmitted through the transmissive surface and irradiated to the object.

Here, in the present embodiment, in particular, the transmission surface of the transmission member is arranged to be inclined with respect to the irradiation light path of the laser beam. That is, the laser light irradiation optical path and the transmission surface are arranged so as not to be orthogonal to each other. Note that the transmission surface is not limited to a flat surface, and may be a curved surface. In addition, it is sufficient that at least one of the front and back surfaces is inclined with respect to the irradiation light path, and the surface opposite to the inclined surface may not be inclined.

Here, if the transmission surface of the transmissive member is not inclined with respect to the laser light irradiation optical path, the laser light irradiated from the light emitting unit is reflected on the transmission surface and becomes return light toward the light emitting unit. More specifically, a return light returning to the light emitting unit is generated by tracing the same path as the irradiated laser beam in the reverse direction. As a result, light interference caused by the return light occurs, and the light emitting section becomes unstable (specifically, mode hop).

However, in this embodiment, as described above, since the transmission surface of the translucent member is inclined with respect to the irradiation light path of the laser light, the light reflected by the light transmission surface returns to the light emitting unit. It will not be. Specifically, the reflection angle changes in accordance with the inclination of the transmission surface, and the return light travels to a position shifted from the light emitting unit. Therefore, destabilization of the light emitting portion due to light interference can be suppressed.

In addition, it is preferable that the inclination angle of the transmission surface is larger than the diffusion angle of the laser beam when irradiated from the light emitting unit. Accordingly, it is possible to prevent the inclined transmission surface and the irradiation optical path of the diffused laser beam (in other words, irradiated with an angle) from being orthogonal to each other. In addition, it is preferable that the angle of inclination of the transmission surface is set small enough to realize an efficient layout of the transmission member. That is, it is preferable to avoid as much as possible that the space for disposing the transmissive member by increasing the inclination angle of the transmissive surface too much.

As described above, according to the laser Doppler sensor according to the present embodiment, the transmissive surface of the transmissive member is inclined, thereby effectively suppressing the instability of the light emitting unit due to the return light. Can do.

<2>
In one aspect of the laser Doppler sensor according to the present embodiment, the laser Doppler sensor further includes a light receiving unit that is disposed on the light emitting unit side when viewed from the transmission surface and receives the laser light scattered by the object.

According to this aspect, the laser light emitted from the light emitting unit and transmitted through the transmission surface and applied to the object is reflected by the object and then transmitted through the transmission surface again and received by the light receiving unit. That is, the laser Doppler sensor according to this aspect is configured as a so-called reflection type laser Doppler sensor.

Also in the reflection type laser Doppler sensor, it is possible to suppress the destabilization of the light emitting part by arranging the transmission surface to be inclined. The transmission surface only needs to be inclined at a portion where the laser light emitted from the light emitting portion is transmitted, and only the light that should be received by the light receiving portion (that is, the light scattered by the object) is transmitted. There is no need to be inclined.

<3>
In the aspect including the light receiving unit described above, the translucent member has a first transmission surface corresponding to the light emitting unit and a second transmission surface corresponding to the light reception unit, and the first transmission surface and The second transmission surfaces may be arranged so as to have an inclination angle symmetrical to each other.

If comprised in this way, the 1st permeation | transmission surface (namely, surface through which the laser beam irradiated mainly from the light emission part will permeate | transmit) corresponding to a light emission part, and the 2nd permeation | transmission surface (namely, mainly target object) corresponding to a light reception part The surface where the laser light scattered in (1) passes is arranged so as to have a symmetrical inclination angle with each other, so that the mounting direction of the components at the time of assembly is not limited.

Here, if the transmission surface of the transparent member is inclined without considering symmetry, the mounting direction of the parts is limited depending on the inclination direction. Specifically, the portion that should become the first transmission surface and the portion that should become the second transmission surface have different shapes, and if the mounting direction is wrong, it may not be used or function properly.

However, in this aspect, as described above, the first transmission surface and the second transmission surface have a symmetrical tilt angle. For this reason, assembly work is possible without being conscious of the difference between the first transmission surface and the second transmission surface. Therefore, production efficiency can be improved.

As can be seen from the above description, “having a symmetrical inclination angle” in this aspect means a symmetric state in which the first transmission surface and the second transmission surface can be assembled without distinguishing each other's shape. Say that. As an example of a shape having a symmetrical inclination angle, a shape in which the first transmission surface and the second transmission surface are arranged in an M shape, or the first transmission surface and the second transmission surface are arranged in a mountain shape. Such a shape etc. are mentioned.

<4>
In the aspect in which the first transmission surface and the second transmission surface described above have a symmetrical tilt angle, the light receiving unit is closer to the symmetrical center of the first transmission surface and the second transmission surface than the light emitting unit. It may be arranged at a position.

With this configuration, since the light receiving unit is disposed at a position close to the symmetry center of the first transmission surface and the second transmission surface, the light reception efficiency of the light reception unit can be increased. Specifically, the light receiving unit can receive light in a wider range through both the first transmission surface and the second transmission surface. As a result, it is possible to prevent an insufficient amount of light received at the light receiving unit.

On the other hand, the light emitting unit is disposed at a position farther from the symmetry center of the first transmission surface and the second transmission surface than the light receiving unit. For this reason, the distance between the light receiving part and the light emitting part can be increased. Therefore, for example, the inconvenience that the laser light emitted from the light emitting unit is directly received by the light receiving unit without passing through the object can be suitably avoided.

<5>
In one aspect of the laser Doppler sensor according to the present embodiment, the laser Doppler sensor further includes a light receiving unit that is provided separately from the light emitting unit and the translucent member and that receives the laser light scattered by the object.

According to this aspect, the laser beam emitted from the light emitting unit, transmitted through the transmission surface and irradiated onto the object is received by the light receiving unit provided separately after passing through the object. That is, the laser Doppler sensor according to this aspect is configured as a so-called transmission type laser Doppler sensor.

Also in the transmission type laser Doppler sensor, it is possible to suppress instability of the light emitting portion by arranging the transmission surface of the transmission member to be inclined. In the case where a transmissive member is also provided on the light receiving unit side, the parts may be shared by inclining the transmissive surface of the transmissive member on the light receiving unit side in the same manner as on the light emitting unit side.

The operation and other gains of the laser Doppler sensor according to this embodiment will be described in more detail in the following examples.

Hereinafter, embodiments of the laser Doppler sensor will be described in detail with reference to the drawings.

<First embodiment>
The laser Doppler sensor according to the first embodiment will be described with reference to FIGS. Note that the laser Doppler sensor according to the first embodiment is configured as a reflective sensor that receives laser light reflected from an object and acquires various types of information.

<Device configuration>
First, the overall configuration of the laser Doppler sensor according to the first embodiment will be described with reference to FIG. FIG. 1 is a perspective view showing the overall configuration of the laser Doppler sensor according to the first embodiment.

1, the laser Doppler sensor according to the first embodiment includes a probe unit 100, a sensor unit 200 provided in the probe unit 100, a connection cable 300, and a connection terminal 400. Although not shown here, the sensor unit 200 includes a light emitting element (that is, an element that irradiates a target with laser light) and a light receiving element (that is, a laser reflected by the target). Element for receiving light).

During the operation of the laser Doppler sensor according to the first embodiment, laser light is emitted from the light emitting element of the sensor unit 200, and the laser light reflected by the object is received by the light receiving element. At this time, the light receiving element generates a signal corresponding to the received laser beam. The generated signal is output via the connection cable 300 and the connection terminal 400 to an external device (for example, a device that can perform various arithmetic processes on the signal and output information on the object).

Next, a specific configuration of the sensor unit 200 will be described in detail with reference to FIG. FIG. 2 is a cross-sectional view showing the configuration of the sensor unit according to the first embodiment.

In FIG. 2, the sensor unit 200 according to the first embodiment is configured to be embedded in the probe 100 and to partially expose the surface. The sensor unit 200 includes an element substrate 210, a light emitting element 221, a light receiving element 222, a mold part 230, and a cover part 240.

The light emitting element 221 is a specific example of the “light emitting unit” and is disposed on the element substrate 210. The light emitting element 221 is configured as a semiconductor laser, for example. The light receiving element 222 is a specific example of the “light receiving unit”, and is disposed on the element substrate 210 in the same manner as the light emitting element 221. The light receiving element 222 is configured as a photodiode, for example. The periphery of the light emitting element 221 and the light receiving element 222 is covered with a mold part 230 made of a transparent material.

The cover part 240 is a specific example of the “translucent member”, and is located further outside the mold part 230, and a part thereof is exposed to the outside of the probe part 100. The cover 240 is made of a material having translucency, such as highly transparent glass, in order to transmit the laser light emitted from the light emitting element 221 and the return light reflected by the object. . The cover part 240 is also a part that comes into contact with an object during operation of the apparatus.

In the present embodiment, in particular, the cover 240 has a first transmission surface 241 through which laser light emitted mainly from the light emitting element 221 is transmitted, and a second transmission surface through which return light to be received by the light receiving element is transmitted. 242. The first transmission surface 241 is disposed to be inclined with respect to the optical path of the laser light emitted from the light emitting element 221. That is, the optical path of the laser light and the first transmission surface 241 are arranged so as not to be orthogonal to each other (for example, in a state of being shifted by about 5 °). The second transmission surface 242 is disposed so as to have an inclination angle symmetrical to the first transmission surface 241 with the symmetry center SC as the center. As a result, the cover part 240 is configured as an M-shaped member.

In this embodiment, the distance L2 from the symmetry center SC to the light receiving element 222 is smaller than the distance L1 from the symmetry center SC to the light emitting element 221 of the cover 240. That is, the light emitting element 221 and the light receiving element 222 are arranged so as to be shifted with respect to the symmetry center SC of the cover 240 so that L1> L2. If the light emitting element 221 and the light receiving element 222 are arranged in this manner, the distance between the light emitting element 221 and the light receiving element can be secured while expanding the light receiving range of the light receiving element 222.

<Effect>
Next, the effect obtained by inclining the cover part 240 will be described in detail with reference to FIGS. 3 and 4. FIG. 3 is a sectional view showing the optical paths of the outgoing light and the return light in the sensor unit. FIG. 4 is a cross-sectional view illustrating a configuration of a sensor unit according to a comparative example according to the first embodiment.

In FIG. 3, when the sensor unit 200 according to the first embodiment is in operation, the emitted light LB is emitted from the light emitting element 221 in a direction directly above the drawing. The emitted light LB passes through the first transmission surface 241 of the cover part 240 and is irradiated onto the object. A part of the emitted light LB is reflected by the first transmission surface 241 and becomes return light RB. The return light RB is reflected at the boundary inside the first transmission surface 241 (namely, the light emitting element 221 side) and reflected at the boundary outside the first transmission surface 241 (namely, the object side). Light. These return lights RB are reflected at an angle shifted from the emitted light LB because the first transmission surface 241 is inclined.

In FIG. 4, consider the sensor unit 200b in which the cover unit 240 is not inclined. Similarly, in the sensor part 200b according to the comparative example, the return light RB is generated by the reflection at the cover part 240. However, the return light RB here has a light (or more specifically, the same path as the emitted light LB) toward the light emitting element 221 because the optical path of the emitted light LB and the surface of the cover 240 are orthogonal to each other. And light returning to the light emitting element 221). In this case, light interference may occur, and the light emitting element 221 may become unstable.

On the other hand, according to the inclined cover 240 as in the present embodiment, the optical path of the return light RB is shifted from the optical path of the outgoing light LB (see FIG. 3). Therefore, instability of the light-emitting element 221 due to light interference can be suppressed. Note that the inclination angle of the first transmission surface 241 is preferably larger than the diffusion angle of the emitted light LB. Thereby, it can prevent that the inclined 1st permeation | transmission surface 241 and the optical path of the diffused outgoing light LB cross at right angles. In addition, the inclination angle of the first transmission surface 241 is preferably set small enough to realize an efficient layout of the cover part 240.

Incidentally, the second transmission surface 242 on the light receiving element 222 side does not have the function of changing the optical path of the return light as described above because the outgoing light LB is not incident thereon. However, since the first transmission surface 241 and the second transmission surface 242 have symmetrical inclination angles, the cover 240 has a symmetrical shape on the light emitting element 221 side and the light receiving element 222 side. As a result, when the parts are assembled in the manufacturing process, the assembly work can be performed without being aware of the difference between the first transmission surface 241 and the second transmission surface 242. That is, the cover part 240 having symmetry is not limited in the mounting direction of components during assembly. Therefore, production efficiency can be improved.

Also, since the shape of the cover part 240 is M-shaped, the object is fixed to the recessed part of the M-shape during use. For this reason, the shift | offset | difference of the target object in use can be reduced and it becomes possible to implement | achieve more suitable measurement.

<Modification>
Next, modified examples of the cover part 240 will be described with reference to FIGS. FIGS. 5 to 12 are cross-sectional views showing the configuration of the sensor unit according to the first to eighth modifications.

5, in the sensor unit 200c according to the first modification, the first transmission surface 241 and the second transmission surface 242 of the cover unit 240 are arranged so as to form a mountain shape. Thus, the inclination directions of the first transmission surface 241 and the second transmission surface 242 are not limited to the M-shape of the first embodiment.

Also in the sensor unit 200c according to the first modification, the first transmission surface 241 is inclined with respect to the optical path of the outgoing light LB, and thus the return light RB is reflected at an angle shifted from the outgoing light LB. Therefore, instability of the light-emitting element 221 due to light interference can be suppressed.

In addition, since the 1st permeation | transmission surface 241 and the 2nd permeation | transmission surface 242 have a symmetrical inclination angle, the symmetry of components is also hold | maintained and production efficiency can be improved. In use, deviation of the object can be reduced because the convex portion of the mountain shape bites into the object.

6 and 7, in the sensor unit 200d according to the second modification and the sensor unit 200e according to the third modification, the first transmission surface 241 and the second transmission surface 242 of the cover unit 240 are configured as curved surfaces, respectively. Yes. Even in such a configuration, since the return light RB is reflected at an angle shifted from the emission light LB, instability of the light-emitting element 221 due to light interference can be suppressed. The first transmission surface 241 and the second transmission surface 242 may have a shape in which a plane and a curved surface coexist.

8 and 9, in the sensor unit 200f according to the fourth modified example and the sensor unit 200g according to the fifth modified example, only the first transmission surface 241 of the cover unit 240 is disposed so as to be inclined, and the second transmission surface 242 is not inclined. When configured in this manner, the symmetry of the cover 240 is lost, but the return light RB is reflected at an angle shifted from the outgoing light LB, so that destabilization of the light emitting element 221 due to light interference is suppressed. can do.

10 and 11, in the sensor unit 200h according to the sixth modification and the sensor unit 200i according to the seventh modification, only one surface of the first transmission surface 241 and the second transmission surface 242 of the cover 240 is inclined. Has been. Specifically, in the sensor unit 200h according to the sixth modification, only the inner surface (that is, the surface on the light emitting element 221 side) of the cover 240 is inclined, and the outer surface (that is, the object side). Surface) is not inclined. On the contrary, in the sensor unit 200i according to the seventh modification, only the outer surface of the cover unit 240 is inclined, and the inner surface is not inclined. Even in such a configuration, the return light RB is reflected at an angle shifted from the outgoing light LB on one inclined surface. Accordingly, instability of the light-emitting element 221 due to light interference can be suppressed.

In FIG. 12, in the sensor unit 200j according to the eighth modification, the transmission surface of the mold unit 230 is disposed in an inclined manner instead of the cover unit 240. Specifically, the first transmissive surface 231 and the second transmissive surface 232 are formed on the mold part 230, respectively, and the mold part 230 functions as a specific example of the “translucent member”. When configured in this manner, the return light RB is reflected at an angle shifted from the emitted light LB on the first transmission surface 231 of the mold part 230. Accordingly, instability of the light-emitting element 221 due to light interference can be suppressed. In addition to the transmission surface of the mold part 230, the transmission surface of the cover part 240 may be inclined.

As described above, according to the laser Doppler sensor according to the first embodiment, the transmissive surface through which the emitted light LB is transmitted is inclined, so that the destabilization of the light emitting element 221 caused by the return light RB is effective. Can be suppressed.

<Second embodiment>
Next, a laser Doppler sensor according to a second embodiment will be described with reference to FIGS. The second embodiment is different from the first embodiment described above only in part of the configuration, and the other parts are substantially the same. For this reason, below, a different part from 1st Example is demonstrated in detail, and description is abbreviate | omitted suitably about another overlapping part.

First, the overall configuration of the laser Doppler sensor according to the second embodiment will be described with reference to FIG. FIG. 13 is a perspective view showing the overall configuration of the laser Doppler sensor according to the second embodiment.

In FIG. 13, the laser Doppler sensor according to the second embodiment includes a light emitting side probe unit 110 having a light emitting side sensor unit 250, a light receiving side probe unit 120 having a light receiving side sensor unit 260, a connection cable 300, and a connection terminal. 400. That is, in the laser Doppler sensor according to the second embodiment, the probe portion is configured as a separate body on the light emitting side and the light receiving side.

When the laser Doppler sensor according to the second embodiment is operated, the object 500 is disposed between the light emitting side probe unit 110 and the light receiving side probe unit 120. In the laser Doppler sensor according to the second embodiment, when laser light is emitted from the light emitting element of the light emitting side sensor unit 250, the laser light transmitted through the object 500 is received by the light receiving element of the light receiving side sensor unit 260. Is done. That is, the laser Doppler sensor according to the second embodiment is configured as a transmission type sensor.

Subsequently, a specific configuration of the sensor unit according to the second embodiment will be described with reference to FIG. FIG. 14 is a cross-sectional view showing the configuration of the sensor unit according to the second embodiment.

In FIG. 14, the light emitting side sensor unit 250 includes an element substrate 210, a light emitting element 221, a mold unit 230, and a cover unit 240. On the other hand, the light receiving side sensor unit 260 includes an element substrate 210b, a light emitting element 222, a mold unit 230b, and a cover unit 240b.

The cover part 240 in the light emitting side sensor part 250 is disposed to be inclined with respect to the optical path of the laser light emitted from the light emitting element 221. That is, the optical path of the emitted light LB and the transmission surface of the cover part 240 are arranged so as not to be orthogonal to each other. Thereby, the return light RB reflected by the cover part 240 is reflected at an angle shifted from the emitted light LB. Accordingly, instability of the light-emitting element 221 due to light interference can be suppressed.

In addition, although the cover part 240b in the light-receiving side sensor part 260 is also inclined in the same manner as the light-emitting side, it is not always necessary to place the cover 240b at an inclination because light interference does not have to be taken into consideration. However, if the cover part 240b inclined like the light emission side is used, parts can be made common and an increase in cost can be prevented.

Incidentally, by making the shapes of the

cover portions

240 and 240b, for example, the M shape shown in FIG. 3 or the mountain shape shown in FIG. 5, the symmetry of the parts can be realized and the productivity can be improved. Also in the second embodiment, it is possible to adopt the respective modifications described in the first embodiment.

As described above, according to the laser Doppler sensor according to the second embodiment, the transmissive surface through which the emitted light LB is transmitted is inclined, so that the destabilization of the light emitting element 221 caused by the return light RB is effective. Can be suppressed.

The present invention is not limited to the above-described embodiment, and can be changed as appropriate without departing from the spirit or concept of the invention that can be read from the claims and the entire specification, and a laser Doppler sensor with such a change. Is also included in the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 100 Probe part 110 Light emission side probe part 120 Light reception side probe part 200 Sensor part 210 Element board | substrate 221 Light emitting element 222 Light receiving element 230 Mold part 240 Cover part 231,241 1st transmission surface 232,242 2nd transmission surface 250 Light emission side sensor part 260 Light-receiving side sensor unit 300 Connection cable 400 Connection terminal 500 Object LB Emission light RB Return light SC Symmetry center

Claims

A light emitting unit for irradiating an object with laser light;
A translucent member that covers the light emitting portion and has a transmission surface through which the laser beam is transmitted;
The laser Doppler sensor, wherein the transmission surface is arranged to be inclined with respect to the irradiation light path of the laser light.
2. The laser Doppler sensor according to claim 1, further comprising a light receiving portion that is disposed on the light emitting portion side when viewed from the transmission surface and receives the laser light scattered by the object.
The translucent member has a first transmission surface corresponding to the light emitting unit and a second transmission surface corresponding to the light receiving unit,
The laser Doppler sensor according to claim 2, wherein the first transmission surface and the second transmission surface are arranged so as to have a symmetrical inclination angle.
The laser Doppler sensor according to claim 3, wherein the light receiving unit is disposed at a position closer to the light emitting unit with respect to a symmetrical center of the first transmission surface and the second transmission surface.
2. The laser Doppler sensor according to claim 1, further comprising a light receiving portion that is provided separately from the light emitting portion and the light transmissive member, and that receives the laser light scattered by the object. .