Displacement Sensor

Abstract

To provide a displacement sensor capable of detecting displacement and the like with high accuracy by appropriately processing stray light. [Solution] The displacement sensor comprises a first member having a recess on its top surface, a second member arranged in the stacking direction of the first member, a laser element arranged in the recess and emitting laser light, a mirror arranged on the side of the recess and reflecting the laser light with an incident angle of less than 45°, a lens arranged in the second member onto which the reflected laser light is incident, and a first photodetector that receives light of the laser light that has passed through the lens and is reflected by an object, and a first gap recessed toward the first region from the side of the recess and connected to the recess is provided between the first member and the second member in a first region on the opposite side of the mirror from the laser element when viewed in the stacking direction.

Description

[Technical Field]

[0001] The present disclosure relates to displacement sensors. [Background technology]

[0002] Displacement sensors such as optical encoders or Doppler sensors are known in which laser light emitted by a laser element is reflected by a mirror, the reflected laser light is collimated by a lens, and the collimated light is reflected by a diffraction grating or a moving object and detected by a photodetector (e.g., Patent Documents 1 to 3). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 5-340719 [Patent Document 2] Japanese Patent Application Publication No. 3-291523 [Patent Document 3] Japanese Patent Application Laid-Open No. 2005-283487 Summary of the Invention [Problem to be solved by the invention]

[0004] A portion of the laser light emitted from the laser element is not reflected by the mirror and becomes stray light. When stray light is received by a photodetector, it causes noise. This makes it difficult to detect displacement with high precision. Furthermore, if stray light leaks to the outside, it becomes a safety issue for laser products.

[0005] An object of the present disclosure is to provide a displacement sensor that can appropriately process stray light and detect displacement and the like with high accuracy. [Means for solving the problem]

[0006] An embodiment of the present disclosure is a displacement sensor comprising: a first member having a recess on an upper surface; a second member arranged in the stacking direction of the first member; a laser element arranged in the recess and emitting laser light; a mirror arranged on a side of the recess and reflecting the laser light with an incident angle of less than 45°; a lens arranged in the second member onto which the reflected laser light is incident; and a first photodetector that receives light of the laser light that has passed through the lens and is reflected by an object; and a first gap recessed toward the first region from the side of the recess and connected to the recess is provided between the first member and the second member in a first region on the opposite side of the mirror from the laser element when viewed in the stacking direction. [Effects of the Invention]

[0007] According to the present disclosure, stray light can be appropriately processed to detect displacement and the like with high accuracy. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a cross-sectional view of a displacement sensor according to the first embodiment. [Figure 2] FIG. 2 is a plan view of a first member of the displacement sensor according to the first embodiment. [Figure 3] FIG. 3 is a plan view of the second member of the displacement sensor according to the first embodiment. [Figure 4] FIG. 4 is a perspective view of the second member of the displacement sensor according to the first embodiment. [Figure 5] FIG. 5 is a cross-sectional view showing the propagation of light in the displacement sensor according to the first embodiment. [Figure 6] FIG. 6 is a cross-sectional view showing the propagation of light in a displacement sensor according to a comparative example. [Figure 7] FIG. 7 is a cross-sectional view of the displacement sensor according to the first embodiment. [Figure 8] FIG. 8 is a plan view of the first member of the displacement sensor according to the second embodiment. [Figure 9] FIG. 9 is a cross-sectional view of the displacement sensor according to the third embodiment. [Figure 10] FIG. 10 is a cross-sectional view of a displacement sensor according to a first modification of the third embodiment. [Figure 11] FIG. 11 is a cross-sectional view of the displacement sensor according to the fourth embodiment. [Figure 12] FIG. 12 is a perspective view of a second member in the displacement sensor according to the fourth embodiment. [Figure 13] FIG. 13 is a cross-sectional view showing the propagation of light within the displacement sensor according to the fourth embodiment. [Figure 14] FIG. 14 is a cross-sectional view showing the propagation of light within the displacement sensor according to the fourth embodiment. [Figure 15] FIG. 15 is a cross-sectional view showing the propagation of light within the displacement sensor according to the fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The following embodiments are examples for embodying the technical ideas of the invention, and the present disclosure is not limited to the described configurations and numerical values. In each drawing, the same components are denoted by the same reference numerals, and duplicate explanations may be omitted as appropriate.

[0010] (First embodiment) FIG. 1 is a cross-sectional view of the displacement sensor according to the first embodiment. FIG. 2 is a plan view of a first member of the displacement sensor according to the first embodiment. FIG. 3 is a plan view of a second member of the displacement sensor according to the first embodiment. FIG. 4 is a perspective view of the second member of the displacement sensor according to the first embodiment. The stacking direction of the first member 10 and the second member 20 is the Z direction, the direction in which laser light 50A is emitted from the laser element 16 is the X direction, and the direction intersecting the X and Z directions is the Y direction. FIG. 3 illustrates the -Z plane transmitted through the second member 20 from the +Z direction. FIG. 1 is a cross-sectional view taken along the line AA of FIGS. 2 and 3.

[0011] As shown in FIG. 1, the displacement sensor 100 according to the first embodiment includes a first member 10, a second member 20, mirrors 15A and 15B, a laser element 16, and a photodetector 26. As shown in FIGS. 1 and 2, the first member 10 has a recess 14 on its top surface (+Z surface). The recess 14 has a bottom surface 12 and side surfaces 11A and 11B. The bottom surface 12 is flat and substantially parallel to the XY plane. The side surfaces 11A and 11B are provided so as to surround the bottom surface 12 when viewed from the Z direction. The side surfaces 11A and 11B are inclined with respect to the bottom surface 12, and the angle θ1 formed between the plane extending from the bottom surface 12 and the side surfaces 11A and 11B is smaller than 90° and larger than 45°. The mirrors 15A and 15B are provided on the side surfaces 11A and 11B, respectively. The surface of the top surface of the first member 10 other than the recess 14 is surface 13. The surface 13 is a substantially flat surface. Note that the flat surface does not mean a strictly flat surface, but allows for irregularities to the extent of manufacturing errors.

[0012] A laser element 16, a thermistor 35, and electrodes 33A and 33B are provided on the bottom surface 12 of the recess 14. The electrodes 33A and 33B are electrically connected to the laser element 16 and the thermistor 35 by bonding wires 34A and 34B, respectively. The laser element 16 is controlled based on temperature information detected by the thermistor 35. The thermistor 35 is an example of a component provided on the bottom surface 12, and components other than the thermistor 35, such as a control circuit for controlling the laser element 16 and a drive circuit for driving the laser element 16, may also be provided on the bottom surface 12. The laser element 16 emits laser beams 50A and 50B from its end faces (+X and -X faces). Mirrors 15A and 15B are provided on the side surfaces 11A and 11B and reflect the laser beams 50A and 50B.

[0013] As shown in Figures 1, 3, and 4, the second member 20 is provided on the first member 10. The second member 20 has recesses 24A and 24B and lenses 25A and 25B on its lower surface (-Z surface). The recess 24A is open in the +X direction, and the recess 24B is open in the -X direction. The recesses 24A and 24B each have a bottom surface 23 and a side surface 21 surrounding the bottom surface 23. The bottom surface 23 is flat. The side surface 21 is inclined with respect to the bottom surface 23. Lenses 25A and 25B are provided on the side surface 21. The lenses 25A and 25B are convex lenses. The surface of the lower surface of the second member 20 other than the recesses 24A and 24B is surface 22. Surface 22 is flat. The photodetector 26 is provided on the upper surface (+Z surface) between the lenses 25A and 25B when viewed from the Z direction.

[0014] 1 to 4, when viewed from the Z direction, the side opposite the laser element 16 with respect to the mirrors 15A and 15B is a first region 40, and the region on the laser element 16 side with respect to the mirrors 15A and 15B is a second region .

[0015] The first member 10 and the second member 20 are arranged so that a surface 22 near the ±Y sides of the second member 20 in Fig. 3 abuts a surface 13 near the ±Y sides of the first member 10 in Fig. 2. As shown in Fig. 1, a gap 30 is provided between the first member 10 and the second member 20 in the first region 40, on the first region 40 side of the side surfaces 11A and 11B of the recess 14, and connected to the recessed recess 14. The gap 30 is, for example, an air gap.

[0016] The bottom surface 23 is located in the +Z direction from the surface 22. This provides a gap 30 between the first member 10 and the second member. Here, the bottom surface 23 (first surface) is the surface of the second member 20 on the first member 10 side in the first region 40. The surface 22 (second surface) is the surface of the second member 20 on the first member 10 side in the second region 42.

[0017] The recesses 24A and 24B may be open in the ±Y directions. The arrangement of the first member 10 and the second member 20 is determined by abutting the surface 22 near the ±Y sides of the second member 20 with the surface 13 near the ±Y sides of the first member 10. In order to stably determine the arrangement of the first member 10 and the second member 20, it is preferable that the surface 22 and the surface 13 are provided along the ±Y sides. Therefore, as shown in Figures 3 and 4, it is preferable that the recesses 24A and 24B are not open in the ±Y directions.

[0018] The first member 10 is, for example, a semiconductor substrate such as a silicon substrate, an insulating substrate, or a metal substrate. The mirrors 15A and 15B are metal films with high reflectivity at the wavelength of the laser light, such as aluminum, gold, or silver films, and are formed on the side surfaces 11A and 11B using, for example, a sputtering method. The second member 20 is a member transparent to the laser light, such as an inorganic insulator such as glass, or a transparent resin. The second member 20 is formed integrally and has no interface. The laser element 16 is, for example, a semiconductor laser element, such as a distributed-feedback (DFB) laser. By appropriately setting the reflectivity of the end faces of the laser element 16, laser light 50A and 50B can be emitted from both end faces of the laser element 16. The photodetector 26 is, for example, a photodiode.

[0019] FIG. 5 is a cross-sectional view showing the propagation of light in the displacement sensor according to the first embodiment. Mirrors 15A and 15B are illustrated as side surfaces 11A and 11B. The intensity distribution of laser beams 50A and 50B emitted from laser element 16 is, for example, a Gaussian distribution. In laser beams 50A to 53A and 50B to 53B, the center line is the line where the intensity is maximum and corresponds to the optical axis. The two outer lines are lines where the intensity of the laser beam is half of the maximum intensity. The distance between the two outer lines is the full width at half maximum.

[0020] As shown in FIG. 5, the laser element 16 emits laser beams 50A and 50B in the +X and -X directions, respectively. The laser beams 50A and 50B are diverging beams. The mirrors 15A and 15B are configured to reflect at least the full width at half maximum (FWHM) of the laser beams 50A and 50B. Because the optical axes of the laser beams 50A and 50B are parallel to the bottom surface 12, the angle θ1 is the angle between the laser beams 50A and 50B and the mirror surfaces of the mirrors 15A and 15B. The angle of incidence θ2 of the laser beams 50A and 50B on the mirrors 15A and 15B is 90°-θ1. The angle of incidence θ2 is set to be smaller than 45°. As a result, the optical axes of the laser beams 51A and 51B reflected by the mirrors 15A and 15B approach each other as they move in the +Z direction. The mirrors 15A and 15B are flat mirrors. The laser beams 51A and 51B are diverging beams.

[0021] The lenses 25A and 25B are convex lenses that transmit the laser beams 51A and 51B as collimated laser beams 52A and 52B. The laser beams 51A and 51B are configured to transmit at least light within the full width at half maximum of the laser beams 51A and 51B. The laser beams 52A and 52B are refracted at the upper surface of the second member 20 and emitted as laser beams 53A and 53B. The laser beams 53A and 53B are collimated beams that approach each other as they move in the +Z direction. Note that the collimated beams do not need to be strictly collimated, as long as they are collimated enough to function as a displacement sensor. An object 36 is located in the +Z direction of the displacement sensor 100. The laser beams 53A and 53B are reflected by the object 36. The photodetector 26 (first photodetector) receives reflected light 54A and 54B of the laser light 53A and 53B reflected by the object 36. The photodetector 26 may be composed of two photodetectors, one for receiving the reflected light 54A and the other for receiving the reflected light 54B. When the object 36 is a diffraction grating, the displacement sensor 100 functions as an encoder. When the object 36 is an object other than a diffraction grating, the displacement sensor 100 functions as a Doppler sensor.

[0022] (Comparative form) Fig. 6 is a cross-sectional view showing the propagation of light in a displacement sensor according to a comparative embodiment. As shown in Fig. 6, in a displacement sensor 110 according to the comparative embodiment, no gap 30 is provided outside the mirrors 15A and 15B. The other configurations are the same as those of the first embodiment.

[0023] In the first embodiment and the comparative example, the incident angle θ2 of the laser beams 51A and 51B onto the mirrors 15A and 15B is less than 45°, so the optical axes of the laser beams 51A and 51B are tilted inward. Therefore, the optical axes of the lenses 25A and 25B are also tilted in accordance with the optical axes of the laser beams 51A and 51B. In the comparative example, a side surface 39 of the second member 20 is provided between the outer sides of the lenses 25A and 25B and the side surfaces 11A and 11B of the first member 10.

[0024] Of laser beams 51A and 51B, light 55A outside the full width at half maximum is irradiated onto side surface 39. Part of light 55A passes through side surface 39 to become light 55B. The remainder of light 55A is reflected by side surface 39, passes through lenses 25A and 25B to become light 55C. The remainder of light 55A is reflected by lenses 25A and 25B to become light 55D.

[0025] Light 55B to 55D are stray light. If light 55B is emitted from the side surface of the second member 20, the effect is small. Light 55C is emitted from the top surface of the second member 20. If light 55C is received by the photodetector 26, it becomes noise. This makes it difficult to detect displacement and the like with high precision. Furthermore, if light 55C is emitted in the +Z direction of the second member 20, it will pose a problem in terms of safety standards for laser products. If light 55D is diffused by the first member 10 and emitted from the top surface of the second member 20, it will also pose a problem similar to light 55C.

[0026] (Description of the First Embodiment) As shown in FIG. 5 , in the first embodiment, a gap 30 (first gap) is provided between the first member 10 and the second member 20. Therefore, light 55 outside the full width at half maximum of laser beams 51A and 51B is introduced into the gap 30 and reflected by the upper surface of the gap 30. The reflected light propagates in the X direction within the gap 30. Therefore, a portion of the light 55 is reduced from being emitted from the front surface of the second member 20. In this manner, stray light can be appropriately processed. This enables highly accurate detection of displacement, etc. Note that the angle of incidence of the light 55 on the upper surface of the gap 30 is at least greater than 45°. Therefore, the light 55 is reflected at a large reflection angle on the upper surface of the gap 30. This reduces a portion of the light 55 from being emitted from the front surface of the second member 20.

[0027] In the comparative example shown in FIG. 6, when the angle θ1 and the incident angle θ2 are 45°, the optical axes of the lenses 25A and 25B are aligned in the Z direction, no side surface 39 is provided, and stray light is unlikely to occur. However, when the angle θ1 and the incident angle θ2 are 45°, the optical axes of the laser beams 53A and 54B do not approach each other even when traveling in the Z direction, and they do not interfere with each other at the target 36. Therefore, when the angle θ1 is greater than 45° and the incident angle θ2 is less than 45°, the optical axes of the lenses 25A and 25B are tilted from the Z direction. In this case, the optical axes of the lenses 25A and 25B are also tilted from the Z direction. Therefore, when the side surface 39 is provided, stray light is likely to occur. From this perspective, it is preferable to provide the gap 30 when the incident angle θ2 is 42° or less or 40° or less. If the incident angle θ2 is too small, the point where the laser beams 53A and 53B intersect is too close to the displacement sensor 100. From this viewpoint, the incident angle θ2 is preferably equal to or greater than 30°.

[0028] On the underside of the second member 20, the bottom surface 23 is located in the +Z direction from the surface 22, thereby providing a gap 30 between the first member 10 and the second member. This allows the optical axes of the lenses 25A and 25B to be tilted from the Z direction, and also provides the gap 30.

[0029] The gap 30 is provided up to the side surfaces of the first member 10 and the second member 20 in the first region 40. This allows the light 55 to be emitted from the side surfaces of the first member 10 and the second member 20. It is preferable to provide a package or the like on the side surfaces of the first member 10 and the second member 20 to prevent the light 55 from being diffusely reflected.

[0030] Gap 30 does not have to penetrate all the way to the side surfaces of first member 10 and second member 20. In this case, if the depth of gap 30 in the X direction is small, light reflected on the side surfaces of gap 30 becomes stray light. Therefore, the depth of gap 30 in the X direction from the upper ends of side surfaces 11A and 11B (depth 57 in FIG. 5) is preferably 0.5 times or more, and more preferably 1 time or more, the full width at half maximum of mirrors 15A and 15B.

[0031] Since it is preferable that the light within the full width at half maximum of the intensity distribution of the laser beams 50A and 50B is reflected by the mirrors 15A and 15B, the intensity of the laser beam in the gap 30 is preferably 1 / 2 or less of the peak intensity of the laser beams 50A and 50B. The intensity of the laser beam in the gap 30 where stray light is likely to be a problem is 1 / e of the peak intensity of the laser beams 50A and 50B. 2 Therefore, the gap 30 is a gap where the intensity of the laser light emitted from the laser element 16 is less than half of the peak intensity and 1 / e 2 It is preferable that the ratio is in the range of 1 / 3 or less and 1 / 5 or more.

[0032] From the viewpoint of positioning the gap 30 so that light 55 is introduced into the gap 30, the height of the gap 30 in the Z direction (the distance in the Z direction between the surfaces 13 and 23) is preferably 0.1 times or more, and more preferably 0.2 times or more, the full width at half maximum of the mirrors 15A and 15B. The height of the gap 30 in the Z direction is preferably 1 time or less the full width at half maximum of the mirrors 15A and 15B.

[0033] The laser element 16 emits a pair of laser beams 50A and 50B in opposite directions, +X and -X. A pair of mirrors 15A and 15B are provided corresponding to the pair of laser beams 50A and 50B. A pair of lenses 25A and 25B are provided corresponding to the pair of laser beams 51A and 51B. The photodetector 26 receives a pair of reflected beams 54A and 54B formed when the pair of laser beams 53A and 53B pass through the pair of lenses 25A and 25B and are reflected by the object 36. By using a diffraction grating as the object 36, the displacement sensor 100 can function as an encoder that detects the relative displacement between the object 36 and the displacement sensor 100. Furthermore, if the object 36 is an object other than a diffraction grating, the laser beams 53A and 53B are scattered by the surface of the object 36. The photodetector 26 detects the reflected beams 54A and 54B, allowing the displacement sensor 100 to function as a Doppler sensor that detects the relative velocity between the object 36 and the displacement sensor 100.

[0034] The intensity ratio between laser beams 50A and 50B may be 1:1 or may be different from 1:1. The intensity ratio between laser beams 50A and 50B may be within a range in which reflected beams 54A and 54B can interfere with each other. Laser element 16 may emit laser beam 50A but not laser beam 50B, and mirror 15B and lens 25B may not be provided. For example, a configuration such as that described in Patent Document 1 may be used.

[0035] 1, thermistor 35, electronic components such as a control circuit and a drive circuit, and wiring such as electrodes 33A and 33B and bonding wires 34A and 34B are not provided within the full width at half maximum range of laser beams 50A and 50B, which makes it possible to prevent laser beams 50A and 50B from being scattered by electronic components, electrodes, wiring, etc.

[0036] (Second embodiment) The second embodiment is an example in which a gap 32 is provided on the bottom surface 12 of the recess 14 of the first member 10. Fig. 7 is a cross-sectional view of the displacement sensor according to the second embodiment. Fig. 8 is a plan view of the first member of the displacement sensor according to the second embodiment. Fig. 7 is a cross-sectional view taken along line AA in Fig. 8.

[0037] As shown in Figures 7 and 8, in the displacement sensor 102 of the second embodiment, a gap 32 is provided on the bottom surface 12 between the laser element 16 and the mirrors 15A and 15B. As shown in Figure 7, the gap 32 penetrates the first member 10 in the Z direction. As shown in Figure 8, when viewed from the Z direction, at least a portion of the gap 32 overlaps with the full width at half maximum range of the intensity of the laser beams 50A and 50B. The gap 32 is, for example, an air gap. The other configurations are the same as those of the first embodiment, and therefore description thereof will be omitted.

[0038] Of the laser light emitted by the laser element 16, light that travels downward and is reflected by the bottom surface 12 becomes stray light. As shown in FIG. 7 , the first member 10 has a gap 32 (second gap) on the bottom surface 12 of the recess 14 between the laser element 16 and the mirrors 15A and 15B. As a result, light 56 ​​travels in the -Z direction while being reflected by the side surfaces of the gap 32. This makes it possible to prevent stray light from being emitted from the second member 20 in the +Z direction. The gap 32 does not have to penetrate the first member 10 in the Z direction, but by having the gap 32 penetrate the first member 10, the light 56 ​​is emitted from the bottom surface of the first member 10. This makes it possible to more appropriately deal with stray light.

[0039] (Third embodiment) The third embodiment and its modified example are examples in which photodetectors are provided in the gaps 30 and 32. FIG. 9 is a cross-sectional view of a displacement sensor according to the third embodiment. As shown in FIG. 9, a displacement sensor 104 according to the third embodiment includes a photodetector 38 in the gap 30. Light 55 is incident on the light-receiving surface of the photodetector 38. A control circuit controls the output of the laser element 16 based on the output of the photodetector 38. The other configurations are the same as those of the first embodiment, and therefore a description thereof will be omitted.

[0040] (Modification 1 of the third embodiment) Fig. 10 is a cross-sectional view of a displacement sensor according to Modification 1 of the third embodiment. As shown in Fig. 10, a displacement sensor 106 according to Modification 1 of the third embodiment includes a photodetector 38A in the gap 32. Light 56 ​​is incident on the light-receiving surface of the photodetector 38A. A control circuit controls the output of the laser element 16 based on the output of the photodetector 38. The other configurations are the same as those of the second embodiment, and therefore a description thereof will be omitted.

[0041] In order to monitor the laser light of the laser element 16, it is common to monitor the laser light emitted from the surface opposite to the laser light emission surface. However, when laser light 50A and 50B are emitted from both end surfaces of the laser element 16, it is not possible to monitor one of the laser lights. According to the third embodiment and the first modification, the photodetector 38 or 38A (second photodetector) is provided in the gap 30 or 32 and detects part of the laser light. This allows part of the stray light to be used as monitoring light for controlling the laser element 16.

[0042] (Fourth embodiment) The fourth embodiment is an example in which the upper surface of the second member 20 has a prism surface. FIG. 11 is a cross-sectional view of the displacement sensor according to the fourth embodiment. FIG. 12 is a perspective view of the second member in the displacement sensor according to the fourth embodiment. As shown in FIGS. 11 and 12, the second member 20 has a recess 28 on its upper surface. The side surfaces of the recess 28 are prism surfaces 27A and 27B. The prism surfaces 27A and 27B are flat surfaces. A photodetector 26 is provided on a bottom surface 29 of the recess 28. The bottom surface 29 is flat. The angle θ3 formed between a plane extending from the bottom surface 29 and the prism surfaces 27A and 27B is smaller than the angle θ1. The other configurations are the same as those of the first embodiment, and therefore description thereof will be omitted.

[0043] 5, when the upper surface of the second member 20 is flat, the distance D0 between the upper surface of the second member 20 and the point where the optical axis of the laser beam 53A and the optical axis of the laser beam 53B intersect depends on the angle θ1. As the angle θ1 increases from 45°, the distance D0 decreases.

[0044] In order to improve the controllability of the angle θ1, the angle θ1 may be fixed. For example, if a single-crystal silicon substrate having a (100) plane as the first member 10 is used, and the recess 14 is formed by etching using a potassium hydroxide solution or the like, the side surfaces 11A and 11B will be (111) planes. In this case, the angle θ1 will be 54.7°, making it difficult to increase the distance D0.

[0045] The distance D2 was calculated by changing the angle θ3. In the calculation, a glass cover 37 equivalent to a package window was provided in the +Z direction of the second member 20. The lenses 25A and 25B were aspherical lenses. The lens shape was determined by Z=Y 2 / [R×[1+{1-(1+k)×Y 2 / R 2} 1 / 2 ]]. Here, Z is the sag with respect to the lens optical axis, Y is the radial distance from the lens optical axis, R is the curvature, and k is the conic constant. R = -0.8 and k = -3.0 were set. The inclination angle of the lens optical axis from the Z direction was 20°. The width of the laser element 16 in the X direction was 0.45 mm, the optical axis distance between the laser element 16 and the mirrors 15A and 15B was 0.7 mm, and the distance in the Z direction between the bottom surface 12 and the surface 13 was 0.4 mm. The thickness of the peripheral portion of the second member 20 was 0.44 mm, the gap between the second member 20 and the glass cover 37 was 0.2 mm, and the thickness of the glass cover 37 was 0.3 mm. The angle θ1 was 54.7°. The wavelength of the laser beams 50A and 50B was 1550 nm, and the refractive index of the second member 20 and the glass cover 37 was 1.78.

[0046] 13 to 15 are cross-sectional views showing the propagation of light within the displacement sensor in the fourth embodiment. The lower part of the first member 10 is not shown. As shown in FIG. 13, in displacement sensor 108A, angle θ3 between prism surfaces 27A and 27B is 20°. Laser beams 53A and 53B emitted from prism surfaces 27A and 27B, respectively, pass through glass cover 37 and are emitted from glass cover 37 as laser beams 53A' and 53B'.

[0047] The distance between the glass cover 37 and the intersection of the optical axes of laser beams 53A' and 53B' is defined as D2. The distance between the glass cover 37 and the intersection of the full width at half maximum light inside laser beam 53A' and the full width at half maximum light inside laser beam 53B' is defined as D1. The distance between the glass cover 37 and the intersection of the full width at half maximum light outside laser beam 53A' and the full width at half maximum light outside laser beam 53B' is defined as D3. The range between distances D1 and D3 is the measurable range. Distances D1, D2, and D3 are 0.62 mm, 1.32 mm, and 2.02 mm, respectively. Distance D4 in the range between distances D1 and D3 is 1.40 mm.

[0048] As shown in FIG. 14, in displacement sensor 108B, the angle θ3 between prism surfaces 27A and 27B is 30°. Distances D1, D2, and D3 are 1.54 mm, 2.66 mm, and 3.77 mm, respectively. Distance D4 is 2.23 mm. When angle θ3 is 30°, distance D2 is approximately twice the distance D2 when angle θ3 is 20°. When angle θ3 is 30°, distance D4 is approximately 0.8 mm longer than distance D4 when angle θ3 is 20°.

[0049] As shown in FIG. 15, in displacement sensor 108C, angle θ3 between prism surfaces 27A and 27B is 35°. Distances D1, D2, and D3 are 2.93 mm, 4.60 mm, and 6.26 mm, respectively. Distance D4 is 3.33 mm. When angle θ3 is 35°, distance D2 is approximately 3.5 times longer than distance D2 when angle θ3 is 20°. When angle θ3 is 35°, distance D4 is approximately 2.0 mm longer than distance D4 when angle θ3 is 20°.

[0050] According to the fourth embodiment, the second member 20 has a pair of prism surfaces 27A and 27B on the surface opposite to the first member 10. As shown in FIG. 15, the prism surfaces 27A and 27B refract the laser beams 52A and 52B so as to reduce the angle θ4 between the pair of laser beams 52A and 52B that have passed through the pair of lenses 25A and 25B to an angle θ5. This allows the measurable range to be extended farther than that of the displacement sensor 100 of the first embodiment, as shown in FIGS. 13 to 15. The measurement range can also be widened. Furthermore, by integrating the prisms and the lenses 25A and 25B, the device can be made more compact.

[0051] The first member 10 includes a silicon substrate whose main surface is a (100) plane, and the surface on which the pair of mirrors 15A and 15B are provided is a (111) plane. In this case, the side surfaces 11A and 11B can be formed with high precision. However, the angle θ1 is 54.7°, and the distances D2 and D4 cannot be increased. Therefore, by providing prism surfaces 27A and 27B, the distances D2 and D4 can be increased. Note that the prism surfaces 27A and 27B are surfaces that form prisms, and in the fourth embodiment, they are surfaces that refract light that has passed through the lenses 25A and 25B.

[0052] The photodetector 26 is provided between the pair of prism surfaces 27A and 27B, so that the reflected light beams 54A and 54B can be detected by the photodetector 26. The prism surfaces 27A and 27B may be provided in the second and third embodiments.

[0053] Although the embodiments have been described above, they are presented as examples and the present invention is not limited to the above embodiments. The above embodiments can be implemented in various other forms, and various combinations, omissions, substitutions, modifications, etc. can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as set forth in the claims.

[0054] The embodiments of the present invention are as follows, for example. <1> a first member having a recess on an upper surface; a second member provided in the stacking direction of the first member; a laser element provided in the recess and emitting laser light; a mirror provided on a side surface of the recess, the mirror reflecting the laser light and having an incident angle of the laser light of less than 45°; a lens provided in the second member onto which the reflected laser light is incident; a first photodetector that receives reflected light of the laser light that has passed through the lens and is reflected by an object; Equipped with a first gap recessed from a side surface of the recess toward the first region and connecting to the recess, between the first member and the second member in a first region on the opposite side of the mirror from the laser element as viewed in the stacking direction. <2> a first surface of the second member on the first member side in the first region is positioned in the stacking direction further than a second surface of the second member on the first member side in a second region on the laser element side of the lens when viewed from the stacking direction, thereby providing the first gap between the first surface and the second surface; <1> The displacement sensor according to claim 1. <3> the first gap is provided up to the side surfaces of the first member and the second member in the first region; <1> or the above <2> The displacement sensor according to claim 1. <4> The first gap is formed such that the intensity of the laser light emitted from the laser element is equal to or less than 1 / 2 of the peak intensity and 1 / e 2 The above range is located <1> From the above <3> 10. The displacement sensor according to claim 9, <5> the first member has a second gap at the bottom surface of the recess between the laser element and the mirror; <1> From the above <4> 10. The displacement sensor according to claim 9, <6> a second photodetector provided in the first gap and configured to detect a portion of the laser light; <1> From the above <5> 10. The displacement sensor according to claim 9, <7> the laser element emits a pair of laser beams in opposite directions; the mirror and the lens are provided in pairs corresponding to the pair of laser beams, the first photodetector receives a pair of reflected light beams formed by the pair of laser beams that have passed through the pair of lenses and are reflected by the object; <1> From the above <6> 10. The displacement sensor according to claim 9, <8> the second member has a pair of prism surfaces on a surface opposite to the first member, the prism surfaces refracting the pair of laser beams transmitted through the pair of lenses so as to reduce the angle between the pair of laser beams; <7> The displacement sensor according to claim 1. <9> the first member includes a silicon substrate having a (100) plane as a main surface, and the plane on which the pair of mirrors are provided is a (111) plane; <8> The displacement sensor according to claim 1. <10> the first photodetector is provided between the pair of prism surfaces; <8> or the above <9> The displacement sensor according to claim 1. [Explanation of symbols]

[0055] 10 First member 11A, 11B, 21 side 12, 23, 29 bottom 13, 22 sides 14, 24A, 24B, 28 recesses 15A, 15B mirrors 16 Laser element 20 Second member 25A, 25B lenses 26, 38, 38A Photodetectors 27A, 27B prism surfaces 30, 32 gap 36 Object 40 First area 42 Second area 50A, 50B, 51A, 51B, 51A, 52B, 53A, 53B, 53A', 53B' Laser light 54A, 54B reflected light 55, 55A, 55B, 55C, 56 light

Claims

1. a first member having a recess on an upper surface; a second member provided in the stacking direction of the first member; a laser element provided in the recess and emitting laser light; a mirror provided on a side surface of the recess, the mirror reflecting the laser light having an incident angle of less than 45°; a lens provided in the second member onto which the reflected laser light is incident; a first photodetector that receives reflected light of the laser light that has passed through the lens and is reflected by an object; Equipped with a first gap recessed from a side surface of the recess toward the first region and connecting to the recess, between the first member and the second member in a first region on the opposite side of the mirror from the laser element when viewed from the stacking direction.

2. 2. The displacement sensor according to claim 1, wherein a first surface of the second member on the first member side in the first region is positioned in the stacking direction further than a second surface of the second member on the first member side in a second region on the laser element side of the lens when viewed from the stacking direction, thereby providing the first gap between the first surface and the second surface.

3. The displacement sensor according to claim 1 , wherein the first gap extends to side surfaces of the first member and the second member in the first region.

4. The first gap is formed such that the intensity of the laser light emitted from the laser element is equal to or less than 1 / 2 of the peak intensity and 1 / e ２ 3. The displacement sensor according to claim 1, which is located in the above range.

5. The displacement sensor according to claim 1 , wherein the first member has a second gap on a bottom surface of the recess between the laser element and the mirror.

6. The displacement sensor according to claim 1 , further comprising a second photodetector provided in the first gap and configured to detect a portion of the laser light.

7. the laser element emits a pair of laser beams in opposite directions; the mirror and the lens are provided in pairs corresponding to the pair of laser beams, 3. The displacement sensor according to claim 1, wherein the first photodetector receives a pair of reflected light beams formed by the pair of laser light beams that have passed through the pair of lenses and are reflected by the object.

8. 8. The displacement sensor according to claim 7, wherein the second member has a pair of prism surfaces on a surface opposite to the first member, the prism surfaces refracting the pair of laser beams transmitted through the pair of lenses so as to reduce an angle between the pair of laser beams.

9. 9. The displacement sensor according to claim 8, wherein the first member includes a silicon substrate having a (100) plane as a main surface, and the plane on which the pair of mirrors are provided is a (111) plane.

10. The displacement sensor according to claim 8 , wherein the first photodetector is provided between the pair of prism surfaces.

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