JP2021124536A - Optical member, light emitting device, rotation speed measurement device, and optical measurement device - Google Patents

Abstract

To provide an optical member capable of achieving both high reflectance and high heat dissipation, a light emitting device, a rotation speed measurement device, and an optical measurement device.SOLUTION: An optical member includes a base substance made of ceramics on which a reflection surface is provided. The reflection surface has a first area and a second area whose porosity is smaller than that of the first area.SELECTED DRAWING: Figure 1

Description

The disclosed embodiments relate to an optical member, a light emitting device, a rotation speed measuring device, and an optical measuring device.

Conventionally, an optical device using a ceramic member such as alumina as a reflector is known (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2006-165326

However, in the conventional technique, when a ceramic member is used as a reflector, it is difficult to achieve both high reflectance and high heat dissipation.

One aspect of the embodiment is made in view of the above, and provides an optical member, a light emitting device, a rotation speed measuring device, and an optical measuring device capable of achieving both high reflectance and high heat dissipation. With the goal.

The optical member according to one aspect of the embodiment is provided with a reflective surface on a substrate made of ceramic, and the reflective surface has a first region and a second region having a porosity smaller than that of the first region. ..

Further, the light emitting device according to one aspect of the embodiment includes the optical member described above and a light emitting element.

Further, the rotation speed measuring device according to one aspect of the embodiment includes the optical member described above and a rotating body on which the optical member is mounted.

Further, the optical measuring device according to one aspect of the embodiment has a pinhole in the first region and includes a heat shield plate composed of the optical member described above.

According to one aspect of the embodiment, it is possible to provide an optical member, a light emitting device, a rotation speed measuring device, and an optical measuring device capable of achieving both high reflectance and high heat dissipation.

FIG. 1 is a perspective view of an optical member according to an embodiment. FIG. 2 is an SEM observation photograph of the first region of the optical member according to the embodiment. FIG. 3 is an SEM observation photograph of the second region of the optical member according to the embodiment. FIG. 4 is a perspective view of another example of the optical member according to the embodiment. FIG. 5 is a perspective view of another example of the optical member according to the embodiment. FIG. 6 is a diagram for explaining a manufacturing process of the optical member according to the embodiment. FIG. 7 is a diagram for explaining a manufacturing process of the optical member according to the embodiment. FIG. 8 is a cross-sectional view of the light emitting device according to the embodiment. FIG. 9 is a cross-sectional view of the light emitting device according to the first modification of the embodiment. FIG. 10 is a cross-sectional view of the light emitting device according to the second modification of the embodiment. FIG. 11 is a cross-sectional view of the light emitting device according to the third modification of the embodiment. FIG. 12 is a diagram for explaining the configuration of the rotation speed measuring device according to the embodiment. FIG. 13 is an enlarged view of the broken line region shown in FIG. FIG. 14 is a diagram for explaining the configuration of the optical measuring device according to the embodiment. FIG. 15 is a diagram for explaining the configuration of the optical measuring device according to the embodiment. FIG. 16 is a cross-sectional view of a heat shield plate of the optical measuring device according to the embodiment.

Hereinafter, embodiments of an optical member, a light emitting device, a rotation speed measuring device, and an optical measuring device will be described with reference to the accompanying drawings. The present invention is not limited to the embodiments shown below.

Conventionally, an optical device using a ceramic member such as alumina as a reflector is known. As described above, when the ceramic member is used as the reflector, the reflectance of the reflecting surface can be improved by increasing the porosity of the member.

This is because the light reflection phenomenon to the ceramic member does not occur only on the surface of the member like metal, but also occurs at the interface between the pores existing on the surface layer and the crystal, so that the porosity of the member should be increased. This is because the reflection phenomenon itself generated on the surface layer can be increased.

On the other hand, when the porosity of the ceramic member is increased, the pores become an obstacle to heat conduction, so that the heat conductivity is lowered. As a result, there is a possibility that an adverse effect may occur due to insufficient heat dissipation from the reflector.

Therefore, it is expected to realize an optical member capable of overcoming the above-mentioned problems and achieving both high reflectance and high heat dissipation.

<Structure of optical member>
First, the configuration of the optical member 1 according to the embodiment will be described with reference to FIGS. 1 to 5. FIG. 1 is a perspective view of the optical member 1 according to the embodiment.

As shown in FIG. 1, the optical member 1 according to the embodiment includes a disk-shaped substrate 2. The substrate 2 is composed of a first site 3 and a second site 4. The substrate 2 according to the embodiment is provided with, for example, a first portion 3 at a central portion and a second portion 4 at a peripheral portion.

The substrate 2 is made of ceramic. As the ceramic constituting the substrate 2, alumina _{(Al 2 O} 3), zirconia _(ZrO 2), spinel (MgAl ₂ O ₄₎ oxide ceramics and the like, silicon carbide (SiC), silicon nitride _(Si 3 _{N 4} ), Non-oxide ceramics such as aluminum nitride (AlN), titanium nitride (TiN), and titanium carbide (TiC).

In the present disclosure, the main component of the substrate 2 is preferably alumina. As a result, high thermal conductivity can be imparted to the optical member 1. The "main component" in the present disclosure is 55% by mass or more when the total amount of the constituent components is 100% by mass.

Further, the optical member 1 according to the embodiment has a reflecting surface 10 on the main surface of the substrate 2. The reflecting surface 10 is composed of a first region 11 and a second region 12.

The first region 11 is a region corresponding to the first region 3 (that is, a region where the first region 3 is exposed on the reflecting surface 10). Further, the second region 12 is a region corresponding to the second portion 4 (that is, a portion where the second region 4 is exposed on the reflection surface 10).

Here, in the optical member 1 according to the embodiment, as shown in FIGS. 2 and 3, the porosity of the first region 11 is larger than the porosity of the second region 12. That is, in the optical member 1 according to the embodiment, the porosity of the first portion 3 is larger than the porosity of the second portion 4.

FIG. 2 is an SEM observation photograph of the first region 11 of the optical member 1 according to the embodiment, and FIG. 3 is an SEM observation photograph of the second region 12 of the optical member 1 according to the embodiment. In addition, in FIG. 2 and FIG. 3, the dense (black) portion is the pore.

In the embodiment, the reflectance of the first region 11 can be improved by making the porosity of the first region 11 larger than the porosity of the second region 12, and thus the reflectance of the entire reflecting surface 10 is improved. Can be made to.

Further, by reducing the porosity of the second region 12 (that is, the second region 4), the thermal conductivity of the second region 4 can be improved. As a result, the heat accumulated in the first portion 3 due to the incident light can be efficiently dissipated through the second portion 4.

As described above, according to the embodiment, in the ceramic optical member 1, both high reflectance and high heat dissipation can be achieved at the same time.

Further, in the embodiment, it is preferable that the first region 11 is provided in the central portion of the reflection surface 10 and the second region 12 is provided so as to surround the first region 11. As a result, the heat accumulated in the first portion 3 due to the incident light can be dissipated in all directions via the second portion 4.

Therefore, according to the embodiment, the heat accumulated in the first portion 3 due to the incident light can be dissipated more efficiently.

The optical member 1 according to the embodiment is not limited to the case where one first region 11 is provided at the central portion of the reflecting surface 10. 4 and 5 are perspective views of another example of the optical member 1 according to the embodiment.

In the optical member 1 according to the embodiment, for example, as shown in FIG. 4, two first regions 11 may be provided side by side on the reflecting surface 10, and as shown in FIG. 5, a ring-shaped first region 11 may be provided. Second regions 12 may be provided inside and outside the region 11, respectively.

<Manufacturing process of optical members>
Next, the manufacturing process of the optical member 1 according to the embodiment will be described. In the following examples, the optical member 1 containing alumina as a main component is shown, but the present disclosure is not limited to the following examples.

First, a powder having an average particle size of about 1.6 μm as alumina _{and at least one powder of silicon oxide (SiO 2} ), calcium oxide (CaO) and magnesium oxide (MgO), which are sintering aids, are prepared. ..

Then, a binder having a predetermined content, a solvent having a predetermined content, and a dispersant having a predetermined content are weighed against the mixed powder weighed so that the total content of each powder is 100% by mass. And put it in a stirrer together with the mixed powder to mix and stir to obtain a slurry.

Next, the slurry is spray-granulated using a spray granulation device (spray dryer) to obtain granules 20 (see FIG. 6). Then, the obtained granules 20 are filled in a mold and molded by a powder press molding method or the like to form a molded body 24 (see FIG. 7) having a desired shape.

6 and 7 are diagrams for explaining the manufacturing process of the optical member 1 according to the embodiment, and specifically, are diagrams for explaining the above-mentioned molding process. As shown in FIG. 6, the granules 20 obtained by spray granulation are filled between the upper punch 22 and the lower punch 23 in the mortar 21.

Further, the lower punch 23 is divided into a first lower punch 23a and a second lower punch 23b, and each can be operated individually. The first lower punch 23a is a lower punch 23 that presses the central portion of the granules 20 filled in the mortar 21, and the second lower punch 23b is a lower punch that presses the peripheral portion of the granules 20 filled in the mortar 21. 23.

Then, when the granules 20 are filled in the mortar 21, the pressing surface of the first lower punch 23a is arranged above the pressing surface of the second lower punch 23b. That is, the central portion of the granules 20 filled in the mortar 21 is thinner than the peripheral portion of the granules 20 filled in the mortar 21. In such a state, the granules 20 are pressed from above and below by the upper punch 22 and the lower punch 23.

At this time, as shown in FIG. 7, the pressing process is controlled so that the pressing surface of the first lower punch 23a and the pressing surface of the second lower punch 23b are substantially flush with each other when the pressing is completed. As a result, the molded body 24 is molded so as to include the first portion 24a and the second portion 24b, which have different densities.

The first portion 24a is a portion pressed by the first lower punch 23a, and the second portion 24b is a portion pressed by the second lower punch 23b. Then, in the embodiment, since the second lower punch 23b is displaced more than the first lower punch 23a, the density of the second portion 24b is higher than the density of the first portion 24a.

Next, the obtained molded body 24 is cut as necessary, and the sintered body is fired by holding it at a desired maximum temperature for a desired time using a firing furnace in an atmospheric (oxidation) atmosphere. obtain. Then, the obtained sintered body is subjected to grinding or the like to obtain the optical member 1 according to the embodiment.

Here, in the embodiment, as shown in FIGS. 6 and 7, the first portion 24a and the second portion 24b having different densities can be formed inside the molded body 24, respectively. Therefore, according to the embodiment, by firing the molded body 24, the first portion 3 and the second portion 4 having different densities (that is, porosity) can be formed inside the optical member 1. ..

<Light emitting device>
Next, the configuration of the light emitting device 30 equipped with the optical member 1 according to the embodiment will be described with reference to FIGS. 8 to 11. FIG. 8 is a cross-sectional view of the light emitting device 30 according to the embodiment. In the example of FIG. 8, the optical member 1 is used as a mounting substrate for the light emitting element 31.

As shown in FIG. 8, the light emitting device 30 according to the embodiment includes an optical member 1, a light emitting element 31, a metal layer 32, and a heat radiating member 33. In the example of FIG. 8, the optical member 1 has a first portion 3 at the central portion of the substrate 2 and a second portion 4 at the peripheral portion.

That is, in the example of FIG. 8, in the reflection surface 10 provided on the upper surface of the optical member 1, the central portion is the first region 11 and the peripheral portion is the second region 12.

The light emitting element 31 is, for example, a laser diode (also referred to as a semiconductor laser), a light emitting diode (LED: Light Emitting Diode), or the like. The metal layer 32 is formed on the reflective surface 10 of the optical member 1 in a predetermined pattern, and functions as a wiring layer that supplies electric power or the like to the light emitting element 31 from the outside.

The metal layer 32 is composed of, for example, silver, copper, aluminum, gold, or the like as a main component. Further, the metal layer 32 may be formed of a metallized film obtained by sintering metal powder. Since this metallized film can be adhered to the surface of the ceramics constituting the optical member 1 with high strength, it is possible to realize a highly reliable light emitting device 30.

The heat radiating member 33 is made of a material (for example, metal) having a higher thermal conductivity than the optical member 1, and is provided so as to be in contact with the second portion 4 of the optical member 1. For example, the heat radiating member 33 is provided along the outer circumference of the second portion 4. By providing the heat radiating member 33, the heat generated during the operation of the light emitting element 31 can be efficiently radiated from the optical member 1 to the outside.

Here, in the embodiment, the light emitting element 31 is mounted in the first region 11 of the optical member 1 via the metal layer 32. As a result, the light emitted from the light emitting element 31 can be efficiently reflected in the first region 11 near the light emitting element 31. Therefore, according to the embodiment, the amount of light emitted from the light emitting device 30 can be increased.

Further, in the embodiment, as shown in FIG. 8, it is preferable that the metal layer 32 reaches the second region 12 of the reflecting surface 10. As a result, heat can be efficiently released from the light emitting element 31 to the second portion 4 via the metal layer 32 having a high thermal conductivity. Therefore, according to the embodiment, the heat dissipation of the light emitting device 30 can be improved.

Further, in the embodiment, it is preferable that the heat radiating member 33 is gradually fitted with the optical member 1 at the second portion 4. As a result, the contact area between the optical member 1 and the heat radiating member 33 can be increased, so that the heat radiating property of the light emitting device 30 can be further improved.

The light emitting device 30 equipped with the optical member 1 according to the embodiment is not limited to the example of FIG. FIG. 9 is a cross-sectional view of the light emitting device 30 according to the first modification of the embodiment.

As shown in FIG. 9, the light emitting device 30 according to the first modification includes an optical member 1, a light emitting element 31, and a metal layer 32. Similar to the example of FIG. 8, the optical member 1 of the modified example 1 has a first portion 3 at the central portion of the substrate 2 and a second portion 4 at the peripheral portion.

That is, in the modified example 1, in the reflection surface 10 provided on the upper surface of the optical member 1, the central portion is the first region 11 and the peripheral portion is the second region 12. Further, the light emitting element 31 is mounted on the first region 11 of the reflecting surface 10 via the metal layer 32.

As a result, the light emitted from the light emitting element 31 can be efficiently reflected in the first region 11 near the light emitting element 31. Therefore, according to the first modification, the amount of light emitted from the light emitting device 30 can be increased.

Further, in the modified example 1, as shown in FIG. 9, the second portion 4 of the optical member 1 is thicker than the first portion 3 of the optical member 1. As a result, the surface area of the second portion 4 can be increased, so that heat can be efficiently released to the outside through the second portion 4 having a higher thermal conductivity than the first portion 3. Therefore, according to the first modification, the heat dissipation of the light emitting device 30 can be improved.

The light emitting device 30 according to the embodiment is not limited to the case where the optical member 1 is used as a mounting substrate for the light emitting element 31. FIG. 10 is a cross-sectional view of the light emitting device 30 according to the second modification of the embodiment.

As shown in FIG. 10, the light emitting device 30 according to the second modification includes an optical member 1, a light emitting element 31, a metal layer 32, and a mounting substrate 34. In the second modification, the optical member 1 has a first portion 3 at the central portion of the substrate 2 and a second portion 4 at the peripheral portion.

That is, in the second modification, in the reflecting surface 10 provided on the bottom surface of the optical member 1, the central portion is the first region 11 and the peripheral portion is the second region 12. The metal layer 32 is formed on the main surface (upper surface in the drawing) of the mounting substrate 34. The mounting substrate 34 is made of an insulating material (for example, ceramic). The light emitting element 31 is mounted on the main surface of the mounting substrate 34 via the metal layer 32.

Here, in the second modification, the light emitting element 31 is mounted on the mounting substrate 34 at a position facing the reflecting surface 10. As a result, as shown in FIG. 10, the light L emitted from the light emitting element 31 can be emitted so as to spread to the outside through the reflecting surface 10 and the metal layer 32. Therefore, according to the second modification, the light emitting device 30 having a wide light distribution angle can be realized.

Further, in the second modification, the reflecting surface 10 provided on the bottom surface of the optical member 1 may have a convex curved surface shape toward the light emitting element 31. Thereby, the light emitting device 30 having a wider light distribution angle can be realized.

Further, in the second modification, it is preferable that the light emitting element 31 is mounted at a position facing the first region 11 of the reflecting surface 10. As a result, the light emitted from the light emitting element 31 can be efficiently reflected in the first region 11, so that the amount of light emitted from the light emitting device 30 can be increased.

FIG. 11 is a cross-sectional view of the light emitting device 30 according to the third modification of the embodiment. As shown in FIG. 11, the light emitting device 30 according to the third modification includes an optical member 1, a light emitting element 31, a metal layer 32, and a mounting substrate 34. In the second modification, the optical member 1 has a first portion 3 at the central portion of the substrate 2 and a second portion 4 at the peripheral portion.

That is, in the modified example 3, in the reflecting surface 10 provided on the bottom surface of the optical member 1, the central portion is the first region 11 and the peripheral portion is the second region 12. The metal layer 32 is formed on the bottom surface of the recess 34a formed in the box-shaped mounting substrate 34. The light emitting element 31 is provided on the bottom surface of the recess 34a in the mounting substrate 34 via the metal layer 32.

Then, in the light emitting device 30, the optical member 1 is provided so as to close the recess 34a at a position facing the light emitting element 31. Further, a through hole 3a is formed in the first portion 3 of the optical member 1. As a result, in the light emitting device 30 according to the third modification, the light L can be emitted from the light emitting element 31 to the outside through the through hole 3a.

Further, in the modification 3, it is preferable that the first region 11 of the reflecting surface 10 provided on the bottom surface of the optical member 1 has a concave curved surface shape toward the light emitting element 31. As a result, as shown in FIG. 11, the light L emitted from the light emitting element 31 can be efficiently emitted to the outside through the first region 11. Therefore, according to the third modification, the amount of light emitted from the light emitting device 30 can be increased.

<Rotation speed measuring device>
The target to which the above-mentioned optical member 1 can be applied is not limited to the light emitting device 30. Therefore, in the following embodiments, an example in which the optical member 1 is applied to various other objects will be described.

First, the configuration of the rotation speed measuring device 40 equipped with the optical member 1 according to the embodiment will be described with reference to FIGS. 12 and 13. FIG. 12 is a diagram for explaining the configuration of the rotation speed measuring device 40 according to the embodiment, and FIG. 13 is an enlarged view of the broken line region A shown in FIG.

As shown in FIG. 12, the rotation speed measuring device 40 according to the embodiment includes a casing 41, a rotor 42, an optical sensor 43, an optical member 1, an optical signal processing unit 44, and an optical signal calculation unit 45. Be prepared. The rotor 42 is an example of a rotating body.

The casing 41 is fixed inside the rotation speed measuring device 40 and is stationary. The rotor 42 is rotatably supported inside the casing 41. The optical sensor 43 is attached to the casing 41 and is arranged so as to view the outer peripheral surface 42a of the rotor 42.

The optical member 1 is fixed on the outer peripheral surface 42a of the rotor 42 so as to reflect the light L (see FIG. 13) incident from the optical sensor 43. The optical signal processing unit 44 performs various processes on the optical signal detected by the optical sensor 43, and sends the processed optical signal to the optical signal calculation unit 45. The optical signal calculation unit 45 calculates the rotation speed of the rotor 42 based on the processed optical signal.

Here, the rotation speed measuring device 40 according to the embodiment detects the outer peripheral surface 42a of the rotor 42 by the optical sensor 43, and is based on the detection frequency of the optical member 1 having a higher reflectance than other parts on the outer peripheral surface 42a. Then, the rotation speed of the rotor 42 is calculated.

Then, in the rotation speed measuring device 40 according to the embodiment, as shown in FIG. 13, the light L emitted from the optical sensor 43 is transmitted to the optical sensor 43 with high reflectance through the first region 11 of the reflecting surface 10. Can be reflected. Therefore, according to the embodiment, the rotation speed of the rotor 42 can be detected with high accuracy.

Further, in the embodiment, since it is fitted to the rotor 42 via the second portion 4 having a small porosity, it is possible to prevent the optical member 1 from being damaged when it is fitted to the rotor 42.

In the examples of FIGS. 12 and 13, the rotor 42 is used as the rotating body to which the optical member 1 is fixed, but the rotating body to which the optical member 1 is fixed is not limited to the rotor.

<Optical measuring device>
Next, the configuration of the optical measuring device 50 equipped with the optical member 1 according to the embodiment will be described with reference to FIGS. 14 to 16. 14 and 15 are views for explaining the configuration of the optical measuring device 50 according to the embodiment, and FIG. 16 is a cross-sectional view of the heat shielding plate 52 of the optical measuring device 50 according to the embodiment.

The optical measuring device 50 according to the embodiment measures the glucose concentration in the living tissue from a signal obtained by irradiating the living body with near-infrared light and receiving diffuse reflected light or transmitted light from the living tissue. It is a device to do.

In the optical measuring device 50 according to the embodiment, as shown in FIG. 14, the near-infrared light emitted from the halogen lamp 51 is the heat shield plate 52, the pinhole 53, the lens 54, the optical fiber bundle 55A, and the measurement device. It is incident on the living tissue 56 (for example, the skin of the subject) via the probe 59.

One end of the measurement optical fiber 57 and one end of the reference optical fiber 58 are connected to the optical fiber bundle 55A. The other end of the measurement optical fiber 57 is connected to the measurement probe 59, and the other end of the reference optical fiber 58 is connected to the reference probe 60.

Further, the measuring probe 59 is connected to the measuring side emitting body 61 via the optical fiber 55B, and the reference probe 60 is connected to the reference side emitting body 62 via the optical fiber 55B.

When the tip surface of the measurement probe 59, which is a sensing means, is brought into contact with the surface of the biological tissue 56 to perform near-infrared spectrum measurement, the near-infrared light incident on the optical fiber bundle 55A from the halogen lamp 51 as a light source is emitted. , Transmission in the optical fiber 57 for measurement.

Then, the near-infrared light transmitted in the measurement optical fiber 57 irradiates the surface of the biological tissue 56 from the 12 light emitting fibers 70 arranged on the concentric circumference at the end face of the measurement probe 59 shown in FIG. Will be done.

At the end face of the measurement probe 59, twelve light emitting fibers 70 are arranged concentrically around the measurement probe 59. Further, in the reference probe 60, 12 light emitting fibers 70 are arranged in the same manner as the measurement probe 59.

The measurement light irradiated to the biological tissue 56 is diffusely reflected in the biological tissue 56, and then a part of the diffusely reflected light is received by the light receiving side optical fiber 69 arranged at the tip of the measurement probe 59.

The light received by the light receiving side optical fiber 69 is emitted from the measuring side ejector 61 via the light receiving side optical fiber 69. The light emitted from the measuring side emitting body 61 is incident on the diffraction grating 64 through the lens 63, is separated, and then detected by the light receiving element 65.

Then, the optical signal detected by the light receiving element 65 is AD-converted by the A / D converter 66 and then input to the arithmetic unit 67 such as a PC (Personal Computer).

On the other hand, the reference measurement is performed by measuring the light reflected from the reference plate 68, which is a ceramic plate, for example, and the reflected light is used as the reference light.

That is, the near-infrared light incident on the optical fiber bundle 55A from the halogen lamp 51 is emitted from the tip of the reference probe 60 to the surface of the reference plate 68 through the reference optical fiber 58. The reflected light of the light applied to the reference plate 68 is emitted from the reference side ejector 62 via the light receiving side optical fiber arranged at the tip of the reference probe 60.

Shutters 71 are arranged between the measuring side emitting body 61 and the lens 63 and between the reference side emitting body 62 and the lens 63, respectively, and the shutter 71 is opened and closed to allow the measuring side emitting body 61 to be released from the measuring side emitting body 61. Either the light or the light from the reference side emitter 62 selectively passes through.

In the optical measuring device 50 described so far, the heat shield plate 52 is configured by the optical member 1 according to the embodiment. Further, in the embodiment, as shown in FIG. 16, a pinhole 53 is formed in the first portion 3 of the optical member 1.

Thereby, the reflectance of the surface of the pinhole 53 formed in the first portion 3 having a large porosity can be improved. That is, in the embodiment, more light L emitted from the halogen lamp 51 can be emitted to the tip of the heat shield plate 52 through the surface of the pinhole 53.

Therefore, according to the embodiment, since the amount of measurement light can be increased, the glucose concentration and the like can be measured with high accuracy.

Further, in the embodiment, the shielded heat can be efficiently released to the outside through the second portion 4 having a higher thermal conductivity than the first portion 3. Therefore, according to the embodiment, the heat dissipation of the heat shield plate 52 can be improved.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit of the present invention. For example, in the above-described embodiment, the case where the optical member 1 has a disk shape is shown, but the shape of the optical member 1 is not limited to the disk shape.

Further, although the example in which the reflecting surface 10 is provided on one surface of the optical member 1 has been shown, the reflecting surface 10 may be provided on two or more surfaces of the optical member 1.

Further effects and other aspects can be easily derived by those skilled in the art. For this reason, the broader aspects of the invention are not limited to the particular details and representative embodiments expressed and described above. Therefore, various modifications can be made without departing from the spirit or scope of the general concept of the invention as defined by the appended claims and their equivalents.

1 Optical member 2 Base 3 1st part 4 2nd part 10 Reflective surface 11 1st area 12 2nd area 30 Light emitting device 31 Light emitting element 32 Metal layer 33 Heat dissipation member 40 Rotation speed measuring device 42 Rotor (example of rotating body)
50 Optical measuring device 52 Heat shield plate 53 Pinhole

Claims (14)

A reflective surface is provided on a substrate made of ceramic,
The reflective surface is an optical member having a first region and a second region having a porosity smaller than that of the first region. The optical member according to claim 1, wherein the first region is provided in the central portion of the reflective surface, and the second region is provided so as to surround the first region. A light emitting device including the optical member according to claim 1 or 2 and a light emitting element. The light emitting device according to claim 3, wherein the light emitting element is mounted in the first region of the reflecting surface. The light emitting element is mounted via a metal layer in the first region of the reflective surface.
The light emitting device according to claim 4, wherein the metal layer reaches the second region of the reflective surface. The light emitting device according to any one of claims 3 to 5, wherein a heat radiating member having a higher thermal conductivity than the optical member is provided so as to be in contact with the optical member. The light emitting device according to claim 6, wherein the heat radiating member is gradually fitted with the optical member at a portion corresponding to the second region. The light emitting device according to any one of claims 3 to 7, wherein the portion of the optical member corresponding to the second region is thicker than the portion of the optical member corresponding to the first region. The light emitting device according to claim 3, wherein the light emitting element is mounted at a position facing the reflecting surface. The light emitting device according to claim 9, wherein the reflecting surface has a convex curved surface shape toward the light emitting element. The light emitting device according to claim 9, wherein the optical member has a through hole in the first region. The light emitting device according to claim 11, wherein the reflecting surface has a concave curved surface shape toward the light emitting element. A rotation speed measuring device including the optical member according to claim 1 or 2 and a rotating body on which the optical member is mounted. An optical measuring device having a pinhole in the first region and provided with a heat shield plate composed of the optical member according to claim 1 or 2.

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