Patent Publication Number: US-11646544-B2

Title: Method of manufacturing optical member

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation application of U.S. patent application Ser. No. 16/230,690, filed on Dec. 21, 2018, which claims priority to Japanese Patent Application No. 2017-249795, filed on Dec. 26, 2017, the contents of which are hereby incorporated by reference in their entirety. 
    
    
     BACKGROUND 
     The present disclosure relates to an optical member, a light emitting device, and a method of manufacturing an optical member. 
     A light emitting device using a laser element is known in the art. In one example of a light emitting device using a laser element, an electrically conductive thin wire or an electrically conductive track is formed on a surface of a fluorescent material plate upon which laser light hits, to detect cracks or the like in the fluorescent material plate, so that leakage of laser light can be prevented (see, for example, JP 2015-60159 A and WO 2017/012763). 
     SUMMARY 
     However, in such a light emitting device, cracks or the like of the fluorescent material plate can be detected, but it is difficult to detect cracks or the like in the vicinity of a boundary portion between the fluorescent material plate and a holding member thereof. Displacement of the fluorescent material plate during use of the light emitting device is not detected as a defect unless the displacement causes breakage of a wire or the like for electrically connecting the electrically conductive thin wire or electrically conductive track to an external circuit. In view of this, prevention of leakage of laser light in such a light emitting device may be insufficient. 
     One object of the present disclosure is to provide a method of manufacturing an optical member that can more accurately detect a defect that may cause leakage of laser light. 
     A method of manufacturing an optical member according to a certain embodiment of the present disclosure includes: providing a conversion member and a holding member connected to the conversion member; removing a portion of the conversion member and a portion of the holding member to obtain a first surface of the conversion member and a second surface of the holding member; and heat-treating the first surface of the conversion member and the second surface of the holding member. 
     With the method of manufacturing an optical member according to the certain embodiment of the present disclosure, it is possible to manufacture an optical member capable of more accurately detecting a defect that causes leakage of laser light. 
    
    
     
       SUMMARY 
         FIG.  1    is a schematic perspective diagram showing a configuration of a light emitting device using an optical member according to a first embodiment. 
         FIG.  2    is a schematic plan view showing a part of a holding member on the light extraction surface side in  FIG.  1   . 
         FIG.  3    is a schematic cross-sectional view taken along line in  FIG.  1   . 
         FIG.  4    is a schematic diagram showing a configuration of a detection circuit which detects a deviation in resistance value of a wiring. 
         FIG.  5 A  is a schematic diagram for illustrating a method of manufacturing an optical member according to the first embodiment. 
         FIG.  5 B  is a schematic diagram for illustrating the method of manufacturing an optical member according to the first embodiment. 
         FIG.  5 C  is a schematic diagram for illustrating the method of manufacturing an optical member according to the first embodiment. 
         FIG.  6    is a schematic perspective diagram showing a configuration of a light emitting device using an optical member according to a second embodiment. 
         FIG.  7    is a schematic bottom view of a holding member in  FIG.  6   . 
         FIG.  8    is a schematic plan view of a heat dissipating member in  FIG.  6   . 
         FIG.  9    is a schematic cross-sectional view taken along line IX-IX in  FIG.  6   . 
         FIG.  10    is a schematic plan view showing a light extraction surface-side of a configuration of an optical member according to a third embodiment. 
         FIG.  11    is a schematic bottom view of a holding member in  FIG.  10   . 
         FIG.  12    is a schematic plan view of a heat dissipating member in  FIG.  10   . 
         FIG.  13    is a schematic cross-sectional view taken along line XIII-XIII in  FIG.  10   . 
         FIG.  14    is a schematic cross-sectional view showing a variant example of the optical member according to the first embodiment. 
         FIG.  15    is a schematic cross-sectional view showing a variant example of the optical member according to the second embodiment. 
         FIG.  16    is a schematic cross-sectional view showing a variant example of the optical member according to the third embodiment. 
         FIG.  17 A  is a schematic plan view showing a variant example of the optical member according to the first embodiment when viewed from the light extraction surface-side. 
         FIG.  17 B  is a partial enlarged view schematically showing a variant example of the optical member according to the first embodiment. 
         FIG.  17 C  is a partial enlarged view schematically showing a variant example of the optical member according to the first embodiment. 
         FIG.  18 A  is a schematic diagram for illustrating a first method of manufacturing a sintered body. 
         FIG.  18 B  is a schematic diagram for illustrating the first method of manufacturing a sintered body. 
         FIG.  18 C  is a schematic diagram for illustrating the first method of manufacturing a sintered body. 
         FIG.  19 A  is a schematic diagram for illustrating a second method of manufacturing a sintered body. 
         FIG.  19 B  is a schematic diagram for illustrating the second method of manufacturing a sintered body. 
         FIG.  19 C  is a schematic diagram for illustrating the second method of manufacturing a sintered body. 
         FIG.  19 D  is a schematic diagram for illustrating the second method of manufacturing a sintered body. 
         FIG.  20 A  is a schematic diagram for illustrating a third method of manufacturing a sintered body. 
         FIG.  20 B  is a schematic diagram for illustrating the third method of manufacturing a sintered body. 
         FIG.  20 C  is a schematic diagram for illustrating the third method of manufacturing a sintered body. 
         FIG.  20 D  is a schematic diagram for illustrating the third method of manufacturing a sintered body. 
         FIG.  21 A  is a schematic diagram for illustrating another method of manufacturing an optical member. 
         FIG.  21 B  is a schematic diagram for illustrating another method of manufacturing an optical member. 
     
    
    
     DETAILED DESCRIPTION 
     Certain embodiments of the present disclosure will be described below with reference to the drawings. However, the embodiments shown below are only examples of an optical member and a light emitting device to give a concrete form to the technical idea of the present invention, and the present disclosure is not limited to the embodiments shown below. Unless otherwise specified, the dimensions, materials, shapes, relative positions, and the like of the constituent components described in the embodiments below are not intended to limit the scope of the present invention thereto, and are merely illustrative. The sizes, positional relationships, and the like of the members shown in the drawings may be exaggerated for clarification of explanation. In the description below, the same names and reference numerals denote the same or similar members, and detailed descriptions thereof are omitted when appropriate. 
     First Embodiment 
     An optical member, a light emitting device, and a method of manufacturing an optical member according to a first embodiment will be described. 
     As shown in  FIGS.  1  to  4   , an optical member  1 A includes a conversion member  2 , a holding member  3  and a wiring  4 . It is preferable that the optical member  1 A further includes a heat dissipating member  9 . 
     A light emitting device  20  includes the optical member  1 A and a laser element  25 . It is preferable that the light emitting device  20  further includes a package  21 . It is more preferable that the light emitting device  20  further includes a detection circuit  30 . 
     The constituent elements of the optical member  1 A and the light emitting device  20  will be described below. 
     Optical Member 
     Conversion Member 
     A conversion member  2  has a first surface as a light extraction surface  2   a , and is adapted to convert laser light, which is emitted by the laser element  25  and is an excitation light, into light having a different wavelength. In the converting member  2 , a surface opposite to the light extraction surface  2   a  (i.e., first surface) is a light-irradiated surface  2   b  on which laser light from the laser element  25  is incident. With the wiring  4  disposed on the light extraction surface  2   a  (i.e., first surface), which is located at a surface side of the conversion member  2 , connection to an external power supply or circuit for supplying the wiring  4  with electricity can be facilitated. 
     The conversion member  2  is preferably made of an inorganic material so that the conversion member  2  is not decomposed when irradiated with laser light. Examples of the inorganic material that forms the conversion member  2  include ceramic or glass containing a fluorescent material adapted to perform wavelength conversion of laser light, and fluorescent material single crystals. The conversion member  2  is preferably a material having a high melting point, with the melting point being preferably in a range of 1300° C. to 2500° C. With the conversion member  2  made of a material having high light resistance and heat resistance, the conversion member  2  is hardly degraded even by irradiation with light of high density such as laser light, and is hardly deformed, discolored and the like even under heat when held by the holding member  3 . Thus, it is preferable that the conversion member  2  is formed of a material having high light resistance and heat resistance. 
     When a fluorescent material is used for the conversion member  2 , examples of the conversion member  2  include yttrium aluminum garnet (YAG) activated with cerium, lutetium aluminum garnet (LAG) activated with cerium, nitrogen-containing aluminosilicate calcium (CaO—Al 2 O 3 —SiO 2 ) activated with europium and/or chromium, silicate ((Sr, Ba) 2 SiO 4 ) activated with europium, an α-sialon fluorescent material, a β-sialon fluorescent material or the like. For the fluorescent material, YAG that is a fluorescent material having favorable heat resistance is preferably used. 
     When a ceramic is used for the conversion member  2 , examples of the conversion member  2  include a material obtained by sintering a fluorescent material and a light-transmissive material such as aluminum oxide (Al 2 O 3 , melting point: approximately 1900° C. to 2100° C.). In the case of using a ceramic for the conversion member  2 , the content of the fluorescent material is preferably in a range of 0.05 to 50% by volume, more preferably in a range of 1 to 30% by volume based on the total volume of the ceramic. A ceramic formed by sintering a fluorescent material powder without using such a light-transmissive material, and substantially made of only a fluorescent material may be used as the conversion member  2 . 
     Holding Member 
     A holding member  3  holds the conversion member  2  and has a surface  3   a  (i.e., second surface) continuous with the light extraction surface  2   a  (i.e., first surface) of the conversion member in the same plane. The holding member  3  has a through-hole  3   b  extending through the holding member  3  in a thickness direction thereof, and is connected to the conversion member  2  with the conversion member  2  inserted in the through-hole  3   b , which allows for holding the conversion member  2 . The shape of the through-hole  3   b  is preferably matched with the shape of the conversion member  2 , and may be, for example, a columnar shape, a conical shape, a circular conical shape, a pyramidal shape or a combination thereof. 
     The through-hole  3   b  may have a polygonal shape such as a triangular shape or a quadrangular shape, a circular shape or an elliptical shape in a plan view. 
     The thickness of the holding member  3  is preferably 0.2 mm or more in view of strength. The holding member  3  may have a thickness allowing the conversion member  2  to be held, and preferably has a thickness of 2.0 mm or less for suppressing an increase in cost and an increase in height of the optical member  1 A. 
     The holding member  3  is preferably made of a material having a high reflectance with respect to laser light and fluorescence emitted by a fluorescent material and having a thermal conductivity high enough to exhaust heat of the conversion member  2  held in the through-hole  3   b . Examples of the material having a high reflectivity and a high thermal conductivity include light reflective ceramics, metals and composites of a ceramic and a metal. A light reflective ceramic which easily exhibits a high reflectance is preferable. It is preferable to use an alumina (Al 2 O 3 ) ceramic as the light reflecting ceramic. Using a material having a high reflectance with respect to the holding member  3  allows for extracting light in the conversion member  2  mainly from the light extraction surface  2   a , so that the luminance can be increased. In addition, laser light irradiated to a component other than the conversion member  2  can be prevented from leaking outside. 
     Wiring 
     A wiring  4  is an elongated body extending continuously along the light extraction surface  2   a  (first surface) of the conversion member  2  and the surface  3   a  (second surface) of the holding member  3 . The wiring  4  is not necessarily formed directly on a surface of the conversion member  2  and a surface of the holding member  3 , and may be formed via a film such as a light-transmissive film  7  (see  FIG.  14   ) disposed therebetween. The wiring  4  has a shape that can be drawn by a single stroke in a plan view. The wiring  4  is electrically connected to an electricity-supplying portion  6  for supplying electricity at both end portions of the wirings. 
     As shown in  FIGS.  1  to  3   , the wiring  4  is disposed over boundary between the conversion member  2  and the holding member  3  to extend continuously along the light extraction surface  2   a  (i.e., first surface) of the conversion member  2  and the surface  3   a  (i.e., second surface) of the holding member  3 , and. Accordingly, not only breakage or the like of the conversion member  2 , but also breakage of a member in the vicinity of a boundary portion where strength tends to be lower as compared to other portions, e.g., cracks and misalignment can be detected from damage of the wiring  4 . As used herein, “breakage of the wiring  4 ” is not limited to disconnection of the wiring  4 , but includes partial or overall reduction in width and/or thickness due to chipping etc. That is, in the wiring  4 , reduction in width or the like causes deviation in the resistance value, and thus the voltage value is deviated, which shows that the wiring  4  is in a state different from a normal state, so that breakage of a member can be detected. In this embodiment, breakage of the conversion member  2  and the holding member  3  in the vicinity of the boundary portion can be detected, and therefore a defect that may cause leakage of laser light can be more accurately detected. In this embodiment, breakage of the conversion member  2  and the holding member  3  in the vicinity of the boundary portion can be detected, and therefore a boundary between the conversion member  2  and the holding member  3  can be located at a position where laser light likely hits, so that the conversion member  2  can be downsized to increase brightness. 
     It is preferable that the wiring  4  covers at least a portion of the light extraction surface  2   a  (i.e., first surface) of the conversion member  2 , a portion of the wiring  4  has a shape having a plurality of bent portions  5   a  in a plan view, and at least one of a plurality of bent portions  5   a  is disposed over the surface  3   a  (i.e., second surface) of the holding member  3 . The number and the pitch of the bent portions  5   a  with a zigzag shape as shown in  FIG.  2    are appropriately selected in consideration of the size of the through-hole  3   b  of the holding member  3  and the width of the wiring  4 . With the wiring  4  having a zigzag shape, the wiring  4  extends over the boundary between the conversion member  2  and the holding member  3  at a plurality of positions, leading to improvement of accuracy of detecting breakage of the conversion member  2  and the holding member  3  in the vicinity of the boundary portion. In other words, the wiring  4  shown in  FIGS.  1  to  3    has a shape including extending portions  5   b  that extend in a single direction and including bent portions  5   a  connecting adjacent ones of the extending portions  5   b.    
     The wiring  4  is made of an electrically conductive material that is generally for as a wiring for the light emitting device  20 . It is preferable that the wiring  4  is made of a light-transmissive electrically conductive material for preventing a decrease in brightness of light extracted from the conversion member  2 . For the light-transmissive electrically conductive material, indium tin oxide (ITO), which has a high transmittance to visible light, is preferable. The electricity supplying portion  6  that is electrically connected to the wiring  4  at both ends of the wirings can also be made of an electrically conductive material and can have a film shape. When ITO is used for the wiring  4 , it is preferable to provide a metal layer such as Ti/Pt/Au layer on the ITO layer so that the metal layer forms the outermost surface of the electricity supplying portion  6  for improving adhesion of a wire or the like. 
     For reducing unevenness in brightness of light extracted from the conversion member  2 , the thickness of the wiring  4  is preferably in a range of 50 to 200 nm, at least above the conversion member  2 . The width of the wiring  4  is preferably in a range of 5 to 50 μm. With a thickness of the wiring  4  less than 50 nm, or a width of the wiring  4  less than 5 μm, breakage of the wiring  4  such as disconnection tends to occur even though the conversion member  2  and the holding member  3  are not broken, and thus erroneous detection of damage of a member easily occurs. With a thickness of the wiring  4  more than 200 nm, or a width of the wiring  4  more than 50 μm, it is difficult to reduce unevenness in brightness of light extracted from the conversion member  2 . 
     Heat Dissipating Member 
     A heat dissipating member  9  is a light-transmissive member disposed on the back surface  3   c  side of the holding member  3 , and transmits laser light from the laser element  25 . Sapphire, which is a material having light-transmissivity and a high thermal conductivity, is preferably used as a main member that forms the heat dissipating member  9 . With the heat dissipating member  9 , heat from the conversion member  2  can be efficiently dissipated. The thickness of the heat dissipating member  9  is, for example, in a range of 0.2 to 1 mm, preferably 0.4 to 0.6 mm. 
     First Metal Layer and Second Metal Layer 
     For bonding the heat dissipating member  9  and the holding member  3  to each other, a first metal layer  10  and a second metal layer  11  can be used. Each of the first metal layer  10  and the second metal layer  11  is preferably made of a metal material containing at least one selected from gold, tin, silver, nickel, rhodium, aluminum, tungsten, platinum, titanium, ruthenium, molybdenum and niobium. Each of the first metal layer  10  and the second metal layer  11  is, for example, a layered film including a titanium film, a platinum film and a gold film, or a layered film including a titanium film, a platinum film, a gold film, and a mixed film made of a gold/tin alloy. The first metal layer  10  is formed at the holding member  3  side, and the second metal layer  11  is formed at the heat dissipating member  9  side. For example, by forming a gold/tin alloy on one of the first metal layer  10  and the second metal layer  11 , bringing the first metal layer  10  and the second metal layer  11  into contact with each other, and then applying heat to a temperature equal to or higher than the melting point of the gold/tin alloy, the heat dissipating member  9  and the holding member  3  can be bonded to each other. A thickness of each of the first metal layer  10  and the second metal layer  11  may be in a range of, for example, 0.1 to 5 μm. In a more specific example, the first metal layer  10  includes Ti (6 nm), Pt (200 nm) and Au (300 nm) sequentially from the holding member  3  side, and the second metal layer  11  includes Ti (6 nm), Pt (200 nm), Au (50 nm) and AuSn (3 μm) sequentially from the heat dissipating member  9  side. In addition, it is preferable that bonding members such as the first metal layer  10  and the second metal layer  11  are not formed at a position facing the conversion member  2 . This allows for preventing laser light from being blocked by a bonding member such as the first metal layer  10 . In this embodiment, the first metal layer  10  surrounds the light-irradiated surface  2   b  of the conversion member  2  that faces the heat dissipating member  9 . Thus, the first metal layer  10  and the heat dissipating member  9  can effectively prevent deposition of dust on the light-irradiated surface  2   b  of the conversion member  2 . Examples of the method for bonding the heat dissipating member  9  and the holding member  3  to each other include, as well as bonding via the first metal layer  10 , normal-temperature bonding such as surface activation bonding or atomic diffusion bonding, and bonding using a resin. An organic material such as a resin may be decomposed by laser light, and thus it is preferable to use an inorganic material such as a metal. 
     Light Emitting Device 
     Laser Element 
     As shown in  FIG.  3   , a laser element  25  is disposed so that the conversion member  2  is irradiated with laser light. The shorter the wavelength of laser light emitted by the laser element  25 , the higher the energy of the laser element  25 , and detection of leakage of laser light is increasingly required. 
     Therefore, it is preferable that an element which emits laser light having a short wavelength is used for the laser element  25 . Examples of the laser element include a nitride semiconductor laser element. The laser element  25  may also include a structure for irradiating the conversion member  2  with laser light, e.g., a reflection member  26 , which is disposed in an optical path of the laser element  25 . 
     For the reflection member  26 , a member in which a reflection film is disposed on an inclined surface of a main body portion having a shape of triangular prism, quadrangular pyramid or the like and being made of glass or the like can be used. The angle of the inclined surface with respect to the bottom surface of the main body portion is preferably approximately 45° for guiding laser light in an orthogonal direction. 
     Package 
     A package  21  surrounds the laser element  25 . The package  21  is a housing having a housing portion such as a recess  27 , where the laser element  25  and the reflection member  26  are disposed and housed. The package  21  mainly includes a housing main body portion  22  made of a ceramic such as aluminum oxide, aluminum nitride, silicon nitride or silicon carbide, or a metal such as Cu, and a cover  24  bonded to the housing main body portion  22  by welding or the like. The housing main body portion  22  can define the recess  27  having an opening in the upper surface of the housing main portion. A frame-shaped welding portion  23 , which is to be welded to the cover  24  and contains iron as a main component, may be disposed at the periphery of the opening of the recess. The housing main body portion  22  has an upper surface including a region that are adjacent to the opening of the recess  27  and surround the opening of the recess  37 . At least one of the regions of the upper surface adjacent to and surround the opening of the recess  27  has a width larger than a width of the other(s) thereof, and an electrode portion  28  is disposed on the at least one region of the upper surface with the larger width. In the electrode portion  28 , an anode and a cathode may be arranged at both sides of the optical member  1 A in a plan view. When the housing main body portion  22  is made of a metal, for example, a lead terminal is used for the electrode portion  28 . 
     The cover  24  is bonded to the housing main body portion  22  by welding or the like to hermetically seal the laser element  25 . This allows for preventing deposition of dust such as an organic substance on the laser element  25 . The cover  24  may include a support portion  24   a  welded to the housing main body portion  22 ; a light transmission portion  24   b  which transmits laser light; and a bonding material  24   c  for bonding the support portion  24   a  and the light transmission portion  24   b . For the support portion  24   a , a material containing iron as a main component can be used. For the light transmission portion  24   b , glass, sapphire or the like can be used. For the bonding material  24   c , low-melting-point glass, gold/tin solder, or the like can be used. Laser light emitted from the laser element  25  is reflected at the reflection member  26 , transmitted through the light transmission portion  24   b  and the heat dissipating member  9 , and irradiated to the light-irradiated surface  2   b  of the conversion member  2 . 
     The package  21  includes the electrode portions  28  exposed at the upper surface of the housing main body portion  22 . In the package  21 , the electrodes portion  28  electrically connected to the outside is provided on a surface other than the lower surface of the housing main body portion  22 , and thus an entirety of the lower surface of the package  21  can serve as a surface to be mounted on another member such as a heat sink. Therefore, the package  21  can easily release heat generated in the light emitting device  20  to the heat sink. 
     Detection Circuit 
     The detection circuit  30  is a circuit that detects a deviation in resistance value due to breakage of the wiring  4 . In the light emitting device  20 , the detection circuit  30  is a circuit connected to the wiring  4  and an electricity supplying circuit of the laser element  25 . With the detection circuit  30 , breakage of the conversion member  2  and the holding member  3  can be detected by detecting a deviation in resistance value due to breakage of the wiring  4 . When a deviation in resistance value of the wiring  4  is detected, occurrence of breakage in the conversion member  2  and the holding member  3  is determined, and driving of the laser element  25  is stopped, so that leakage of laser light can be prevented. 
     The detection circuit  30  is configured to detect breakage of the wiring  4 . The detection circuit  30  preferably has a circuit configuration as shown in  FIG.  4   . 
     In the detection circuit  30 , a deviation in resistance value due to breakage of the wiring  4  is detected by detecting deviation in voltage value as shown in  FIG.  4   . The detection circuit  30  includes a first connecting conductor  31  and a second connecting conductor  32 . A power source for supplying electricity, the wiring  4 , the laser element  25  and a switch element  33  are connected to the first connecting conductor  31 . A voltage detecting resistor  34  is connected to the second connecting conductor  32 . Electricity is supplied to the wiring  4  and the voltage detecting resistor  34  by the power source for supplying electricity. The switch element  33  controls the stopping of driving of the laser element  25  based on, for example, comparison of the voltage across the voltage detecting resistor  34  with a reference voltage. 
     In the detection circuit  30 , when electricity is supplied without causing breakage in the wiring  4 , the resistance value of the wiring  4  is normally low, and the voltage across the wiring  4  is low, so that the voltage of the voltage detecting resistor  34  is relatively high, and thus is equal to or higher than the reference voltage. Meanwhile, driving of the laser element  25  is continued in response to an input from the switch element  33 . If resistance of the wiring  4  is increased due to breakage of the wiring  4 , the voltage of the wiring  4  increases, so that the voltage of the voltage detecting resistor  34  is relatively low. At this time, driving of the laser element  25  is stopped in response to an input from the switch element  33 . 
     For the switch element  33 , an operational amplifier, a comparator, a bipolar transistor, a metal-oxide-semiconductor field-effect transistor (MOSFET) or the like can be used. In particular, a transistor element such as a MOSFET, which can be turned ON and OFF in accordance with the voltage of the voltage detecting resistor  34 , is preferable. For the switch element  33 , for example, a transistor element such as a MOSFET, which is turned ON when the voltage of the voltage detecting resistor  34  is equal to or higher than the reference voltage, can be used. Accordingly, when the voltage of the voltage detecting resistor  34  decreases to a voltage lower than the reference voltage, the switch element  33  is turned OFF, so that supply of a current to the laser element  25  can be automatically stopped. 
     In the light emitting element  20 , the optical member  1 A is fixed to the package  21  so that laser light passing through the light transmission portion  24   b  and the heat dissipating member  9  from the recess  27  reaches the conversion member  2 . It is preferable that a plurality of bent portions  5   a  of the wiring  4  is arranged so as to extend over boundary portions between the conversion member  2  and the holding member  3 . This arrangement allows for accurately detecting damage of boundary portions between the conversion member  2  and the holding member  3  using the wiring  4 . For fixing the optical member  1 A to the package  21 , the heat dissipating member  9 , first metal layer  10  and the like can be used. 
     Method of Manufacturing Optical Member 
     A method of manufacturing the optical member  1 A will be described. 
     As shown in  FIGS.  5 A to  5 C , the method of manufacturing an optical member includes the steps of: providing a sintered body; removing a part of a conversion member and a holding member; and forming a wiring. Hereinafter, steps in the method of manufacturing the optical member will be described. 
     (1) Providing Sintered Body 
     As shown in  FIG.  5 A , in the step of providing a sintered body, the conversion member  2  and the holding member  3  are brought into contact with each other to integrally form a sintered body  100 . In one embodiment, a method of providing the sintered body  100  includes the steps of: providing the conversion member  2 ; forming a molded article that forms the holding member  3 ; and sintering the conversion member  2  and the molded article. 
     Generally, the sintered body refers to an article obtained by heating a powdered material at a temperature lower than the melting point thereof so as to harden the powdered material. However, even when the conversion member  2  composed of a molded article and the powdery holding member  3  that has not yet been sintered are heated, a sintering that is similar to a general sintering is considered to occur on the surface of the conversion member  2  and on the surface of the powdery holding member  3 . Therefore, in this specification, an article made integrally from the conversion member  2  composed of a molded article and the powdery holding member  3  is also referred to as a “sintered body.” Similarly, a product made integrally from the powdery conversion member  2  and the holding member  3  composed of a molded article is also referred to as a “sintered body.” 
     As a sintering method, for example, a discharge plasma sintering method (SPS method: spark plasma sintering method) or a hot-pressing sintering method (HP method: hot pressing method) can be employed. When aluminum oxide (alumina) is used for the powdered holding member  3 , the sintering temperature is preferably set to preferably 1200° C. or higher and 1800° C. or lower, more preferably 1400° C. or higher and 1500° C. or lower. With the sintering temperature of 1200° C. or higher, strength of the holding member  3  can be ensured. With the sintering temperature of 1800° C. or lower, the possibility of an increase in the light-transmissivity of the holding member  3  can be reduced. 
     (2) Removing a Part of Conversion Member and Holding Member 
     In the step of providing the sintered body, the upper surface of the conversion member  2  is covered with the holding member  3 . Thus, as shown in  FIG.  5 B , a portion of the conversion member  2  and the holding member  3  is removed from upper surface side of the sintered body  100  until the conversion member  2  is exposed. Accordingly, as shown in  FIG.  5 C , the conversion member  2  having a first surface as the light extraction surface  2   a , and the holding member  3  having the surface  3   a  (second surface) continuous with the first surface of the conversion member  2  are obtained when the sintered body  100  is divided. 
     Examples of a method of removing a portion of the sintered body  100  include grinding, polishing, chemical-mechanical planarization (CMP) and the like. In this method of manufacturing, the sintered body  100  is removed only from one side. However, alternatively, for removing deposits on the lower surface of the conversion member  2  and the lower surface of the holding member  3 , a portion of the sintered body  100  may be removed from the lower surface side, followed by removing the holding member  3  of the sintered body  100  from the upper surface side. 
     At the time of dividing the sintered body  100 , the sintered body  100  is divided so that a single sintered body  100  includes a single conversion member  2 . For example, by using one or more of a scribing technique, a dicing technique, and a breaking technique, the sintered body  100  can be divided into a plurality of sintered bodies  100 . In this method of manufacturing, the sintered body  100  is divided so that a single sintered body  100  includes a single conversion member  2 , but the sintered body  100  may alternatively be divided in such a manner that one sintered body  100  includes a plurality of conversion members  2 . 
     (3) Forming Wiring 
     In the step of forming a wiring, the wiring  4  is formed to extend continuously along the light extraction surface  2   a  (i.e., first surface) of the conversion member  2  and the surface  3   a  (i.e., second surface) of the holding member  3 . Examples of a method of forming the wiring  4  include a sputtering method, a chemical vapor deposition method and an atomic layer deposition method. By using the sintered body  100  in which the conversion member  2  and the holding member  3  are brought into contact with each other to be integrally molded, the wiring  4  extending continuously along the conversion member  2  and the holding member  3  can be formed. With the wiring  4  extending continuously along the light extraction surface  2   a  (i.e., first surface) of the conversion member  2  and the surface  3   a  (i.e., second surface) of the holding member  3 , breakage in the vicinity of the boundary between the light extraction surface  2   a  (i.e., first surface) of the conversion member  2  and the surface  3   a  (i.e., second surface) of the holding member  3  can be detected by detecting breakage of the wiring  4 . Thus, a defect that may cause leakage of laser light can be more accurately detected. 
     The method of manufacturing the optical member  1 A includes bonding the heat dissipating member  9  and the holding member  3  to each other using the first metal layer  10  formed by a sputtering method or the like, after forming a wiring. 
     Second Embodiment 
     Next, an optical member, a light emitting device, and a method of manufacturing an optical member according to a second embodiment will be described. 
     As shown in  FIGS.  6  to  9   , an optical member  1 B to be used for a light emitting device  20  includes a conversion member  2 , a holding member  3  and a wiring  4 . The optical member  1 B preferably includes a heat dissipating member  9 . 
     The light emitting device  20  preferably includes the optical member  1 B, a laser element  25 , and a package  21 . The light emitting device  20  more preferably includes a detection circuit  30  similarly to the light emitting device  20  according to the first embodiment. 
     The constituent elements of the optical member  1 B and the light emitting device  20  will be described. Configurations other than those shown below are the same as in the optical member  1 A and light emitting device  20  shown in  FIGS.  1  to  4   . 
     Optical Member 
     In the optical member  1 B, light-irradiated surface  2   b  the conversion member  2  at a back surface-side, which will be the heat dissipating member  9 , is a first surface. The wiring  4  is disposed to be extend continuously along the light-irradiated surface  2   b  (i.e., first surface) and a back surface  3   c  (i.e., second surface) of the holding member  3 , over boundaries therebetween. In other words, the wiring  4  is disposed between the conversion member  2  and the heat dissipating member  9  and between the holding member  3  and the heat dissipating member  9 . With this arrangement of the wiring  4 , breakage of the wiring  4  in the vicinity of the boundary between the conversion member  2  and the holding member  3  can be detected, and therefore a defect that may cause leakage of laser light can be more accurately detected. In addition, a surface of the conversion member  2  opposite to the light-irradiated surface  2   b  is the light extraction surface  2   a  from which light subjected to wavelength conversion is emitted. With the wiring  4  disposed on the light-irradiated surface  2   b  rather than the light extraction surface  2   a  as described above, light subjected to wavelength conversion and extracted from the conversion member  2  is not affected by the wiring  4 , and therefore unevenness in brightness can be reduced. 
     In the optical member  1 B, for bonding the holding member  3  and the heat dissipating member  9  to each other, a second metal layer  11  is used in addition to a first metal layer  10 . 
     First Metal Layer 
     The first metal layer  10  includes a center-side first metal layer  10   a  and an end portion-side first metal layers  10   b , and serves to bond the holding member  3  and the heat dissipating member  9  to each other. A material and a thickness of each of the center-side first metal layer  10   a  and the end portion-side first metal layers  10   b  are the same as a material and a thickness of the first metal layer  10  of the optical member  1 A. 
     The center-side first metal layer  10   a  has a substantially rectangular ring shape at the center of the back surface  3   c  (i.e., second surface) of the holding member  3  to surround the wiring  4  disposed on the light-irradiated surface  2   b  (i.e., first surface) of the conversion member  2  in a plan view. When the center-side first metal layer  10   a  is electrically connected to the wiring  4 , it is difficult to detect breakage of the wiring  4 . Thus, the center-side first metal layer  10   a  is insulated from the wiring  4  by an insulating film  14  disposed between the center-side first metal layer  10   a  and the wiring  4 . The smaller the area of a portion where the center-side first metal layer  10   a  and the wiring  4  overlap each other in a plan view, the smaller the possibility of leakage between the center-side first metal layer  10   a  and the wiring  4  can be. Thus, it is preferable that the center-side first metal layer  10   a  and the wiring  4  overlap each other at two portions in a plan view as shown in  FIG.  7   . For obtaining such an arrangement, the center-side first metal layer  10   a  may be disposed outside a bent portion  5   a  of the wiring  4 . 
     The end portion-side first metal layers  10   b  are disposed spaced apart from the center of the back surface  3   c , on which the center-side first metal layer  10   a  is disposed, at a left side and a right side thereof to cover two electricity supplying portions  6  for supplying the wiring  4  with electricity, and each of the end portion-side first metal layers  10   b  has a substantially rectangular shape in a plan view. Each of the two end portion-side first metal layers  10   b  is electrically connected to the wiring  4 , and serve as an anode and a cathode for the wiring  4 . 
     Second Metal Layer 
     The second metal layer  11  includes a center-side second metal layer  11   a  and an end portion-side second metal layer  11   b . A material and a thickness of each of the center-side second metal layer  11   a  and the end portion-side second metal layers  11   b  are the same as a material and a thickness of the second metal layer  11  of the optical member  1 A. 
     The center-side second metal layer  11   a  is disposed on the center side of a surface of the heat dissipating member  9  facing the holding member  3 , to cover the center-side first metal layer  10   a  disposed on the back surface  3   c  (second surface). Similarly to the center-side first metal layer  10   a , the center-side second metal layer  11   a  has a rectangular ring shape surrounding the wiring  4 . 
     The end portion-side second metal layers  11   b  are disposed at a left side and a right side of a surface of the heat dissipating member  9  facing the holding member  3  to be spaced apart from the center-side second metal layer  11   a , and each of the end portion-side second metal layers  11   b  has a substantially rectangular shape. At the left and right sides, each of the end portion-side second metal layers  11   b  has a rectangular shape having a size that allows each of the end portion-side second metal layers  11   b  partially protrude outward of the holding member  3  in a plan view at the time of bonding the holding member  3  and the heat dissipating member  9  to each other. Each of the two end portion-side second metal layers  11   b  is electrically connected to the electricity supplying portion  6  (i.e., a respective one of the end portion-side first metal layers  10   b ) to serve to supply electricity to the electricity supplying portion  6  of the wiring  4  from the outside, in addition to bonding the holding member  3  and the heat dissipating member  9  to each other. Thus, the end portion-side second metal layers  11   b  are disposed so as to be partially exposed from the holding member  3  in a plan view after bonding. This allows for connecting a wire or the like to the portion of each of the end portion-side second metal layers  11   b  exposed from the holding member  3 . With the end portion-side second metal layers  11   b  to be connected to the outside disposed outward of the center-side second metal layer  11   a  as described above, the end portion-side second metal layers  11   b  is easily drawn outward. 
     The center-side first metal layer  10   a  and the center-side second metal layer  11   a  are formed to surround the light-irradiated surface  2   b  (first surface) of the conversion member  2  together with the heat dissipating member  9 . Thus, deposition of dust on the light-irradiated surface  2   b  (first surface) of the conversion member  2  can be effectively prevented. For obtaining this effect, the shape of each of the center-side first metal layer  10   a  and the center-side second metal layer  11   a  in a plan view is preferably a ring shape. Further, for increasing the bonding area as much as possible, it is preferable that each of the center-side first metal layer  10   a  and the center-side second metal layer  11   a  has a shape corresponding to the outer edge of the holding member  3  and the shape of the wiring  4 . For example, when the holding member has a circular shape, each of the center-side first metal layer  10   a  and the center-side second metal layer  111   a  may have a circular ring shape. 
     Since the optical member  1   b  includes the second metal layer  11 , an external electrode or a circuit can be easily connected to the wiring  4  even when the wiring  4  is disposed between the conversion member  2  and holding member  3  and the heat dissipating member  9 . 
     Insulating Film 
     The insulating film  14  is a film which insulates the center-side first metal layer  10   a  and the wiring  4  from each other. The insulating film  14  is disposed on at least a portion where the center-side first metal layer  10   a  and the wiring  4  overlap each other in a plan view. When the insulating film  14  is also disposed on a path of laser light, the insulating film  14  is preferably light-transmissive. The insulating film  14  can cover the light-irradiated surface  2   b  (first surface) of the conversion member  2  except a region provided with two electricity supplying portions  6  for supplying the wiring  4  with electricity, and an entirety of the wiring  4  and an entirety of the back surface  3   c  (second surface) of the holding member  3 . The insulating film  14  may also serve as a protective film  8  in a variant example of the first embodiment as described below. A material and a thickness of the insulating film  14  may be the same as a material and a thickness of the protective film  8 . 
     Light Emitting Device 
     The light emitting device  20  is the same as in the first embodiment except that in the light emitting device  20  using the optical member  1 A in the first embodiment (see  FIG.  3   ), the optical member  1 B is used in place of the optical member  1 A as shown in  FIG.  9   . In the light emitting device  20  having such a configuration, using the optical member  1 B allows for reducing unevenness in brightness of extracted light. 
     Method of Manufacturing Optical Member 
     The optical member  1 B can be manufactured by the same manufacturing method as in the first embodiment. In the optical member  1 B, the light-irradiated surface  2   b  of the conversion member  2  is a first surface that is provided with the wiring  4 . The method of manufacturing the optical member  1 B includes, after forming a wiring, bonding the heat dissipating member  9  and the holding member  3  to each other using the center-side first metal layer  10   a  and end portion-side first metal layers  10   b  and the center-side second metal layer  11   a  and end portion-side second metal layers  11   b , which are formed by a sputtering method or the like. 
     Third Embodiment 
     Next, an optical member, a light emitting device, and a method of manufacturing an optical member according to a third embodiment will be described. 
     A part of an optical member  1 C according to the third embodiment is different from a corresponding part of the optical member  1 B according to the second embodiment, as shown in  FIGS.  10  to  13   . More specifically, in the optical member  1 C, instead of the center-side second metal layer  11   a  of the second metal layer  11  in the second embodiment, a leakage checking electrode  15 , which has a shape different from a shape of the center-side second metal layer  11   a  in the second embodiment so as to partially expose the center-side second metal layer from a holding member  3  in a plan view, is disposed. 
     The optical member  1 C includes a conversion member  2 , the holding member  3 , a wiring  4 , a first metal layer  10 , an insulating film  14 , the leakage checking electrode  15 , wiring electrodes  16  and a heat dissipating member  9 . 
     It is preferable that a light emitting device  20  further includes the optical member  1 C, a laser element  25 , and a package  21 . It is more preferable that the light emitting device  20  further includes a detection circuit  30 . 
     The constituent elements of the optical member  1 C will be described. Configurations other than those shown below are the same as in the optical member  1 B shown in  FIGS.  6  to  9   . 
     Optical Member 
     Leakage Checking Electrode 
     The leakage checking electrode  15  includes a central portion  15   a , and a terminal portion  15   b  connected to the central portion  15   a  through a linear connection portion  15   c . The leakage checking electrode  15  is used for checking whether insulation between a center-side first metal layer  10   a  and the wiring  4  are secured after the holding member  3  and the heat dissipating member  9  are bonded to each other. The leakage checking electrode  15  is electrically connected to the center-side first metal layer  10   a . Accordingly, whether or not leakage occurs between the center-side first metal layer  10   a  and the wiring  4  can be determined by, with the terminal portion  15   b  of the leakage checking electrode  15  being an anode, applying a voltage between the anode and the cathode side of the wiring electrodes  16 , and checking whether or not a current passes therethrough. The anode and the cathode described above may be reversed. 
     The central portion  15   a  has a rectangular ring shape on the heat dissipating member  9  side such that the central portion  15   a  covers the center-side first metal layer  10   a  surrounding the conversion member  2  (first surface) in a plan view. The central portion  15   a  can have a size identical to that of the center-side first metal layer  10   a . In addition, for establishing electrical connection to the outside, the terminal portion  15   b  has a size and disposed at a position that allow the terminal portion  15   b  to partially protrude outward of the holding member  3  in a plan view at the time of bonding the holding member  3  and the heat dissipating member  9  to each other. The terminal portion  15   b  is electrically connected to the central portion  15   a  through the connection portion  15   c . The terminal portion  15   b  is disposed at the heat dissipating member  9  side and has a substantially oblong shape along one side of the heat dissipating member  9 . 
     The central portion  15   a , the connection portion  15   c  and the terminal portion  15   b  correspond to the center-side second metal layer  11   a  in the optical member  1 B, and a material and a thickness thereof may be the same as a material and a thickness of the center-side second metal layer  11   a  in the optical member  1 B. The central portion  15   a , the connection portion  15   c  and the terminal portion  15   b  are also used for bonding the holding member  3  and the heat dissipating member  9  to each other. 
     Wiring Electrodes 
     The wiring electrodes  16  correspond to the end portion-side second metal layers  11   b  in the optical member  1 B, and is different only in shape from the end portion-side second metal layers  11   b , and a material and a thickness of the wiring electrode  16  may be the same as a material and a thickness of the end portion-side second metal layers  11   b . Each of the wiring electrodes  16  includes a central portion  16   a , and a terminal portion  16   b  connected to the central portion  16   a  through a linear connection portion  16   c . The central portion  16   a  has a rectangular shape at the heat dissipating member  9  side with a size identical to that of the end portion-side first metal layer  10   b  for supplying the wiring  4  with electricity by electrically connecting the central portion  16   a  to each of two electricity supplying portions  6  through the end portion-side first metal layer  10   b . The terminal portion  16   b  has a substantially rectangular shape and is disposed at a corner portion of the heat dissipating member  9  with a size and a position that allows the terminal portion  16   b  to partially protrude outward of the holding member  3  at the time of bonding the holding member  3  and the heat dissipating member  9  to each other. The central portion  16   a  and the terminal portion  16   b  are formed to be electrically connected to each other through the connection portion  16   c . The central portion  16   a , the connection portion  16   c  and the terminal portion  16   b  are also used for bonding the holding member  3  and the heat dissipating member  9  to each other. 
     Light Emitting Device 
     The light emitting device  20  is the same as in the second embodiment except that, in the light emitting device  20  using the optical member  1 B of the second embodiment (see  FIG.  9   ), the optical member  1 C is used in place of the optical member  1 B. The insulating film  14  is a film similar to the protective film  8  (see  FIG.  14   ). The leakage checking electrode  15  (i.e., central portion  15   a  and terminal portion  15   b ) is a bonding layer similar to the center-side second metal layer  11   a  and the end portion-side second metal layer  11   b  (see  FIGS.  8  and  9   ). 
     Method of Manufacturing Optical Member 
     The optical member  1 C can be manufactured by the same manufacturing method as in the second embodiment. The method of manufacturing the optical member  1 C may include, after forming a wiring, bonding the heat dissipating member  9  and the holding member  3  to each other using the center-side first metal layer  10   a , end portion-side first metal layer  10   b , the leakage checking electrode  15  (i.e., central portion  15   a , connection portion  15   c  and terminal portion  15   b ), and the wiring electrode  16  (central portion  16   a , connection portion  16   c  and terminal portion  16   b ), which are formed by a sputtering method or the like. 
     Variant Examples of First to Third Embodiments 
     Next, variant example of the configurations of the first to third embodiments will be described with reference to  FIGS.  14  to  17 C . 
     Optical Member 
     Variant Examples of the Optical Member Will be Described. 
     As shown in  FIG.  14   , an optical member  1 D, which is a variant example of the optical member  1 A according to the first embodiment, includes a conversion member  2 , a holding member  3 , a wiring  4 , a light-transmissive film  7 , a protective film  8 , a heat dissipating member  9 , a dielectric multilayer film  17  and an antireflection film  18 . The optical member  1 D may include one or more of the light-transmissive film  7 , the protective film  8 , the dielectric multilayer film  17 , and the antireflection film  18 . The conversion member  2 , the holding member  3 , the wiring  4  and the heat dissipating member  9  of the optical member  1 D are the same as in the optical member  1 A, and therefore descriptions thereof are omitted. The light-transmissive film  7 , the protective film  8 , the dielectric multilayer film  17  and the antireflection film  18  of the optical member  1 D will be described below. 
     Light-Transmissive Film 
     The light-transmissive film  7  is a film covering a light extraction surface  2   a  (i.e., first surface) of the conversion member  2  and a surface  3   a  (i.e., second surface) of the holding member  3 . With the light-transmissive film  7 , the conversion member  2  and the holding member  3  can be covered by the light-transmissive film  7  having a surface with an improved flatness. With the light-transmissive film  7 , the wiring  4  is not formed directly on a surface of the conversion member  2  and a surface of the holding member  3 , but formed on a surface of the light-transmissive film  7 . Therefore, the wiring  4  is formed on the surface of the light-transmissive film  7  having improved surface flatness as compared to the conversion member  2  and the holding member  3 , so that the possibility that disconnection of the wiring  4  occur during formation can be reduced. 
     When the conversion member  2  is formed of two or more materials, and a surface of the conversion member  2  is subjected to a flattening treatment such as CMP, steps are easily generated on the surface due to variation in the removal rate between the materials. Thus, it is preferable to form the light-transmissive film  7  on the surface of the conversion member  2 . Similarly, when the holding member  3  is made of a light reflecting ceramic, it is preferable to form the light-transmissive film  7  on a surface of the holding member  3  because a ceramic having a higher reflectivity tends to have a higher porosity, leading to deterioration of the flatness of the surface of the holding member  3 . 
     The light-transmissive film  7  is made of a light-transmissive material. Examples of the light-transmissive material transmissive to visible light include materials containing silicon oxide such as SiO 2 . The light-transmissive film  7  is, for example, a SiO 2  film. It is preferable that the light-transmissive film  7  has such a thickness that allows the flatness of the conversion member  2  and the holding member  3  to be improved. 
     More specifically, the thickness of the light-transmissive film  7  is preferably in a range of 1 μm to 15 μm. The light-transmissive film  7  may cover a light-irradiated surface  2   b  of the conversion member  2  and a back surface  3   c  of the holding member  3 . 
     Protective Film 
     The protective film  8  is a light-transmissive film covering at least the light extraction surface  2   a  (first surface) of the conversion member  2  and the wiring  4 . The protective film  8  preferably covers an entirety of the light extraction surface  2   a  (i.e., first surface). With the protective film  8 , the wiring  4  can be protected so that the wiring  4  is not broken by an impact which is too small to break the conversion member  2 . Further, light can be spread in the protective film  8 , and thus it is thought that unevenness in brightness of light extracted through the protective film  8  from the conversion member  2  can be improved. 
     A thickness of the protective film  8  is equal to or greater than the wavelength of excitation light (e.g., 450 nm) and equal to or less than 20 μm. 
     Like the light-transmissive film  7 , the protective film  8  is made of a light-transmissive material. Examples of the light-transmissive material transmissive to visible light include materials containing silicon oxide such as SiO 2 . The protective film  8  is, for example, SiO 2 . 
     When the wiring  4  is light-transmissive, it is preferable that the refractive index of the protective film  8  is close to the refractive index of the wiring  4 , and the protective film  8  is disposed in at least a region which is not provided with the wiring  4 . This allows for reducing difference in refractive index between a region provided with the wiring  4  and a region which is not provided with the wiring  4 , so that unevenness in brightness can be reduced. Because silicon oxide such as SiO 2  has a refractive index lower than that of a conductive oxide film of ITO or the like, it is preferable that the protective film  8  contains silicon oxide and a material having a refractive index higher than that of silicon oxide. Thus, with the protective film  8  containing a material having a high refractive index, unevenness in brightness can be reduced as described above. More specifically, it is preferable that a material in which a predetermined amount of tantalum oxide is mixed with silicon oxide is used for the protective film  8 . The protective film  8  may be, for example, a film in which SiO 2  and Ta 2 O 5  are mixed. When the wiring  4  is made of ITO, a mixed film of SiO 2  and Ta 2 O 5  with a SiO 2  content of about 25 to 35% by weight is suitable for the protective film  8 . 
     Dielectric Multilayer Film 
     The dielectric multilayer film  17  is a multilayer film disposed on an upper surface of the heat dissipating member  9 , which is located at a conversion member  2 -and-holding member  3  side. The dielectric multilayer film  17  is a film in which two or more dielectric films having different refractive indices and each including a dielectric material such as, for example, aluminum nitride, silicon oxide, aluminum oxide, zirconium oxide, titanium oxide, niobium oxide and tantalum oxide and having different refractive indices are layered to be multi-layers. The dielectric multilayer film  17  is a film that transmits laser light from the laser element  25 , and reflects wavelength-converted light emitted from the light-irradiated surface  2   b  of the conversion member  2 . In other words, the dielectric multilayer film  17  is a film having a reflectance with respect to light subjected to wavelength conversion in the conversion member  2  higher than a reflectance to excitation light (i.e., laser light from the laser element  25 ). Accordingly, light passing from the conversion member  2  toward the laser element  25  can be reflected, and returned to the conversion member  2 , and therefore the light extraction efficiency from the light extraction surface  2   a  of the conversion member  2  can be improved. A thickness of the dielectric multilayer film  17  may be in a range of, for example, 1 to 10 μm. 
     Antireflection Film 
     The antireflection film  18  is a film is disposed on a lower surface, which is a surface on which laser light is incident, of the heat dissipating member  9 . The antireflection film  18  is made of a dielectric material containing as a main component at least one selected from, for example, aluminum nitride, silicon oxide, aluminum oxide, zirconium oxide, titanium oxide, niobium oxide and tantalum oxide. The antireflection film  18  is a film in which a thickness, a composition ratio and the like are adjusted to obtain a greatly small reflectance, such as 1% or less, to laser light emitted from the laser element  25 . With the antireflection film  18 , the amount of laser light enters the conversion member  2  can be increased. A thickness of the antireflection film  18  may be in a range of, for example, 0.2 μm to 1 μm. 
     Variant Examples of Optical Members According to Second and Third Embodiments 
     As shown in  FIG.  15   , an optical member  1 E, which is a variant example of the optical member  1 B according to the second embodiment, includes a conversion member  2 , a holding member  3 , a wiring  4 , a light-transmissive film  7 , a heat dissipating member  9 , a dielectric multilayer film  17  and an antireflection film  18 . As shown in  FIG.  16   , an optical member  1 F, which is a variant example of the optical member  1 C according to the third embodiment, includes a conversion member  2 , a holding member  3 , a wiring  4 , a light-transmissive film  7 , a heat dissipating member  9 , a dielectric multilayer film  17  and an antireflection film  18 . 
     Thus, in an optical member in which the wiring  4  is disposed at the light-irradiated surface  2   b  side, one or more of the light-transmissive film  7 , the protective film  8 , the dielectric multilayer film  17  and the antireflection film  18  can be provided. The conversion member  2 , the holding member  3 , the wiring  4  and the heat dissipating member  9  in each of the optical members  1 E and  1 F are the same as in the optical member  1 B. The light-transmissive film  7 , the dielectric multilayer film  17  and the antireflection film  18  in each of the optical members  1 E and  1 F are the same as in the optical member  1 D. In each of the optical members  1 E and  1 F, the light-transmissive film  7  covers a light-irradiated surface  2   b  (i.e., first surface) of the conversion member  2  and a back surface  3   c  (i.e., second surface) of the holding member  3 . With the light-transmissive film  7  covering surfaces at a wiring  4  side (i.e., light-irradiated surface  2   b  and back surface  3   c ), the possibility that disconnection of the wiring  4  occur during formation can be reduced as described above. The light-transmissive film  7  may be disposed to cover a light extraction surface  2   a  of the conversion member  2  and a surface  3   a  of the holding member  3 . 
     Shape of Wiring 
     As shown in  FIG.  17 A , the wiring  4  shown in each of the embodiments and modifications may have a spiral shape in a plan view. A portion of the spiral-shaped portion of the wiring  4  covers the conversion member  2 , and another portion thereof is formed on the holding member  3 . The number of turns and the pitch in the spiral shape are appropriately selected in consideration of the size of a through-hole  3   b  of the holding member  3 , and the width of the wiring  4 . With the wiring  4  having a zigzag shape as shown in  FIG.  2   , for example, cracks extending laterally in  FIG.  2    in the conversion member  2 , may cause breakage of the conversion member  2  without breaking the wiring  4 . However, with the wiring  4  having a spiral shape as shown in  FIG.  17 A , either cracks extending laterally or cracks extending vertically in the figure causes breakage in the wiring  4 , so that a defect can be detected. The pitch of the spiral shape is preferably 60 μm or less, which allows for more accurately detecting a defect. The pitch of the spiral shape refers to, in other words, a width of a passage portion, which is a portion that is not provided with the wiring  4 . The pitch of the spiral shape is preferably 5 μm or more so that the passage portion is not collapsed during formation of the wiring  4 . 
     As shown in  FIG.  17 B , the wiring  4  shown in each of the first to third embodiments and their variant examples may have a shape in which an outermost extending portion  5   b  extends further in a direction different from that of an inner extending portion  5   b  in a plan view. In the wiring  4  shown in  FIGS.  1  to  3   , the outermost extending portion  5   b  among extending portions  5   b  extending in a single direction overlaps the boundary between the conversion member  2  and the holding member  3  in a plan view. When the optical member is manufactured with such a shape, the acceptable degree of displacement of the extending portion  5   b  in the widthwise direction is equal to or less than a width of the outermost extending portion, and when displacement at larger than a width of the outermost extending portion, the outermost extending portion  5   b  does not overlap the boundary between the conversion member  2  and the holding member  3 . On the other hand, with the wiring  4  having a shape in which the inner extending portions  5   b  extends in a first direction, and the outermost extending portions  5   b , which are located at both sides of the inner extending portions  5   b , extends further in a second direction as shown in  FIG.  17 B , the acceptable degree of displacement may be greater than the width of the wiring  4 . Each of the bent portions connects corresponding ones of the extending portions  5   b , and consequently, the wiring  4  has a one-stroke-drawn shape. 
     When the conversion member  2  has a polygonal shape in a plan view, as shown in  FIG.  17 C , the wiring  4  shown in each of the first to third embodiments and variant examples thereof may have a one-stroke-drawn shape having a plurality of extending portions  5   b  extending in a direction crossing all the sides forming the outer periphery of the conversion member  2 , and the bent portions  5   a  each connecting corresponding adjacent ones of the extending portions  5   b . Accordingly, the acceptable degree of displacement of the wiring  4  with respect to the boundary between the conversion member  2  and the holding member  3  can be expanded as compared to the case of the wiring  4  shown in  FIGS.  1  to  3   , while portions other than the bent portions  5   a  in the wiring  4  overlapping the conversion member  2  extend only in a single direction. 
     Each of the bent portions  5   a  has a linear shape, but may alternatively have a curved-line shape, for example, forming a semicircle. Each of the extending portion  5   b  also has a linear shape, but it may alternatively have a shape other than a linear shape, such as a shape of repeated linear irregularities or repeated curved irregularities. 
     Method of Manufacturing Optical Member 
     Next, varied examples of the method of manufacturing an optical member will be described. 
     A varied example of the method of manufacturing the optical member  1 A according to the first embodiment includes the steps of: (1) providing a sintered body; (2) removing a portion of a conversion member and a portion of a holding member; (A) performing a heat treatment; (B) forming a light-transmissive film; and (3) forming a wiring. 
     In the modification, the steps of (1) to (3) are the same as in the above-described manufacturing method, and descriptions thereof are omitted. 
     The steps of (A) and (B) will be described below. These configurations are similar in a varied example of the method of manufacturing the optical member  1 B or  1 C according to the second or third embodiments. 
     (A) Performing Heat Treatment 
     The light extraction surface  2   a  (i.e., first surface) of the conversion member  2  and the surface  3   a  (i.e., second surface) of the holding member  3  of the holding member  3  are subjected to a heat treatment between the step of removing a part of the conversion member  2  and the holding member  3  and the step of forming the wiring  4 . The heat treatment is performed preferably at 300° C. or higher, more preferably at 800° C. or higher, in the air. By performing the heat treatment, organic substances remaining in voids of a sintered body that forms the holding member  3  can be removed. When organic substances remain in voids of the holding member  3 , the holding member  3  is heated while at least a part of a pathway through which the organic substances are discharged is blocked by the wiring  4  etc., in the subsequent steps, so that the remaining organic substances are blackened, resulting in occurrence of an appearance defect in the holding member  3 . Thus, by performing the heat treatment before formation of the wiring  4  etc., the amount of remaining organic substances in the holding member  3  can be reduced, so that the possibility of occurrence of an appearance defect in the holding member  3  can be reduced. The heat treatment temperature is preferably lower than the sintering temperature of the sintered body that forms the holding member  3 . This allows for reducing the possibility of occurrence of shrinkage, warpage, and the like of a material of the sintered body due to re-sintering, caused by the heat treatment. For example, the heat treatment is preferably performed at a temperature of 1200° C. or lower. 
     (B) Forming Light-Transmissive Film 
     Between the step of performing a heat treatment and the step of forming the wiring  4 , the light-transmissive film  7  is formed to cover the light extraction surface  2   a  (i.e., first surface) of the conversion member  2  and the surface  3   a  (i.e., second surface) of the holding member  3 , which have been subjected to the heat treatment. The light-transmissive film  7  can be formed by a sputtering method, a chemical vapor deposition method, an atomic layer deposition method, or the like. The light-transmissive film  7  may alternatively be formed on the light-irradiated surface  2   b , which is a surface opposite to the first surface, of the conversion member  2  and on the back surface  3   c , which is opposite to the second surface, of the holding member  3  after the heat treatment. 
     By formation of the light-transmissive film  7 , organic substances can be prevented from re-penetrating into voids in a material that forms the holding member  3 . Thus, the possibility of occurrence of an appearance defect in the holding member  3  due to blackening of remaining organic substances can be reduced. For preventing organic substances from re-penetrating, it is preferable that the light-transmissive film  7  has a large thickness, and can cover the surface of the holding member  3  without a break. Thus, it is preferable that the light-transmissive film  7  is deposited by a chemical vapor deposition method, and then deposited by an atomic layer deposition method. For formation of the light-transmissive film  7 , for example, a SiO 2  film having a thickness of 5 μm is first formed by a chemical vapor deposition method, and a SiO 2 /Al 2 O 3  multilayer film having a thickness of 1 μm is then formed using an atomic layer deposition method. As described above, the conversion member  2  and the holding member  3  can be covered by the light-transmissive film  7  having a surface with an improved flatness, and therefore it is possible to reduce the possibility that the wiring  4  is broken during formation. 
     The method of manufacturing an optical member according to the first embodiment may further include forming the protective film  8  by using a sputtering method, a chemical vapor deposition method, an atomic layer deposition method or the like so as to cover the light extraction surface  2   a , on which the light-transmissive film  7  is disposed, and to cover the wiring  4  as shown in  FIG.  14   , between the step of forming the wiring  4  and the step of disposing the heat dissipating member  9 . The method of manufacturing an optical member according to the second or third embodiment may further include a step of forming the insulating film  14  by a sputtering method, a chemical vapor deposition method, an atomic layer deposition method, or the like so as to cover the light-irradiated surface  2   b  provided with the light-transmissive film  7  and cover the wiring  4  as shown in  FIGS.  15  and  16   , between the step of forming the wiring  4  and the step of disposing the heat dissipating member  9 . 
     Other Methods of Manufacturing Sintered Body 
     In the methods of manufacturing an optical member according to the first to third embodiments, the sintered body may be provided by first to third methods of manufacturing described below. 
     The first to third methods of manufacturing the sintered body will be described in the case where the optical member  1 A is manufactured in which the light extraction surface  2   a  of the conversion member  2  is a first surface provided with the wiring  4  as an example, and the same applies to a case where the optical member  1 B or  1 C is manufactured in which the light-irradiated surface  2   b  of the conversion member  2  is a first surface, on which the wiring  4  is to be disposed. 
     In the descriptions of the first to third methods of manufacturing the sintered body described below, for example, the expressions “powdered conversion member” and “conversion member composed of sintered body” are used, and the expression “conversion member” is used for a conversion member irrespective of the state thereof. Similarly, in the descriptions of the first to third methods of manufacturing the sintered body described below, for example, the expressions “powdered holding member” and “holding member composed of sintered body” are used, and the expression “holding member” is used for a holding member irrespective of the state thereof. 
     First Method of Manufacturing the Sintered Body 
     The first method of manufacturing a sintered body will be described. 
     (1) Obtaining Sintered Body 
     As shown in  FIGS.  18 A to  18 C , in the step of obtaining a sintered body, the conversion member  2  and the holding member  3  are brought into contact with each other to be integrally molded, which allows for obtaining a sintered body  100 . More specifically, the step of obtaining the sintered body includes: providing the conversion member  2 ; disposing the holding member  3 ; and providing the sintered body  100 . 
     (1-1) Preparing Conversion Member 
     As shown in  FIG.  18 A , a powdered material (e.g., the same material as that of the holding member  3 ) is disposed as a buffer member  70  in a container before providing the conversion member  2 . In this manufacturing method, a sintering die  80  and a lower punch  90  serve as the container. Although the buffer member  70  may not be disposed, it is preferable to use the buffer member  70 . Accordingly, even when the conversion member  2  made of a sintered body is used, the pressure applied to the conversion member  2  at the time of subsequently sintering the holding member  3  can be substantially uniform (see  FIG.  18 C ). Therefore, breakage or the like of the conversion member  2  made of a sintered body can be reduced. 
     Next, a release sheet  60  is disposed above the buffer member  70  so that the sintered body  100  (see  FIG.  18 C ) composed of the conversion member  2  and the holding member  3  is easily taken out from the container in a later step. For the release sheet  60 , for example, a polyethylene sheet or a carbon sheet can be used. 
     In providing of the conversion member  2 , a powder in which a powdered fluorescent material and a powdered sintering aid containing a material identical to the holding member  3  are mixed is sintered to form a plate-shaped sintered body in a region surrounded by the lower punch  90  and the sintering die  80  that are provided with the buffer member  70  and the release sheet  60 . Further, using a machining center, a plurality of projected portions are formed in the plate-shaped sintered body to obtain the conversion member  2  composed of a sintered body including a plurality of projected portions at the upper surface side. 
     (1-2) Disposing Holding Member 
     Next, the powdered holding member  3  is disposed between a plurality of projected portions in the conversion member  2  as shown in  FIG.  18 B . Using the powdered holding member  3  allows for facilitating charging the holding member  3  between adjacent ones of the projected portions, so that gaps between the conversion member  2  and the holding member  3  can be substantially eliminated. In this method of manufacturing the sintered body, the conversion member  2  is disposed such that the projected portions face upward, and the powdered holding member  3  is disposed from the upper side, so that the holding member  3  is disposed between the projected portions of the conversion member  2 . 
     In  FIG.  18 B , the conversion member  2  made of a sintered body is disposed at the lower side, and the powdered holding member  3  is disposed at the upper side, but order of arrangement may be reversed. That is, after the powdered holding member  3  is disposed in the container, the conversion member  2  made of a sintered body is then disposed above the holding member  3  such that the projected portions of the conversion member  2  face downward, and pressing is performed as necessary. Also in this manner, the holding member  3  can be disposed between a plurality of projected portions in the conversion member  2 . 
     (1-3) Providing Sintered Body 
     Next, the powdered holding member  3  and the conversion member  2  including a plurality of projected portions is sintered to provide the sintered body  100  in which the conversion member  2  and the holding member  3  are molded integrally with each other as shown in  FIG.  18 C . The conversion member  2  and the holding member  3  are preferably sintered while being pressurized at 10 MPa or more and 50 MPa or less. This allows for improving bonding strength between the conversion member  2  and the holding member  3 . 
     The sintered body  100  is preferably subjected to a heat treatment at 1000° C. or higher and 1500° C. or lower in an oxidizing atmosphere (e.g., air atmosphere) after the step of providing a sintered body. Accordingly, penetration of carbon of the sintering mold to an oxide contained in the holding member  3  or deoxidation can be reduced, so that the reflectance of the holding member  3  can be increased. 
     Second Method of Manufacturing a Sintered Body 
     The second method of manufacturing a sintered body will be described. 
     The second method of manufacturing a sintered body are substantially identical to the first method of manufacturing a sintered body except for manner described below, but the second manufacturing method is different from the first manufacturing method in that a powdered conversion member and a powdered holding member are sintered. Hereinafter, steps in the second method of manufacturing a sintered body will be described. 
     (1) Obtaining Sintered Body 
     As shown in  FIGS.  19 A to  19 D , the conversion member  2  and the holding member  3  are brought into contact with each other to integrally form the sintered body  100 . More specifically, the step includes: providing the holding member  3 ; disposing the conversion member  2 ; and providing the sintered body  100 . 
     (1-1) Providing Holding Member 
     The holding member  3  with a plurality of recesses provided on an upper surface thereof is provided. In the second method of manufacturing a sintered body, the step of providing the holding member  3  includes: charging the powdered holding member  3  in a container (the lower punch  90  and sintering die  80 ) as a sintering mold (see  FIG.  19 A ); and forming the holding member  3  including a plurality of projected portions or recesses by pressing the powdered holding member  3  with a pressing member  92  having a plurality of projected portions or recesses (see  FIG.  19 B ). In this manner, the holding member  3  that is powdered and maintains to have a certain shape (shape with a plurality of recesses) can be formed by a relatively simple method. In the step of providing the holding member  3 , the holding member  3  made of a sintered body may be provided. 
     (1-2) Disposing Conversion Member 
     The powdered conversion member  2  containing a fluorescent material is provided. The powdered conversion member  2  is disposed in a plurality of recesses in the holding member  3  (see  FIG.  19 C ). That is, in the second method of manufacturing a sintered body, the powdered conversion member  2  is disposed on the powdered holding member  3 . When the holding member  3  made of a sintered body is provided, the holding member  3  and the conversion member  2  are arranged in any appropriate order. That is, the holding member  3  composed of a sintered body may be disposed at the lower side, with the powdered conversion member  2  disposed on the upper side. Alternatively, the order of arranging the holding member  3  and the conversion member  2  may be reversed. 
     (1-3) Obtaining Sintered Body 
     Next, both the powdered conversion member  2  and the powdered holding member  3  are sintered to obtain the sintered body  100  in which the conversion member  2  and the holding member  3  are integrally molded, as shown in  FIG.  19 D . In the second method of manufacturing a sintered body, both the powdered conversion member  2  and the powdered holding member  3  are sintered to provide the sintered body  100  in one step. At this time, it is necessary to increase the transmittance of a sintering aid contained in the conversion member  2 , and therefore the sintering temperature is preferably higher than that in the first method of manufacturing a sintered body. 
     Third Method of Manufacturing a Sintered Body 
     The third method of manufacturing a sintered body will be described. 
     The third method of manufacturing a sintered body is substantially identical to the second manufacturing method except for the steps that will be described below, and the third method of manufacturing a sintered body is different from the second method of manufacturing a sintered body in that a portion of the sintered body at the upper surface side thereof is composed only of the conversion member, and a portion of the sintered body at the lower surface side thereof is composed of the conversion member and the holding member. Hereinafter, steps of the third method will be described. 
     (1) Obtaining Sintered Body 
     As shown in  FIGS.  20 A to  20 D , in the step of obtaining a sintered body, the conversion member  2  and the holding member  3  are brought into contact with each other to be integrally molded, which allows for obtaining the sintered body  100 . More specifically, the step of obtaining the sintered body includes: providing the holding member  3 ; disposing the conversion member  2 ; and obtaining the sintered body  100 . 
     (1-1) Providing Holding Member 
     The holding member  3  defining a plurality of through-holes extending through the placed holding member  3  in a thickness direction and being in a powder form that maintains to be a certain shape is provided (see  FIGS.  20 A and  20 B ). In this step, the holding member  3  made of a sintered body may be provided. 
     (1-2) Disposing Conversion Member 
     The powdered conversion member  2  containing a fluorescent material is provided. The powdered conversion member  2  is disposed to fill a plurality of through-holes in the holding member  3  (see  FIG.  20 C ). 
     (1-3) Obtaining Sintered Body 
     Next, both the powdered conversion member  2  and the powdered holding member  3  are sintered to obtain the sintered body  100  in which the conversion member  2  and the holding member  3  are molded integrally with each other, as shown in  FIG.  20 D . 
     Other Examples of Method of Manufacturing Optical Member 
     In the above-described method of manufacturing an optical member, a sintered body in which a conversion member and a holding member are molded integrally with each other is used, but a fixed body may be used in which the conversion member and the holding member are firmly bonded to each other via glass or the like disposed therebetween to be integrally molded. Hereinafter, other examples of the method of manufacturing an optical member using the fixed body will be described. 
     As shown in  FIGS.  21 A and  21 B , one of such examples of the method of manufacturing an optical member includes: (1) obtaining a fixed body; (2) removing a portion of a glass film; and (3) forming a wiring. Hereinafter, steps will be described. 
     (1) Obtaining Fixed Body 
     As shown in  FIG.  21 A , a fixed body in which the conversion member  2  and the holding member  3  are integrally molded is obtained. More specifically, this step includes: forming a glass film  12 ; and fixing the conversion member  2 . 
     (1-1) Forming Glass Film 
     The glass film  12  is formed on an inner wall surface of a through-hole  3   b  defined in the holding member  3 , or on the inner wall surface and a surface of the holding member  3  on the upper surface side. For forming the through-hole  3   b  in the holding member  3 , a perforation processing method that is conventionally known can be used. The through-hole  3   b  can have any appropriate size according to the size of the conversion member  2 . The glass film  12  is formed by sputtering or the like. The thickness of the glass film  12  may be in a range of 0.1 μm to 20 μm. 
     With the thickness of the glass film  12  less than 0.1 μm, the inner wall surface of the through-hole  3   b  tends to have a portion where the glass film  12  is not formed, so that the holding strength of the conversion member  2  is easily reduced in the manufactured optical member. With the thickness of the glass film  12  more than 20 μm, absorption of light by the glass film  12  may be increased, so that light emission efficiency in the optical member tends to be deteriorated. 
     For a material of the glass film  12 , light-transmissive glass such as borosilicate glass, soda quartz glass, soda glass or lead glass is preferably used. The glass film  12  preferably has a softening point lower than that of each of the conversion member  2  and the holding member  3  in order to perform thermal fuse-bonding in the next step. 
     (1-2) Fixing Conversion Member 
     The conversion member  2  is fixed to the holding member  3  via the glass film  12  disposed therebetween. The conversion member  2  is disposed in the through-hole  3   b  with the glass film  12  disposed on the inner wall surface defining the through-hole, and the glass film  12  is heated at a first atmospheric temperature to provide a fixed body in which the conversion member  2  is fixed to the holding member  3  with the glass film  12  disposed therebetween. 
     At this time, to allow the glass film  12  to be deformed and thermally fuse-bonded, the first atmospheric temperature is appropriately selected according to the softening point of the glass film  12  formed on the inner wall surface of the through-hole  3   b . The glass film  12  formed on the inner wall surface is solid at a room temperature, and is softened by heating, and hardened when returned to room temperature. Accordingly, the conversion member  2  disposed in the through-hole  3   b  can be fixed to the holding member  3  without breakage. 
     (2) Removing a Portion of Glass Film 
     A portion of the fixed body at an upper surface side thereof is removed by grinding, polishing, CMP or the like, as shown in  FIG.  21 B . In this step, it is preferable that the glass film  12  is removed until a surface of the holding member  3  at the upper surface side thereof is exposed. Accordingly, a first surface, which is to be a light-irradiated surface or light extraction surface, of the conversion member  2 , and a second surface, which is in the same plane as the first surface of the holding member  3 , are obtained. With the conversion member  2  fixed to the holding member  3  without a gap, it is possible to obtain a surface on which the wiring  4  can be formed. This step may be omitted. In this manufacturing method, (3) forming wiring is the same as that in each of the first to third embodiments. 
     The light extraction surface of the conversion member  2  may be covered using glass which can be softened like the glass film  12 . Steps other than those described above, the same steps or the like as in the first to third embodiments can be employed.