Beam splitter and beam splitter manufacturing method

Abstract

The present invention provides a beam splitter for splitting incident light into a plurality of different components and emitting the split light, the beam splitter comprising: a first light-transmitting member having a first surface and transmissive to the incident light; a second light-transmitting member that has a second surface and is transmissive to the incident light; an optical branching film having a function of branching the incident light into the plurality of components; and an adhesive member for adhering the first light-transmitting member and the second light-transmitting member, the first light-transmitting member and the second light-transmitting member being disposed so that the first surface and the second surface face each other with the optical branching film interposed therebetween.

Description

Technical Field

[0001] This disclosure relates to a beam splitter and a method for manufacturing the beam splitter. Background Technology

[0002] Patent Document 1 describes a cubic non-polarizing beam splitter. In this non-polarizing beam splitter, a dielectric layer and a metal layer are sequentially coated on the inclined surface of an isosceles right-angled triangular prism, which serves as the incident medium. Furthermore, another isosceles right-angled triangular prism is attached to the inclined surface of this isosceles right-angled triangular prism, holding these two layers in place. Examples of materials used for the dielectric layer and the metal layer include TiO2 and Ag, respectively.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 01-092702 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] In the non-polarizing beam splitter of Patent Document 1, both the dielectric layer and the metal layer are positioned to reach the outer edge of the prism's inclined plane, and their ends protrude onto the outer surface of the beam splitter. Therefore, the metal layer is susceptible to corrosion due to contact with the atmosphere, potentially degrading the optical properties of the beam splitter.

[0008] The purpose of this disclosure is to provide a beam splitter capable of suppressing the degradation of optical properties, and a method for manufacturing the beam splitter.

[0009] Technical solutions for solving the problem

[0010] The beam splitter disclosed herein is as follows, [1] "A beam splitter for splitting incident light into multiple different components and emitting it, comprising: a first light-transmitting member having a first surface that is transmissive to the incident light; a second light-transmitting member having a second surface that is transmissive to the incident light; an optical branching film having the function of splitting the incident light into the multiple components; and an adhesive member for bonding the first light-transmitting member and the second light-transmitting member, the first light-transmitting member and the second light-transmitting member being arranged opposite each other with the first surface and the second surface sandwiching the optical branching film, the optical branching film having: a first layer formed on the first surface; and a second layer stacked on the first surface and the first layer along a first direction intersecting the first surface, the second layer comprising: a first portion having The adhesive member extends in a manner that covers the upper surface opposite to the first surface of the first layer; a second portion, which is connected to the end of the first portion in a second direction intersecting the first direction, and extends along the first direction in a manner that covers the side surface of the first layer from the end of the first portion; and a third portion, which is connected to the end of the second portion opposite to the connection portion of the first portion, and extends in the second direction toward the opposite side of the first layer, the adhesive member having: a first adhesive portion disposed in a region of the region held between the first surface and the second surface that is opposite to the first portion of the second layer; and a second adhesive portion integrally formed with the first adhesive portion and disposed in a region of the region held between the first surface and the second surface that is opposite to the second portion and the third portion of the second layer.

[0011] In this beam splitter, a first light-transmitting member and a second light-transmitting member are bonded together by an adhesive member while being interposed in an optical splitting film. The optical splitting film includes: a first layer formed on a first surface of the first light-transmitting member opposite to the second light-transmitting member; and a second layer stacked on the first surface and the first layer. Furthermore, the second layer includes: a first portion extending to cover the upper surface of the first layer; a second portion extending from the first portion to cover the side surface of the first layer; and a third portion extending from the second portion toward the opposite side of the first layer. Thus, the side surface of the first layer is covered by the second layer in areas where at least the second portion exists. As a result, the side surface of the first layer is prevented from being exposed to the outside, suppressing corrosion and other degradation of the first layer. Additionally, the upper surface of the first layer is also covered by the first portion of the second layer. Therefore, corrosion and other degradation of the first layer are suppressed during the period until the first and second light-transmitting members are bonded together (during manufacturing). Therefore, according to this beam splitter, degradation of optical properties is suppressed.

[0012] Furthermore, in this beam splitter, the second layer, which helps suppress the degradation of the first layer, is the layer constituting the optical branching film. Therefore, compared to the case where a protective film is formed separately from the optical branching film, it is possible to simplify the manufacturing process and reduce costs. Moreover, in this beam splitter, the bonding member includes: a first bonding portion disposed in a region of the area sandwiched between the first and second surfaces that faces the first portion of the second layer; and a second bonding portion disposed in a region of the area sandwiched between the first and second surfaces that faces the second and third portions of the second layer. Therefore, the bonding between the first light-transmitting member and the second light-transmitting member becomes strong.

[0013] The beam splitter disclosed herein can also be as follows, [2] "According to the beam splitter described in [1] above, wherein the optical branching film has a third layer stacked along the first direction on the first surface, the first layer, and the second layer, the third layer comprising: a fourth portion extending in a manner covering the first portion of the second layer; a fifth portion connected to an end of the fourth portion in the second direction, extending along the first direction in a manner covering the second portion of the second layer from the end of the fourth portion; and a sixth portion connected to an end of the fifth portion opposite to the connection portion of the fourth portion, extending in the second direction toward the opposite side of the first layer, the sixth portion being configured opposite to the third portion." In this case, the side surfaces of the first layer in the region where at least the second portion exists are further covered by the third layer. Additionally, the upper surface of the first layer is also further covered by the third layer. As a result, corrosion degradation of the first layer is reliably suppressed, and degradation of optical properties is reliably suppressed.

[0014] The beam splitter disclosed herein may also be as follows, [3] "According to the beam splitter described in [2] above, wherein the third layer is an oxide layer, the third layer forming the surface of the optical branching film opposite to the first surface and in contact with the bonding member." In this case, oxidation of the second layer is suppressed during the period until the first and second light-transmitting members are bonded together (during manufacturing).

[0015] The beam splitter disclosed herein may also be as follows, [4] "The beam splitter according to any one of [1] to [3] above, wherein the optical splitting film comprises: a pair of fourth layers arranged to sandwich the first layer along the first direction; and a pair of fifth layers arranged to sandwich the first layer and the pair of fourth layers along the first direction, wherein the first portion of the second layer is formed on and in contact with the fifth layer." The optical splitting film may also be composed of such a multilayer structure.

[0016] The beam splitter disclosed herein can also be as follows, [5] "According to the beam splitter described in [4] above, wherein the fourth layer is made of a first material, and the fifth layer is an oxide layer made of a material to which the first material has been oxidized." In this case, the increase in absorption coefficient (decrease in reflectivity and transmittance) caused by the oxidation of the first layer can be suppressed. In addition, the oxidation of the fourth layer can be suppressed during the period until the second layer is formed (during manufacturing).

[0017] The beam splitter disclosed herein may also be as follows, [6] "According to the beam splitter described in [4] or [5] above, wherein the fourth layer is composed of one of Si, Ge, SiN, and ZnS, and the fifth layer is composed of one of SiO2, Al2O3, TiO2, Y2O3, and Ta2O5." The materials for the fourth and fifth layers may also be selected from these materials.

[0018] The beam splitter disclosed herein can also be as follows, [7] "the beam splitter according to any one of [4] to [6] above, wherein the fourth layer is made of the same material as the second layer." In this case, the number of film-forming sources can be reduced when manufacturing the optical branching film, making the manufacturing of the optical branching film easier.

[0019] The beam splitter disclosed herein may also be as follows: [8] "According to any one of [1] to [7] above, the outer edge of the first layer when viewed from the first direction includes a short side and a long side extending in a direction intersecting the short side, and when viewed from the first direction, the distance between the short side and the outer edge of the first surface is greater than the distance between the long side and the outer edge of the first surface." In this case, when the first light-transmitting member and the second light-transmitting member are bonded (during manufacturing), even if a positional deviation occurs in the direction intersecting the short side of the first layer, the exposure of the first layer to the outer edge of the second surface is suppressed.

[0020] The beam splitter disclosed herein may also be as follows, [9] "The beam splitter according to any one of [1] to [8] above, wherein the outer edge of the first surface includes a first side facing the external member when the beam splitter is mounted on the external member, and the first layer extends such that a portion of the outer edge of the first layer overlaps with the first side when viewed from the first direction." In this case, forming a wider first layer enables the formation of a wider effective area. On the other hand, a portion of the outer edge of the first layer reaches the first side of the outer edge of the first surface, but this first side is the side facing the external member when the beam splitter is mounted on the external member. Therefore, a portion of the outer edge of the first layer is prevented from being exposed to the outside.

[0021] The beam splitter disclosed herein may also be as follows,

[10] "The beam splitter according to any one of [1] to [9] above, wherein the corner of the first layer when viewed from the first direction is formed in an arc shape." In this case, even if a notch is formed at the corner of the first light-transmitting member or the second light-transmitting member, the first layer is not easily exposed.

[0022] The beam splitter disclosed herein may also be as follows:

[11] "The beam splitter according to any one of [1] to

[10] above, wherein it comprises: an incident surface of the incident light; and a third surface located on the opposite side of the incident surface, separated from the first surface, the optical branching film, and the second surface, wherein a reflective film is formed on the third surface to reflect light that has been transmitted through the optical branching film." In this case, light transmitted through the optical branching film can be reflected in a predetermined direction.

[0023] The beam splitter disclosed herein may also be as follows,

[12] "The beam splitter according to any one of [1] to

[11] above, wherein it has an exit surface that emits light reflected by the optical branching film to the outside, and an anti-reflective film is formed on the exit surface." In this case, when emitting light reflected by the optical branching film, reflections on the exit surface are suppressed.

[0024] The beam splitter disclosed herein may also be as follows,

[13] "The beam splitter according to any one of [1] to

[12] above, wherein the incident light has an incident surface, and an anti-reflection film is formed on the incident surface." In this case, reflection on the incident light at the incident surface is suppressed.

[0025] The beam splitter disclosed herein may also be as follows,

[14] "The beam splitter according to any one of [1] to

[13] above, wherein the first layer is made of a metallic material and the second layer is made of a semiconductor material or a dielectric material." In this case, corrosion and other deterioration of the first layer made of the metallic material are suppressed.

[0026] The beam splitter disclosed herein may also be as follows,

[15] "The beam splitter according to any one of [1] to

[14] above, wherein the first layer is composed of Ag or Al, and the second layer is composed of one of Si, Ge, SiO2, SiN, Al2O3, Y2O3, Ta2O5, TiO2, and ZnS." In this case, corrosion and other deterioration of the first layer composed of Ag or Al are suppressed.

[0027] The beam splitter manufacturing method disclosed herein is as follows,

[16] "A beam splitter manufacturing method for manufacturing a beam splitter according to any one of [1] to

[15] above, comprising: a first step of preparing a first member including a plurality of portions that become first light-transmitting members and a second member including a plurality of portions that become second light-transmitting members; a second step of, after the first step, forming the optical branching film on the first surface of each of the plurality of portions that become first light-transmitting members included in the first member; a third step of, after the second step, bonding the first member and the second member by means of the adhesive member through the optical branching film to form a structure including a plurality of continuous beam splitters; and a fourth step of, after the third step, obtaining a plurality of beam splitters from the structure by monolithizing the structure."

[0028] According to this method, beam splitters capable of suppressing the degradation of optical properties can be manufactured efficiently.

[0029] The beam splitter manufacturing method disclosed herein can also be described as follows:

[17] "According to the beam splitter manufacturing method described in

[16] above, a fifth step is provided between the third and fourth steps to grind the surface of the structure, the beam splitter including a contact surface that contacts the external component when the beam splitter is mounted on the external component, and in the fifth step, at least the surface of the structure including a plurality of the contact surfaces is ground." In this case, by flattening the contact surface of the beam splitter with the external component, it is easy to mount the beam splitter on the external component. In addition, when the contact surface is set as the light emission surface in the beam splitter, the deviation of the optical path length from the incident surface to the emission surface can be reduced by grinding the contact surface that serves as the emission surface.

[0030] Invention Effects

[0031] According to this disclosure, a beam splitter capable of suppressing the degradation of optical properties and a method for manufacturing the beam splitter can be provided. Attached Figure Description

[0032] Figure 1 This is a cross-sectional view showing an optical module according to one embodiment.

[0033] Figure 2 It means Figure 1 The cross-sectional view of the reflector unit and beam splitter shown.

[0034] Figure 3 yes Figure 1 , 2 A three-dimensional view of the beam splitter shown.

[0035] Figure 4 It is along Figure 3A schematic cross-sectional view of line IV-IV.

[0036] Figure 5 It indicates observation from the first direction. Figure 4 A schematic diagram showing the first surface and the first layer.

[0037] Figure 6 This is a diagram illustrating one step in the manufacturing process of a beam splitter.

[0038] Figure 7 This is a diagram illustrating one step in the manufacturing process of a beam splitter.

[0039] Figure 8 This is a diagram illustrating one step in the manufacturing process of a beam splitter.

[0040] Figure 9 This is a schematic diagram showing the first surface and first layer of the modified example as viewed from the first direction. Detailed Implementation

[0041] Hereinafter, an embodiment will be described with reference to the accompanying drawings. Furthermore, in the description of each drawing, the same or equivalent elements are labeled with the same reference numerals, and repeated descriptions are sometimes omitted. Additionally, in each drawing, a rectangular coordinate system is sometimes shown defining the X direction, the Y direction intersecting the X direction, and the Z direction intersecting both the X and Y directions. Alternatively, in each drawing, an additional rectangular coordinate system is sometimes shown defining a first direction D1, a second direction D2 intersecting the first direction D1, and a third direction D3 intersecting both the first direction D1 and the second direction D2.

[0042] Figure 1 This is a cross-sectional view showing an optical module according to one embodiment. For example... Figure 1 As shown, the optical module 1 includes a mirror unit 2, a beam splitter 3, a light incident section 4, a first photodetector 6, a second light source 7, a second photodetector 8, a support body 9, a first support structure 11, and a second support structure 12. The mirror unit 2 is disposed on one side of the support body 9 in the Z direction, for example, and is mounted to the support body 9 by adhesive. The support body 9 is formed of copper-tungsten, for example, and is in the shape of a rectangular plate. The mirror unit 2 includes a movable mirror 22 that moves along the Z direction and a fixed mirror 16 whose position is fixed. Furthermore, the Z direction is, for example, the vertical direction, and one side in the Z direction is, for example, the upper side.

[0043] Beam splitter 3 is disposed on one side of mirror unit 2 in the Z direction and is supported by first support structure 11. First support structure 11 is mounted to support body 9, for example, by adhesive. Light incident part 4 is disposed on one side of beam splitter 3 in the X direction and is supported by second support structure 12. First photodetector 6, second light source 7, and second photodetector 8 are disposed on one side of beam splitter 3 in the Z direction and are supported by second support structure 12. Second support structure 12 is mounted to support body 9, for example, by bolts.

[0044] In optical module 1, the beam splitter 3, the movable mirror 22, and the fixed mirror 16 constitute an interferometric optical system for the measurement light L0 and the laser L10, respectively. The interferometric optical system constituting the measurement light L0 and the laser L10 is, for example, a Michelson interferometric optical system.

[0045] For the measurement light L0, the interference light L1 of the measurement light is detected as follows. That is, when the measurement light L0, which is incident from the first light source (not shown) via the measurement object (not shown) or emitted from the measurement object (e.g., the emission of light from the measurement object itself), is incident from the light incident section 4 onto the beam splitter 3, the measurement light L0 is split into a portion and a remaining portion in the beam splitter 3. Furthermore, a portion of the measurement light L0 is reflected back to the beam splitter 3 by a movable mirror 22 that moves back and forth along the Z direction. On the other hand, the remaining portion of the measurement light L0 is reflected back to the beam splitter 3 by a fixed mirror 16. The portion and the remaining portion of the measurement light L0 that return to the beam splitter 3 are emitted from the beam splitter 3 as the interference light L1, which is detected by the first photodetector 6.

[0046] For laser L10, the interference light L11 is detected as follows: When laser L10 emitted from the second light source 7 is incident on beam splitter 3, it is split into a portion and a remaining portion within beam splitter 3. Furthermore, a portion of laser L10 is reflected back to beam splitter 3 by a movable mirror 22 that reciprocates along the Z direction. Conversely, the remaining portion of laser L10 is reflected back to beam splitter 3 by a fixed mirror 16. The portion and the remaining portion of laser L10 returning to beam splitter 3 are emitted as interference light L11, which is detected by the second photodetector 8.

[0047] Based on the detection results of the interference light L11 of the laser in the optical module 1, the position of the movable mirror 22 in the Z direction can be measured. Based on the measurement results of this position and the detection results of the interference light L1 of the measurement light, spectral analysis of the measured object can be performed.

[0048] Figure 2 It means Figure 1 The cross-sectional view of the reflector unit and beam splitter shown. Figure 1 , 2As shown, the beam splitter 3 is mounted, for example, on the surface 112a opposite to the mirror device 20 in the light-transmitting member 112 of the first support structure 11 by means of an optical adhesive that also acts as a refractive index matching agent.

[0049] The mirror device 20 is part of the mirror unit 2. That is, the mirror unit 2 includes an optical functional component 13, a fixed mirror 16, and the mirror device 20. The mirror device 20 includes a base 21, a movable mirror 22, and a drive unit 23. The base 21 has a first surface 21a (a surface on one side in the Z direction) and a second surface 21b opposite to the first surface 21a. The first surface 21a and the second surface 21b are the main surfaces of the base 21. The base 21 is, for example, in the shape of a rectangular plate. The movable mirror 22 has a mirror surface 22a and a movable part 22b on which the mirror surface 22a is disposed. The movable mirror 22 is supported on the base 21 in a manner that allows it to move along the Z direction perpendicular to the first surface 21a. The drive unit 23 moves the movable mirror 22 along the Z direction.

[0050] A pair of light-passing portions 24 and 25 are provided on the reflector device 20. The pair of light-passing portions 24 and 25 are arranged on both sides of the movable reflector 22 in the X direction. The light-passing portion 24 constitutes the first part of the optical path between the beam splitter 3 and the fixed reflector 16.

[0051] The substrate 21, the movable part 22b of the movable mirror 22, and the driving part 23 are, for example, made of an SOI (Silicon On Insulator) substrate. That is, the mirror device 20 is made of an SOI substrate. The mirror device 20 is, for example, formed into a rectangular plate shape. The SOI substrate has a support layer 101, a device layer 102, and an intermediate layer 103. The support layer 101 is a first silicon layer. The device layer 102 is a second silicon layer. The intermediate layer 103 is an insulating layer disposed between the support layer 101 and the device layer 102. The SOI substrate has the support layer 101, the intermediate layer 103, and the device layer 102 sequentially from one side in the Z direction.

[0052] The substrate 21 is composed of a support layer 101, a device layer 102, and a portion of an intermediate layer 103. A first surface 21a of the substrate 21 is the surface opposite to the intermediate layer 103 in the support layer 101. A second surface 21b of the substrate 21 is the surface opposite to the intermediate layer 103 in the device layer 102. The support layer 101 constituting the substrate 21 is thicker than the device layer 102 constituting the substrate 21. The thickness of the support layer 101 constituting the substrate 21 is, for example, about four times the thickness of the device layer 102 constituting the substrate 21. In the mirror unit 2, as described later, the second surface 21b of the substrate 21 and the third surface 13a of the optical functional component 13 are joined together.

[0053] In the reflector device 20, an electrical signal for moving the movable reflector 22 along the Z direction is input to the drive unit 23 via leads and wires (not shown). This enables the movable reflector 22 to reciprocate along the Z direction at its resonant frequency level. Thus, the drive unit 23 functions as an electrostatic actuator.

[0054] The optical functional component 13 has a third surface 13a (a surface on one side in the Z direction) opposite to the second surface 21b of the substrate 21, and a fourth surface 13b on the opposite side of the third surface 13a. The optical functional component 13 is integrally formed from a material that is transmissive to the measurement light L0 and the laser L10. The optical functional component 13 is formed from glass in a rectangular plate shape, for example, having dimensions of approximately 15 mm × 20 mm × 4 mm (thickness). Furthermore, the material of the optical functional component 13 is selected, for example, by choosing glass when the sensitivity wavelength of the optical module 1 is in the near-infrared region, and silicon when the sensitivity wavelength of the optical module 1 is in the mid-infrared region, depending on the sensitivity wavelength of the optical module 1.

[0055] A light-transmitting portion 14 is provided on the optical functional component 13. The light-transmitting portion 14 is the part of the optical functional component 13 that is opposite to the light-passing portion 24 of the reflector device 20 in the Z direction. The surface of the light-transmitting portion 14 on the reflector device 20 side is located on the same plane as the third surface 13a. The light-transmitting portion 14 constitutes the second part (a portion) of the optical path between the beam splitter 3 and the fixed reflector 16. The light-transmitting portion 14 is the part that corrects the optical path difference generated between the optical path between the beam splitter 3 and the movable reflector 22, and between the optical path between the beam splitter 3 and the fixed reflector 16.

[0056] The optical functional component 13 has a fifth surface 13d that faces the movable mirror 22 and the drive unit 23 of the mirror device 20. The fifth surface 13d is located on the side closer to the fourth surface 13b than the third surface 13a. Therefore, the fifth surface 13d is separated from the mirror device 20 in the region facing the movable mirror 22 and the drive unit 23. In addition, the surface of the light-transmitting portion 14 faces the light-passing portion 24 of the mirror device 20. Thus, in the mirror unit 2, when the movable mirror 22 reciprocates along the Z direction, contact between the movable mirror 22 and the drive unit 23 and the optical functional component 13 is prevented.

[0057] The fixed mirror 16 is disposed on the opposite side of the mirror device 20 relative to the optical functional member 13, and the position of the mirror device 20 relative to the substrate 21 is fixed. The fixed mirror 16 is formed on the fourth surface 13b of the optical functional member 13, for example, by vapor deposition. The fixed mirror 16 has a mirror surface 16a perpendicular to the Z direction. In this embodiment, the mirror surface 22a of the movable mirror 22 and the mirror surface 16a of the fixed mirror 16 face one side in the Z direction (beam splitter 3 side). Furthermore, the fixed mirror 16 is continuously formed on the fourth surface 13b of the optical functional member 13 to reflect light transmitted through each light-transmitting portion 14 of the optical functional member 13.

[0058] Beam splitter 3 is mounted, for example, on the surface 112a opposite to the mirror device 20 in the light-transmitting member 112 via an optical adhesive that also acts as a refractive index matching agent. Beam splitter 3 has a first mirror surface 31, a second mirror surface 32, and multiple optical surfaces 33a, 33b, 33c, and 33d. Beam splitter 3 is constructed by joining multiple optical blocks 34 and 35. Each optical block 34 and 35 is formed of a material with the same or similar refractive index as the optical functional member 13.

[0059] The first reflecting mirror surface 31 is a reflecting mirror surface (e.g., a semi-reflecting mirror surface) that is inclined relative to the Z direction, and is formed between the optical block 34 and the optical block 35. In this embodiment, the first reflecting mirror surface 31 is a surface parallel to the Y direction and at a 45° angle to the Z direction, and is inclined in such a way that the closer to the reflecting mirror device 20, the further away from the light incident portion 4. The first reflecting mirror surface 31 has the function of reflecting a portion of the measurement light L0 and allowing the remaining portion of the measurement light L0 to be transmitted, and reflecting a portion of the laser L10 and allowing the remaining portion of the laser L10 to be transmitted. The first reflecting mirror surface 31 is formed, for example, from a dielectric multilayer film. When viewed from the Z direction, the first reflecting mirror surface 31 overlaps with the light passing portion 24 of the reflecting mirror device 20, the light transmitting portion 14 of the optical functional member 13, and the reflecting mirror surface 16a of the fixed reflecting mirror 16, and when viewed from the X direction, it overlaps with the light incident portion 4 (see reference). Figure 1 That is, the first reflecting mirror 31 is opposite to the fixed reflecting mirror 16 in the Z direction and opposite to the light incident part 4 in the X direction.

[0060] The second reflecting mirror 32 is a reflecting mirror (e.g., a total internal reflection mirror) parallel to the first reflecting mirror 31, and is formed on the optical block 35 on the opposite side of the light incident section 4 relative to the first reflecting mirror 31. The second reflecting mirror 32 has the function of reflecting the measurement light L0 and reflecting the laser L10. The second reflecting mirror 32 is formed, for example, from a metal film. When viewed from the Z direction, the second reflecting mirror 32 overlaps with the reflecting mirror 22a of the movable reflecting mirror 22 of the reflecting mirror device 20, and when viewed from the X direction, it overlaps with the first reflecting mirror 31. That is, the second reflecting mirror 32 is opposite to the movable reflecting mirror 22 in the Z direction and opposite to the first reflecting mirror 31 in the X direction.

[0061] Optical surface 33a is a surface perpendicular to the Z-direction, formed on the optical block 35 such that it is located on the opposite side of the reflector device 20 relative to the first reflector surface 31. Optical surface 33b is a surface perpendicular to the Z-direction, formed on the optical block 35 such that it is located on the side of the reflector device 20 relative to the second reflector surface 32. Optical surface 33c is a surface perpendicular to the Z-direction, formed on the optical block 34 such that it is located on the side of the reflector device 20 relative to the first reflector surface 31.

[0062] Optical surfaces 33b and 33c are located on the same plane. Optical surface 33d is a surface perpendicular to the X direction and is formed on the optical block 34 on the side of the light incident section 4 relative to the first reflecting mirror surface 31. Each optical surface 33a, 33b, 33c, and 33d has the function of allowing the measurement light L0 to be projected and the laser L10 to be projected. The beam splitter 3 configured as described above is fixed to the surface 112a of the light-transmitting member 112 by optical surfaces 33b and 33c located on the same plane, for example, using an optical adhesive, and is mounted on the light-transmitting member 112.

[0063] Here, the optical paths of the measurement light L0 and the laser L10 in the reflector unit 2 and beam splitter 3 will be described. When the measurement light L0 is incident on the beam splitter 3 along the X direction via the optical surface 33d, a portion of the measurement light L0 is projected through the first reflector surface 31 and reflected by the second reflector surface 32, and then reaches the reflector surface 22a of the movable reflector 22 via the optical surface 33b and the light-transmitting member 112. A portion of the measurement light L0 is reflected by the reflector surface 22a of the movable reflector 22, travels in the opposite direction along the same optical path P1, and is reflected by the first reflector surface 31.

[0064] The remaining portion of the measurement light L0 is reflected by the first reflecting mirror 31, and passes through the optical surface 33c, the light-transmitting member 112, the light-passing portion 24 of the reflecting mirror device 20, and the light-transmitting portion 14 of the optical functional member 13, reaching the reflecting mirror surface 16a of the fixed reflecting mirror 16. The remaining portion of the measurement light L0 is reflected by the reflecting mirror surface 16a of the fixed reflecting mirror 16, travels in the opposite direction along the same optical path P2, and is projected through the first reflecting mirror 31. A portion of the measurement light L0 reflected by the first reflecting mirror 31 and the remaining portion of the measurement light L0 transmitted through the first reflecting mirror 31 become the interference light L1. The interference light L1 of the measurement light is emitted from the beam splitter 3 along the Z-axis direction via the optical surface 33a.

[0065] On the other hand, when laser L10 is incident on beam splitter 3 along the Z direction via optical surface 33a, a portion of laser L10 is reflected by first reflecting mirror 31 and second reflecting mirror 32, and reaches reflecting mirror 22a of movable reflecting mirror 22 via optical surface 33b and light-transmitting member 112. A portion of this laser L10, reflected by reflecting mirror 22a of movable reflecting mirror 22, travels in the opposite direction along the same optical path P3 and is reflected by first reflecting mirror 31.

[0066] The remaining portion of laser L10 is projected through the first reflecting mirror 31, and then through the optical surface 33c, the light-transmitting member 112, the light-passing portion 24 of the reflecting mirror device 20, and the light-transmitting portion 14 of the optical functional member 13, reaching the reflecting mirror surface 16a of the fixed reflecting mirror 16. The remaining portion of laser L10 is reflected by the reflecting mirror surface 16a of the fixed reflecting mirror 16, travels in the opposite direction along the same optical path P4, and is projected through the first reflecting mirror 31. A portion of laser L10 reflected by the first reflecting mirror 31 and the remaining portion of laser L10 transmitted through the first reflecting mirror 31 become interference light L11. This interference light L11 exits from the beam splitter 3 along the Z direction via the optical surface 33a.

[0067] As described above, the light-passing portion 24 of the reflector device 20 constitutes the first part P2a of the optical path P2 of the measurement light L0 and the first part P4a of the optical path P4 of the laser L10 in the optical path between the beam splitter 3 and the fixed reflector 16. Furthermore, the light-transmitting portion 14 of the optical functional member 13 constitutes the second part P2b of the optical path P2 of the measurement light L0 and the second part P4b of the optical path P4 of the laser L10 in the optical path between the beam splitter 3 and the fixed reflector 16.

[0068] By constructing the second portion P2b of the optical path P2 for measuring light L0 using the light-transmitting portion 14, the optical path difference between optical paths P1 and P2 is corrected, thereby reducing the difference between the optical path length of optical path P1 (which takes into account the refractive index of each medium through which the optical path passes) and the optical path length of optical path P2 for measuring light L0. Similarly, by constructing the second portion P4b of the optical path P4 for laser L10 using the light-transmitting portion 14, the optical path difference between optical paths P3 and P4 is corrected, thereby reducing the difference between the optical path lengths of optical paths P3 and P4 for laser L10. In this embodiment, the refractive index of the light-transmitting portion 14 is equal to the refractive index of each optical block constituting the beam splitter 3, and the distance between the first reflecting mirror 31 and the second reflecting mirror 32 along the X direction is equal to the thickness of the light-transmitting portion 14 along the Z direction (i.e., the distance between the surface of the light-transmitting portion 14 along the Z direction and the fourth surface 13b of the optical functional member 13).

[0069] Next, details about beam splitter 3 will be explained. Figure 3 yes Figure 1 , 2 A three-dimensional view of the beam splitter shown. Figure 4 It is along Figure 3 A schematic cross-sectional view of line IV-IV. As described above, Figure 3 , 4 The beam splitter 3 shown branches the incident light (measurement light L0 and laser L10) into multiple different components (a portion and the remainder of measurement light L0, and a portion and the remainder of laser L10) and emits them. Therefore, the beam splitter 3 includes an optical block 34 (first light-transmitting member), an optical block 35 (second light-transmitting member), an adhesive member 40, and an optical branching film 50. Furthermore, the beam splitter 3 can also function as a semi-reflective mirror that equally divides the incident light on the transmission and reflection sides.

[0070] Optical block 34 has a first surface 34a that is transmissive to incident light. In this embodiment, optical block 34 is formed as a triangular prism with a pair of parallel right-angled triangular end faces, and the first surface 34a is a side surface (sloping surface) connecting the approximately orthogonal optical surfaces 33d and 33c in optical block 34. Optical block 35 has a second surface 35a that is transmissive to incident light. In this embodiment, optical block 35 is formed as a quadrangular prism with a pair of parallelogram-shaped end faces, and the second surface 35a is a side surface (sloping surface) connecting the parallel optical surfaces 33a and 33b in optical block 35.

[0071] Optical blocks 34 and 35 are arranged opposite each other with first surfaces 34a and second surfaces 35a. An adhesive member 40, which is transmissive to incident light, is disposed between the first surfaces 34a and 35a. An optical branching film 50, disposed between the first surfaces 34a and 35a, functions to branch the incident light into multiple components. Furthermore, when the beam splitter 3 functions as a semi-reflective mirror, the optical branching film 50 functions to equally split the incident light on the transmission and reflection sides.

[0072] Therefore, optical blocks 34 and 35 are arranged opposite each other with the adhesive member 40 and the optical branching film 50 sandwiched between their first surface 34a and second surface 35a, and are bonded to each other by the adhesive member 40. Thus, in this embodiment, the beam splitter 3 is generally formed as a quadrangular prism with a pair of parallel trapezoidal end faces. The adhesive member 40 and the optical branching film 50 constitute the first reflecting mirror surface 31 described above. That is, the first surface 34a is the surface of optical block 34 facing the first reflecting mirror surface 31, and the second surface 35a is the surface of optical block 35 facing the first reflecting mirror surface 31. The first surface 34a and the second surface 35a are substantially parallel to each other.

[0073] The first direction D1 is the direction that intersects (or is orthogonal) with the first surface 34a and the second surface 35a. The first direction D1 is inclined at, for example, 45° with respect to the Z direction. Therefore, the first surface 34a and the second surface 35a are also inclined at, for example, 45° with respect to the Z direction. The second direction D2 is the direction that intersects (or is orthogonal) with the first direction D1 and the second direction D2 and is along the direction of the first surface 34a and the second surface 35a. The second direction D2 is aligned with the Y direction. The third direction D3 is the direction that intersects (or is orthogonal) with the first direction D1 and the second direction D2 and is along the direction of the first surface 34a and the second surface 35a. The third direction D3 is inclined at, for example, 45° with respect to the X direction.

[0074] As an example, the optical branching film 50 is formed on the first surface 34a (or possibly on the second surface 35a) and is composed of multiple layers stacked along the first direction D1 (having a multilayer film structure). More specifically, the optical branching film 50 has a first layer 51 formed on the first surface 34a and a second layer 52 stacked along the first direction D1 on the first surface 34a and the first layer 51. Moreover, in this embodiment, the optical branching film 50 includes a third layer 53 stacked along the first direction D1 on the first surface 34a, the first layer 51, and the second layer 52; a pair of fourth layers 54a and 54b arranged along the first direction D1 to clamp the first layer 51; and a pair of fifth layers 55a and 55b arranged along the first direction D1 to clamp the first layer 51 and the fourth layers 54a and 54b.

[0075] Thus, in the main portion (effective region 50p) including the center of the optical branching film 50, a fifth layer 55a, a fourth layer 54a, a first layer 51, a fourth layer 54b, a fifth layer 55b, a second layer 52, and a third layer 53 are sequentially stacked from the first surface 34a side. The first portion 52a of the second layer 52 is formed on and in contact with the fifth layer 55b. Adjacent layers among these layers are in contact with each other. Furthermore, the optical branching film 50 has a substrate layer 56 in contact with the first surface 34a, on which the aforementioned layers are stacked.

[0076] Viewed from the first direction D1, the first layer 51 has a rectangular shape. The first layer 51 is a flat layer that, when viewed from the first direction D1, covers the entire surface of the substrate layer 56. The first layer 51 is made of a metallic material such as Ag or Al.

[0077] Viewed from the first direction D1, the second layer 52 is rectangular. Viewed from the first direction D1, the second layer 52 covers the first layer 51 and extends beyond the outer edge 51e of the first layer 51 onto the first surface 34a. The portion of the second layer 52 that extends beyond the outer edge 51e of the first layer 51 contacts the first surface 34a. More specifically, the second layer 52 is composed of a first portion 52a, a second portion 52b, and a third portion 52c. The first portion 52a extends in a manner that covers the upper surface opposite to the first surface 34a of the first layer 51. Viewed from the first direction D1, the first portion 52a covers the first layer 51.

[0078] The second portion 52b connects to the end of the first portion 52a in the second direction D2, extending along the first direction D1 such that it covers the side surface of the first layer 51 (here, the surface intersecting the second direction D2) from the end of the first portion 52a. In this embodiment, the second portion 52b extends to the first surface 34a in such a way that it covers not only the side surface of the first layer 51 but also the side surfaces of the fourth layers 54a, 54b, the fifth layers 55a, 55b, and the substrate layer 56. The third portion 52c connects to the end of the second portion 52b opposite to the connection portion of the first portion 52a, extending in the second direction D2 (and the third direction D3) toward the opposite side (outer side) of the first layer 51. The third portion 52c contacts the first surface 34a. Thus, a step is formed in the second layer 52 between the first portion 52a and the third portion 52c. Furthermore, the end of the second portion 52b in the first direction D1 is connected to both the first portion 52a and the third portion 52c.

[0079] The second layer 52 is composed of a semiconductor material or a dielectric material. Examples of semiconductor materials constituting the second layer 52 include Si or Ge. Examples of dielectric materials constituting the second layer 52 include SiO2, SiN, Al2O3, Y2O3, Ta2O5, TiO2, and ZnS. The second layer 52 can be composed of a material with higher moisture resistance than the first layer 51. As an example, in this embodiment, the second layer 52 is composed of Si. Furthermore, the material of the substrate layer 56 can be, for example, the same material as the material of the second layer 52.

[0080] Viewed from the first direction D1, the third layer 53 is rectangular. Viewed from the first direction D1, the third layer 53 covers the second layer 52. More specifically, the third layer 53 is composed of a fourth part 53a, a fifth part 53b, and a sixth part 53c. The fourth part 53a extends in a manner that covers the first part 52a of the second layer 52. The fifth part 53b connects to the end of the fourth part 53a in the second direction D2, extending along the first direction D1 in a manner that covers the second part 52b of the second layer 52 from the end of the fourth part 53a. The sixth part 53c connects to the end of the fifth part 53b on the opposite side of the connection portion with the fourth part 53a, extending in the second direction D2 (and the third direction D3) toward the opposite side (outer side) of the first layer 51. Thus, a step is formed in the third layer 53 between the fourth part 53a and the sixth part 53c.

[0081] The sixth portion 53c is arranged opposite to the third portion 52c of the second layer 52. In this embodiment, the sixth portion 53c is in contact with the third portion 52c. Furthermore, in this embodiment, the third layer 53 is the outermost layer of the optical branching film 50, having the surface 50s of the optical branching film 50. That is, the third layer 53 forms the surface 50s of the optical branching film 50 opposite to the first surface 34a and is in contact with the adhesive member 40. The third layer 53 is, for example, an oxide layer, and as an example, is composed of SiO2.

[0082] Viewed from the first direction D1, the fourth layers 54a and 54b are rectangular in shape. Viewed from the first direction D1, the fourth layers 54a and 54b cover the first layer 51. The fourth layers 54a and 54b are flat layers. The fourth layers 54a and 54b may be composed of, for example, one of Si, Ge, SiN, and ZnS. Alternatively, the fourth layers 54a and 54b may be composed of the same material as the second layer 52. In this embodiment, as an example, the fourth layers 54a and 54b are composed of Si.

[0083] Viewed from the first direction D1, the fifth layers 55a and 55b are rectangular. Viewed from the first direction D1, the fifth layers 55a and 55b cover the first layer 51 and the fourth layers 54a and 54b. The fifth layers 55a and 55b may be composed of, for example, one of SiO2, Al2O3, TiO2, Y2O3, and Ta2O5. In this embodiment, the fifth layers 55a and 55b are composed of, for example, SiO2. As an example, the fourth layers 54a and 54b are composed of a first material (e.g., Si) that has not undergone oxidation treatment, and the fifth layers 55a and 55b may be oxide layers composed of a material (e.g., SiO2) that has undergone oxidation treatment of the first material.

[0084] The adhesive member 40 is composed of a first adhesive portion 41 and a second adhesive portion 42. The first adhesive portion 41 is disposed (filled) in the region of the optical branching film 50 sandwiched between the first surface 34a and the second surface 35a, opposite to the first portion 52a of the second layer 52 (i.e., the fourth portion 53a of the third layer 53), and is bonded to the second surface 35a and the surface 50s in this region. The second adhesive portion 42 is disposed (filled) in the region of the optical branching film 50 sandwiched between the first surface 34a and the second surface 35a, opposite to the second portion 52b of the second layer 52 (i.e., the fifth portion 53b of the third layer 53) and the third portion 52c of the second layer 52 (i.e., the sixth portion 53c of the third layer 53), and is bonded to the second surface 35a and the surface 50s in this region. The first adhesive portion 41 and the second adhesive portion 42 are integrally formed with each other. Thus, the adhesive member 40 is formed in such a way that it fills the stepped portion of the optical branching film 50, and the first surface 34a and the second surface 35a are bonded together through the optical branching film 50.

[0085] As described above, the optical branching film 50 is composed of an effective region 50p and an annular ineffective region 50r. The effective region 50p is formed by stacking a first layer 51, a second layer 52, a third layer 53, a fourth layer 54a, 54b, and a fifth layer 55a, 55b, and is relatively thick. The ineffective region 50r is formed on the outside of the effective region 50p in a manner that surrounds the effective region 50p, and is formed by stacking a second layer 52 and a third layer 53, and is relatively thin and annular.

[0086] Furthermore, the optical surface 33c of optical block 34 and the optical surface 33b of optical block 35 constitute the bottom surface 3s of beam splitter 3. The bottom surface 3s is the contact surface that contacts the external component when beam splitter 3 is mounted on the external component (here, the light-transmitting component 112).

[0087] Figure 5 It indicates observation from the first direction. Figure 4 A schematic diagram showing the first surface and the first layer. (See diagram below.) Figure 4 , 5As shown, when viewed from the first direction D1, the first surface 34a of the optical block 34 is a long rectangle in the third direction D3 compared to the second direction D2. Therefore, the outer edge 34e of the first surface 34a (i.e., the outer edge of the optical block 34 when viewed from the first direction D1) is composed of a pair of parallel short sides E1 and a pair of parallel long sides E2 extending in a direction intersecting the short sides E1. One short side E1 corresponds to the first side of the bottom surface 3s (optical surface 33c) facing (contacting) the external component when the beam splitter 3 is mounted on the external component. The other short side E1 corresponds to the optical surface 33a, which serves as the incident surface of the laser L10 and the exit surface of the interference beams L1 and L11 in the beam splitter 3.

[0088] Similarly, viewed from the first direction D1, the first layer 51 of the optical branching film 50 is a rectangular shape that is elongated in the third direction D3 compared to the second direction D2. Therefore, the outer edge 51e of the first layer 51 includes a pair of parallel short sides F1 and a pair of parallel long sides F2 extending in a direction intersecting the short sides F1. The short sides F1 are opposite to each of the short sides E1 of the first surface 34a and extend parallel to that short side E1. The long sides F2 are opposite to each of the long sides E2 of the first surface 34a and extend parallel to that long side E2. The corner 51r where the short sides F1 and long sides F2 intersect in the first layer 51 is chamfered, forming an arc shape convex outwards from the first layer 51.

[0089] When viewed from the first direction D1, the distance T1 between the short side F1 of the first layer 51 and the outer edge 34e of the first surface 34a is greater than the distance T2 between the long side F2 of the first layer 51 and the outer edge 34e of the first surface 34a. Distance T1 is the distance between each of the short sides F1 and each of the short sides E1 of the first surface 34a opposite to that short side F1. Similarly, distance T2 is the distance between each of the long sides F2 and each of the long sides E2 of the first surface 34a opposite to that long side F2.

[0090] Furthermore, the first portion 52a of the second layer 52, the fourth portion 53a of the third layer 53, the fourth layers 54a, 54b, and the fifth layers 55a, 55b, i.e., the effective area 50p of the optical branching film 50, have the same shape as the first layer 51 when viewed from the first direction D1. Additionally, in Figure 5 (Illustrations omitted) In this embodiment, the second layer 52 and the third layer 53 reach the outer edge 34e of the first surface 34a (however, they may not). Therefore, in this embodiment, an optical branching film 50 is formed on the entire first surface 34a.

[0091] Furthermore, in the beam splitter 3, films with optical functions, such as reflective films or antireflective films, can be formed on each surface. For example, in the beam splitter 3, antireflective films can be formed on the optical surface 33d, which serves as the incident surface for one incident light (measurement light L0), and the optical surface 33a, which serves as the incident surface for another incident light (laser L10). Additionally, in the beam splitter 3, a reflective film that reflects light transmitted through the optical branching film 50 can be formed on the second reflective mirror 32 (third surface), located on the opposite side of the optical surface 33d, separated from the first reflective mirror surface 31 (optical branching film 50). Moreover, in the beam splitter 3, antireflective films can be formed on the exiting surfaces, namely the optical surfaces 33b and 33c, where light reflected by the optical branching film 50 exits to the outside.

[0092] Next, an embodiment of the beam splitter manufacturing method for manufacturing the above-mentioned beam splitter 3 will be described. Figures 6-8 This is a diagram illustrating one step in the manufacturing process of a beam splitter. (Example:) Figure 6 As shown, here, firstly, a first component 34P and a second component 35P are prepared (step S101, first step). The first component 34P is a component comprising a plurality of optical blocks 34 continuously arranged in one direction, and the second component 35P is a component comprising a plurality of optical blocks 35 continuously arranged in one direction. In other words, the first component 34P comprises a plurality of portions that become optical blocks 34 by cutting in step S104 described later, and the second component 35P comprises a plurality of portions that become optical blocks 35 by cutting in step S104 described later.

[0093] Next, an optical branching film 50 is formed on the first surface 34a of each of the plurality of optical blocks 34 included in the first component 34P (step S102, second step). Here, the optical branching film 50 is formed together with the plurality of first surfaces 34a that are continuous in one direction. At this time, the optical branching films 50 that are adjacent to each other are connected to each other in the non-effective region 50r, and can also be separated.

[0094] Next, as Figure 7 As shown, the first component 34P and the second component 35P are bonded together by the adhesive member 40 (step S103, third step). At this time, the first component 34P and the second component 35P are arranged opposite each other with a surface 34m formed by a plurality of first surfaces 34a of the first component 34P and a surface 35m formed by a plurality of second surfaces 35a of the second component 35P, and then bonded together. Thus, an optical splitting film 50 is interposed between each of the first surfaces 34a and each of the second surfaces 35a, forming a structure MP including a plurality of beam splitters 3.

[0095] Next, as Figure 8As shown, for example, by cutting the structure MP into a single piece, multiple beam splitters 3 are obtained from the structure MP (step S104, fourth step). Furthermore, a grinding step on the surface of the structure MP can be performed between step S103 and step S104 (step S105, fifth step). In step S105, at least the bottom surface 3s (optical surfaces 33b, 33c) that contacts the external component when the beam splitter 3 is mounted on the external component can be ground. Alternatively, step S105 can be performed after step S104. That is, after step S104, at least the surfaces such as the bottom surface 3s (optical surfaces 33b, 33c) of the beam splitter 3 obtained by single-piece cutting of the structure MP can be ground.

[0096] As explained above, in the beam splitter 3, optical blocks 34 and 35 are bonded together by adhesive members 40 while being interposed in an optical branching film 50. The optical branching film 50 includes a first layer 51 formed on a first surface 34a of the optical block 34 opposite to the optical block 35, and a second layer 52 stacked on the first surface 34a and the first layer 51. Furthermore, the second layer 52 includes a first portion 52a extending to cover the upper surface of the first layer 51, a second portion 52b extending from the first portion 52a to cover the side of the first layer 51, and a third portion 52c extending from the second portion 52b toward the opposite side of the first layer 51.

[0097] Thus, the side surface of the first layer 51 is covered by the second layer 52 in the area where at least the second portion 52b exists (in this embodiment, the entire circumference of the side surface of the first layer 51 is covered by the second layer 52). As a result, the side surface of the first layer 51 is prevented from being exposed to the outside, suppressing corrosion and other degradation of the first layer 51. In addition, the upper surface of the first layer 51 is also covered by the first portion 52a of the second layer 52. Therefore, corrosion and other degradation of the first layer 51 are also suppressed until the optical blocks 34 and 35 are bonded (during manufacturing). Therefore, according to the beam splitter 3, degradation of optical properties is suppressed.

[0098] Furthermore, in the beam splitter 3, the second layer 52, which helps to suppress the deterioration of the first layer 51, is a layer constituting the optical branching film 50. Therefore, compared with the case where a protective film is formed separately from the optical branching film 50, it is possible to simplify the manufacturing process and reduce costs. Moreover, in the beam splitter 3, the bonding member 40 includes a first bonding portion 41 disposed in the region sandwiched by the first surface 34a and the second surface 35a, in a region opposite to the first portion 52a of the second layer 52, and a second bonding portion 42 disposed in the region opposite to the second portion 52b and the third portion 52c of the second layer 52. Therefore, the bonding between the optical block 34 and the optical block 35 becomes strong.

[0099] Furthermore, in the beam splitter 3, the optical branching film 50 has a third layer 53 stacked along the first direction D1 on the first surface 34a, the first layer 51, and the second layer 52. The third layer 53 includes: a fourth portion 53a extending to cover the first portion 52a of the second layer 52; a fifth portion 53b connected to the end of the fourth portion 53a in the second direction D2, extending along the first direction D1 to cover the second portion 52b of the second layer 52 from the end of the fourth portion 53a; and a sixth portion 53c connected to the end of the fifth portion 53b opposite to the connection portion of the fourth portion 53a, extending in the second direction D2 toward the opposite side of the first layer 51. The sixth portion 53c is arranged opposite to the third portion 52c. Therefore, the side surface of the first layer 51 is further covered by the third layer 53 in the area where at least the second portion 52b is present (in this embodiment, the entire circumference). In addition, the upper surface of the first layer 51 is also further covered by the third layer 53. As a result, corrosion and other degradation of the first layer 51 are reliably suppressed, as are degradation of optical properties.

[0100] Alternatively, in the beam splitter 3, the third layer 53 can also be an oxide layer, forming the surface 50s of the optical branching film 50 opposite to the first surface 34a, and contacting the bonding member 40. In this case, oxidation of the second layer 52 is suppressed during the period until the optical blocks 34 and 35 are bonded together (during manufacturing).

[0101] Furthermore, in the beam splitter 3, the optical branching film 50 includes a pair of fourth layers 54a and 54b arranged along the first direction D1 to clamp the first layer 51, and a pair of fifth layers 55a and 55b arranged along the first direction D1 to clamp the first layer 51 and the pair of fourth layers 54a and 54b. Moreover, a first portion 52a of the second layer 52 is formed on and in contact with the fifth layer 55b. The optical branching film 50 can also be constructed from such a multilayer structure.

[0102] Alternatively, in the beam splitter 3, the fourth layers 54a and 54b can be made of the first material, and the fifth layers 55a and 55b can be oxide layers made of the first material that has undergone an oxidizing treatment. In this case, the increase in the absorption coefficient (decrease in reflectivity and transmittance) caused by the oxidation of the first layer 51 can be suppressed. In addition, the oxidation of the fourth layers 54a and 54b can be suppressed during the period until the second layer 52 is formed (during manufacturing).

[0103] Alternatively, in the beam splitter 3, the fourth layers 54a and 54b can be composed of one of Si, Ge, SiN, and ZnS, and the fifth layers 55a and 55b can be composed of one of SiO2, Al2O3, TiO2, Y2O3, and Ta2O5. In this way, the materials for the fourth and fifth layers can also be selected from these materials.

[0104] Alternatively, in the beam splitter 3, the fourth layers 54a and 54b can also be made of the same material as the second layer 52. In this case, the number of film-forming sources can be reduced when manufacturing the optical branching film 50, making the manufacturing of the optical branching film 50 easier.

[0105] Furthermore, in the beam splitter 3, the outer edge 51e of the first layer 51, when viewed from the first direction D1, includes a short side F1 and a long side F2 extending in a direction intersecting the short side F1. Moreover, when viewed from the first direction D1, the distance T1 between the short side F1 and the outer edge 34e of the first surface 34a is greater than the distance T2 between the long side F2 and the outer edge 34e of the first surface 34a. Therefore, when bonding the optical blocks 34 and 35 (during manufacturing), even if a positional deviation occurs in the direction intersecting the short side F1 of the first layer 51, the first layer 51 is prevented from reaching the outer edge of the second surface 35a and becoming exposed.

[0106] Furthermore, in the beam splitter 3, the corner 51r of the first layer 51 when viewed from the first direction D1 can also be formed into an arc shape. In this case, even if a notch is formed at the corner of the optical block 34 or the optical block 35, the first layer 51 is not easily exposed.

[0107] Furthermore, the beam splitter 3 includes a third surface (second reflecting mirror surface 32) located on the opposite side of the incident surface (optical surface 33d), separated from the first surface 34a, the optical branching film 50, and the second surface 35a. Moreover, a reflective film that reflects light transmitted through the optical branching film 50 can be formed on this third surface. In this case, light transmitted through the optical branching film 50 can be reflected along a predetermined direction.

[0108] Alternatively, in beam splitter 3, an anti-reflective film can be formed on the exit surface where light reflected by the optical branching film 50 is emitted to the outside. In this case, reflections on the exit surface are suppressed when light reflected by the optical branching film 50 is emitted.

[0109] Alternatively, an anti-reflective coating can be formed on the incident surface in beam splitter 3. In this case, reflection of the incident light on the incident surface is suppressed.

[0110] Alternatively, in the beam splitter 3, the first layer 51 can be made of a metallic material, and the second layer 52 can be made of a semiconductor or dielectric material. In this case, corrosion and other degradation of the first layer 51 made of metallic material can be suppressed.

[0111] Alternatively, in the beam splitter 3, the first layer 51 may be composed of Ag or Al, and the second layer 52 may be composed of one of Si, Ge, SiO2, SiN, Al2O3, Y2O3, Ta2O5, TiO2, and ZnS. In this case, corrosion and other deterioration of the first layer 51 composed of Ag or Al can be suppressed.

[0112] Here, the beam splitter manufacturing method includes: step S101, preparing a first member 34P comprising a plurality of portions forming optical blocks 34 and a second member 35P comprising a plurality of portions forming optical blocks 35; step S102, forming an optical branching film 50 on the first surface 34a of each of the plurality of optical blocks 34 included in the first member 34P; step S103, bonding the optical blocks 34 and optical blocks 35 together with an adhesive member 40 through the optical branching film 50 to form a structure MP comprising a plurality of continuous beam splitters 3; and step S104, obtaining a plurality of beam splitters 3 from the structure MP by monolithizing the structure MP. According to this method, a beam splitter capable of suppressing the degradation of optical characteristics can be manufactured with high efficiency.

[0113] Alternatively, the beam splitter manufacturing method may include a step S105 between steps S103 and S104, in which the surface of the structure MP is ground. Furthermore, in step S105, at least the surfaces of the structure MP, including multiple bottom surfaces 3s, may be ground. In this case, by flattening the contact surface (bottom surface 3s) of the beam splitter 3 with the external component, it is easier to mount the beam splitter 3 onto the external component. Additionally, when this contact surface is set as the light emission surface of the beam splitter 3, the deviation in the optical path length from the incident surface to the emission surface can be reduced by grinding the contact surface that serves as the emission surface.

[0114] The above embodiments illustrate one aspect of the present invention. Therefore, the present invention is not limited to the above embodiments and can be modified in any way.

[0115] For example, such as Figure 9As shown, in the beam splitter 3, the outer edge 34e of the first surface 34a includes a first side (corresponding to one of the bottom surfaces 3s in a pair of short sides E1) facing the external component when the beam splitter 3 is mounted on the external component. Furthermore, the first layer 51 can also extend in such a way that a portion of the outer edge 51e of the first layer 51 (the side facing the bottom surface 3s in the short side F1) overlaps with the first side when viewed from the first direction D1. That is, the first layer 51 can also extend to the outer edge of the optical block 34 on the bottom surface 3s side. In this case, forming a wider first layer 51 enables the formation of a wider effective area 50p. On the other hand, a portion of the outer edge 51e of the first layer 51 reaches the first side of the outer edge 34e of the first surface 34a, but this first side is the side facing (contacting) the external component when the beam splitter 3 is mounted on the external component. Therefore, this portion of the outer edge 51e of the first layer 51 is prevented from being exposed to the outside.

[0116] Furthermore, the stacked structure of the optical branching film 50 in the above embodiment can be arbitrarily modified within the range of maintaining the first layer 51 and the second layer 52. For example, at least one layer other than the first layer 51 and the second layer 52 can be omitted, or other layers can be added.

[0117] Furthermore, the corners 51r of the first layer 51 may not be chamfered, and even if chamfered, they may not be rounded. Additionally, the shape of the first layer 51 when viewed from the first direction D1 is not limited to a long, narrow rectangle; it can be square or other shapes. The same applies to the shapes of the other layers of the optical branching film 50 or the first surface 34a.

[0118] Industrial availability

[0119] A beam splitter capable of suppressing the degradation of optical properties and a method for manufacturing the beam splitter are provided.

[0120] Explanation of reference numerals in the attached figures

[0121] 3……Beam splitter; 34……Optical block (first light-transmitting component); 34a……First surface; 35……Optical block (second light-transmitting component); 35a……Second surface; 40……Adhesive component; 41……First adhesive part; 42……Second adhesive part; 50……Optical branching film; 51……First layer; 52……Second layer; 52a……First part; 52b……Second part; 52c……Third part; 53……Third layer; 53a……Fourth part; 53b……Fifth part; 53c……Sixth part; 54a, 54b……Fourth layer; 55a, 55b……Fifth layer; E1, F1……Short side; E2, F2……Long side.

Claims

1. A beam splitter, wherein, It is a beam splitter used to split incident light into multiple different components and emit them outwards. The beam splitter includes: A first light-transmitting component has a first surface that transmits the incident light; The second light-transmitting component has a second surface that is transmissive to the incident light; An optical branching film, which has the function of branching the incident light into the multiple components; as well as An adhesive component for bonding the first light-transmitting component and the second light-transmitting component. The first light-transmitting member and the second light-transmitting member are arranged opposite each other such that the optical branching film is sandwiched between the first surface and the second surface. The optical branching film has the following characteristics: The first layer is formed on the first surface; as well as The second layer is stacked on top of the first surface and the first layer along a first direction intersecting the first surface. The second layer includes: The first part extends in such a way as to cover the upper surface opposite to the first surface of the first layer; The second portion connects to the end of the first portion in a second direction intersecting the first direction, extending along the first direction such that it covers the side of the first layer from the end of the first portion; and The third part connects to the end of the second part opposite to the connection portion of the first part, and extends in the second direction toward the opposite side of the first layer. The adhesive component has: A first adhesive portion, disposed in a region of the second layer opposite to the first portion thereof in the area sandwiched between the first and second surfaces; and The second adhesive portion, which is integrally formed with the first adhesive portion, is disposed in the region of the second layer opposite to the second portion and the third portion of the second layer in the region sandwiched between the first surface and the second surface.

2. The beam splitter according to claim 1, wherein, The optical branching film has a third layer stacked along the first direction on the first surface, the first layer, and the second layer. The third layer includes: The fourth part extends in a manner that covers the first part of the second layer; The fifth portion, which connects to the end of the fourth portion in the second direction, extends along the first direction such that it covers the second portion of the second layer from the end of the fourth portion; and The sixth part, which connects to the end opposite to the connection portion of the fourth part in the fifth part, extends in the second direction toward the opposite side of the first layer. The sixth part is configured in a manner opposite to the third part.

3. The beam splitter according to claim 2, wherein, The third layer is an oxide layer. The third layer forms the surface of the optical branching film opposite to the first surface and is in contact with the adhesive member.

4. The beam splitter according to any one of claims 1 to 3, wherein, The optical branching film includes: A pair of fourth layers, configured to clamp the first layer along the first direction; and A pair of fifth layers, configured to sandwich the first layer and the pair of fourth layers along the first direction. The first portion of the second layer is formed on and connected to the fifth layer.

5. The beam splitter according to claim 4, wherein, The fourth layer is made of the first material. The fifth layer is an oxide layer made of a material that has undergone an oxidizing treatment on the first material.

6. The beam splitter according to claim 4 or 5, wherein, The fourth layer is composed of one of Si, Ge, SiN, and ZnS. The fifth layer is composed of one of SiO2, Al2O3, TiO2, Y2O3, and Ta2O5.

7. The beam splitter according to any one of claims 4 to 6, wherein, The fourth layer is made of the same material as the second layer.

8. The beam splitter according to any one of claims 1 to 7, wherein, When viewed from the first direction, the outer edge of the first layer includes a short side and a long side extending in a direction intersecting the short side. Viewed from the first direction, the distance between the short side and the outer edge of the first surface is greater than the distance between the long side and the outer edge of the first surface.

9. The beam splitter according to any one of claims 1 to 8, wherein, The outer edge of the first surface includes a first side facing the external component when the beam splitter is mounted on the external component. The first layer extends such that a portion of the outer edge of the first layer overlaps with the first edge when viewed from the first direction.

10. The beam splitter according to any one of claims 1 to 9, wherein, When viewed from the first direction, the corners of the first layer are formed into an arc shape.

11. The beam splitter according to any one of claims 1 to 10, wherein, have: The incident surface of the incident light; and The third surface, located on the opposite side of the incident surface, is separated from the first surface, the optical branching film, and the second surface. A reflective film is formed on the third surface to reflect the light that has been transmitted through the optical branching film.

12. The beam splitter according to any one of claims 1 to 11, wherein, It has: an exit surface that allows light reflected by the optical branching film to exit to the outside. An anti-reflective film is formed on the emission surface.

13. The beam splitter according to any one of claims 1 to 12, wherein, It has an incident surface for the incident light. An anti-reflective film is formed on the incident surface.

14. The beam splitter according to any one of claims 1 to 13, wherein, The first layer is made of metallic material. The second layer is composed of semiconductor material or dielectric material.

15. The beam splitter according to any one of claims 1 to 14, wherein, The first layer is composed of Ag or Al. The second layer is composed of one of Si, Ge, SiO2, SiN, Al2O3, Y2O3, Ta2O5, TiO2, and ZnS.

16. A method for manufacturing a beam splitter, wherein, This is a method for manufacturing a beam splitter used to manufacture any one of claims 1 to 15. have: The first step involves preparing a first component comprising multiple portions that become the first light-transmitting component and a second component comprising multiple portions that become the second light-transmitting component; In the second step, after the first step, the optical branching film is formed on the first surface of each of the plurality of portions that become the first light-transmitting member included in the first member; The third step, after the second step, involves bonding the first component and the second component together using the adhesive member through the optical branching film to form a structure comprising a plurality of continuous beam splitters. as well as The fourth step, following the third step, involves monolithizing the structure to obtain a plurality of beam splitters from the structure.

17. The method for manufacturing a beam splitter according to claim 16, wherein, Between the third and fourth steps, there is a fifth step that grinds the surface of the structure. The beam splitter includes a contact surface that contacts the external component when the beam splitter is mounted on the external component. In the fifth step, at least the surfaces of the structure, including the plurality of contact surfaces, are ground.

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