Light source unit and optical head

Abstract

This light source unit comprises a plurality of light sources that emit light that is to illuminate an object and a holding part that holds the plurality of light sources and has, formed therein, an insertion hole that an optical fiber for propagating light from the object is inserted into. The holding part holds the plurality of light sources such that the areas illuminated by the light from the plurality of light sources are on one side of the holding part. The insertion hole includes a first opening that faces the illuminated areas and a second opening that is a different opening from the first opening. The insertion hole is formed in the holding part such that when the optical fiber is inserted into the insertion hole, one end surface of the optical fiber is exposed from the first opening and faces the illumination areas and such that when the optical fiber is inserted into the insertion hole, one end part including the one end surface of the optical fiber is positioned between the plurality of light sources with a light blocking member between the one end part and the plurality of light sources.

Description

[Technical field]

[0001] The present disclosure relates to a light source unit and an optical head. [Background technology]

[0002] Patent Document 1 describes a near-infrared interactance spectroscopy measurement device. This measurement device includes a device body and a probe. A flexible cable is provided so as to connect the device body and the probe, and an optical fiber is housed in the flexible cable. A spectrometer, a detector, and the like are provided inside the device body. The probe includes a housing. A plurality of light-emitting light sources are arranged inside the housing, facing a measurement opening provided in one wall of the housing. An incident end of an optical fiber is arranged on another wall of the housing. Interactance light from a sample irradiated with light from the light source is incident on the incident end of the optical fiber via a right-angle prism and a condenser lens. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-4498 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the probe of the above-mentioned measuring device, the light source is provided close to the measurement opening of the housing, while the incident end of the optical fiber is arranged in a wall part of the housing different from the wall part in which the measurement opening is formed. Therefore, even if the probe is arranged so that the measurement opening and the light source are close to the sample, the incident end of the optical fiber cannot be brought close to the sample, so it is difficult to effectively propagate weak light from the sample to the detector through the optical fiber. In response to this, it is possible to arrange the incident end of the optical fiber in the probe of the above-mentioned measuring device near the measurement opening, but in this case, stray light is likely to be incident on the optical fiber.

[0005] Therefore, an object of the present disclosure is to provide a light source unit and an optical head that enable effective propagation of light from an object through an optical fiber while suppressing the incidence of stray light into the optical fiber. [Means for solving the problem]

[0006] The light source unit of the present disclosure comprises a plurality of light sources that emit light to be irradiated onto an object, and a holding portion that holds the plurality of light sources and has an insertion hole formed therein through which an optical fiber for propagating light from the object is inserted, the holding portion holds each of the plurality of light sources such that an irradiation area of ​​the light of each of the plurality of light sources is formed on one side of the holding portion, the insertion hole includes a first opening that is an opening facing the irradiation area and a second opening that is different from the first opening, and is formed in the holding portion such that when the optical fiber is inserted, one end face of the optical fiber is exposed from the first opening and faces the irradiation area, and when the optical fiber is inserted into the insertion hole, one end including one end face of the optical fiber is positioned between the plurality of light sources via a light-shielding member.

[0007] In this light source unit, a holding part that holds a plurality of light sources is formed with an insertion hole through which an optical fiber is inserted. In particular, when the optical fiber is inserted into the insertion hole, one end including one end face of the optical fiber is positioned between the plurality of light sources via the light shielding member. Therefore, by disposing this light source unit so that the light source is close to the object, it is possible to bring one end face of the optical fiber close to the object as well, so that weak light from the object can be effectively propagated by the optical fiber. Furthermore, by interposing a light shielding member between the light source and one end of the optical fiber, it is possible to suppress the incidence of stray light into the optical fiber.

[0008] In the light source unit according to the present disclosure, the insertion hole may be formed in the holding part such that one end face of the optical fiber protrudes from the first opening when the optical fiber is inserted. In this case, the protruding one end face of the optical fiber allows the one end face of the optical fiber to be closer to the object. This allows weak light from the object to be effectively propagated by the optical fiber.

[0009] In the light source unit according to the present disclosure, the inner surface of the insertion hole may include a tapered portion that is tapered so that the insertion hole expands from the first opening toward the second opening and is connected to the second opening. In this case, when the optical fiber is inserted into the insertion hole from the second opening of the insertion hole, one end of the optical fiber can be guided toward the first opening by the tapered portion of the inner surface of the insertion hole.

[0010] In the light source unit according to the present disclosure, the holding portion may include a flat portion intersecting a direction from the first opening toward the second opening, and the flat portion may be formed on at least one of an end face of the holding portion where the second opening is formed and an inner surface of the insertion hole. In this case, when the optical fiber is inserted into the insertion hole, for example, by abutting a separate member that holds the optical fiber against the flat portion of the holding portion, it becomes possible to position the optical fiber in the direction from the first opening toward the second opening (i.e., the optical axis direction of the optical fiber inserted into the insertion hole).

[0011] In the light source unit according to the present disclosure, the holding portion may include a light-shielding member protruding along the edge of the first opening so as to cover one end of the optical fiber when the optical fiber is inserted into the insertion hole and protrudes from the first opening. By providing the light-shielding member in the holding portion in this manner, it is not necessary to perform an operation such as covering one end of the optical fiber with a light-shielding member when suppressing the incidence of stray light into the optical fiber. However, the optical fiber may be covered with a light-shielding member.

[0012] In the light source unit according to the present disclosure, the holding section holds the multiple light sources such that the irradiation regions of the multiple light sources overlap each other, and the insertion hole may be formed such that, when the optical fiber is inserted, the optical axis of the optical fiber passes through an overlapping region where the irradiation regions of the multiple light sources overlap. In this case, an intersection is formed where the irradiation regions of the multiple light sources intersect with the optical axis of the optical fiber inserted into the insertion hole. Therefore, by arranging the light source unit so that the target is aligned with this intersection, it is possible to effectively make the light from the target enter the optical fiber.

[0013] In the light source unit according to the present disclosure, the holder is formed with a hole in which the multiple light sources are arranged, the holder holds the multiple light sources with the outer surfaces of the multiple light sources in contact with the inner surface of the hole, and at least the portion of the inner surface of the hole that contacts the outer surfaces of the multiple light sources may be formed in a shape that conforms to the shape of the outer surfaces of the light sources. In this case, the contact area between the inner surface of the hole and the light source is increased, enabling effective heat dissipation from the light source to the holder.

[0014] In the light source unit according to the present disclosure, the holding part may include a resin part filled between the inner surface of the hole part and the outer surface of the light source. In this case, more effective heat dissipation from the light source to the holding part is possible. Furthermore, as described above, when the light source is in contact with the inner surface of the hole part and the shape of the inner surface of the hole part is aligned with the shape of the outer surface of the light source, filling the space between the inner surface of the hole part and the outer surface of the light source with resin reduces the amount of resin used, and as a result, the resin is less likely to strain (stress) the light source.

[0015] The optical head according to the present disclosure is an optical head for irradiating an object with light and providing light from the object to a photodetector, and includes the above-mentioned light source unit, a fixing portion for holding the optical fiber and fixing the position of the optical fiber, an optical fiber fixed to the fixing portion and inserted into the insertion hole, a housing for accommodating at least a portion of the light source unit, the fixing portion, and the optical fiber, and a light-transmitting window member arranged to face one end face of the optical fiber.

[0016] This optical head includes the light source unit described above. Therefore, it is possible to achieve the same effects as the light source unit described above. Furthermore, this optical head includes a window member arranged to face one end face of the optical fiber. Therefore, it is possible to keep one end face of the optical fiber clean. As described above, this light source unit allows the one end face of the optical fiber to be closer to the object, so that it is more effective to prevent contamination of the one end face of the optical fiber by using the window member.

[0017] The optical head according to the present disclosure may include a light-shielding member provided on the optical fiber so as to cover at least one end of the optical fiber while leaving one end surface exposed. By providing the light-shielding member on the optical fiber in this manner, it is not essential to provide a light-shielding member on the holding portion of the light source unit when suppressing the incidence of stray light into the optical fiber. However, the light-shielding member may be provided on the holding portion.

[0018] In the optical head according to the present disclosure, the light source unit and the fixed part are formed separately from each other, the fixed part holds the optical fiber with one end of the optical fiber protruding from the fixed part, and the light source unit may be detachably attached to the fixed part with the one end of the optical fiber protruding from the fixed part inserted into the insertion hole. In this case, for example, when the light source breaks down, it becomes possible to easily replace the entire light source unit.

[0019] In the optical head according to the present disclosure, the window member may face the multiple light sources so that the light emitted from the multiple light sources passes through the window member, and may be provided in a position with respect to the optical axis direction of the optical fiber such that the light emitted from the multiple light sources and reflected by the window member does not enter the optical fiber. In this case, it is possible to prevent the light reflected by the window member without passing through the object from entering the optical fiber as stray light.

[0020] In the optical head according to the present disclosure, the window member is provided facing the multiple light sources so that the light emitted from the multiple light sources passes through, the wavelength range of the light emitted from the multiple light sources includes a first wavelength range included in the sensitivity range of the photodetector and a second wavelength range different from the sensitivity range of the photodetector, and the window member may reduce the reflectance of the first wavelength range and reduce the transmittance of the second wavelength range. In this case, the component of the first wavelength range included in the sensitivity range of the photodetector of the light from the light source can be efficiently irradiated onto the object, and the component of the second wavelength range not included in the sensitivity range of the photodetector of the light from the light source can be prevented from reaching the object, thereby preventing damage to the object.

[0021] The optical head according to the present disclosure includes a circuit board having a main surface and electrically connected to a light source, and a support member supporting a light source unit and a fixed portion, the light source unit and the fixed portion being arranged along a direction from a first opening to a second opening, the circuit board being arranged to face the light source unit and the fixed portion when viewed from a direction along the main surface, and the support member may be formed such that a path from the light source unit to the circuit board via the support member is longer than a distance between the circuit board and the light source unit in a direction intersecting the main surface when viewed from a direction along the main surface. In this case, space is reduced by arranging the circuit board, the light source unit, and the fixed portion opposite each other using the support member. At this time, the path from the light source unit to the circuit board via the support member is longer than a direct distance between the light source unit and the circuit board, so that the heat generated by the light source can be suppressed from being transmitted to the circuit board. This suppresses malfunctions and deterioration of characteristics due to heat.

[0022] The optical head according to the present disclosure may include a connector provided at the other end of the optical fiber for connecting the optical fiber to another optical fiber, in which case the optical fiber can be easily connected to another optical fiber using the connector.

[0023] The optical head according to the present disclosure includes a connector holding member for holding a connector and a fixing member for fixing the connector holding member to a housing, and the connector holding member may be provided with an elongated hole, the connector holding member may be disposed on a wall of the housing such that the elongated hole is aligned with the optical axis direction of the optical fiber, and may be fixed to the wall by a fixing member inserted into the elongated hole. In this case, the positions of the optical fiber, the connector, and the connector holding member can be easily adjusted in the extension direction of the elongated hole (i.e., the optical axis direction of the optical fiber).

[0024] The optical head according to the present disclosure may include a cap that holds the window member, and the cap may be disposed outside the housing and attached to the housing, in which case the window member can be attached and detached outside the housing.

[0025] In the optical head according to the present disclosure, the fixing portion may include a light-shielding member that covers one end of the optical fiber and is inserted into the insertion hole together with the optical fiber and protrudes from the first opening. By providing the light-shielding member on the fixing portion in this manner, it is not necessary to cover one end of the optical fiber with a light-shielding member or to provide a light-shielding member on the holding portion when suppressing the incidence of stray light into the optical fiber. However, the optical fiber may be covered with a light-shielding member, or a light-shielding member may be provided on the holding portion.

[0026] The optical head according to the present disclosure may include a spacer detachably attached to a holder, the spacer having a third opening for exposing the first opening and allowing light from each of the multiple light sources to pass therethrough, and the window member is attached to the holder and is interposed between the light source and the spacer. In this case, the window member keeps one end face of the optical fiber clean, and the optical head can be used both with the spacer attached and with the spacer removed.

[0027] The optical head according to the present disclosure may include a power connector attached to the housing so as to extend from the outside to the inside of the housing, for supplying power to the light source, and wiring for connecting the power connector and each lead wire of the light source. In this case, it is possible to achieve a smaller size compared to a case where the power connector and the light source are connected via a circuit board or the like. In addition, by increasing the number of light sources, for example to four or more, and using each light source with low power, heat generation of the light source can be suppressed. In this case, further miniaturization can be achieved without providing a heat sink or a cooling fan in the housing. In addition, in this case, the life of the light source can be extended. Effect of the Invention

[0028] According to the present disclosure, it is possible to provide a light source unit and an optical head that enable effective propagation of light from an object through an optical fiber while suppressing the incidence of stray light into the optical fiber. [Brief description of the drawings]

[0029] [Figure 1] FIG. 1 is a diagram showing a measurement device according to an embodiment. [Diagram 2] FIG. 2 is a perspective view showing the appearance of the optical head shown in FIG. [Diagram 3] FIG. 3 is a perspective view showing the external appearance of the optical head shown in FIG. 1, seen from another direction. [Figure 4] FIG. 4 is a perspective view showing the optical head shown in FIG. 2 with the housing omitted. [Diagram 5] FIG. 5 is a perspective view showing a state in which the housing is omitted from the optical head shown in FIG. [Figure 6] FIG. 6 is a cross-sectional view of the optical head shown in FIGS. [Figure 7] FIG. 7 is a cross-sectional view of the optical head shown in FIGS. [Figure 8] FIG. 8 is an enlarged cross-sectional view of the light source unit shown in FIGS. [Figure 9]FIG. 9 is a front view of the optical head shown in FIGS. [Figure 10] FIG. 10 is a schematic diagram for explaining the positional relationship between the light source, the optical fiber, and the window member. [Figure 11] FIG. 11 is a graph showing the spectral radiant emittance of a halogen lamp (assuming emissivity ε=1) at 2800K calculated from Planck's law of distribution. [Figure 12] FIG. 12 is a graph ((a) of FIG. 12) showing the measurement results of the spectrum of a halogen lamp when taking into account the light absorption in the glass tube, and a graph ((b) of FIG. 12) showing the characteristics of a high-pass filter made of AR-coated Si material. [Figure 13] FIG. 13 is an exploded and enlarged cross-sectional view of a part of the optical head according to the first modified example. [Figure 14] FIG. 14 is a perspective view showing a part of an optical head according to the second modified example. [Figure 15] FIG. 15 is a cross-sectional view of the optical head shown in FIG. [Figure 16] FIG. 16 is a perspective view showing a part of an optical head according to a third modified example. [Figure 17] FIG. 17 is an exploded cross-sectional view of the optical head shown in FIG. [Figure 18] FIG. 18 is an exploded cross-sectional view of the optical head shown in FIG. [Figure 19] FIG. 19 is a diagram showing a schematic view of a part of an optical head according to a fourth modified example. [Figure 20] FIG. 20 is a diagram showing an optical head according to the fifth modified example. [Figure 21] FIG. 21 is a cross-sectional view taken along line XXI-XXI in FIG. 20(b). [Figure 22] FIG. 22 is a cross-sectional view taken along line XXII-XXII in FIG. 20(b). [Figure 23] FIG. 23 is an enlarged view of a portion of FIGS. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] An embodiment will be described below with reference to the drawings. In each drawing, the same or corresponding parts are denoted by the same reference numerals, and duplicated explanations may be omitted. In addition, each drawing may show an orthogonal coordinate system defined by an X-axis, a Y-axis, and a Z-axis.

[0031] FIG. 1 is a diagram showing a measurement device according to an embodiment. As shown in FIG. 1, the measurement device A1 includes a spectrometer A2 and an optical head 1. The spectrometer A2 is, for example, a Fourier transform infrared spectrometer. The spectrometer A2 includes, for example, an optical interferometer and a control circuit. The optical interferometer includes, for example, a light input unit, a beam splitter, a fixed mirror, a movable mirror, and a photodetector. The photodetector acquires a light intensity signal that changes depending on the position of the movable mirror. The spectrometer A2 can be connected to a computer such as a PC using a USB or the like.

[0032] The optical head 1 is optically connected to the spectrometer A2 by an optical fiber A3. A power cable A4 is also connected to the optical head 1. The optical head 1 is placed near an object and receives power via the power cable A4 to irradiate the object with light. A portion of the light irradiated from the optical head 1 to the object is specularly reflected by the surfaces of particles that make up the object, and the remaining portion of the light enters the object. The light that enters the object is diffused while repeatedly undergoing refraction and transmission, light scattering, and surface reflection within the object, and a portion of the light is again emitted from the surface of the object to the outside of the object.

[0033] This light is repeatedly transmitted through the inside of the object multiple times during the light diffusion process, so the diffuse reflection spectrum is a measurement similar to the transmission spectrum. Therefore, this light is incident on the optical head 1 and provided to the spectrometer A2 via the optical fiber A3, so that the object can be analyzed using absorbance. In this way, the optical head 1 is used to irradiate the object with light, and also to input the return light from the object and provide it to the spectrometer A2 (and thus to the photodetector of the spectrometer A2).

[0034] FIG. 2 is a perspective view showing the appearance of the optical head shown in FIG. 1. FIG. 3 is a perspective view showing the appearance of the optical head shown in FIG. 1 from another direction. As shown in FIGS. 2 and 3, the optical head 1 includes a housing 2 and a cap 3 attached to the housing 2. The housing 2 is formed in the shape of a rectangular parallelepiped box here. The housing 2 includes a distal end wall portion 21 and a proximal end wall portion 22 facing each other, and four side walls 23 connecting the distal end wall portion 21 and the proximal end wall portion 22. The cap 3 is attached to the distal end wall portion 21.

[0035] The base end wall portion 22 is provided with a power switch 24, a connection portion 25 for connecting the optical fiber A3, a connection portion 26 for connecting the power cable A4, and an adjustment portion (adjustment knob) 27 for adjusting the output of the light source 40, which will be described later. Here, three of the four side walls 23 are formed with ventilation holes 28 at positions closer to the tip wall portion 21 than the base end wall portion 22.

[0036] 4 is a perspective view showing a state where a part of the housing is omitted from the optical head shown in FIG. 2. FIG. 5 is a perspective view showing a state where a part of the housing is omitted from the optical head shown in FIG. 3. FIGS. 6 and 7 are cross-sectional views of the optical head shown in FIGS. 2 and 3. As shown in FIGS. 4 to 7, the optical head 1 has a light source unit 4, a fixed portion 5, an optical fiber 6, a circuit board 7, a support member 8, a heat sink 9, a fan 10, and a holding member 11. A part of the light source unit 4 on the fixed portion 5 side, the fixed portion 5, the optical fiber 6, the circuit board 7, the support member 8, the heat sink 9, the fan 10, and the holding member 11 are housed in the housing 2.

[0037] The light source unit 4 includes a plurality of light sources 40 and a holder 41 that holds the plurality of light sources 40. The light source 40 is, for example, a halogen lamp. However, any light source can be used as the light source 40. For example, the light source 40 can be a thermal light source, an incandescent light bulb, a halogen lamp, a tungsten lamp, a graphene light source, or the like, and can be a light emitting diode (LED), a laser diode (LD), a super luminescent diode (SLD), a vertical cavity surface emitting laser (VCSEL), or the like, as a light emitting diode or a semiconductor laser. The light sources 40 are each electrically connected to the circuit board 7. As a result, the light source 40 can be turned on and off in response to the operation of the power switch 24, and the output can be adjusted in response to the operation of the adjustment unit 27. The holder 41 is formed with an insertion hole 42 through which the optical fiber 6 is inserted. Details of the light source unit 4 will be described later.

[0038] The fixing portion 5 holds the optical fiber 6 and fixes the position of the optical fiber 6. More specifically, the fixing portion 5 has a through hole 51 extending along one direction (here, the Y direction) formed therein. Thus, openings of the through hole 51 are formed on both end faces of the fixing portion 5 intersecting (orthogonal to) the Y direction. In particular, the fixing portion 5 includes a rectangular plate-shaped base portion 52 with the Y direction (extension direction of the through hole 51) as the longitudinal direction, and a protruding portion 53 provided protruding from the base portion 52 along the Y direction.

[0039] The base portion 52 includes an end face 52a that intersects (is perpendicular to) the Y direction, and an end face 52b that intersects (is perpendicular to) the Y direction and is opposite to the end face 52a. The protrusion 53 protrudes from the end face 52a, and includes an end face 53a that intersects (is perpendicular to) the Y direction and faces the opposite side to the base portion 52. The through hole 51 opens to the end face 52b of the base portion 52 and also opens to the end face 53a of the protrusion 53.

[0040] The light source unit 4 and the fixed portion 5 are configured separately from each other and are arranged along the Y direction. In this state, the light source unit 4 is fixed to the fixed portion 5 by a fixing member 49 such as a screw.

[0041] When inserted into the through hole 51, the optical fiber 6 protrudes from the end faces 52b and 53a, and is pressed against and fixed to the inner surface of the through hole 51 by a fixing member 54 such as a screw that penetrates the protruding portion 53 in a direction intersecting the Y direction and reaches the inside of the through hole 51. Therefore, the Y direction, which is the extension direction of the through hole 51, is the extension direction of the optical fiber 6 and is also the optical axis direction of the optical fiber 6. One end 61 of the optical fiber 6 protrudes from the fixing portion 5 and is inserted into the insertion hole 42 of the holding portion 41 of the light source unit 4. The other end 62 of the optical fiber 6 protrudes from the fixing portion 5.

[0042] At least one end 61 of the optical fiber 6 is covered by a sleeve 63 while exposing one end face 61a of the optical fiber 6. Here, the sleeve 63 extends to reach the one end face 61a. That is, here, the end of the sleeve 63 and the one end face 61a are flush with each other. The sleeve 63 is a light-shielding member made of, for example, metal. The fixing member 54 is disposed so as to come into contact with the sleeve 63 when fixing the optical fiber 6. A connector 64 is attached to the other end 62 of the optical fiber 6 for connecting the optical fiber 6 to another optical fiber (for example, the optical fiber A3).

[0043] The circuit board 7 includes a main surface 7s. When viewed from the Y direction, the circuit board 7 is disposed such that the main surface 7s faces the light source unit 4 and the fixed portion 5. That is, when viewed from the Y direction, the circuit board 7, the light source unit 4, and the fixed portion 5 are stacked along the Z direction, which is a direction intersecting (orthogonal to) the main surface 7s. In this state, the circuit board 7 is attached to the bottom plate 29, which is one of the side wall portions 23 of the housing 2, while being spaced apart from the bottom plate 29.

[0044] The support member 8 supports the light source unit 4 and the fixing portion 5 on the bottom plate 29 and the circuit board 7 while separating the light source unit 4 and the fixing portion 5 from the circuit board 7 along the Z direction. The support member 8 is attached to the bottom plate 29. For example, the light source unit 4 can be supported by the support member 8 via the fixing portion 5 by the fixing portion 5 being supported by the support member 8. The heat sink 9 is disposed in contact with the surface of the fixing portion 5 opposite to the surface on the circuit board 7 side. The fan 10 is disposed on the heat sink 9. As a result, for example, a part of the heat generated by the light source 40 of the light source unit 4 is input to the heat sink 9 via the fixing portion 5 and discharged to the outside by the fan 10.

[0045] Here, the holding member 11 is formed in an L-shaped plate shape. More specifically, the holding member 11 includes a plate-shaped fixing portion 111 extending along the bottom plate 29, and a plate-shaped holding portion 112 extending from the fixing portion 111 along the base end wall portion 22 of the housing 2. The holding member 11 contacts the bottom plate 29 at the fixing portion 111, and contacts the base end wall portion 22 at the holding portion 112. The holding member 11 is fixed to the bottom plate 29 at the fixing portion 111, and holds the connection portion 25 at the holding portion 112. The connector 64 attached to the other end portion 62 of the optical fiber 6 is attached to the connection portion 25 held by the holding portion 112. That is, the holding member 11 is a connector holding member that holds the connector 64 via the connection portion 25.

[0046] Further, here, a fixing member 113 is used for fixing the holding member 11 to the housing 2. An elongated hole 111h is formed in the fixing portion 111. The holding member 11 is disposed on the bottom plate 29 (wall portion) of the housing 2 so that the elongated hole 111h is aligned with the optical axis direction of the optical fiber 6, and is fixed to the bottom plate 29 by the fixing member 113 inserted into the elongated hole 111h.

[0047] As shown in FIG. 6, the cap 3 includes a light-transmitting window member 31 arranged to face one end face 61a of the optical fiber 6 and the light source 40, and as shown in FIG. 7, is fixed to the tip wall portion 21 of the housing 2 by a fixing member 32 such as a screw.

[0048] Next, the light source unit will be described in detail. Fig. 8 is an enlarged cross-sectional view of the light source unit shown in Figs. 6 and 7. Fig. 8 shows a state in which the light source unit 4 is removed from the fixed part 5. As shown in Figs. 6 to 8 and as described above, the light source unit 4 includes a plurality of light sources 40 and a holder 41 that holds the light sources 40. The holder 41 is formed in a trapezoidal plate shape when viewed from the Z direction. More specifically, the holder 41 is formed in a trapezoid shape that decreases with increasing distance from the fixed part 5 when viewed from the Z direction.

[0049] The holding portion 41 includes an end face 43 that intersects (is perpendicular to) the Y direction and faces the side opposite to the fixed portion 5, and an end face 44 that intersects (is perpendicular to) the Y direction and faces the fixed portion 5. The holding portion 41 also has a recess 45 that opens into the end face 43, and a plurality of holes 46 that open into the end face 44 and are connected to the recess 45. A light source 40 is disposed in each of the plurality of holes 46. Therefore, the number of holes 46 is at least the same as the number of light sources 40. The holes 46 are inclined from the end face 44 toward the end face 43 so as to approach the central axis of the holding portion 41 along the Y direction (here, the optical axis of the optical fiber 6).

[0050] The light source 40 is pressed and fixed against the inner surface 46s of the hole 46 by a fixing member 47, such as a screw, which passes through the holding portion 41 and reaches into the hole 46. That is, the holding portion 41 holds the light source 40 in a state in which the outer surface 40s of the light source 40 is in contact with the inner surface 46s of the hole 46. The inner surface 46s of the hole 46 has a shape that follows the shape of the outer surface 40s of the light source 40, at least in the portion that contacts the outer surface 40s of the light source 40.

[0051] As an example, here, the outer surface 40s of the light source 40 is cylindrical, and the inner surface 46s of the hole 46 is cylindrical with a larger diameter than the outer surface 40s of the light source 40. Here, there is a gap between the inner surface 46s of the hole 46 and the outer surface 40s of the light source 40, but the light source unit 4 may have a resin portion filled between the inner surface 46s of the hole 46 and the outer surface 40s of the light source 40.

[0052] Here, the insertion hole 42 through which the optical fiber 6 is inserted is connected to the recess 45 and has an opening (first opening) in the recess 45, and has an opening (second opening) 42b on the end surface 44. In this manner, the insertion hole 42 and the hole 46 are both opened in the recess 45. The light source 40 is arranged such that its light emitting portion 40p is disposed in the recess 45, and is disposed in the hole 46 so that the light emitting portion 40p faces the side opposite the fixed portion 5. That is, the holding portion 41 holds the multiple light sources 40 such that the light irradiation area 40A of each of the multiple light sources 40 is formed on one side of the holding portion 41 (the side opposite the fixed portion 5). The irradiation area 40A is an area irradiated with light emitted from the light source 40 (light emitting portion 40p).

[0053] Therefore, the opening 42a of the insertion hole 42 is an opening facing the irradiation area 40A, and one end face 61a of the optical fiber 6 inserted in the insertion hole 42 faces the irradiation area 40A. In this way, the insertion hole 42 is formed in the holding part 41 so that when the optical fiber 6 is inserted, the one end face 61a of the optical fiber 6 is exposed from the opening 42a and faces the irradiation area 40A. In particular, here, the insertion hole 42 is formed so that when the optical fiber 6 is inserted, the one end face 61a of the optical fiber 6 protrudes from the opening 42a. Furthermore, in the light source unit 4, when the optical fiber 6 is inserted in the insertion hole 42, the one end 61 including the one end face 61a of the optical fiber 6 is positioned between the multiple light sources 40 via the sleeve (light shielding member) 63. As an example, in a state in which the optical fiber 6 is inserted in the insertion hole 42, the end of the light source 40 on the end face 43 side and the one end face 61a of the optical fiber 6 are flush with each other.

[0054] A flat surface 42p intersecting (orthogonal to) the Y direction is formed on the inner surface 42s of the insertion hole 42. When the light source unit 4 is attached to the fixed portion 5 while inserting the optical fiber 6 through the insertion hole 42, an end surface 53a of the protruding portion 5 of the fixed portion 5 abuts against this flat surface 42p. Similarly, when the light source unit 4 is attached to the fixed portion 5, an end surface 52a of the base portion 52 of the fixed portion 5 abuts against an end surface 44 of the holding portion 41. That is, the holding portion 41 includes a flat surface that intersects with a direction from the opening 42a of the insertion hole 42 toward the opening 42b (Y direction), and the flat surface is formed on at least one of the end surface 44 of the holding portion 41 where the opening 42b is formed and the inner surface 42s of the insertion hole 42 (here, both).

[0055] Here, a flange portion 48 is formed on the holding portion 41. The holding portion 41 is fixed to the fixing portion 5 by a fixing member 49 inserted into the flange portion 48. Also, a hole portion through which a positioning pin B is inserted is formed on the flange portion 48.

[0056] This positioning pin B is used when attaching the light source unit 4 to the fixed portion 5. That is, when attaching the light source unit 4 to the fixed portion 5, the positioning pin B is attached to the fixed portion 5 in advance. The fixed portion 5 holds the optical fiber 6 in a state in which one end 61 of the optical fiber 6 protrudes from the end face 53a of the protrusion 53. In this state, the positioning pin B is inserted into the hole of the flange portion 48. Then, the light source unit 4 is slid along the positioning pin B so that the optical fiber 6 is inserted into the insertion hole 42 of the holder 41, and is brought into contact with the fixed portion 5.

[0057] Thereafter, the light source unit 4 is attached to the fixing portion 5 by fixing the flange portion 48 to the fixing portion 5 using the fixing member 49. After this, the positioning pin B is removed. In this way, the light source unit 4 is detachably attached to the fixing portion 5 with one end portion 61 of the optical fiber 6 protruding from the fixing portion 5 inserted into the insertion hole 42. Also, during attachment, the position in the plane intersecting the Y direction is kept constant by the positioning pin B. Therefore, when it becomes necessary to replace the light source 40, it is possible to remove and replace only the light source 40, but it is also possible to easily and accurately detach and replace the entire light source unit 4.

[0058] As described above, as shown in FIG. 9, the light source unit 4 is supported by the support member 8 so as to face the circuit board 7 together with the fixing portion 5 when viewed from the direction along the main surface 7s of the circuit board 7 (here, the Y direction). In particular, when viewed from the Y direction, the support member 8 is formed such that the path from the light source unit 4 to the circuit board 7 via the support member 8 is longer than the distance between the circuit board 7 and the light source unit 4 in the direction (here, the Z direction) intersecting the main surface 7s.

[0059] More specifically, the support member 8 includes a flat plate-like first portion 81 that extends along the main surface 7s and on which the light source unit 4 and the fixing portion 5 are placed when viewed from the Y direction, a flat plate-like second portion 82 that extends from both end portions of the first portion 81 toward the bottom plate 29 along the Z direction, and a flat plate-like third portion 83 that extends along the main surface 7s from a portion of the second portion 82 opposite to the connection portion with the first portion 81 and is fixed to the bottom plate 29, and is formed in a C-shaped plate form. And the circuit board 7 is arranged in the space surrounded by the first portion 81, the second portion 82, and the third portion 83. Thereby, the path from the light source unit 4 to the circuit board 7 via each part of the support member 8 is made longer than the direct distance between the circuit board 7 and the light source unit 4.

[0060] Fig. 10 is a schematic diagram for explaining the positional relationship between the light source, the optical fiber, and the window member. In Fig. 10, the structure of the light source unit 4 is schematicized to facilitate understanding of the positional relationship of each part. As shown in Fig. 9, the window member 31 is disposed so as to face one end face 61a of the optical fiber 6 and the light emitting portion 40p of the light source 40, and so as to pass the light emitted from the light emitting portion 40p of the light source 40. Therefore, a part of the light L1 emitted from the light emitting portion 40p of the light source 40 passes through the window member 31 and is irradiated onto the object 100.

[0061] The multiple light sources 40 are held by the holder 41 such that the irradiation regions 40A of the light L1 overlap each other. The optical fiber 6 is arranged so that its optical axis 6x passes through an overlapping region 40x where the irradiation regions 40A overlap. In other words, the insertion hole 42 is formed so that when the optical fiber 6 is inserted, the optical axis 6x of the optical fiber 6 passes through the overlapping region 40x where the irradiation regions 40A of the multiple light sources 40 overlap each other.

[0062] Furthermore, here, the bottom surface of the truncated cone L2 spreading from the edge of one end surface 61a of the optical fiber 6 at the maximum light receiving angle is made to coincide with the overlapping region 40x. As an example, when the diameter of the core of the optical fiber 6 is 600 μm, the NA is 0.22, the inclination angle of the light source 40 is 30 degrees, and the irradiation size of the light source 40 (e.g., the diameter of the light emitting part 40p) is 2.58 mm, at a position where the distance from one end surface 61a of the optical fiber 6 is 4 mm and the penetration of the light L1 into the target 100 is 0.5 mm, the size of the overlapping region 40x and the bottom surface L2s becomes approximately 3 mm and coincides with each other.

[0063] Meanwhile, another part of the light emitted from the light emitting portion 40p of the light source 40, light L3, is specularly reflected by the surface of the window member 31 on the light source unit 4 side. The window member 31 is provided at a position in the optical axis direction of the optical fiber 6 such that the light L3 specularly reflected by the window member 31 does not enter one end face 61a of the optical fiber 6. The light L3 is blocked by the sleeve 63, which is a light-blocking member.

[0064] Fig. 11 is a graph showing the spectral radiant emittance of a halogen lamp (assuming emissivity ε = 1) at 2800K calculated from Planck's law of distribution. As shown in Fig. 11, the halogen lamp radiates light energy in a wavelength range wider than the sensitivity range W1 of the spectrometer A2 (the sensitivity range of the photodetector of the spectrometer A2). The light energy input to the object is converted into heat according to the absorption rate of the object. For this reason, when using a halogen lamp or the like as the light source 40, it is desirable to cut off light in wavelength ranges other than the sensitivity range W1.

[0065] On the other hand, actual halogen lamps are equipped with a glass tube. Figure 12(a) is a graph showing the measurement results of the spectrum of a halogen lamp when light absorption in the glass tube is taken into account. In the graph of Figure 12(a), the values ​​on the vertical axis are normalized by the maximum value of wavelengths of 2 μm or more. As shown in Figure 12(a), light with wavelengths of 2.8 μm or more is unlikely to be emitted from a halogen lamp due to light absorption by the glass tube. In other words, it is considered that light on the longer wavelength side is sufficiently cut off by the glass tube with respect to the sensitivity range W1.

[0066] From this viewpoint, the window member 31 has a function of cutting light on the shorter wavelength side with respect to the sensitivity region W1. Furthermore, the window member 31 has a function of preventing reflection of light with wavelengths included in the sensitivity region W1. As an example, when the light source 40 is a halogen lamp and the sensitivity region W1 is 1100 nm to 2500 nm, the window member 31 may be made of an AR-coated Si material in order to provide both of the above functions. FIG. 12(b) is a graph showing the characteristics of a high-pass filter of an AR-coated Si material. Combining the spectrum of the halogen lamp in FIG. 12(a) and the characteristics of the filter in FIG. 12(b), it can be understood that by making the window member 31 of an AR-coated Si material, it is possible to suitably irradiate the object 100 with light of a wavelength of 1100 nm to 2500 nm.

[0067] In this way, when the wavelength range of the light emitted from the multiple light sources 40 includes a first wavelength range included in the sensitivity range W1 of the spectrometer A2 (the photodetector of the spectrometer A2) and a second wavelength range different from the sensitivity range W1 of the spectrometer A2, the window member 31 can be configured to reduce the reflectance of the first wavelength range and reduce the transmittance of the second wavelength range.

[0068] The cap 3 that holds the window member 31 as described above is disposed outside the housing 2 and attached to the housing 2 as described above. As shown in FIG. 7, the thickness H3 of the cap 3 in the Y direction defines the distance from one end face 61a of the optical fiber 6 to the object 100 when the cap 3 is brought into contact with the object 100. As an example, the thickness H3 of the cap 3 can be determined so that the end face 3s of the cap 3 opposite the housing 2 is at a position where the bottom face of the truncated cone L2 that spreads from the edge of one end face 61a of the optical fiber 6 at the maximum light receiving angle coincides with the overlapping region 40x (or a position on the housing 2 side from that position by the amount of penetration of the light L1 into the object 100). In this way, by bringing the end face 3s of the cap 3 into contact with the object 100, it is possible to easily and appropriately set the distance between the light source 40, one end face 61a of the optical fiber 6, and the object 100.

[0069] As described above, in the light source unit 4 according to the present embodiment, the insertion hole 42 through which the optical fiber 6 is inserted is formed in the holding portion 41 that holds the multiple light sources 40. In particular, when the optical fiber 6 is inserted into the insertion hole 42, the one end 61 including the one end face 61a of the optical fiber 6 is positioned between the multiple light sources 40 via the light shielding member (sleeve 63). Therefore, by disposing the light source unit 4 so that the light source 40 is close to the object 100, the one end face 61a of the optical fiber 6 can also be close to the object 100, so that the weak light from the object 100 can be effectively propagated by the optical fiber 6. Furthermore, by interposing a light shielding member between the light source 40 and the one end 61 of the optical fiber 6, it is possible to suppress the incidence of stray light into the optical fiber 6.

[0070] Moreover, in the light source unit 4, the holding portion 41 includes a planar portion (planar portion 42p and end face 44) that intersects with the direction from the opening 42a toward the opening 42b, and the planar portion is formed on at least one of (here, both of) the end face 44 of the holding portion 41 where the opening 42b is formed and the inner surface 42s of the insertion hole 42. For this reason, when the optical fiber 6 is inserted into the insertion hole 42, for example, by abutting a separate member (fixing portion 5) that holds the optical fiber 6 against the planar portion of the holding portion 41, it is possible to position the optical fiber 6 in the direction from the opening 42a toward the opening 42b (i.e., the optical axis direction of the optical fiber 6 inserted into the insertion hole 42, which is the Y direction here).

[0071] Moreover, in the light source unit 4, the holder 41 holds the multiple light sources 40 such that the irradiation regions 40A of the multiple light sources 40 overlap each other, and the insertion hole 42 is formed such that, when the optical fiber 6 is inserted, the optical axis 6x of the optical fiber 6 passes through an overlapping region 40x where the irradiation regions 40A of the multiple light sources 40 overlap. Therefore, an intersection is formed where the irradiation regions 40A of the multiple light sources 40 and the optical axis 6x of the optical fiber 6 inserted into the insertion hole 42 intersect. Therefore, by arranging the light source unit 4 so that the target 100 is aligned with this intersection, it is possible to effectively make the light from the target 100 enter the optical fiber 6.

[0072] Furthermore, in the light source unit 4, the holding part 41 is formed with holes 46 in which the multiple light sources 40 are arranged, and the holding part 41 holds the multiple light sources 40 with the outer surfaces 40s of the multiple light sources 40 in contact with the inner surfaces 46s of the holes 46, and at least the parts of the inner surfaces 46s of the holes 46 that contact the outer surfaces 40s of the multiple light sources 40 are formed in a shape that follows the shape of the outer surfaces 40s of the light sources 40. This increases the contact area between the inner surfaces 46s of the holes 46 and the light sources 40, enabling effective heat dissipation from the light sources 40 to the holding part 41.

[0073] Furthermore, in the light source unit 4, the holding portion 41 may include a resin portion filled between the inner surface 46s of the hole portion 46 and the outer surface 40s of the light source 40. In this case, more effective heat dissipation from the light source 40 to the holding portion 41 is possible. Note that, here, the holding portion 41 holds the two light sources 40 such that the two light sources 40 are arranged on a straight line perpendicular to the optical axis 6x of the optical fiber 6.

[0074] Here, the optical head 1 according to this embodiment is for irradiating the object 100 with light and providing the light from the object 100 to the spectroscope A2 (and thus the photodetector of the spectroscope A2). The optical head 1 includes a light source unit 4, a fixing portion 5 for holding the optical fiber 6 and fixing the position of the optical fiber 6, the optical fiber 6 fixed to the fixing portion 5 and inserted into the insertion hole 42, a housing 2 for accommodating at least a part of the light source unit 4, the fixing portion 5, and the optical fiber 6, and a light-transmitting window member 31 arranged to face one end face 61a of the optical fiber 6.

[0075] The optical head 1 includes the light source unit 4 described above. Therefore, it is possible to achieve the same effects as the light source unit 4 described above. Furthermore, the optical head 1 includes a window member 31 arranged to face one end face 61a of the optical fiber 6. Therefore, it is possible to keep one end face 61a of the optical fiber 6 clean. As described above, the light source unit 4 allows one end face 61a of the optical fiber 6 to be closer to the object 100, so that it is more effective to prevent contamination of one end face 61a of the optical fiber 6 by the window member 31.

[0076] The optical head 1 also includes a sleeve 63 provided on the optical fiber 6 so as to cover at least one end 61 of the optical fiber 6 while leaving one end face 61a exposed. By providing the light-shielding member on the optical fiber 6 in this manner, it is not essential to provide a light-shielding member on the holding portion 41 of the light source unit 4 when suppressing the incidence of stray light into the optical fiber 6. However, the light-shielding member may be provided on the holding portion 41.

[0077] In the optical head 1, the light source unit 4 and the fixed part 5 are formed separately from each other, the fixed part 5 holds the optical fiber 6 with one end 61 of the optical fiber 6 protruding from the fixed part 5, and the light source unit 4 is detachably attached to the fixed part 5 with the one end 61 of the optical fiber 6 protruding from the fixed part 5 inserted into the insertion hole 42. For this reason, for example, when the light source 40 breaks down, it becomes possible to easily replace the entire light source unit 4.

[0078] Moreover, in the optical head 1, the window member 31 faces the multiple light sources 40 so that the light L1 emitted from the multiple light sources 40 passes through, and is provided in a position with respect to the optical axis direction of the optical fiber 6 such that the light L3 emitted from the multiple light sources 40 and reflected by the window member 31 does not enter the optical fiber 6. Therefore, it is possible to prevent the light L3 reflected by the window member 31 without passing through the object 100 from entering the optical fiber 6 as stray light.

[0079] In addition, in the optical head 1, the window member 31 is provided facing the multiple light sources 40 so that the light emitted from the multiple light sources 40 passes through. The wavelength region of the light emitted from the multiple light sources 40 includes a first wavelength region included in the sensitivity region W1 of the photodetector and a second wavelength region different from the sensitivity region W1 of the photodetector. The window member 31 reduces the reflectance of the first wavelength region and reduces the transmittance of the second wavelength region. Therefore, the component of the first wavelength region included in the sensitivity region W1 of the photodetector out of the light from the light source 40 can be efficiently irradiated onto the object 100, and the component of the second wavelength region not included in the sensitivity region W1 of the photodetector out of the light from the light source 40 can be prevented from reaching the object 100, thereby preventing damage to the object 100.

[0080] The optical head 1 also includes a circuit board 7 having a main surface 7s and electrically connected to the light source 40, and a support member 8 supporting the light source unit 4 and the fixed portion 5. The light source unit 4 and the fixed portion 5 are arranged along a direction (Y direction) from the opening 42a toward the opening 42b. The circuit board 7 is disposed so as to face the light source unit 4 and the fixed portion 5 when viewed from a direction along the main surface 7s (e.g., Y direction). The support member 8 is formed so that a path from the light source unit 4 to the circuit board 7 via the support member 8 is longer when viewed from a direction along the main surface 7s (e.g., Y direction) than a distance between the circuit board 7 and the light source unit 4 in a direction intersecting the main surface 7s (e.g., Z direction).

[0081] In this way, the support member 8 is used to arrange the circuit board 7, the light source unit 4, and the fixing portion 5 so as to face each other, thereby reducing space. At this time, the path from the light source unit 4 to the circuit board 7 via the support member 8 is made longer than the direct distance between the light source unit 4 and the circuit board 7, thereby making it possible to prevent the heat generated by the light source 40 from being transmitted to the circuit board 7. This prevents malfunctions and deterioration of characteristics due to heat.

[0082] The optical head 1 also includes a connector 64 that is provided at the other end 62 of the optical fiber 6 and is used to connect the optical fiber 6 to another optical fiber. This makes it possible to easily connect the optical fiber 6 to another optical fiber using the connector 64.

[0083] The optical head 1 also includes a holding member 11 that holds the connector 64, and a fixing member 113 for fixing the holding member 11 to the housing 2. An elongated hole 111h is formed in the holding member 11, and the holding member 11 is disposed on the bottom plate 29 of the housing 2 so that the elongated hole 111h is aligned with the optical axis direction of the optical fiber 6, and is fixed to the bottom plate 29 by a fixing member 113 inserted into the elongated hole 111h. This makes it possible to easily adjust the positions of the optical fiber 6, the connector 64, and the holding member 11 in the extension direction of the elongated hole 111h (i.e., the optical axis direction of the optical fiber 6, the Y direction).

[0084] Furthermore, the optical head 1 includes a cap 3 that holds the window member 31, and the cap 3 is disposed outside the housing 2 and attached to the housing 2. This makes it possible to attach and detach the window member 31 outside the housing 2.

[0085] The above embodiment describes one aspect of the present disclosure. Therefore, the present disclosure is not limited to the above embodiment and may be modified as desired. Next, modified examples will be described. [First Modification]

[0086] Fig. 13 is an exploded and enlarged cross-sectional view of a part of the optical head according to the first modified example. As shown in Fig. 13, the optical head 1 according to the first modified example can include a light source unit 4A instead of the light source unit 4. The light source unit 4A is different from the light source unit 4 in that the shape of the insertion hole 42 is different compared to the light source unit 4. In the light source unit 4A, the insertion hole 42 includes a tapered portion 42r whose inner surface 42s is tapered so that the insertion hole 42 expands from the opening 42a toward the opening 42b and is connected to the opening 42b.

[0087] According to this configuration, when the optical fiber 6 is inserted into the insertion hole 42 from the opening 42b of the insertion hole 42, the one end 61 of the optical fiber 6 can be guided toward the opening 42a by the tapered portion 42r of the inner surface 42s of the insertion hole 42. At this time, if a sleeve 63 is provided on the optical fiber 6, the sleeve 63 slides on the tapered portion 42r, and the one end face 61a of the optical fiber 6 is prevented from contacting the inner surface 42s of the insertion hole 42. [Second modified example]

[0088] FIG. 14 is a perspective view showing a part of an optical head according to a second modified example. FIG. 15 is a cross-sectional view of the optical head shown in FIG. 14. As shown in FIGS. 14 and 15, the optical head 1 according to the second modified example includes a light source unit 70 instead of the light source unit 4. The light source unit 70 is configured by integrating the light source unit 4 and a fixing portion 5. Therefore, in addition to the configuration of the light source unit 4, the light source unit 70 further includes at least an optical fiber 6 and a sleeve 63 as a light blocking member. In such a light source unit 70, for example, when the light source 40 breaks down, only the light source 40 can be replaced. [Third Modification]

[0089] Fig. 16 is a perspective view showing a part of an optical head according to a third modified example. Figs. 17 and 18 are cross-sectional views showing an exploded view of the optical head shown in Fig. 16. As shown in Figs. 16 to 18, the optical head 1 according to the third modified example differs from the optical head 1 according to the embodiment in that it includes a light source unit 4B instead of the light source unit 4, that it includes two circuit boards 7, and that it does not include the heat sink 9 and the fan 10. The light source unit 4B differs from the light source unit 4 in that it has more light sources 40 than the light source unit 4.

[0090] Here, the light source unit 4B has four light sources 40. The four light sources 40 are arranged at equal intervals (not necessarily at equal intervals) on a circumference centered on the optical axis 6x of the optical fiber 6. In this way, the light source unit 4B has more light sources 40, so that the output of each light source 40 can be reduced. As a result, the amount of heat generated by the light source 40 can be reduced. Therefore, in the optical head 1 according to the third modification, the heat sink 9 and the fan 10 are not necessary, and the circuit board 7 can be arranged on both sides of the fixed part 5 in the Z direction by utilizing the space for the heat sink 9 and the fan 10. In this way, the light source unit can have any number of light sources 40 greater than or equal to two. [Fourth Modification]

[0091] FIG. 19 is a diagram showing a schematic view of a part of an optical head according to a fourth modified example. In the above embodiment and other modified examples, the light-shielding member for suppressing the incidence of stray light into the optical fiber 6 is provided only on the optical fiber 6 as a sleeve 63. However, as shown in FIG. 19, the light-shielding member for suppressing the incidence of stray light into the optical fiber 6 may be provided on the holding part 41. That is, here, the holding part 41 includes a light-shielding part (light-shielding member) 90 protruding along the edge of the opening 42a so as to cover one end 61 of the optical fiber 6 when the optical fiber 6 is inserted into the insertion hole 42 and protrudes from the opening 42a. According to this configuration, when suppressing the incidence of stray light into the optical fiber 6, an operation such as covering one end 61 of the optical fiber 6 with the sleeve 63 is not essential. However, the optical fiber 6 may be covered with the sleeve 63. [Fifth Modification]

[0092] Fig. 20 is a diagram showing an optical head according to a fifth modified example. Fig. 20(a) is a perspective view, and Fig. 20(b) is a top view. Fig. 21 is a cross-sectional view taken along line XXI-XXI in Fig. 20(b), and Fig. 22 is a cross-sectional view taken along line XXII-XXII in Fig. 20(b).

[0093] As shown in FIGS. 20 to 22, the optical head 1A includes a light source unit 4, a fixing portion 5, and an optical fiber 6. The light source unit 4 includes a plurality of (four in this case) light sources 40 and a holding portion 41 that holds the light sources 40. Compared to the optical head 1, the optical head 1A does not include a circuit board 7, a support member 8, a heat sink 9, a fan 10, and a holding member 11. The optical head 1A includes a housing 120, a spacer 130, and a cover member 140. The housing 120 is formed in a tubular shape (cylindrical shape in this case) with both ends open. The spacer 130 is provided at one end of the housing 120, and the cover member 140 is provided at the other end of the housing 120.

[0094] The holding part 41 is inserted into one end of the housing 120 and disposed within the housing 120. The holding part 41 has an outer shape that conforms to the inner surface of the housing 120. That is, the holding part 41 has a columnar shape (here, a cylindrical shape). When the holding part 41 is inserted into one end of the housing 120, it is fixed to the housing 120 by a fixing member 121 such as a screw.

[0095] A power connector 150 is provided penetrating the cover member 140. That is, the power connector 150 is provided so as to reach the inside of the housing 120 from the outside, and is attached to the housing 120 via the cover member 140. For example, a power cable A4 is connected to the power connector 150 on the outside side of the housing 120. On the other hand, the light source 40 is connected to the power connector 150 on the inside side of the housing 120. The light source 40 and the power connector 150 are directly connected to each other by a wiring W40 (without passing through a circuit board or the like). Here, one end of the wiring W40 is connected to the power connector 150, and the other end is connected to a lead pin (lead wire) of the light source 40. That is, the optical head 1A includes a wiring W40 that connects the power connector 150 to each lead wire of the light source 40.

[0096] In addition, the head of a fixing member 141 such as a screw is exposed on the cover member 140. A plurality of support columns 170 are provided between the cover member 140 and the holding part 41. The support columns 170 include an axis portion 171 and a protruding portion 172 protruding from one end face 171a of the axis portion 171. The support columns 170 are fixed to the holding part 41 by abutting one end face 171a of the axis portion 171 against the end face 44 of the holding part 41 and by connecting (for example, screwing) the protruding portion 172 to the holding part 41. On the other hand, the other end face of the axis portion 171 of the support column 170 is abutted against the cover member 140 and is fixed to the cover member 140 by the fixing member 141. As a result, the support columns 170 support the cover member 140 while generating a space on the holding part 41 according to the length of the axis portion 171.

[0097] Furthermore, an optical fiber connector 160 is provided penetrating the cover member 140. That is, the optical fiber connector 160 is attached to the housing 120 via the cover member 140 so as to reach the inside of the housing 120 from the outside. The optical fiber connector 160 includes a connection part 161 that protrudes to the outside of the housing 120 and is fixed to the cover member 140, and receives a connection with another optical fiber such as the optical fiber A3. The optical fiber connector 160 is also held by the connection part 161 inside the housing 120, and includes a holding part 162 that holds the optical fiber 6 inside.

[0098] The fixing part 5 is provided at the end of the holding part 162 opposite to the connection part 161, and holds the optical fiber 6 protruding from the holding part 162. The fixing part 5 has a through hole 51 extending along one direction (here, the Y direction). The fixing part 5 includes a cylindrical base part 52 whose longitudinal direction is the extension direction of the through hole 51, and a protruding part 53 provided protruding from the base part 52 along the extension direction. The optical fiber 6 is inserted through the through hole 51 and reaches the tip of the protruding part 53. Here, an end face 53a of the protruding part 53 and one end face 61a of one end part 61 of the optical fiber are substantially flush with each other. As a result, one end part 61 of the optical fiber 6 is covered by the protruding part 53 except for the one end face 61a.

[0099] FIG. 23 is a partially enlarged view of FIGS. 21 and 22. As shown in FIG. 23, a part of the base part 52 and the protruding part 53 of the fixing part 5 are inserted into the insertion hole 42 of the holding part 41 in a state where the optical fiber 6 is held. A part of the protruding part 53 and a part of one end 61 of the optical fiber 6 are protruding into the recess 45. As a result, the one end 61 of the optical fiber 6, including its one end face 61a, is positioned between the multiple light sources 40 via the protruding part 53. Therefore, here, the protruding part 53 of the fixing part 5 functions as a light shielding member for suppressing the incidence of stray light into the optical fiber 6. In other words, here, the fixing part 5 covers the one end 61 of the optical fiber 6 and includes a light shielding member (protruding part 53) that is inserted into the insertion hole 42 together with the optical fiber 6 and protrudes from the opening 42a. Here, four holes 46 are formed in the holding part 41, and a light source 40 is disposed in each of the holes 46. Therefore, in this example, one end 61 of the optical fiber 6 is arranged so as to be surrounded by the four light sources 40 via the protrusion 53. The end surface 52a of the base portion 52 of the fixing portion 5 and the flat portion 42p provided on the inner surface 42s of the insertion hole 42 of the holding portion 41 may be in contact with each other, but in the illustrated example, a gap is formed between them and they are separated from each other. In this example, the fixing portion 5 that holds the optical fiber 6 is attached to the optical fiber connector 160 attached to the cover member 140, and the cover member 140 and the holding portion 41 are fixed to each other by the support 170. This allows the position of the optical fiber 6 held by the fixing portion 5 to be fixed. In other words, in this case, the fixing portion 5 fixes the position of the optical fiber 6 via another member. Alternatively, the fixing portion 5 may be fitted into the insertion hole 42 of the holding portion 41 to fix the position of the optical fiber 6 without relying on another member. That is, even if the end face 52a of the fixing part 5 and the flat part 42p of the holding part 41 facing the end face 52a are separated from each other, the fixing part 5 can be regarded as a member for fixing the position of the optical fiber 6. Also, even if the end face 52a of the fixing part 5 and the flat part 42p of the holding part 41 facing the end face 52a, and the outer surface (side surface) of the base part 52 and the inner surface 42s of the insertion hole 42 are not in contact with each other and a clearance is provided, the fixing part 5 can be regarded as a member for fixing the position of the optical fiber 6 by cooperation with the holding part 41.

[0100] The spacer 130 is attached to the holding part 41 in a state of contacting the end face 43 of the holding part 41. A recess 43p connected to the recess 45 is formed in the end face 43. The recess 43p includes a bottom face 43s facing the spacer 130. The bottom face 43s is formed in an annular shape so as to surround the opening of the recess 45 when viewed from a direction intersecting the end face 43. The window member 31 is disposed in the recess 43p and attached to the bottom face 43s. In this manner, the window member 31 is attached to the holding part 41 (bottom face 43s) interposed between the light source 40 and the spacer 130.

[0101] The spacer 130 has an opening (third opening) 130h formed therein to expose the opening 42a of the insertion hole 42 when viewed from a direction intersecting the end face 43 and to pass the light L1 from each of the light sources 40 and the light L4 toward the end face 61s of the optical fiber 6. Therefore, in a state in which the spacer 130 is attached to the holding part 41, it is possible to irradiate the light L1 to the object 100 and detect the light L4 from the object 100. On the other hand, in a state in which the window member 31 is attached to the holding part 41, the spacer 130 is detachable from the holding part 41. Therefore, even in a state in which the spacer 130 is detached, it is possible to irradiate the light L1 to the object 100 and detect the light L4 from the object 100 through the window member 31.

[0102] As described above, the optical head 1A according to this modification provides the same effects as those of the optical head 1. Furthermore, in the optical head 1A, the fixed portion 5 includes a light-shielding member (protruding portion 53) that covers one end 61 of the optical fiber 6 and is inserted into the insertion hole 42 together with the optical fiber 6 and protrudes from the opening 42a. By providing the light-shielding member in the fixed portion 5 in this manner, it is not essential to cover the one end 61 of the optical fiber 6 with a light-shielding member or to provide a light-shielding member in the holding portion 41, for example, when suppressing the incidence of stray light into the optical fiber 6. However, the optical fiber 6 may be covered with a light-shielding member, or a light-shielding member may be further provided in the holding portion 41.

[0103] The optical head 1A also includes a spacer 130 detachably attached to the holder 41 by a fixing member 131 such as a screw, and the spacer 130 has an opening 130h formed therein so as to expose the opening 42a and pass the light L1 from each of the light sources 40. The window member 31 is attached to the holder 41, being interposed between the light source 40 and the spacer 130. This allows the optical fiber to be used both in a state where the spacer 130 is attached and in a state where the spacer 130 is removed, while the one end surface 61a of the optical fiber is kept clean by the window member 31. As an example, in a state where the spacer 130 is attached, the distance between the light source 40 and the sample (object 100) can be easily determined by making a measurement with the spacer 130 in contact with the sample. On the other hand, in a state where the spacer is removed, a measurement can be performed by providing a space between the light source 40 and the sample through which, for example, a fluid flows, while maintaining the distance between the light source 40 and the sample.

[0104] Furthermore, the optical head 1A is provided with a power connector 150 that is attached to the housing 120 so as to reach the inside of the housing 120 and supplies power to the light source 40, and a wiring W40 that connects the power connector 150 and each lead wire of the light source 40. This makes it possible to achieve a smaller size compared to a case where the power connector 150 and the light source 40 are connected via a circuit board or the like. Note that by increasing the number of light sources 40, for example to four or more, and using each light source 40 with low power, heat generation of the light source 40 can be suppressed. In this case, further miniaturization can be achieved without providing a heat sink or a cooling fan in the housing 120. In addition, in this case, the life of the light source 40 can be extended.

[0105] In the optical head 1A, a heat sink can be provided on the outside of the housing 120, which has been made compact. In this case, as an example, the heat sink can be formed into a cylindrical shape having an inner shape similar to the outer shape of the housing 120, and the housing 120 can be inserted into the heat sink so that the inner side of the heat sink and the outer circumferential surface of the housing 120 come into contact with each other. At this time, the flange portion 142 of the cover member 140 can be used to fix the heat sink. A plurality of fins can be formed on the outer circumferential surface of the heat sink, which are arranged radially when viewed from the axial direction of the heat sink. In this case, each of the fins may be configured to extend over substantially the entire heat sink along the axial direction. [Other variations]

[0106] In the above embodiment, the holding unit 41 holds two light sources 40 such that the two light sources 40 are arranged on a straight line perpendicular to the optical axis 6x of the optical fiber 6. However, the multiple light sources 40 may be arranged at any distance from each other as long as they are spaced apart by at least the diameter of the optical fiber 6 (the outer diameter of the sleeve 63 if a sleeve 63 is provided). As an example, the holding unit 41 may hold the multiple light sources 40 such that the angle between the two light sources 40 and the optical axis 6x of the optical fiber 6 is 90° or more when viewed from the optical axis direction (Y direction) of the optical fiber 6.

[0107] In the above embodiment, the light source unit 4 and the optical head 1, 1A are used together with the spectrometer A2, but the light source unit 4 and the optical head 1, 1A may be used in any device for irradiating an object with light and providing light from the object to a photodetector. Furthermore, even when the light source unit 4 and the optical head 1, 1A are used together with the spectrometer A2, they may be configured to provide visible light of about 400 nm to 800 nm to the photodetector of the spectrometer A2.

[0108] In addition, at least a part of the configurations of the above embodiment and the first to fifth modified examples may be arbitrarily replaced and adopted. For example, the light source unit 4B according to the third modified example may be integrally configured with the fixing part 5 like the light source unit 70 according to the second modified example. Also, the light shielding part 90 according to the fourth modified example may be provided on the holding part 41 according to the other modified examples. [Industrial Applicability]

[0109] It is possible to provide a light source unit and an optical head that are capable of effectively propagating light from an object through an optical fiber while suppressing the incidence of stray light into the optical fiber. [Explanation of symbols]

[0110] 1,1A...optical head, 2...housing, 3...cap, 4,4A,4B...light source unit, 5...fixing portion, 6...optical fiber, 6x...optical axis, 7...circuit board, 7s...main surface, 8...support member, 11...holding member (connector holding member), 31...window member, 40...light source, 41...holding portion, 42...insertion hole, 42a...opening (first opening), 42b...opening (second opening), 42s...inner surface, 42p...flat portion, 42r...tapered portion, 43,44...end surface, 46...hole portion, 46s...inner surface, 61...one end portion, 61a...one end surface, 62...other end portion, 63...sleeve (light-shielding member), 64...connector, 90...light-shielding portion (light-shielding member), 120...housing, 130...spacer, 130h...opening (third opening), 150...power connector, W40...wiring.

Claims

1. A plurality of light sources that emit light to be irradiated onto an object; a holder that holds the plurality of light sources and has an insertion hole through which an optical fiber for propagating the light from the object is inserted; Equipped with the holding section holds each of the plurality of light sources such that an illumination region of the light from each of the plurality of light sources is formed on one side of the holding section, the insertion hole includes a first opening facing the irradiation area and a second opening different from the first opening, and is formed in the holding part such that, when the optical fiber is inserted, one end face of the optical fiber is exposed from the first opening and faces the irradiation area; When the optical fiber is inserted into the insertion hole, one end of the optical fiber including the one end face is positioned between the plurality of light sources via a light blocking member. Light source unit.

2. the insertion hole is formed in the holding portion such that, when the optical fiber is inserted, one end face of the optical fiber protrudes from the first opening; The light source unit according to claim 1 .

3. the holding portion includes a plane portion intersecting a direction from the first opening toward the second opening, The flat surface portion is formed on at least one of an end surface of the holding portion where the second opening is formed and an inner surface of the insertion hole. The light source unit according to claim 1 .

4. the holding portion includes the light blocking member protruding along an edge portion of the first opening so as to cover the one end portion of the optical fiber when the optical fiber is inserted into the insertion hole and protrudes from the first opening, The light source unit according to any one of claims 1 to 3.

5. an inner surface of the insertion hole includes a tapered portion that is tapered so that the insertion hole expands from the first opening toward the second opening and is connected to the second opening; The light source unit according to any one of claims 1 to 4.

6. the holding section holds the plurality of light sources such that the illumination regions of the plurality of light sources overlap each other, The insertion hole is formed such that, when the optical fiber is inserted, an optical axis of the optical fiber passes through an overlapping region where the irradiation regions of the plurality of light sources overlap. The light source unit according to any one of claims 1 to 5.

7. the holding portion is formed with holes in which the plurality of light sources are arranged, the holding portion holds the plurality of light sources in a state in which outer surfaces of the plurality of light sources are in contact with an inner surface of the hole portion, At least a portion of the inner surface of the hole that comes into contact with the outer surfaces of the plurality of light sources is formed in a shape that conforms to the shape of the outer surfaces of the light sources. The light source unit according to any one of claims 1 to 6.

8. The holding portion includes a resin portion filled between an inner surface of the hole portion and an outer surface of the light source. The light source unit according to claim 7 .

9. an optical head for illuminating an object with light and providing light from the object to a photodetector, A light source unit according to any one of claims 1 to 8, a fixing portion for holding the optical fiber and fixing a position of the optical fiber; the optical fiber being fixed to the fixing portion and inserted into the insertion hole; a housing that accommodates at least a part of the light source unit, the fixing portion, and the optical fiber; a light-transmitting window member disposed opposite the one end surface of the optical fiber; Equipped with Optical head.

10. The light source unit and the fixing portion are formed separately from each other, the fixing portion holds the optical fiber in a state in which the one end of the optical fiber protrudes from the fixing portion, the light source unit is detachably attached to the fixing portion in a state in which the one end of the optical fiber protruding from the fixing portion is inserted into the insertion hole, 10. The optical head according to claim 9.

11. the light shielding member is provided on the optical fiber so as to cover at least the one end of the optical fiber while exposing the one end surface; 11. The optical head according to claim 9 or 10.

12. the window member faces the plurality of light sources so that the light emitted from the plurality of light sources passes therethrough, and is provided at a position in an optical axis direction of the optical fiber such that the light emitted from the plurality of light sources and reflected by the window member does not enter the optical fiber.

12. The optical head according to claim 9.

13. the window member is provided opposite the plurality of light sources so that the light emitted from the plurality of light sources passes therethrough; the wavelength ranges of the light emitted from the plurality of light sources include a first wavelength range included in a sensitivity range of the photodetector and a second wavelength range different from the sensitivity range of the photodetector; the window member reduces the reflectance in the first wavelength region and reduces the transmittance in the second wavelength region; 13. The optical head according to claim 9.

14. a circuit board having a major surface and electrically connected to the light source; a support member for supporting the light source unit and the fixed portion; Equipped with the light source units and the fixing portion are arranged along a direction from the first opening toward the second opening, the circuit board is disposed so as to face the light source unit and the fixed portion when viewed from a direction along the main surface, the support member is formed such that, when viewed from a direction along the main surface, a path from the light source unit to the circuit board via the support member is longer than a distance between the circuit board and the light source unit in a direction intersecting the main surface. The optical head according to any one of claims 9 to 13.

15. a connector provided at the other end of the optical fiber for connecting the optical fiber to another optical fiber; 15. The optical head according to claim 9.

16. a connector holding member for holding the connector; a fixing member for fixing the connector holding member to the housing; Equipped with The connector holding member has a slot formed therein, the connector holding member is disposed on a wall portion of the housing such that the elongated hole is aligned with the optical axis direction of the optical fiber, and is fixed to the wall portion by the fixing member inserted into the elongated hole; 16. The optical head according to claim 15.

17. a cap for holding the window member; The cap is disposed outside the housing and attached to the housing.

17. The optical head according to claim 9.

18. the fixing portion includes the light blocking member that covers the one end of the optical fiber and is inserted into the insertion hole together with the optical fiber and protrudes from the first opening.

10. The optical head according to claim 9.

19. A spacer is provided which is detachably attached to the holding portion, a third opening is formed in the spacer to expose the first opening and to pass the light from each of the plurality of light sources; The window member is attached to the holding portion and is interposed between the light source and the spacer.

19. The optical head according to claim 9 or 18.

20. a power connector provided from the outside of the housing to the inside thereof for supplying power to the light source; Wiring connecting the power connector and each lead wire of the light source; Equipped with 20. An optical head according to claim 9, 18 or 19.

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