Light source unit and optical head

A light source unit includes a plurality of light sources emitting light for irradiating an object, and a holding portion holding the plurality of light sources having an insertion hole for an optical fiber inserted therethrough to propagate the light from the object formed therein. The holding portion holds each of the plurality of light sources such that an irradiation region of the light of each of the plurality of light sources is formed on one side of the holding portion. The insertion hole has a first opening that is an opening facing the irradiation region and a second opening that is an opening different from the first opening, and is formed in the holding portion such that one end surface of the optical fiber is exposed from the first opening and faces the irradiation region when the optical fiber is inserted therethrough.

TECHNICAL FIELD

The present disclosure relates to a light source unit and an optical head.

BACKGROUND ART

Patent Literature 1 discloses a near-infrared interactance spectrometric measurement device. This measurement device includes a device main body and a probe. Further, a flexible cable is provided in a manner of connecting the device main body and the probe, and an optical fiber is stored in the flexible cable. A spectrometer, a detector, or the like is provided inside the device main body. The probe has a casing. Inside the casing, a plurality of light sources emitting light are disposed in a manner of facing a measurement opening provided in one wall portion of the casing. In addition, an incidence end of the optical fiber is disposed in another wall portion of the casing. Interactance light from a sample which has received light irradiation from the light sources is incident on the incidence end of the optical fiber via a rectangular prism and a condensing lens.

CITATION LIST

Patent Literature

SUMMARY OF INVENTION

Technical Problem

In the probe of the foregoing measurement device, the light sources are provided close to the measurement opening of the casing. On the other hand, the incidence end of the optical fiber is disposed in a wall portion different from the wall portion in which the measurement opening is formed in the casing. Therefore, even if the probe is disposed such that the measurement opening and the light sources become closer to a sample, since the incidence end of the optical fiber cannot be brought closer to the sample, it is difficult to effectively propagate feeble light from the sample to the detector via the optical fiber. In contrast, in the probe of the foregoing measurement device, it is conceivable that the incidence end of the optical fiber be disposed in the vicinity of the measurement opening. However, in this case, stray light is likely to be incident on the optical fiber.

Hence, an object of the present disclosure is to provide a light source unit capable of curbing incidence of stray light on an optical fiber while effectively propagating light from an object through the optical fiber, and an optical head.

Solution to Problem

A light source unit according to the present disclosure includes a plurality of light sources configured to emit light for irradiating an object, and a holding portion configured to hold the plurality of light sources and formed with an insertion hole configured to be inserted an optical fiber for propagating the light from the object. The holding portion holds each of the plurality of light sources such that an irradiation region 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 region and a second opening that is an opening different from the first opening, and is formed in the holding portion such that one end surface of the optical fiber is exposed from the first opening and faces the irradiation region when the optical fiber is inserted therethrough. One end portion of the optical fiber including the one end surface is positioned between the plurality of light sources with a light blocking member therebetween when the optical fiber is inserted through the insertion hole.

In this light source unit, the insertion hole for the optical fiber inserted therethrough is formed in the holding portion holding the plurality of light sources. Particularly, the one end portion of the optical fiber including the one end surface is positioned between the plurality of light sources with the light blocking member therebetween when the optical fiber is inserted through the insertion hole. Therefore, since the one end surface of the optical fiber can also be brought closer to the object by disposing this light source unit such that the light sources become closer to the object, feeble light from the object can be effectively propagated through the optical fiber. Moreover, since the light blocking member is interposed between the light sources and the one end portion of the optical fiber, incidence of stray light on the optical fiber can be curbed.

In the light source unit according to the present disclosure, the insertion hole may be formed in the holding portion such that one end surface of the optical fiber protrudes from the first opening when the optical fiber is inserted therethrough. In this case, since the one end surface of the optical fiber protrudes, the one end surface of the optical fiber can be brought closer to the object. For this reason, feeble light from the object can be effectively propagated through the optical fiber.

In the light source unit according to the present disclosure, an inner surface of the insertion hole may include a tapered portion formed into a tapered shape such that the insertion hole expands from the first opening toward the second opening, and connected to the second opening. In this case, when the optical fiber is inserted through the insertion hole from the second opening of the insertion hole, the one end portion of the optical fiber can be guided toward the first opening due to the tapered portion on the inner surface of the insertion hole.

In the light source unit according to the present disclosure, the holding portion may include a flat surface portion intersecting a direction toward the second opening from the first opening. The flat surface portion may be formed on at least one of an end surface of the holding portion having the second opening formed therein and an inner surface of the insertion hole. In this case, when the optical fiber is inserted through the insertion hole, the optical fiber can be positionally set in a direction toward the second opening from the first opening (that is, an optical axis direction of the optical fiber in a state of being inserted through the insertion hole), for example, by causing another member holding the optical fiber to abut the flat surface portion of the holding portion.

In the light source unit according to the present disclosure, the holding portion may include the light blocking member provided in a manner of protruding along an edge portion of the first opening such that the one end portion of the optical fiber is covered when the optical fiber is inserted through the insertion hole and protrudes from the first opening. In this manner, by providing the light blocking member in the holding portion, when incidence of stray light on the optical fiber is curbed, for example, work of coating the one end portion of the optical fiber with the light blocking member or the like is no longer essential. However, the optical fiber may be coated with the light blocking member.

In the light source unit according to the present disclosure, the holding portion may hold the plurality of light sources such that the irradiation regions of the plurality of respective light sources overlap each other. The insertion hole may be formed such that an optical axis of the optical fiber passes through an overlapping region where the irradiation regions of the plurality of light sources overlap each other when the optical fiber is inserted therethrough. In this case, an intersection where the irradiation regions of the plurality of light sources and the optical axis of the optical fiber inserted through the insertion hole intersect each other is formed. Therefore, light from the object can be effectively incident on the optical fiber by disposing the light source unit such that the object can be aligned with this intersection.

In the light source unit according to the present disclosure, hole portions for disposing the plurality of light sources may be formed in the holding portion. The holding portion may hold the plurality of light sources in a state where outer surfaces of the plurality of light sources are in contact with inner surfaces of the hole portions. At least parts on the inner surfaces of the hole portions coining into contact with the outer surfaces of the plurality of light sources may be formed into shapes along shapes of the outer surfaces of the light sources. In this case, contact areas between the inner surfaces of the hole portions and the light sources can be increased, and heat can effectively dissipate from the light sources to the holding portion.

In the light source unit according to the present disclosure, the holding portion may include resin portions filling spaces between the inner surfaces of the hole portions and the outer surfaces of the light sources. In this case, heat can more effectively dissipate from the light sources to the holding portion. In addition, as described above, if spaces between the inner surfaces of the hole portions and the outer surfaces of the light sources are filled with a resin in a state where the light sources are in contact with the inner surfaces of the hole portions and the shapes of the inner surfaces of the hole portions lie along the shapes of the outer surfaces of the light sources, the amount of resin used is reduced. As a result, distortion (stress) of a resin is unlikely to be applied to the light sources.

An 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. The optical head includes the foregoing light source unit; a fixing portion holding the optical fiber and fixing a position of the optical fiber; the optical fiber inserted through the insertion hole while being fixed to the fixing portion; a casing accommodating at least a part of the light source unit, the fixing portion, and the optical fiber; and a light transmissive window member disposed in a manner of facing the one end surface of the optical fiber.

This optical head includes the foregoing light source unit. Therefore, it is possible for effects similar to those of the foregoing light source unit to be exhibited. Moreover, this optical head includes the window member disposed in a manner of facing the one end surface of the optical fiber. Therefore, the one end surface of the optical fiber can be kept clean. As described above, according to this light source unit, since the one end surface of the optical fiber can be brought even closer to the object, fouling of the one end surface of the optical fiber is more effectively prevented by the window member.

The optical head according to the present disclosure may further include the light blocking member provided in the optical fiber such that at least the one end portion of the optical fiber is coated therewith while the one end surface is exposed. In this manner, by providing the light blocking member in the optical fiber, when incidence of stray light on the optical fiber is curbed, work of providing the light blocking member in the holding portion of the light source unit is no longer essential. However, the light blocking member may be provided in the holding portion.

In the optical head according to the present disclosure, the light source unit and the fixing portion may be formed separately from each other. The fixing portion may hold the optical fiber in a state where the one end portion of the optical fiber protrudes from the fixing portion. The light source unit may be detachably attached to the fixing portion in a state where the one end portion of the optical fiber protruding from the fixing portion is inserted through the insertion hole. In this case, for example, when the light sources break down or the like, the light source unit in its entirety can be easily replaced.

In the optical head according to the present disclosure, the window member may face the plurality of light sources such that the light emitted from the plurality of light sources passes therethrough, and may be provided at a position where the light emitted from the plurality of light sources and reflected by the window member is not incident on the optical fiber in an optical axis direction of the optical fiber. In this case, incidence of light reflected by the window member without going through the object on the optical fiber as stray light can be curbed.

In the optical head according to the present disclosure, the window member may be provided in a manner of facing the plurality of light sources such that light emitted from the plurality of light sources passes therethrough. A wavelength region of the light emitted from the plurality of light sources may include a first wavelength region included in a sensitivity region of the photodetector, and a second wavelength region different from the sensitivity region of the photodetector. The window member may reduce a reflectance of the first wavelength region and reduce a transmittance of the second wavelength region. In this case, the object can be efficiently irradiated with components of light from the light sources in the first wavelength region included in the sensitivity region of the photodetector, arrival of components of light from the light sources in the second wavelength region not included in the sensitivity region of the photodetector at the object is curbed, and damage to the object can be curbed.

The optical head according to the present disclosure may further include a circuit board having a main surface and electrically connected to the light sources, and a support member supporting the light source unit and the fixing portion. The light source unit and the fixing portion may be arrayed in a direction toward the second opening from the first opening. The circuit board may be disposed in a manner of facing the light source unit and the fixing portion when viewed in a direction along the main surface. The support member may be formed such that a path from the light source unit toward the circuit board with the support member therebetween is longer than a distance between the circuit board and the light source unit in a direction intersecting the main surface when viewed in a direction along the main surface. In this case, a space is reduced by disposing the circuit board such that it faces the light source unit and the fixing portion using the support member. At this time, since the path reaching the circuit board from the light source unit with the support member therebetween is longer than a direct distance between the light source unit and the circuit board, transfer of heat generated in the light sources to the circuit board can be curbed. Accordingly, malfunction due to heat and deterioration in characteristics are curbed.

The optical head according to the present disclosure may further include a connector provided in the other end portion of the optical fiber and connecting the optical fiber to another optical fiber. In this case, the optical fiber can be easily connected to another optical fiber using the connector.

The optical head according to the present disclosure may further include a connector holding member holding the connector, and a fixing member for fixing the connector holding member to the casing. A long hole may be formed in the connector holding member. The connector holding member may be disposed on a wall portion of the casing such that the long hole lies along an optical axis direction of the optical fiber, and be fixed to the wall portion by the fixing member inserted through the long hole. In this case, positions of the optical fiber, the connector, and the connector holding portion can be easily adjusted in an extending direction of the long hole (that is, the optical axis direction of the optical fiber).

The optical head according to the present disclosure may further include a cap holding the window member. The cap may be disposed on an outward side of the casing and attached to the casing. In this case, the window member can be attached and detached outside the casing.

In the optical head according to the present disclosure, the fixing portion may include the light blocking member covering the one end portion of the optical fiber, inserted through the insertion hole together with the optical fiber, and protruding from the first opening. In this manner, by providing the light blocking member in the fixing portion, when incidence of stray light on the optical fiber is curbed, for example, work of coating the one end portion of the optical fiber with the light blocking member or providing the light blocking member in the holding portion is no longer essential. However, the optical fiber may be coated with the light blocking member, and the light blocking member may be provided in the holding portion.

The optical head according to the present disclosure may further include a spacer detachably attached to the holding portion. A third opening may be formed in the spacer such that the first opening is exposed and the light of each of the plurality of light sources passes therethrough. The window member may be attached to the holding portion in a manner of being interposed between the light sources and the spacer. In this case, while the one end surface of the optical fiber is kept clean by the window member, it can be used in both the state where the spacer is attached and the state where the spacer is detached.

The optical head according to the present disclosure may further include a power source connector attached to the casing in a manner of reaching the inside of the casing from the outside and supplying power to the light sources, and wirings connecting the power source connector and lead wires of the respective light sources. In this case, miniaturization can be achieved compared to when the power source connector and the light sources are connected via the circuit board or the like. Heat generation in the light sources can be restrained by increasing the number of light sources to four or more, for example, and using each of the light sources with low power. In this case, further miniaturization can be achieved without providing a heat sink, a cooling fan, or the like inside the casing. In addition, in this case, the life of the light sources can also be extended.

Advantageous Effects of Invention

According to the present disclosure, it is possible to provide a light source unit capable of curbing incidence of stray light on an optical fiber while effectively propagating light from an object through the optical fiber, and an optical head.

DESCRIPTION OF EMBODIMENT

Hereinafter, an embodiment will be described with reference to the drawings. In each of the drawings, the same reference signs are applied to parts which are the same or corresponding, and duplicate description thereof may be omitted. In addition, in each of the drawings, an orthogonal coordinate system defined by an X axis, a Y axis, and a Z axis may be indicated.

FIG.1is a view illustrating a measurement device according to an embodiment. As illustrated inFIG.1, a measurement device A1includes a spectrometer A2and an optical head1. For example, the spectrometer A2is a Fourier transform infrared spectrometer. For example, the spectrometer A2has an optical interferometer and a control circuit. For example, the optical interferometer includes a light incidence portion, a beam splitter, a fixed mirror, a movable mirror, and a photodetector. The photodetector acquires a light intensity signal which varies depending on the position of the movable mirror. For example, the spectrometer A2may be connected to a computer such as a PC or the like using a USB or the like.

The optical head1is optically connected to the spectrometer A2through an optical fiber A3. In addition, a power source cable A4is connected to the optical head1. The optical head1is disposed in the vicinity of an object and irradiates the object with light upon reception of supply of power via the power source cable A4. A part of light used for irradiating an object from the optical head1is subjected to regular reflection on particle surfaces constituting the object, and the remaining light enters the inside of the object. The light which has entered the inside of the object is diffused while being repeatedly subjected to refractive transmission, light scattering, and surface reflection inside the object, and a part thereof radiates again from the surface of the object to the outside of the object.

Since this light is repeatedly transmitted through the inside of an object a plurality of times during a process of light diffusion, a diffuse reflectance spectrum thereof is measured in a manner similar to that of a transmission spectrum. Therefore, an object can be analyzed using an absorbance by causing this light to be incident on the optical head1and providing it to the spectrometer A2via the optical fiber A3. In this manner, the optical head1irradiates an object with light, and return light from the object is incident thereon and provided to the spectrometer A2(the photodetector of the spectrometer A2as well).

FIG.2is a perspective view illustrating an appearance of the optical head illustrated inFIG.1.FIG.3is a perspective view in another direction illustrating an appearance of the optical head illustrated inFIG.1. As illustrated inFIGS.2and3, the optical head1includes a casing2, and a cap3attached to the casing2. Here, the casing2is formed into a rectangular parallelepiped box. The casing2includes a distal end wall portion21and a proximal end wall portion22facing each other, and four side wall portions23connecting the distal end wall portion21and the proximal end wall portion22to each other. The cap3is attached to the distal end wall portion21.

The proximal end wall portion22is provided with a power source switch24, a connection portion25for connecting the optical fiber A3, a connection portion26for connecting the power source cable A4, and an adjustment portion (adjustment knob)27for adjusting an output of light sources40(which will be described below). Here, in three side wall portions23of the four side wall portions23, a vent hole28is formed at a position on the distal end wall portion21side from the proximal end wall portion22.

FIG.4is a perspective view illustrating a state where a part of the casing is omitted from the optical head illustrated inFIG.2.FIG.5is another perspective view illustrating a state where a part of the casing is omitted from the optical head illustrated inFIG.3.FIGS.6and7are cross-sectional views of the optical head illustrated inFIGS.2and3. As illustrated inFIGS.4to7, the optical head1has a light source unit4, a fixing portion5, an optical fiber6, a circuit board7, a support member8, a heat sink9, a fan10, and a holding member11. A part of the light source unit4on the fixing portion5side, the fixing portion5, the optical fiber6, the circuit board7, the support member8, the heat sink9, the fan and the holding member11are accommodated in the casing2.

The light source unit4includes a plurality of light sources40and a holding portion41holding the plurality of light sources40. As an example, the light sources40are halogen lamps. However, arbitrary light sources can be used as the light sources40. For example, the light sources40may be halogen lamps, tungsten lamps, graphene light sources, or the like as thermal light sources or incandescent light bulbs, or may be light emitting diodes (LED), laser diodes (LD), super luminescent diodes (SLD), vertical cavity surface emitting lasers (VCSEL), or the like as light emitting diodes or semiconductor lasers. Each of the light sources40is electrically connected to the circuit board7. Accordingly, the light sources40are turned on and off in response to an operation of the power source switch24, and the output thereof may be adjusted in response to an operation of the adjustment portion27. An insertion hole42for the optical fiber6inserted therethrough is formed in the holding portion41. Details of the light source unit4will be described below.

The fixing portion5holds the optical fiber6and fixes the position of the optical fiber6. More specifically, a penetration hole51extending in one direction (here, a Y direction) is formed in the fixing portion5. Therefore, an opening of the penetration hole51is formed on both end surfaces intersecting (orthogonal to) the Y direction of the fixing portion Particularly, the fixing portion5includes a rectangular plate-shaped base portion52having the Y direction (an extending direction of the penetration hole51) as a longitudinal direction, and a protruding portion53provided in a manner of protruding from the base portion52in the Y direction.

The base portion52includes an end surface52aintersecting (orthogonal to) the Y direction, and an end surface52bintersecting (orthogonal to) the Y direction on a side opposite to the end surface52a. The protruding portion53is provided on the end surface52ain a protruding manner, and the protruding portion53includes an end surface53aintersecting (orthogonal to) the Y direction and facing a side opposite to the base portion52. Further, the penetration hole51opens on the end surface52bof the base portion52and opens on the end surface53aof the protruding portion53.

The light source unit4and the fixing portion5are constituted separately from each other and are arrayed in the Y direction. In this state, the light source unit4is fixed to the fixing portion5, for example, using a fixing member49such as a screw.

The optical fiber6protrudes from the end surface52band the end surface53ain a state of being inserted through the penetration hole51, penetrates the protruding portion53in a direction intersecting the Y direction, and is pressed and fixed to an inner surface of the penetration hole51using a fixing member54such as a screw reaching the inside of the penetration hole51. Therefore, the Y direction that is an extending direction of the penetration hole51is an extending direction of the optical fiber6, and it is also an optical axis direction of the optical fiber6. One end portion61of the optical fiber6protrudes from the fixing portion5and is inserted through the insertion hole42of the holding portion41of the light source unit4. The other end portion62of the optical fiber6protrudes from the fixing portion5.

At least the one end portion61of the optical fiber6is coated with a sleeve63while one end surface61aof the optical fiber6is exposed. Here, the sleeve63extends in a manner of reaching the one end surface61a. That is, here, an end portion of the sleeve63and the one end surface61aare flush with each other. For example, the sleeve63is a light blocking member made of a metal. The fixing member54is disposed in a manner of being in contact with this sleeve63when the optical fiber6is fixed. A connector64for connecting the optical fiber6to another optical fiber (for example, the optical fiber A3) is attached to the other end portion62of the optical fiber6.

The circuit board7includes a main surface7s. The circuit board7is disposed such that the main surface7sfaces the light source unit4and the fixing portion5when viewed in the Y direction. That is, the circuit board7, the light source unit4, and the fixing portion5are stacked in a Z direction that is a direction intersecting (orthogonal to) the main surface7swhen viewed in the Y direction. In this state, the circuit board7is attached to a bottom plate29while being separated from the bottom plate29that is one of the side wall portions23of the casing2.

The support member8causes the light source unit4and the fixing portion5to be separated from the circuit board7in the Z direction and supports the light source unit4and the fixing portion5on the bottom plate29and the circuit board7. The support member8is attached to the bottom plate29. For example, since the fixing portion5is supported by the support member8, the light source unit4may be supported by the support member8with the fixing portion5therebetween. The heat sink9is disposed in a manner of being in contact with a surface on a side opposite to a surface of the fixing portion5on the circuit board7side. The fan10is disposed on the heat sink9. Accordingly, for example, a part of heat generated in the light sources40of the light source unit4is input to the heat sink9via the fixing portion5and discharged to the outside by the fan10.

Here, the holding member11is formed into an L-shaped plate. More specifically, the holding member11includes a plate-shaped fixing portion111extending along the bottom plate29, and a plate-shaped holding portion112extending along the proximal end wall portion22of the casing2from the fixing portion111. The holding member11comes into contact with the bottom plate29in the fixing portion111and comes into contact with the proximal end wall portion22in the holding portion112. Further, the holding member11is fixed to the bottom plate29in the fixing portion111and holds the connection portion25in the holding portion112. The connector64attached to the other end portion62of the optical fiber6is attached to the connection portion25held by the holding portion112. That is, the holding member11is a connector holding member holding the connector64with the connection portion25therebetween.

In addition, here, a fixing member113for fixing the holding member11to the casing2is used. A long hole111his formed in the fixing portion111. The holding member11is disposed on the bottom plate29(wall portion) of the casing2such that the long hole111hlies in the optical axis direction of the optical fiber6, and it is fixed to the bottom plate29by the fixing member113inserted through the long hole111h.

The cap3includes a light transmissive window member31disposed in a manner of facing the one end surface61aof the optical fiber6and the light sources40as illustrated inFIG.6, and it is fixed to the distal end wall portion21of the casing2, for example, using a fixing member32such as a screw, as illustrated inFIG.7.

Subsequently, details of the light source unit will be described.FIG.8is an enlarged cross-sectional view of the light source unit illustrated inFIGS.6and7.FIG.8illustrates a state where the light source unit4is detached from the fixing portion5. As illustrated inFIGS.6to8, and as described above, the light source unit4includes the plurality of light sources40, and the holding portion41holding the light sources40. The holding portion41is formed into a trapezoidal plate shape when viewed in the Z direction. More specifically, the holding portion41is formed into a trapezoidal shape decreasing as it goes away from the fixing portion5when viewed in the Z direction.

The holding portion41includes an end surface43intersecting (orthogonal to) the Y direction and facing a side opposite to the fixing portion5, and an end surface44intersecting (orthogonal to) the Y direction and facing the fixing portion5side. In addition, a recessed portion45opening on the end surface43, and a plurality of hole portions46opening on the end surface44and connected to the recessed portion are formed in the holding portion41. The light sources40are disposed in the plurality of respective hole portions46. Therefore, the number of hole portions46is the same as at least the number of light sources40. The hole portions46are inclined in a manner of approaching the center axis of the holding portion41(here, the optical axis of the optical fiber6) in the Y direction from the end surface44toward the end surface43.

The light sources40penetrate the holding portion41and are pressed and fixed to inner surfaces46sof the hole portions46using fixing members47such as screws reaching the insides of the hole portions46. That is, the holding portion41holds the light sources40in a state where outer surfaces40sof the light sources40are brought into contact with the inner surfaces46sof the hole portions46. The inner surfaces46sof the hole portions46have shapes along the shapes of the outer surfaces of the light sources40in parts coining into contact with at least the outer surfaces40sof the light sources40.

As an example, here, the outer surfaces40sof the light sources have cylindrical shapes, and the inner surfaces46sof the hole portions46have cylindrical shapes having larger diameters than the outer surfaces of the light sources40. Here, although parts between the inner surfaces46sof the hole portions46and the outer surfaces40sof the light sources40are voids, the light source unit4may have resin portions filling the spaces between the inner surfaces46sof the hole portions46and the outer surfaces40sof the light sources40.

Here, the insertion hole42having the optical fiber6inserted therethrough is connected to the recessed portion45, has an opening (first opening) inside the recessed portion45, and has an opening (second opening)42bon the end surface44. In this manner, both the insertion hole42and the hole portions46open inside the recessed portion45. Further, in each of the light sources40, a light emission portion40pthereof is disposed inside the recessed portion45, and the light emission portion40pis disposed inside the hole portion46in a manner of facing a side opposite to the fixing portion5. That is, the holding portion41holds the plurality of light sources40such that an irradiation region40A of light of each of the plurality of light sources40is formed on one side of the holding portion41(a side opposite to the fixing portion5). The irradiation region40A is a region irradiated with light emitted from each of the light sources40(light emission portions40p).

Therefore, an opening42aof the insertion hole42is an opening facing the irradiation region40A, and the one end surface61aof the optical fiber6inserted through the insertion hole42faces the irradiation region40A. In this manner, the insertion hole42is formed in the holding portion41such that the one end surface61aof the optical fiber6is exposed from the opening42aand faces the irradiation region40A when the optical fiber6is inserted therethrough. Particularly, here, the insertion hole42is formed such that the one end surface61aof the optical fiber6protrudes from the opening42awhen the optical fiber6is inserted therethrough. Moreover, in the light source unit4, when the optical fiber6is inserted through the insertion hole42, the one end portion61including the one end surface61aof the optical fiber6is positioned between the plurality of light sources40with a sleeve (light blocking member)63therebetween. As an example, in a state where the optical fiber6is inserted through the insertion hole42, end portions of the light sources40on the end surface43side and the one end surface61aof the optical fiber6are flush with each other.

A flat surface portion42pintersecting (orthogonal to) the Y direction is formed on an inner surface42sof the insertion hole42. The end surface53aof the protruding portion53of the fixing portion5abuts this flat surface portion42pwhen the light source unit4is attached to the fixing portion5while the optical fiber6is inserted through the insertion hole42. In addition, similarly, when the light source unit4is attached to the fixing portion5, the end surface52aof the base portion52of the fixing portion5abuts the end surface44of the holding portion41. That is, the holding portion41includes a flat surface portion intersecting a direction toward the opening42bfrom the opening42aof the insertion hole42(Y direction), and the flat surface portion is formed on at least one of (here, both) the end surface44of the holding portion41having the opening42bformed therein and the inner surface42sof the insertion hole42.

Here, a flange portion48is formed in the holding portion41. Further, the holding portion41is fixed to the fixing portion5by the fixing member49inserted through the flange portion48. In addition, a hole portion having a position-setting pin B inserted therethrough is formed in the flange portion48.

This position-setting pin B is used when the light source unit4is attached to the fixing portion5. That is, when the light source unit4is attached to the fixing portion5, the position-setting pin B is attached to the fixing portion5in advance. In addition, the fixing portion5holds the optical fiber6in a state where the one end portion61of the optical fiber6protrudes from the end surface53aof the protruding portion53. In this state, the position-setting pin B is inserted through the hole portion of the flange portion48. Further, the light source unit4is caused to slide along the position-setting pin B such that the optical fiber6is inserted through the insertion hole42of the holding portion41, and it is brought into contact with the fixing portion5.

Thereafter, the light source unit4is attached to the fixing portion5by fixing the flange portion48to the fixing portion5using the fixing member49. Thereafter, the position-setting pin B is detached. In this manner, the light source unit4is detachably attached to the fixing portion in a state where the one end portion61of the optical fiber6protruding from the fixing portion5is inserted through the insertion hole42. In addition, when it is attached, the position within a plane intersecting the Y direction is uniformly maintained by the position-setting pin B. Therefore, when there is a need to replace the light source40, only the light source40can be detached and replaced, but the light source unit4in its entirety can be replaced by easily and accurately detaching and attaching it.

As illustrated inFIG.9, when viewed in a direction along the main surface7sof the circuit board7(here, the Y direction), the light source unit4as described above is supported by the support member8in a manner of facing the circuit board7together with the fixing portion5. Particularly, when viewed in the Y direction, the support member8is formed such that a path from the light source unit4toward the circuit board7with the support member8therebetween is longer than a distance between the circuit board7and the light source unit4in a direction intersecting the main surface7s(here, the Z direction).

More specifically, the support member8is formed into a C-shaped plate when viewed in the Y direction by a flat plate-shaped first part81which extends along the main surface7sand in which the light source unit4and the fixing portion5are placed, a flat plate-shaped second part82which extends from both end portions of the first part81toward the bottom plate29in the Z direction, and a flat plate-shaped third part83which extends along the inside of the main surface7sfrom a part on a side opposite to a connection portion in the second part82with respect to the first part81and is fixed to the bottom plate29. Further, the circuit board7is disposed inside a space surrounded by the first part81, the second part82, and the third part83. Accordingly, a path from the light source unit4toward the circuit board7via each part of the support member8is longer than a direct distance between the light source unit4and the circuit board7.

FIG.10is an explanatory schematic view of a positional relationship among the light sources, the optical fiber, and the window member. InFIG.10, in order to facilitate understanding of the positional relationship of each part, the structure of the light source unit4is schematized. As illustrated inFIG.9, the window member31is disposed such that it faces the one end surface61aof the optical fiber6and the light emission portions40pof the light sources40and light emitted from the light emission portions40pof the light sources40passes therethrough. Therefore, light L1that is a part of light emitted from the light emission portions40pof the light sources40is transmitted through the window member31, and an object100is irradiated therewith.

The plurality of light sources40are held by the holding portion41such that the irradiation regions40A of this light L1overlap each other. Further, in the optical fiber6, an optical axis6xthereof passes through an overlapping region40xwhere the irradiation regions40A overlap each other. In other words, when the optical fiber6is inserted therethrough, the insertion hole42is formed such that the optical axis6xof the optical fiber6passes through the overlapping region40xwhere the irradiation regions40A of the plurality of light sources40overlap each other.

Moreover, here, a bottom surface of a truncated cone L2extending from an edge of the one end surface61aof the optical fiber6at the largest light receiving angle and the overlapping region40xcoincide with each other. As an example, when the core diameter of the optical fiber6is 600 μm, the NA is 0.22, the inclination angles of the light sources40are 30 degrees, and the irradiation sizes of the light sources40(for example, the diameters of the light emission portions40p) are 2.58 mm, the sizes of the overlapping region40xand a bottom surface L2sbecome approximately 3 mm and coincide with each other at a position where the distance from the one end surface61aof the optical fiber6is 4 mm and penetration of the light L1into the object100is 0.5 mm.

Meanwhile, light L3that is another part of light emitted from the light emission portions40pof the light sources40is subjected to regular reflection on a surface of the window member31on the light source unit4side. The window member31is provided at a position where the light L3subjected to regular reflection in this window member31is not incident on the one end surface61aof the optical fiber6in the optical axis direction of the optical fiber6. The light L3is blocked by the sleeve63that is a light blocking member.

FIG.11is a graph showing a spectral radiant exitance of a halogen lamp at 2,800 K (on the assumption of emissivity ε=1) calculated based on Planck's law of distribution. As illustrated inFIG.11, the halogen lamp emits a light energy in a wider wavelength region than a sensitivity region W1of the spectrometer A2(a sensitivity region of the photodetector of the spectrometer A2). Alight energy input to an object is converted into heat in accordance with the absorption coefficient of the object. For this reason, when halogen lamps or the like are used as the light sources40, it is desirable to cut light in wavelength regions other than the sensitivity region W1.

On the other hand, a glass tube is provided in actual halogen lamps.FIG.12(a)is a graph showing measurement results of a spectrum of the halogen lamp when light absorption in a glass tube is taken into consideration. In the graph ofFIG.12(a), the numerical values in the vertical axis are normalized with the largest value at a wavelength of 2 μm or longer. As illustrated inFIG.12(a), due to light absorption of the glass tube, light having a wavelength of 2.8 μm or longer is unlikely to be emitted from the halogen lamp. That is, it is conceivable that light on a longer wavelength side than that in the sensitivity region W1be sufficiently cut by the glass tube.

From such a viewpoint, the window member31has a function of cutting light on a shorter wavelength side than that in the sensitivity region W1. Moreover, the window member31has a function of preventing reflection of light having a wavelength included in the sensitivity region W1. As an example, when the light sources40are halogen lamps and the sensitivity region W1is 1,100 nm to 2,500 nm, in order to have the foregoing functions, the window member31may be made of an Si material with AR coating.FIG.12(b)is a graph showing characteristics of a high-pass filter made of an Si material with AR coating. When the spectrum of the halogen lamp inFIG.12(a)and the characteristics of the filter inFIG.12(b)are combined, it is understood that the object100can be favorably irradiated with light having a wavelength of 1,100 nm to 2,500 nm by having the window member31made of an Si material with AR coating.

In this manner, when the wavelength region of light emitted from the plurality of light sources40includes a first wavelength region included in the sensitivity region W1of the spectrometer A2(the photodetector of the spectrometer A2) and a second wavelength region different from the sensitivity region W1of the spectrometer A2, the window member31may be constituted to reduce the reflectance of the first wavelength region and reduce the transmittance of the second wavelength region.

The cap3holding the window member31as described above is disposed on the outward side of the casing2and attached to the casing2as described above. Further, as illustrated inFIG.7, a thickness H3of the cap3in the Y direction defines the distance from the one end surface61aof the optical fiber6to the object100when the cap3is brought into contact with the object100. As an example, the thickness H3of the cap3may be determined such that an end surface3son a side opposite to the casing2of the cap3is at a position where the bottom surface of the truncated cone L2extending from the edge of the one end surface61aof the optical fiber6at the largest light receiving angle and the overlapping region40xcoincide with each other (or a position on the casing2side by an amount of penetration of the light L1into the object100from the position). Consequently, the distances between the light sources40, the one end surface61aof the optical fiber6, and the object100can be easily and appropriately set by bringing the end surface3sof the cap3into contact with the object100.

As described above, in the light source unit4according to the present embodiment, the insertion hole42having the optical fiber6inserted therethrough is formed with respect to the holding portion41holding the plurality of light sources40. Particularly, when the optical fiber6is inserted through the insertion hole42, the one end portion61including the one end surface61aof the optical fiber6is positioned between the plurality of light sources40with the light blocking member (the sleeve63) therebetween. Therefore, since the one end surface61aof the optical fiber6can also be brought closer to the object100by disposing the light source unit4such that the light sources40become closer to the object100, feeble light from the object100can be effectively propagated through the optical fiber6. Moreover, since the light blocking member is interposed between the light sources40and the one end portion61of the optical fiber6, incidence of stray light on the optical fiber6can be curbed.

In addition, in the light source unit4, the holding portion41includes the flat surface portion (the flat surface portion42pand the end surface44) intersecting a direction toward the opening42bfrom the opening42a, and the flat surface portion is formed on at least one of (here, both) the end surface44of the holding portion41having the opening42bformed therein and the inner surface42sof the insertion hole42. For this reason, when the optical fiber6is inserted through the insertion hole42, the optical fiber6can be positionally set in a direction toward the opening42bfrom the opening42a(that is, the optical axis direction of the optical fiber6in a state of being inserted through the insertion hole42, here, the Y direction), for example, by causing another member (the fixing portion5) holding the optical fiber6to abut the flat surface portion of the holding portion41.

In addition, in the light source unit4, the holding portion41holds the plurality of light sources40such that the irradiation regions40A of the plurality of respective light sources40overlap each other, and the insertion hole42is formed such that the optical axis6xof the optical fiber6passes through the overlapping region40xwhere the irradiation regions of the plurality of light sources40overlap each other when the optical fiber6is inserted therethrough. For this reason, the intersection where the irradiation regions40A of the plurality of light sources40and the optical axis6xof the optical fiber6inserted through the insertion hole42intersect each other is formed. Therefore, light from the object100can be effectively incident on the optical fiber6by disposing the light source unit4such that the object100can be aligned with this intersection.

In addition, in the light source unit4, the hole portions46for disposing the plurality of light sources40are formed in the holding portion41. The holding portion41holds the plurality of light sources40in a state where the outer surfaces40sof the plurality of light sources are in contact with the inner surfaces46sof the hole portions46. At least parts on the inner surfaces46sof the hole portions46coining into contact with the outer surfaces40sof the plurality of light sources40are formed into shapes along shapes of the outer surfaces40sof the light sources40. For this reason, contact areas between the inner surfaces46sof the hole portions46and the light sources40can be increased, and heat can effectively dissipate from the light sources40to the holding portion41.

In addition, in the light source unit4, the holding portion41may include resin portions filling spaces between the inner surfaces46sof the hole portions46and the outer surfaces40sof the light sources40. In this case, heat can more effectively dissipate from the light sources40to the holding portion41. Here, the holding portion41holds two light sources40such that the two light sources40are disposed on a straight line orthogonal to the optical axis6xof the optical fiber6.

Here, the optical head1according to the present embodiment irradiates the object100with light and provides light from the object100to the spectrometer A2(the photodetector of the spectrometer A2as well). The optical head1includes the light source unit4; the fixing portion5holding the optical fiber6and fixing the position of the optical fiber6; the optical fiber6inserted through the insertion hole42while being fixed to the fixing portion5; the casing2accommodating at least a part of the light source unit4, the fixing portion5, and the optical fiber6; and the light transmissive window member31disposed in a manner of facing the one end surface61aof the optical fiber6.

The optical head1includes the foregoing light source unit4. Therefore, it is possible for effects similar to those of the foregoing light source unit4to be exhibited. Moreover, the optical head1includes the window member31disposed in a manner of facing the one end surface61aof the optical fiber6. Therefore, the one end surface61aof the optical fiber6can be kept clean. As described above, according to the light source unit4, since the one end surface61aof the optical fiber6can be brought even closer to the object100, fouling of the one end surface61aof the optical fiber6is more effectively prevented by the window member31.

In addition, the optical head1includes the sleeve63provided in the optical fiber6such that at least the one end portion61of the optical fiber6is coated therewith while the one end surface61ais exposed. In this manner, by providing the light blocking member in the optical fiber6, when the incidence of stray light on optical fiber6is curbed, work of providing the light blocking member in the holding portion41of the light source unit4is no longer essential. However, the light blocking member may be provided in the holding portion41.

In addition, in the optical head1, the light source unit4and the fixing portion5are formed separately from each other. The fixing portion5holds the optical fiber6in a state where the one end portion61of the optical fiber6protrudes from the fixing portion5. The light source unit4is detachably attached to the fixing portion5in a state where the one end portion61of the optical fiber6protruding from the fixing portion5is inserted through the insertion hole42. For this reason, for example, when the light sources40break down or the like, the light source unit4in its entirety can be easily replaced.

In addition, in the optical head1, the window member31faces the plurality of light sources40such that the light L1emitted from the plurality of light sources40passes therethrough, and is provided at a position where the light L3emitted from the plurality of light sources40and reflected by the window member31is not incident on the optical fiber6in the optical axis direction of the optical fiber6. For this reason, incidence of the light L3reflected by the window member31without going through the object100on the optical fiber6as stray light can be curbed.

In addition, in the optical head1, the window member31is provided in a manner of facing the plurality of light sources40such that light emitted from the plurality of light sources40passes therethrough. The wavelength region of light emitted from the plurality of light sources40includes the first wavelength region included in the sensitivity region of a photodetector W1, and the second wavelength region different from the sensitivity region of the photodetector W1. The window member31reduces the reflectance of the first wavelength region and reduces the transmittance of the second wavelength region. For this reason, the object100can be efficiently irradiated with the components of light from the light sources40in the first wavelength region included in the sensitivity region of the photodetector W1, arrival of the components of light from the light sources40in the second wavelength region not included in the sensitivity region of the photodetector W1at the object100is curbed, and damage to the object100can be curbed.

In addition, the optical head1includes the circuit board7having the main surface7sand electrically connected to the light sources40, and the support member8supporting the light source unit4and the fixing portion5. The light source unit4and the fixing portion5are arrayed in a direction toward the opening42bfrom the opening42a(Y direction). The circuit board7is disposed in a manner of facing the light source unit4and the fixing portion5when viewed in a direction along the main surface7s(for example, the Y direction). The support member8is formed such that the path from the light source unit4toward the circuit board7with the support member8therebetween is longer than the distance between the circuit board7and the light source unit4in a direction intersecting the main surface7s(for example, the Z direction) when viewed in a direction along the main surface7s(for example, the Y direction).

In this manner, a space is reduced by disposing the circuit board7such that it faces the light source unit4and the fixing portion5using the support member8. At this time, since the path reaching the circuit board7from the light source unit4with the support member8therebetween is longer than the direct distance between the light source unit4and the circuit board7, transfer of heat generated in the light sources40to the circuit board7can be curbed. Accordingly, malfunction due to heat and deterioration in characteristics are curbed.

In addition, the optical head1includes the connector64provided in the other end portion62of the optical fiber6and connecting the optical fiber6to another optical fiber. For this reason, the optical fiber6can be easily connected to another optical fiber using the connector64.

In addition, the optical head1includes the holding member11holding the connector64, and the fixing member113for fixing the holding member11to the casing2. The long hole111his formed in the holding member11. The holding member11is disposed on the bottom plate29of the casing2such that the long hole111hlies along the optical axis direction of the optical fiber6, and is fixed to the bottom plate29by the fixing member113inserted through the long hole111h. For this reason, the positions of the optical fiber6, the connector64, and the holding member11can be easily adjusted in the extending direction of the long hole111h(that is, the optical axis direction of the optical fiber6, the Y direction).

Moreover, the optical head1includes the cap3holding the window member31. The cap3is disposed on the outward side of the casing2and attached to the casing2. For this reason, the window member31can be attached and detached outside the casing2.

The foregoing embodiment has described an aspect of the present disclosure Therefore, the present disclosure is not limited to the foregoing embodiment and may be arbitrarily modified. Subsequently, modification examples will be described.

First Modification Example

FIG.13is an exploded and enlarged cross-sectional view illustrating a part of the optical head according to a first modification example. As illustrated inFIG.13, the optical head1according to the first modification example can include a light source unit4A in place of the light source unit4. The light source unit4A differs from the light source unit4in that the insertion hole42has a different shape compared to the light source unit4. In the light source unit4A, the insertion hole42includes a tapered portion42rof which the inner surface42sis formed into a tapered shape and connected to the opening42bsuch that the insertion hole42expands from the opening42atoward the opening42b.

According to this constitution, when the optical fiber6is inserted through the insertion hole42from the opening42bof the insertion hole42, the one end portion61of the optical fiber6can be guided toward the opening42adue to the tapered portion42ron the inner surface42sof the insertion hole42. At this time, if the sleeve63is provided in the optical fiber6, the sleeve63slides along the tapered portion42rso that contact of the one end surface61aof the optical fiber6with the inner surface42sof the insertion hole42is curbed.

Second Modification Example

FIG.14is a perspective view illustrating a part of the optical head according to a second modification example.FIG.15is a cross-sectional view of the optical head illustrated inFIG.14. As illustrated inFIGS.14and15, the optical head1according to the second modification example includes a light source unit70in place of the light source unit4. The light source unit70is constituted of the light source unit4and the fixing portion5which are integrated. Therefore, in addition to the constitution of the light source unit4, the light source unit70further includes at least the optical fiber6and the sleeve63serving as the light blocking member. In such a light source unit70, for example, when the light sources40break down, only the light sources40can be replaced.

Third Modification Example

FIG.16is a perspective view illustrating a part of the optical head according to a third modification example.FIGS.17and18are exploded cross-sectional views illustrating the optical head illustrated inFIG.16. As illustrated inFIGS.16to18, the optical head1according to the third modification example differs from the optical head1according to the embodiment in including a light source unit4B in place of the light source unit4, in including two circuit boards7, and in not including the heat sink9and the fan10. The light source unit4B differs from the light source unit4in having more light sources40than those of the light source unit4.

Here, the light source unit4B has four light sources40. The four light sources40are disposed at equal intervals (do not have to be disposed at equal intervals) on the circumference about the optical axis6xof the optical fiber6. In this manner, in the light source unit4B, since more light sources40are provided, an output of one light source40can be restrained. As a result, the amounts of heat generation in the light sources40can be restrained. For this reason, in the optical head1according to the third modification example, the heat sink9and the fan are no longer necessary, and the circuit boards7can be disposed on both sides of the fixing portion5in the Z direction by utilizing the spaces for the heat sink9and the fan10. In this manner, the light source unit can include any arbitrary number (two or more) of light sources40.

Fourth Modification Example

FIG.19is a view schematically illustrating a part of the optical head according to a fourth modification example. In the foregoing embodiment and other modification examples, a case where the light blocking member for curbing incidence of stray light on the optical fiber6is provided as the sleeve63in only the optical fiber6has been described as an example. However, as illustrated inFIG.19, the light blocking member for curbing incidence of stray light on the optical fiber6may be provided in the holding portion41. That is, here, the holding portion41includes a light blocking portion (light blocking member)90provided in a manner of protruding along an edge portion of the opening42asuch that the one end portion61of the optical fiber6is covered when the optical fiber6is inserted through the insertion hole42and protrudes from the opening42a. According to this constitution, when incidence of stray light on the optical fiber6is curbed, work of coating the one end portion61of the optical fiber6with the sleeve63or the like is no longer essential. However, the optical fiber6may be coated with the sleeve63.

Fifth Modification Example

FIG.20is a view illustrating the optical head according to a fifth modification example.FIG.20(a)is a perspective view, andFIG.20(b)is a top view.FIG.21is a cross-sectional view along line XXI-XXI inFIG.20(b), andFIG.22is a cross-sectional view along line XXII-XXII inFIG.20(b).

As illustrated inFIGS.20to22, an optical head1A includes the light source unit4, the fixing portion5, and the optical fiber6. The light source unit4has a plurality of (here, four) light sources40and the holding portion41holding the light sources40. Compared to the optical head1, the optical head1A does not include the circuit board7, the support member8, the heat sink9, the fan10, and the holding member11. The optical head1A includes a casing120, a spacer130, and a lid member140. The casing120is formed into a tubular shape (here, a cylindrical shape) of which both ends open. The spacer130is provided at one end of the casing120, and the lid member140is provided at the other end of the casing120.

The holding portion41is inserted into the one end of the casing120and disposed inside the casing120. The holding portion41has an external shape along the inner surface of the casing120. That is, the holding portion41exhibits a pillar shape (here, a columnar shape). The holding portion41is fixed to the casing120in a state of being inserted into the one end of the casing120, for example, using a fixing member121such as a screw.

In the lid member140, a power source connector150is provided in a penetrating manner. Namely, the power source connector150is provided in a manner of reaching the inside of the casing120from the outside and attached to the casing120with the lid member140therebetween. For example, the power source cable A4is connected to the power source connector150on the outer side of the casing120. Meanwhile, the light sources40are connected to the power source connector150on the inner side of the casing120. The light sources40and the power source connector150are directly connected to each other (without going through a circuit board or the like) through wirings W40. Here, in each of the wirings W40, one end is connected to the power source connector150and the other end is connected to a lead pin (lead wire) of each of the light sources40. That is, the optical head1A includes the wirings W40connecting the power source connector150to the respective lead wires of the light sources40.

In addition, a head portion of a fixing member141such as a screw is exposed in the lid member140. A plurality of struts170are provided between the lid member140and the holding portion41. The struts170each include a shaft portion171, and a protruding portion172protruding from one end surface171aof the shaft portion171. The struts170are fixed to the holding portion41when the one end surface171aof the shaft portion171abuts the end surface44of the holding portion41and the protruding portion172is coupled (for example, screwed) to the holding portion41. Meanwhile, the struts170, in which the other end surface of the shaft portion171abuts the lid member140, are fixed to the lid member140by the fixing member141. Accordingly, the struts170support the lid member140while generating spaces according to the length of the shaft portion171on the holding portion41.

Moreover, an optical fiber connector160is provided in a penetrating manner in the lid member140. Namely, the optical fiber connector160is attached to the casing120with the lid member140therebetween in a manner of reaching the inside of the casing120from the outside. The optical fiber connector160includes a connection portion161protruding to the outside of the casing120, fixed to the lid member140, and receives connection of another optical fiber such as the optical fiber A3, for example. In addition, the optical fiber connector160includes a holding portion162held by the connection portion161inside the casing120and internally holding the optical fiber6.

The fixing portion5is provided at an end portion of the holding portion162on a side opposite to the connection portion161and holds the optical fiber6protruding from the holding portion162. The penetration hole51extending in one direction (here, the Y direction) is formed in the fixing portion5. The fixing portion5includes the tubular base portion52having the extending direction of the penetration hole51as the longitudinal direction, and the protruding portion53provided in a manner of protruding from the base portion52in the extending direction. The optical fiber6is inserted through the penetration hole51and reaches the distal end of the protruding portion53. Here, the end surface53aof the protruding portion53and the one end surface61aof the one end portion61of the optical fiber are substantially flush with each other. Accordingly, the one end portion61of the optical fiber6is covered by the protruding portion53except for the one end surface61a.

FIG.23is an enlarged view of a part inFIGS.21and22. As illustrated inFIG.23, a part of the base portion52of the fixing portion5and the protruding portion53are inserted through the insertion hole42of the holding portion41in a state of holding the optical fiber6. Further, a part of the protruding portion53and a part of the one end portion61of the optical fiber6protrude inside the recessed portion45. Accordingly, the optical fiber6is set such that the one end portion61including the one end surface61athereof is positioned between the plurality of light sources40with the protruding portion53therebetween. Therefore, here, the protruding portion53of the fixing portion5functions as the light blocking member for curbing incidence of stray light on the optical fiber6. In other words, here, the fixing portion5includes the light blocking member (the protruding portion53) covering the one end portion61of the optical fiber6, inserted through the insertion hole42together with the optical fiber6, and protruding from the opening42a. Here, four hole portions46are formed in the holding portion41, and the light sources40are disposed in the respective hole portions46. Therefore, here, the one end portion61of the optical fiber6is disposed in a manner of being surrounded by the four light sources40with the protruding portion53therebetween. The end surface52aof the base portion52of the fixing portion5and the flat surface portion42pprovided on the inner surface42sof the insertion hole42of the holding portion41may come into contact with each other, but in the illustrated example, they are separated from each other with a gap formed therebetween. In this example, the fixing portion5holding the optical fiber6is attached to the optical fiber connector160that is attached to the lid member140, and the lid member140and the holding portion41are fixed to each other by the struts170. Accordingly, the position of the optical fiber6held by the fixing portion5may be fixed. In other words, in this case, the fixing portion5fixes the position of the optical fiber6with another member therebetween. Alternatively, the position of the optical fiber6may be fixed without depending on another member by fitting the fixing portion5into the insertion hole42of the holding portion41. That is, even when the end surface52aof the fixing portion5and the flat surface portion42pof the holding portion41facing the end surface52aare separated, the fixing portion5may be regarded as a member for fixing the position of the optical fiber6. In addition, even when the end surface52aof the fixing portion5and the flat surface portion42pof the holding portion41facing the end surface52a, and the outer surface (side surface) of the base portion52and the inner surface42sof the insertion hole42are not in contact with each other and a clearance is provided therebetween, the fixing portion5may be regarded as a member for fixing the position of the optical fiber6in cooperation with the holding portion41.

The spacer130is attached to the holding portion41in a state of being in contact with the end surface43of the holding portion41. A recessed portion43pleading to the recessed portion45is formed on the end surface43. The recessed portion43pincludes a bottom surface43sfacing the spacer130side. The bottom surface43sis formed into an annular shape in a manner of surrounding an opening portion of the recessed portion45when viewed in a direction intersecting the end surface43. The window member31is disposed inside the recessed portion43pand attached to the bottom surface43s. In this manner, the window member31is attached to the holding portion41(the bottom surface43s) in a manner of being interposed between the light sources40and the spacer130.

An opening (third opening)130his formed in the spacer130such that the opening42aof the insertion hole42is exposed when viewed in a direction intersecting the end surface43and the light L1from each of the plurality of light sources40and light L4toward an end surface61sof the optical fiber6pass therethrough. Therefore, in a state where the spacer130is attached to the holding portion41, the object100can be irradiated with the light L1, and the light L4from the object100can be detected. On the other hand, in a state where the window member31is attached to the holding portion41, the spacer130can be attached and detached with respect to the holding portion41. Therefore, even in a state where the spacer130is detached, the object100can be irradiated with the light L1and the light L4from the object100can be detected with the window member31therebetween.

As described above, the optical head1A according to the present modification example exhibits effects similar to those of the foregoing optical head1. Moreover, in the optical head1A, the fixing portion5includes the light blocking member (the protruding portion53) covering the one end portion61of the optical fiber6, inserted through the insertion hole42together with the optical fiber6, and protruding from the opening42a. In this manner, by providing the light blocking member in the fixing portion5, when incidence of stray light on the optical fiber6is curbed, for example, work of coating the one end portion61of the optical fiber6with the light blocking member or providing the light blocking member in the holding portion41is no longer essential. However, the optical fiber6may be coated with the light blocking member, and the light blocking member may further be provided in the holding portion41.

In addition, the optical head1A includes the spacer130detachably attached to the holding portion41using a fixing member131such as a screw, and the opening130his formed in the spacer130such that the opening42ais exposed and the light L1of each of the plurality of light sources40passes therethrough. Further, the window member31is attached to the holding portion41in a manner of being interposed between the light sources40and the spacer130. For this reason, while the one end surface61aof the optical fiber is kept clean by the window member31, it can be used in both the state where the spacer130is attached and the state where the spacer130is detached. As an example, in the state where the spacer130is attached, the distances between the light sources40and a sample (the object100) can be simply determined through measurement in which the spacer130is brought into contact with the sample. Meanwhile, in the state where the spacer is detached, measurement can be performed by providing a space with respect to a fluidal sample such as a fluid, for example, while the distances between the light sources40and the sample are maintained.

Moreover, the optical head1A includes the power source connector150attached to the casing120in a manner of reaching the inside of the casing120from the outside and supplying power to the light sources40, and the wirings W40connecting the power source connector150to the respective lead wires of the light sources40. For this reason, miniaturization can be achieved compared to when the power source connector150and the light sources40are connected via the circuit board or the like. Heat generation in the light sources40can be restrained by increasing the number of light sources40to four or more, for example, and using each of the light sources40with low power. In this case, further miniaturization can be achieved without providing a heat sink, a cooling fan, or the like inside the casing120. In addition, in this case, the life of the light sources40can also be extended.

In the optical head1A, a heat sink can be provided on the outward side of the miniaturized casing120. In this case, as an example, a heat sink may be formed into a tubular shape having an internal shape similar to the external shape of the casing120, and the casing120may be inserted into the heat sink such that the inner surface of the heat sink and the outer circumferential surface of the casing120come into contact with each other. At this time, a flange portion142of the lid member140can be utilized for fixing the heat sink. A plurality of fins arrayed radially when viewed in the axial direction of the heat sink can be formed on the outer circumferential surface of the heat sink. In this case, each of the fins may be constituted in a manner of extending in the axial direction substantially throughout the entire heat sink.

Other Modification Examples

In the foregoing embodiment, a case where the holding portion41holds two light sources40such that the two light sources40are disposed on a straight line orthogonal to the optical axis6xof the optical fiber6has been described as an example. However, the plurality of light sources40need only be disposed separately from each other by at least the diameter of the optical fiber6or longer (when the sleeve63is provided, the outer diameter of the sleeve63), and they may be arbitrarily disposed. As an example, the holding portion41can also hold the plurality of light sources40such that the angle of the corner connecting two light sources40and the optical axis6xof the optical fiber6becomes or larger when viewed in the optical axis direction of the optical fiber6(Y direction).

In addition, in the foregoing embodiment, an example in which the light source unit4and the optical head1or1A are utilized together with the spectrometer A2has been described, but it is not limited to this. The light source unit4and the optical head1or1A may be utilized for an arbitrary device for irradiating an object with light and providing light from the object to the photodetector. Moreover, even when the light source unit4and the optical head1or1A are utilized together with the spectrometer A2, they may be constituted such that visible light of approximately 400 nm to 800 nm is provided to the photodetector of the spectrometer A2.

Furthermore, a constitution in which at least a part of the foregoing embodiment and the foregoing first to fifth modification examples is arbitrarily replaced may be employed. For example, the light source unit4B according to the third modification example may be constituted integrally with the fixing portion5as in the light source unit according to the second modification example. In addition, the light blocking portion90according to the fourth modification example may be provided in the holding portion41according to other modification examples.

INDUSTRIAL APPLICABILITY

It is possible to provide a light source unit capable of curbing incidence of stray light on an optical fiber while effectively propagating light from an object through the optical fiber, and an optical head.

REFERENCE SIGNS LIST