JP5502623B2 - Spectrometer - Google Patents

Description

  The present invention relates to a spectroscopic device that selects light in a predetermined wavelength range, and more particularly to a spectroscopic device that incorporates a dielectric thin film interference filter.

  Conventionally, a spectroscopic device using an interference filter in which dielectric thin films having different refractive indexes are alternately stacked and an intermediate cavity layer is formed of a dielectric thin film having an intermediate refractive index has been known (the following patents). Reference 1). This spectroscopic device has an interference filter provided so as to be rotatable, and the transmission wavelength is continuously changed by changing the incident angle with respect to the interference filter when collimated light is incident on the interference filter.

  By controlling the incident angle of the parallel light to the dielectric multilayer filter by rotating the rotary table provided with the dielectric multilayer filter, the wavelength variability according to the incident angle is improved. A wavelength tunable filter to be realized is known (see Patent Document 2 below). This wavelength tunable filter realizes output of transmitted light having a wider wavelength range by adopting a configuration in which four filters are rotationally symmetrically arranged on a rotary table.

Japanese Patent Application Laid-Open No. 62-22034 JP 2004-184673 A

  However, in the above-described conventional wavelength tunable filter, when incident light is incident on the filter obliquely, the optical axis of the incident light after passing through the filter changes according to the incident angle, resulting in an optical axis shift of the output light. Tended to occur. This tendency becomes conspicuous when a large variable range of the incident angle to the filter is set in order to widen the variable range of the transmission wavelength.

  Therefore, the present invention has been made in view of such problems, and an object thereof is to provide a spectroscopic device that can easily widen a variable range of a selected wavelength while reducing an optical axis shift of output light. And

  In order to solve the above problems, a spectroscopic device of the present invention includes a polarization separation element that separates light from a light source into first and second linearly polarized light components that are orthogonal to each other, and first and first outputs output from the polarization separation element. A mirror that reflects any one of the two linearly polarized light components toward the polarized light separating element, a filter portion provided between the polarized light separating element and the mirror member, and the polarized light separating element and the mirror member The filter unit selectively transmits a light component based on the linearly polarized light component from the polarization separation element in a wavelength range corresponding to the incident angle of the light component. The dielectric thin film interference filter is rotatably supported so that the incident angle can be changed. The “dielectric thin film interference filter” refers to a filter whose center wavelength representing the performance of the filter shifts according to the incident angle to the filter.

  According to such a spectroscopic device, the linearly polarized light component separated by the polarization separation element out of the light from the light source is returned toward the polarization separation element by the mirror member, so that the polarization separation element and the mirror member are separated. After being reciprocated and transmitted through the filter unit and the quarter-wave plate, the light is separated from the light from the light source through the polarization separation element and extracted. Thereby, the optical axis shift of output light is reduced irrespective of the incident angle with respect to the dielectric thin film interference filter which comprises a filter part. At this time, a light component based on the separated linearly polarized light component is incident back and forth through the filter unit, and the light component selectively interferes with the dielectric thin film in a wavelength range corresponding to the incident angle to the dielectric thin film interference filter. It is transmitted through the filter and output. At this time, the incident angle of the light component with respect to the dielectric thin film interference filter can be changed by rotating the dielectric thin film interference filter. Therefore, the transmission wavelength of the light component can be freely changed. As a result, the variable range of the selected wavelength can be easily widened while reducing the optical axis deviation of the output light.

  The filter unit includes n (n is an integer of 3 or more) dielectric thin film interference filters and dielectric thin film interference filters that are erected on the main surface, and are rotatable around a predetermined point along the main surface. Each of the n dielectric thin film interference filters has an end surface on the light incident side or the light emitting side, which has a predetermined point on the surface of the rotation support member and the main surface. It is preferable that the dielectric thin film interference filter is disposed so as to be inclined with respect to a line connecting the center point of the dielectric thin film interference filter.

  In this case, by rotating the rotation support member around a predetermined point on the main surface, the n dielectric thin film interference filters through which light is transmitted can be switched alternately, and each of the n dielectric thin film interference filters can be switched. The incident angle of light to the filter can also be changed. Therefore, it is possible to continuously change the transmission wavelength. In particular, the dielectric thin film interference filter is arranged such that its end face is inclined with respect to a line connecting a predetermined point on the main surface and the center point of the dielectric thin film interference filter, thereby providing a plurality of dielectric thin film interference filters. Interference between them is reduced over a wide range of rotation angles. As a result, the variable range of the selected wavelength can be broadened while reducing the optical axis deviation of the output light.

  Further, it is preferable that the n dielectric thin film interference filters are mounted such that each intersection formed by the main surface and the end surface is in contact with one inscribed circle. In this case, the range of the incident angle of light of each dielectric thin film interference filter can be made uniform, and the variable range of the selected wavelength can be efficiently expanded with respect to the area of the main surface of the limited rotation support member. I can do it.

  It is also preferable that each of the n dielectric thin film interference filters is disposed so as to be located outside the inscribed circle on the main surface. By adopting such a configuration, it is possible to further reduce the interference between the plurality of dielectric thin film interference filters.

  Further, the n dielectric thin film interference filters are arranged such that lines connecting a predetermined point on the main surface and a center point of the dielectric thin film interference filter on the main surface are at an equal angle to each other. Is also suitable. By using such a dielectric thin film interference filter, the range of the incident angle of light of each dielectric thin film interference filter can be made uniform, and the variable range of the selection wavelength can be efficiently performed with respect to the area of the limited rotation support member. Can spread well.

  It is also preferable that the n dielectric thin film interference filters are arranged so as to be n times rotationally symmetric about a predetermined point on the main surface. By adopting such a configuration, the variable range of the selection wavelength can be further expanded with respect to the limited area of the rotation support member.

  Furthermore, it is also preferable that the quarter wavelength plate is provided between the filter unit and the mirror. By providing such a quarter-wave plate, the linearly polarized light component reciprocatingly incident on the filter unit can be separated and extracted from the light from the light source by the polarization separation element.

  It is also preferable that the quarter wavelength plate is provided between the polarization separation element and the filter unit. By providing such a quarter-wave plate, the circularly polarized light component reciprocatingly incident on the filter unit can be separated from the light from the light source by the polarization separation element, and the circularly polarized light component can be extracted from the dielectric thin film. By making the light incident perpendicular to the interference filter, the wavelength range of the output light can be broadened.

  According to the present invention, it is possible to easily expand the variable range of the selection wavelength while reducing the optical axis shift of the output light.

It is a top view which shows schematic structure of the light source device which concerns on 1st Embodiment of this invention. It is a top view of the filter rotary body of FIG. It is a graph which shows the incident angle dependence of the peak wavelength of the transmission wavelength range of the band pass filter contained in the filter rotary body of FIG. (A)-(d) is a graph which respectively shows the wavelength characteristic of the light transmittance of the four band pass filters of FIG. FIGS. 3A and 3B are diagrams illustrating an incident state of light to the bandpass filter of FIG. 2, in which FIG. 3A is an incident angle of 0 degree, FIG. 2B is an incident angle of 25 degrees, and FIG. It is a figure which shows the case of degree. It is a graph which shows the wavelength characteristic of the light transmittance in the output of the light source device of FIG. It is a figure which shows the optical path at the time of the light incidence with respect to the band pass filter of FIG. It is a top view which shows schematic structure of the light source device which concerns on 2nd Embodiment of this invention. It is a graph which shows the wavelength characteristic of the light transmittance in the output of the light source device of FIG. 8, (a) is the wavelength characteristic at the time of perpendicular incidence to a band pass filter, (b) is the time of the oblique incidence to a band pass filter. The wavelength characteristic of is shown. It is a top view which shows schematic structure of the light source device which concerns on 3rd Embodiment of this invention. It is a top view which shows schematic structure of the light source device which concerns on 4th Embodiment of this invention. It is a top view which shows schematic structure of the light source device which concerns on 5th Embodiment of this invention. It is a graph which shows the wavelength characteristic of the light transmittance in the output of the light source device of FIG. It is a top view of the filter rotator which is a modification of the present invention. It is a top view of the filter rotator which is a modification of the present invention. It is a top view of the filter rotator which is a modification of the present invention. It is a top view of the filter rotator which is a modification of the present invention, where (a) is an incident angle of 20 degrees, (b) is an incident angle of 35 degrees, and (c) is an incident angle of 50 degrees. It is a figure which shows a case. It is a graph which shows the transmission wavelength range characteristic of the band pass filter which is a modification of this invention. It is a top view of the filter rotating body which is a comparative example of the present invention. It is a top view of the filter rotating body which is a comparative example of the present invention. It is a top view of the filter rotating body which is a comparative example of the present invention. It is a top view of the filter rotating body which is a comparative example of the present invention. It is a top view of the filter rotating body which is a comparative example of the present invention.

  Hereinafter, preferred embodiments of a spectroscopic device according to the present invention will be described in detail with reference to the drawings. In the description of the drawings, the same or corresponding parts are denoted by the same reference numerals, and redundant description is omitted. Each drawing is made for the purpose of explanation, and is drawn so as to particularly emphasize the target portion of the explanation. Therefore, the dimensional ratio of each member in the drawings does not necessarily match the actual one.

[First Embodiment]
FIG. 1 is a plan view showing a schematic configuration of the light source device according to the first embodiment of the present invention. A light source device 1 shown in the figure is a device used as a light source having a specific emission wavelength region in various inspection devices such as a semiconductor inspection device. The light source device 1 is an aspect of a spectroscopic device that selects a specific wavelength region of light from a light source. The light source 3 is mounted on a heat sink 2 as a heat dissipation mechanism, and is irradiated from the light source 3. A light conversion optical system 5 that receives light, converts the light, and outputs the light externally via the optical fiber 4, and a control system 30 that controls the light source 3 and the light conversion optical system 5 are configured. Here, in FIG. 1, the X axis is taken in the direction along the optical axis of the light source 3 on the plane of the paper, and the Y axis, the direction perpendicular to the X axis and the Y axis are taken along the direction perpendicular to the X axis on the plane of the paper. Along the Z axis.

  The light source 3 is a light source device such as a halogen lamp, a xenon lamp, or a white LED that widely includes a predetermined wavelength range from a visible light component to an infrared component as an emission wavelength range, and is provided in the light conversion optical system 5 positioned in the + X axis direction. The diffused light in a non-polarized state is emitted.

  First, the configuration of the light conversion optical system 5 will be described. The light conversion optical system 5 includes a collimator lens 6, a wavelength selection element 7, a polarization separation element 8, a filter rotating body (filter unit) 9, and a quarter wavelength plate in order from the vicinity of the light source 3 along the + X axis direction. 10 and a high reflection mirror (mirror member) 11 are provided.

  Diffused light from the light source 3 is converted into parallel light L <b> 1 by the collimator lens 6 and enters the wavelength selection element 7. The wavelength selection element 7 is an element for selecting light in a predetermined wavelength range (for example, 350 nm to 750 nm) from the parallel light L1 having the light emission wavelength range of the light source 3 as a wavelength range. It is a dichroic mirror that transmits light in the wavelength range and reflects light outside the wavelength range. The wavelength selection element 7 is disposed with its reflection surface inclined with respect to the X axis. When the parallel light L1 enters from the collimating lens 6, the wavelength selection element 7 transmits the light L2 having a predetermined wavelength range toward the polarization separation element 8 in the + X-axis direction, and does not require light of other wavelength components. Is reflected in the −Y-axis direction as a simple light and disappears by the beam damper 12. The wavelength range selected by the wavelength selection element 7 includes at least a wavelength variable range (for example, 400 nm to 700 nm, hereinafter referred to as “assumed wavelength range”) of light finally output from the light source device 1. Is set.

  The polarization separation element 8 is an optical element that receives the light L2 transmitted through the wavelength selection element 7 and separates the light L2 into first and second linear polarization components orthogonal to each other. For example, the polarization separation element 8 is a cube-shaped polarization beam. Splitter (PBS). Specifically, the polarization separation element 8 separates the first polarization component L3 having a polarization direction along the Y axis from the light L2 (hereinafter also referred to as “horizontal polarization component”) to the + X axis direction. Simultaneously with the transmission, a second polarization component L4 (hereinafter also referred to as “vertical polarization component”) having a polarization direction along the Z-axis is separated from the light L2 and reflected in the + Y-axis direction. The first polarization component L3 transmitted through the polarization separation element 8 is incident on the filter rotating body 9, and at the same time, the second polarization component L4 reflected from the polarization separation element 8 is lost by entering the beam damper 13. .

  Here, the structure of the filter rotating body 9 will be described in detail with reference to FIG.

  The filter rotator 9 is a rotating table (rotating support member) 90 that is a disk-like member rotatably supported by a rotating mechanism 94 having a rotating shaft along the Z axis, and a main surface 90 a of the rotating table 90. It is composed of four band-pass filters 91a, 91b, 91c and 91d which are erected so as to be rotationally symmetric along the periphery.

  These band-pass filters 91a, 91b, 91c, 91d have a so-called dielectric thin film interference type having a flat plate shape including a known laminated structure of dielectric thin films between the light incident surface 92 and the light emitting surface 93. It is a filter. With such a structure, the band-pass filters 91a, 91b, 91c, and 91d can selectively transmit light in a wavelength range corresponding to the incident angle of light with respect to the light incident surface 92. And the material and film thickness of each dielectric thin film are set so that the characteristic of the transmission wavelength range with respect to an incident angle may differ between the four band pass filters 91a-91d.

  3 shows the incident angle dependence of the peak wavelength in the transmission wavelength range of the bandpass filters 91a to 91d with respect to the incident light, and FIGS. 4A to 4D show the incident angles of the respective bandpass filters 91a to 91d. The wavelength characteristic of each light transmittance is shown. For example, when the incident angle of light with respect to the light incident surface 92 is 0 degree (perpendicular incidence), the band pass filter 91a has characteristics of a transmission wavelength region with a center wavelength of about 700 nm and a half-value width of several nm. As the angle increases, the transmission wavelength region shifts to the short wavelength side. When the incident angle is 50 degrees, the transmission wavelength region has a characteristic of a transmission wavelength region with a center wavelength of about 610 nm. The bandpass filters 91b, 91c, and 91d have center wavelengths of about 610 nm, about 530 nm, and about 460 nm when the incident angle is 0 degrees, and about 530 nm and about 460 nm when the incident angle is 50 degrees. , Which is about 400 nm, and has a transmission wavelength band characteristic different from that of the bandpass filter 91a. In other words, the peak wavelength becomes shorter as the absolute value of the incident angle becomes larger with reference to the peak wavelength where the incident angle is 0 degree, the change rate becomes maximum when the incident angle is 45 degrees, and the change rate becomes larger than that. Decrease.

Returning to FIG. 2, the bandpass filters 91 a to 91 d configured as described above are fixed so that the light incident surface 92 and the light emitting surface 93 are substantially perpendicular to the main surface 90 a of the turntable 90. In particular, connecting the rotational center _{C 1} of the center point 95a~95d the principal surface 90a on the main surface 90a of the band-pass filter 91a to 91d lines, respectively, the light incident surface of the band-pass filter 91a to 91d 92 And the light exit surface 93 is inclined so that the inclination angles are equal to each other. Further, four intersecting lines 96a to 96d formed by the respective light emitting surfaces 93 and the main surface 90a are in contact with one virtual inscribed circle 97, and the center point 95a of the bandpass filters 91a to 91d. ˜95d is set so as to be located outside the inscribed circle 97. In addition, the band-pass filter 91a to 91d, 4 single line connecting the center point thereof 95a~95d the rotation center _{C 1} is arranged so as to form an equal angle, i.e. 90 degrees. That is, four bandpass filters 91a~91d will be arranged around the rotational center C ₁ on the main surface 90a so as to be 4-fold rotational symmetry.

Further, the band-pass filter 91a to 91d, the inclination angle of the light incident surface 92 and the light emitting surface 93 against the vicinity of a line drawn between the center point 95a~95d the rotation center _{C 1} of the center point 95a~95d Rotating shaft members 98a to 98d such as shaft members and screw members may be attached for fine adjustment.

Filter rotating body 9 of the structure is parallel main surface 90a is the XY plane, is arranged such that the horizontally polarized light component L3 incident on between the peripheral portion of the rotation center C ₁ and the main surface 90a on the main surface 90a The As a result, any one of the bandpass filters 91a to 91d can be rotated so as to be positioned on the optical path of the polarization component L3, and the polarization component L3 can be selectively incident, and the bandpass filters 91a to 91d can be made to enter. The incident angle can be changed within a predetermined angle range. In this case, the variable range of the incident angle of each bandpass filter is determined by the beam diameter of the polarization component L3, the number of bandpass filters, and the shape and arrangement of the bandpass filters.

  Returning to FIG. 1, the quarter wavelength plate 10 disposed between the filter rotator 9 and the high reflection mirror 11 converts the polarization component L3 transmitted through the filter rotator 9 in the + X-axis direction from the horizontally polarized light. Convert to circularly polarized light. The high reflection mirror 11 reflects the polarization component L3 converted into circularly polarized light so as to return to the quarter-wave plate 10, the filter rotator 9, and the polarization separation element 8 along the −X axis direction. The quarter-wave plate 10 converts the polarization component L3 reflected by the high reflection mirror 11 from circularly polarized light to vertical polarized light. The polarized light component L3 converted into the vertically polarized light passes through the filter rotator 9 again along the −X axis direction, enters the polarization separation element 8, and is reflected by the polarization separation element 8 in the −Y axis direction. Is separated from the light L2 from the light source 3.

  Further, the light conversion optical system 5 is provided with a beam sampler 14, a depolarization plate 15, a shutter 16, and a condenser lens 17 so as to be arranged in order in the −Y-axis direction with respect to the polarization separation element 8. A part of the polarization component L3 reflected in the −Y-axis direction by the polarization separation element 8 is reflected by the beam sampler 14 and guided to the power monitor 18 to monitor its light intensity. On the other hand, the polarization component L3 is emitted to the outside by being guided to the optical fiber 4 through the beam sampler 14, the depolarization plate 15, the shutter 16, and the condenser lens 17. The depolarizing plate 15 is an element for changing the polarization component L3 that is linearly polarized light into a random polarization component (non-polarized light).

  Next, the configuration of the control system 30 will be described. The control system 30 includes a light source power source 31 that supplies power to the light source 3, a drive circuit 32 that rotationally drives the rotation mechanism 94, a light source power source 31, a drive circuit 32, and The control circuit 33 is connected to the power monitor 18.

  A computer terminal 34 is connected to the control circuit 33 so that the light intensity value monitored by the power monitor 18 can be output to the computer terminal 34, and a light source power source is supplied in accordance with a control signal from the computer terminal 34. By adjusting the output of 31, the light amount of the light source 3 can be adjusted.

  The control circuit 33 also has a function of controlling the rotation angle of the rotation mechanism 94 in accordance with a control signal from the computer terminal 34. At this time, the control circuit 33 changes and controls the rotation angle of the rotation mechanism 94 so that the incident angles with respect to the bandpass filters 91a to 91d become a predetermined angle. This rotation angle is determined corresponding to the center wavelength of the light emission wavelength region that is finally output from the light source device 1.

With reference to FIG. 5, the variable range of the incident angle of the band-pass filter 91a is illustrated. In the figure, the beam diameter of the polarized light component L3 is 5 mm, the width and thickness along the main surface 90a of the band-pass filter 91a is 11 mm, 2 mm, the shortest distance R ₁ from the center of rotation C ₁ to band pass filter 91a is 16.6 The incident state of the polarization component L3 to the bandpass filter 91a in the case of mm is shown. First, FIG. 5A shows a case where the incident angle of the band-pass filter 91a is 0 degree. At this time, no other band-pass filter is positioned on the optical path of the polarization component L3. There is no interference between the filters 91a to 91d. FIG. 5B shows a state in which the bandpass filters 91a to 91d are rotated counterclockwise so that the incident angle to the bandpass filter 91a is set to 25 degrees, and FIG. 5C shows the bandpass filters. This shows a state in which the filters 91a to 91d are further rotated counterclockwise to set the incident angle to the bandpass filter 91a to 50 degrees, and in either case, there is no interference between the bandpass filters 91a to 91d. . If the bandpass filter 91b is further rotated from the state of FIG. 5C, the transmission characteristics of the two bandpass filters 91a and 91b interfere with each other because the bandpass filter 91b enters the optical path of the polarization component L3. A stable output wavelength cannot be obtained. Accordingly, in this case, the variable range of the incident angle of each of the bandpass filters 91a to 91d is 0 degree to 50 degrees.

  FIG. 6 shows a simplified wavelength characteristic of the light transmittance when the incident angle to the bandpass filters 91a to 91d is changed in the range of 0 degree to 50 degrees in the present embodiment. In this way, it is understood that a wide range of about 400 nm to 700 nm is realized as the variable range of the emission wavelength of the light source device 1 by controlling the incident angles related to them while switching the bandpass filters 91a to 91d.

According to the light source device 1 described above, the linearly polarized light component L3 separated by the polarization separation element 8 out of the light from the light source 3 is returned toward the polarization separation element 8 by the high reflection mirror 11, whereby polarization separation is performed. After reciprocating and passing through the filter rotating body 9 and the quarter wavelength plate 10 disposed between the element 8 and the high reflection mirror 11, the light is separated from the light from the light source 3 through the polarization separation element 8. It is taken out. Thereby, the optical axis shift of output light is reduced irrespective of the incident angle with respect to the band pass filters 91a-91d which comprise the filter rotary body 9. FIG. That is, as shown in FIG. 7, assuming that the polarization component L3 is incident on the end face 92 of the bandpass filter 91a having the refractive index n and the thickness t at the incident angle θ and the refraction angle θ ′, the end face 92 The optical axis deviation D at the time of emission from the following formula (1):
D = t × sin θ × {1-cos θ / (n × cos θ ′)}
Calculated by Here, the polarization component L3 is incident on and transmitted through the bandpass filter 91a from the end surface 92 side, is then reflected by the high reflection mirror 11, and is incident on the bandpass filter 91a again from the end surface 93 side for transmission. As a result, when the light is returned to the polarization separation element 8, the optical axis shift of the polarization component L3 is cancelled.

  Further, the polarization component L3 reciprocates through the filter rotator 9 to obtain a square light blocking effect in the band-pass filter, thereby reducing a decrease in light blocking performance that has conventionally occurred during oblique incidence. be able to.

Furthermore, in the light source device 1, the polarization component L3 is reciprocated along the main surface 90a of the rotary table 90 of the filter rotator 9, and the polarization component L3 corresponds to the incident angle to the bandpass filters 91a to 91d. The light is selectively transmitted through the bandpass filters 91a to 91d in the selected wavelength range. At this time, by rotating the rotary table 90 around the rotation center C ₁ of the main surface 90a, with the four band-pass filters 91a~91d polarization component L3 is transmitted may be switched alternately, each of the four The incident angle of light to the individual bandpass filters 91a to 91d can also be changed. Therefore, it is possible to continuously change the transmission wavelength. In particular, the band-pass filter 91a to 91d, with respect to a line that end surfaces 92 and 93 connecting the center point 95a~95d on the main surface 90a of the rotation center _{C 1} and the band pass filter 91a to 91d on the main surface 90a By arranging to incline, interference between a plurality of bandpass filters is reduced in a wide range of rotation angles. As a result, it is possible to easily widen the variable range of the selected wavelength while reducing the optical axis shift of the output light when the variable range of the incident angle to the bandpass filter is increased.

In particular, the band-pass filter 91a to 91d, so that the light incident surface 92 is inclined with respect to a line connecting the center point 95a~95d of the rotation center _{C 1} and the band pass filter 91a to 91d on the main surface 90a arranged As a result, interference between the plurality of band-pass filters 91a to 91d is reduced in a wide range of rotation angles (incident angles). As a result, the variable range of the emission wavelength can be easily widened without increasing the rotation table 90. be able to.

  The four band pass filters 91a to 91d are mounted so that the intersecting lines 96a to 96d formed by the main surface 90a and the light incident surface 92 or the light emitting surface 93 are in contact with one inscribed circle 97. Therefore, the variable range of the incident angle of light of each of the bandpass filters 91a to 91d can be made uniform, and the variable range of the emission wavelength can be efficiently expanded with respect to the limited area of the rotary table 90. I can do it.

  Further, since the four band pass filters 91a to 91d are respectively located outside the inscribed circle 97 on the main surface 90a, interference between the band pass filters 91a to 91d can be further reduced.

Furthermore, the four band-pass filters 91a to 91d, the line connecting the center point 95a~95d of the rotation center _{C 1} and the band-pass filter 91a to 91d are at an equal angle to each other, the rotation on the main surface 90a since then the center C ₁ centered are disposed such that the 4-fold rotational symmetry, the variable range of the incident angle of light of the respective band-pass filter 91a~91d can be made uniform, limited turntable The variable range of the emission wavelength can be more efficiently expanded with respect to the area of 90.

  Here, the expansion effect of the variable range of the emission wavelength according to the present embodiment will be described by comparing with a comparative example. 19 and 20 are plan views showing the structure of a filter rotator as a comparative example of the present invention.

Filter rotating body 909A shown in FIG. 19, band-pass filters 91a~91d width and thickness along the main surface 90a is 10mm, and a 2 mm, band pass filter 91a~91d is the shortest from the center of rotation _{C 1} distance 1 mm, an example in which the inclination angle of the light incident surface 92 is arranged such that 0 ° with respect to the line connecting the rotational center C ₁ and the center point 95a to 95d. When this filter rotator 909A is rotated, in order to prevent interference between the bandpass filters 91a to 91d, the variable range of the incident angle of the polarization component L3 having a beam diameter of 5 mm is 0 degrees (solid line in FIG. 19). ) To 21 degrees (state indicated by a dotted line in FIG. 19).

Further, the filter rotating body 909B shown in FIG. 20 (a) is an example of a case in which spread the shortest distance from the rotation center _{C 1} of the filter rotating body 909A to 5 mm. In this case, the variable range of the incident angle of the polarization component L3 having a beam diameter of 5 mm is slightly expanded from 0 degrees to 27 degrees, but is considerably limited as compared with the filter rotating body 9 of the present embodiment.

Further, the filter rotating body 909C shown in FIG. 20 (b), the filter rotating body 909A, and change the width and thickness of the band-pass filter 91a to 91d 18 mm, in 2 mm, the shortest distance from the center of rotation _{C 1} This is an example when the width is expanded to 32 mm. In this case, the variable range of the incident angle of the polarization component L3 having a beam diameter of 5 mm is expanded to 0 to 39 degrees, but is narrower than the filter rotating body 9 of the present embodiment. Nevertheless, it is necessary to make the diameter of the rotary table 90 of the filter rotary body 909C considerably larger than that of the rotary table 90 of the filter rotary body 9 to about 102 mm.

Thus, when placed along the line connecting the bandpass filter 91a~91d rotational center C ₁ and the center point 95a to 95d, the angle of incidence allocated per one filter by interference between adjacent filters Restrictions occur. Further, since the incident angle to the bandpass filters 91a to 91d is in a range of positive and negative angles over 0 degrees (for example, in the case of the filter rotating body 909A, a range of ± 21 degrees), the substantial incident angle change amount Becomes half the angle variable range. Efficiency contrast, in the case of the present embodiment is arranged to be inclined to the line connecting the bandpass filter 91a~91d rotational center C ₁ and the center point 95a to 95d, the angle of incidence allocated per one filter In addition, the substantial incident angle can be changed by effectively utilizing the variable range of the incident angle. Furthermore, in the case of this embodiment, such a merit can be realized without increasing the size of the filter rotator 9.

  Here, in FIG. 1, the wavelength component guided from the wavelength selection element 7 to the beam damper 12 is also provided with a wavelength selection mechanism having a similar configuration including a filter rotator and a rotation mechanism, whereby two wavelengths in different wavelength regions are provided. Can be output simultaneously. In this case, if the wavelength selecting element 7 is a half mirror, light of two wavelengths can be output simultaneously in the same wavelength region. Furthermore, in this case, it is possible to obtain a multi-wavelength output by appropriately selecting the transmittance of the wavelength selection element 7 and arranging a plurality of stages and providing a wavelength selection mechanism corresponding thereto.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. FIG. 8 is a plan view showing a schematic configuration of the light source device according to the second embodiment of the present invention. The difference between the light source device 101 shown in the figure and the light source device 1 according to the first embodiment is that a quarter-wave plate 10 is disposed between the polarization separation element 8 and the filter rotator 9, and the horizontal polarization component L3. The light component converted into the circularly polarized light based on the above is configured to reciprocate through the filter rotator 9.

  In such a light source device 101, the horizontal polarization component L 3 that has passed through the polarization separation element 8 from the light source 3 side is converted into circularly polarized light by passing through the quarter-wave plate 10 and is incident on the filter rotator 9. The polarized light component L3 that has passed through the filter rotator 9 is reflected by the high reflection mirror 11, passes through the filter rotator 9 again, and then converted into vertical polarization by the quarter-wave plate 10. The polarization component L3 converted into the vertically polarized light is reflected by the polarization separation element 8, separated from the light from the light source 3, and output. Here, when the incident angle of the polarization component L3 with respect to the bandpass filters 91a to 91d in the filter rotator 9 is set to 0 degree, the wavelength component reflected by the light incident surface 92 of the bandpass filters 91a to 91d. And the wavelength component transmitted through the band-pass filters 91a to 91d and reflected back by the high reflection mirror 11 is converted into vertical polarized light by the quarter wavelength plate and simultaneously incident on the polarization separating element 8. Reflected by the polarization separation element 8 toward the optical fiber 4. Thereby, the light in the wavelength range emitted from the light source 3 and selected by the wavelength selection element 7 can be extracted as broadband light (white output) as it is.

  FIG. 9A shows the wavelength characteristics of light transmittance when the angle of incidence on the band-pass filters 91a to 91d is 0 degree (vertical incidence) in the present embodiment, and FIG. The wavelength characteristics of the light transmittance when the incident angles to the filters 91a to 91d are changed in the range of 0 degree to 50 degrees (oblique incidence) are shown in a simplified manner. In this way, by controlling the incident angles relating to the bandpass filters 91a to 91d while switching the bandpass filters 91a to 91d, a wide range from about 400 nm to 700 nm is realized as a variable range of the emission wavelength of the light source device 101, and a white output is also provided. It can be easily realized.

[Third Embodiment]
Next, a third embodiment of the present invention will be described. FIG. 10 is a plan view showing a schematic configuration of a light source device according to the third embodiment of the present invention. The difference between the light source device 201 shown in the figure and the light source device 1 according to the first embodiment is the same as the filter rotating body 9, the quarter wavelength plate 10, and the high reflection mirror (mirror member) 11 of the light source device 1. This is a point having two systems.

  Specifically, in addition to the filter rotating body 9A, the quarter wavelength plate 10A, and the high reflection mirror 11A that are sequentially arranged from the polarization separation element 8 along the + X-axis direction, the polarization separation element 8 extends in the + Y-axis direction. A filter rotating body 9B, a quarter-wave plate 10B, and a high reflection mirror 11B are provided in this order.

  In the light source device 201 having such a configuration, the vertical polarization component L4 reflected by the polarization separation element 8 and traveling in the + Y-axis direction is reflected by the high reflection mirror 11B, whereby the filter rotators 9B and ¼. The light passes back and forth through the wave plate 10B. As a result, a desired wavelength component can be selected from the polarization component L4, and it is separated from the light from the light source 3 by being incident on the polarization separation element 8 in the state of horizontal polarization, and is extracted to the optical fiber 4 side. Can do. Therefore, two wavelengths of the filter rotators 9A and 9B are provided, and the rotation angles of the filter rotators 9A and 9B are controlled by the computer terminal 34 connected to the control circuit 33, so that the two wavelengths can be simultaneously transmitted to the optical fiber 4. It is also possible to increase the bandwidth by superimposing two systems of output light. Further, by matching the rotation angles of the bandpass filters of the two filter rotators 9A and 9B, a single wavelength output can be freely obtained with little energy loss.

[Fourth Embodiment]
Next, a fourth embodiment of the present invention will be described. FIG. 11: is a top view which shows schematic structure of the light source device which concerns on 4th Embodiment of this invention. The difference between the light source device 301 shown in the figure and the light source device 101 according to the second embodiment is the same as the quarter wavelength plate 10, the filter rotating body 9, and the high reflection mirror (mirror member) 11 of the light source device 101. This is a point having two systems.

  Specifically, in addition to the quarter-wave plate 10A, the filter rotating body 9A, and the high reflection mirror 11A arranged in order along the + X axis direction from the polarization separation element 8, the polarization separation element 8 extends in the + Y axis direction. A quarter-wave plate 10B, a filter rotator 9B, and a high reflection mirror 11B are provided in this order.

  In the light source device 301 having such a configuration, the vertical polarization component L4 reflected by the polarization separation element 8 and traveling in the + Y-axis direction is reflected by the high reflection mirror 11B, whereby the quarter wavelength plate 10B and the filter It passes back and forth through the rotating body 9B. As a result, a desired wavelength component can be selected from the polarization component L4, and it is separated from the light from the light source 3 by being incident on the polarization separation element 8 in the state of horizontal polarization, and is extracted to the optical fiber 4 side. Can do. Furthermore, it is also possible to output broadband light from the optical fiber 4 by controlling the incident angle of the polarization component L4 to the bandpass filters 91a to 91d of the filter rotating body 9B to be 0 degree. Therefore, two wavelengths of the filter rotators 9A and 9B are provided, and the rotation angles of the filter rotators 9A and 9B are controlled by the computer terminal 34 connected to the control circuit 33, so that the two wavelengths can be simultaneously transmitted to the optical fiber 4. Or a white output can be easily obtained. Further, by matching the rotation angles of the band-pass filters of the two filter rotators 9A and 9B, a single wavelength output and a white output can be freely obtained with little energy loss.

[Fifth Embodiment]
Next, a fifth embodiment of the present invention will be described. FIG. 12 is a plan view showing a schematic configuration of a light source device according to the fifth embodiment of the present invention. The difference between the light source device 401 shown in the figure and the light source device 201 according to the third embodiment is that a filter 19B is provided instead of the filter rotating body 9B.

  Specifically, the filter 19B is an optical element for transmitting a predetermined wavelength band among the wavelength bands included in the polarization component L4. The spectral shape in the predetermined wavelength range can be determined by the transmittance characteristic of the filter 19B.

  In the light source device 401 of this embodiment, the polarization component L4 that reciprocates through the filter 19B and the quarter-wave plate 10B and the polarization component L3 that reciprocates through the filter rotator 9A and the quarter-wave plate 10A are combined to produce light. The light is emitted from the fiber 4. As a result, a light output in which the polarization component L4 of white light having a wide wavelength band and the polarization component L3 having a wavelength component of a desired narrow band are controlled by controlling the rotation angle of the filter rotating body 9A is obtained. Can do.

  FIG. 13 shows a simplified wavelength characteristic of light transmittance when the angle of incidence of the filter rotating body 9A on the bandpass filters 91a to 91d in the present embodiment is changed in the range of 0 degrees to 50 degrees. . In this way, by controlling the rotation angle of the filter rotating body 9A, it is possible to realize output light in which a narrowband component that changes in a range of about 400 nm to 700 nm is superimposed on white light.

  In addition, this invention is not limited to embodiment mentioned above. For example, the number of band-pass filters mounted on the filter rotators 9, 9A, 9B is not limited to a specific number, and is 3 or more depending on the assumed wavelength range and the area of the filter rotators 9, 9A, 9B. Any number of sheets may be selected.

FIG. 14 shows a structure of a filter rotating body 109 having five band pass filters 91a to 91e. In this case, the beam diameter of the polarized light component L3 is 5 mm, the width and thickness along the main surface 90a of the band-pass filter 91a~91e is 10 mm, 2 mm, the shortest distance R from the center of rotation _{C 1} to bandpass filter 91a~91e _{When 1} is 15.3 mm and the bandpass filters 91a to 91e are rotated counterclockwise, the variable range of the incident angle of each of the bandpass filters 91a to 91e is set to 0 degree to 45 degrees.

FIG. 15 shows the structure of a filter rotating body 209 having six bandpass filters 91a to 91f. In this case, the beam diameter of the polarized light component L3 is 5 mm, the width and thickness along the main surface 90a of the band-pass filter 91a~91f is 12 mm, 2 mm, the shortest distance R from the center of rotation _{C 1} to bandpass filter 91a~91f _{When 1} is 39.4 mm and the bandpass filters 91a to 91f are rotated counterclockwise, the variable range of the incident angle of each of the bandpass filters 91a to 91f is set to 0 degree to 45 degrees.

FIG. 16 shows a structure of a filter rotating body 309 having three band pass filters 91a to 91c. In this case, the beam diameter of the polarized light component L3 is 10 mm, the shortest distance of the width and thickness along the main surface 90a of the band-pass filter 91 a - 91 c is 18 mm, 2 mm, from the center of rotation _{C 1} to band pass filter 91 a - 91 c R _{When 1} is 3.16 mm and the bandpass filters 91a to 91c are rotated counterclockwise, the variable range of the incident angle of each of the bandpass filters 91a to 91c is set to 0 degree to 50 degrees.

On the other hand, the filter rotator 909D, which is a comparative example of the present invention shown in FIG. 21A, has a width and thickness along the main surface 90a of the bandpass filters 91a to 91e of 10 mm and 2 mm, bandpass filter 91a~91e is the shortest distance from the rotation center _{C 1} is 1.38 mm, the inclination angle of the light incident surface for a line connecting the center point of the rotation center _{C 1} and the band-pass filter 91a~91e becomes 0 degrees This is an example of the arrangement. When this filter rotator 909D is rotated, the variable range of the incident angle of the polarization component L3 having a beam diameter of 5 mm is limited to 0 degrees to 9 degrees in order to prevent interference between the bandpass filters 91a to 91e. Is done. Further, a filter rotating body 909E which is a comparative example of the present invention shown in FIG. 21B has a width and thickness along the main surface 90a of the bandpass filters 91a to 91e of 10 mm and 2 mm, and the bandpass filter 91a~91e is arranged such shortest distance from the center of rotation _{C 1} is 16.38Mm, the inclination angle of the light incident surface for a line connecting the center point of the rotation center _{C 1} and the band-pass filter 91a~91e becomes 0 degrees This is an example. When the filter rotator 909E is rotated, the variable range of the incident angle of the polarization component L3 having a beam diameter of 5 mm is limited to 0 degree to 24 degrees. Furthermore, the filter rotator 909F, which is a comparative example of the present invention shown in FIG. 21C, has a width and thickness along the main surface 90a of the bandpass filters 91a to 91e of 12 mm and 2 mm. 91a~91e is the shortest distance from the rotation center _{C 1} is 32 mm, are arranged such inclination angle of the light incident surface is 0 degrees relative to a line connecting the center point of the rotation center _{C 1} and the band-pass filter 91a~91e This is an example. When the filter rotator 909F is rotated, the variable range of the incident angle of the polarization component L3 having a beam diameter of 5 mm is limited to 0 degrees to 29 degrees, although the diameter of the rotary table 90 is increased. Thus, the variable range of the incident angle is greatly limited as compared with the filter rotating body 109 of FIG. 14 using the same number of bandpass filters.

Further, the filter rotator 909G, which is a comparative example of the present invention shown in FIG. 22, is 12 mm and 2 mm in width and thickness along the main surface 90a of the bandpass filters 91a to 91f, and the bandpass filters 91a to 91f. but the shortest distance from the center of rotation C ₁ is 32 mm, in the example the tilt angle of the light incident surface is disposed such that 0 ° with respect to a line connecting the center point of the rotation center C ₁ and the band-pass filter 91a~91f is there. When the filter rotator 909G is rotated, the variable range of the incident angle of the polarization component L3 having a beam diameter of 5 mm is limited to 0 degrees to 23 degrees. As described above, the variable range of the incident angle is greatly limited as compared with the filter rotating body 209 of FIG. 15 using the same number of band-pass filters.

Further, a filter rotating body 909H, which is a comparative example of the present invention shown in FIG. 23A, has a width and thickness along the main surface 90a of the bandpass filters 91a to 91c of 18 mm and 2 mm, and the bandpass filter 91a~91c is arranged such shortest distance from the center of rotation _{C 1} is 0.577Mm, the inclination angle of the light incident surface for a line connecting the center point of the rotation center _{C 1} and the band-pass filter 91a~91c becomes 0 degrees This is an example. When the filter rotator 909H is rotated, the variable range of the incident angle of the polarization component L3 having a beam diameter of 10 mm is limited to 0 degree to 38 degrees, and compared with the filter rotator 309 in FIG. The variable range of is greatly limited. Further, a filter rotating body 909I which is a comparative example of the present invention shown in FIG. 23B has a width and thickness along the main surface 90a of the bandpass filters 91a to 91c of 26 mm and 2 mm, and the bandpass filter 91a~91c is arranged such shortest distance from the center of rotation _{C 1} is 14.577Mm, the inclination angle of the light incident surface for a line connecting the center point of the rotation center _{C 1} and the band-pass filter 91a~91c becomes 0 degrees This is an example. When this filter rotator 909I is rotated, the variable range of the incident angle of the polarization component L3 having a beam diameter of 10 mm is 0 to 50 degrees, but the rotary table 90 is compared with the filter rotator 309 in FIG. The diameter becomes larger than twice.

  The variable range of the incident angle with respect to the bandpass filters 91a to 91d of the filter rotators 9, 9A and 9B can be set to various ranges by changing the inclination angles of the bandpass filters 91a to 91d.

For example, the minimum angle included in the variable range of the incident angle is not limited to 0 degrees. Specifically, as shown in FIG. 17, a band-pass filter 91A～91f, the inclination angle of the light incident surface for a line connecting the center point of the rotation center _{C 1} and the band-pass filter 91A～91f on the main surface 90a May be set such that the variable range of the incident angle with respect to the band-pass filters 91a to 91f is, for example, 20 degrees to 50 degrees. In the figure, the width and thickness along the main surface 90a of the band-pass filter 91a~91f is 11 mm, a 2 mm, band pass filter 91a~91f is the shortest distance from the rotation center _{C 1} is 16.6mm In this example, the beam diameter of the polarization component L3 is set to 5 mm. In this way, by setting the minimum angle included in the variable range of incident angles to be greater than 0 degrees, it is possible to increase the change in the transmission wavelength region with respect to the change in the incident angle, thereby greatly expanding the entire wavelength variable range. it can. For example, in the case of the bandpass filter 91a having the incident angle dependence of the peak wavelength in the transmission wavelength region as shown in FIG. 3, when the incident angle is changed from 0 degree to 30 degrees, the change width of the peak wavelength is It is 5.43% with respect to the maximum peak wavelength. On the other hand, when the incident angle of the bandpass filter 91a is changed between 20 degrees and 50 degrees, the change width of the peak wavelength is 11.18%, and the change in the transmission wavelength region can be greatly increased by the same change in the incident angle. I understand that I can do it.

  In addition, the bandpass filters 91a to 91d built in the light source devices 1, 101, 201, 301, and 401 of the present embodiment have different center wavelengths in the transmission wavelength region with respect to the same incident angle, but have the same center wavelength. The half width may be different. FIGS. 18A to 18D show examples of the characteristics of the transmission wavelength range when the incident angles are changed in the range of 0 degree to 50 degrees at intervals of 5 degrees in the bandpass filters 91a to 91d, respectively. ing. When bandpass filters 91a to 91d having the same center wavelength are used in this way, the variable range of the selected wavelength can be easily widened while switching the bandwidth.

  As an embodiment of the spectroscopic device of the present invention, in addition to the light source device described above, a spectroscopic device for spectroscopically separating a predetermined wavelength component among light input from the outside may be used. It may be a light detection device incorporating a detector for detection.

  As the dielectric thin film interference filter used in each of the above-described embodiments of the present invention, a high pass filter, a low pass filter, a notch filter, or the like may be applied in addition to the band pass filter.

DESCRIPTION OF SYMBOLS 1,101,201,301,401 ... Light source device, 3 ... Light source, 8 ... Polarization separation element, 9, 9A, 9B, 109, 209, 309 ... Filter rotating body (filter part) 10, 10A, 10B ... 1 / 4 wavelength plate, 11, 11A, 11B ... high reflection mirror (mirror member), 90 ... rotary table (rotary support member), 90a ... main surface, 91a to 91f ... band pass filter (dielectric thin film interference filter), 92 ... the light incident surface (end surface), 93 ... light exit surface (end surface), 95a to 95d ... center point, 96A～96d ... intersection line, 97 ... inscribed circle, C 1 _... center of rotation, L3, L4 ... linearly polarized light component .

Claims (8)

A polarization separation element that separates light from the light source into first and second linearly polarized light components orthogonal to each other;
A mirror member that reflects any one of the first and second linearly polarized light components separated by the polarized light separating element so as to return to the polarized light separating element;
A filter portion provided between the polarization separation element and the mirror member;
A quarter wave plate provided between the polarization separation element and the mirror member;
The filter unit is
A light component based on the linearly polarized light component from the polarization separation element is selectively transmitted in a wavelength range corresponding to the incident angle of the light component, and the dielectric is rotatably supported so that the incident angle can be changed. Having a thin film interference filter,
A spectroscopic device characterized by that. The filter unit is
n (n is an integer of 3 or more) the dielectric thin film interference filter;
The dielectric thin film interference filter is provided on a main surface, and has a plate-like rotation support member that is rotatable around a predetermined point along the main surface,
Each of the n dielectric thin film interference filters has a light incident side or light emission side end surface at the predetermined point on the surface of the rotation support member and the center of the dielectric thin film interference filter on the main surface. It is arranged to be inclined with respect to the line connecting the points.
The spectroscopic apparatus according to claim 1. The n dielectric thin film interference filters are mounted such that each intersection formed by the main surface and the end surface is in contact with one inscribed circle,
The spectroscopic device according to claim 2. Each of the n dielectric thin film interference filters is disposed on the main surface so as to be located outside the inscribed circle.
The spectroscopic device according to claim 3. The n dielectric thin film interference filters are arranged such that lines connecting the predetermined point on the main surface and the center point of the dielectric thin film interference filter on the main surface are equiangular with each other. ,
The spectroscopic device according to claim 2, wherein the spectroscopic device is provided. The n dielectric thin film interference filters are arranged so as to be n times rotationally symmetric about the predetermined point on the main surface.
The spectroscopic device according to claim 5. The spectroscopic device according to claim 1, wherein the quarter-wave plate is provided between the filter unit and the mirror member. The spectroscopic device according to claim 1, wherein the ¼ wavelength plate is provided between the polarization separation element and the filter unit.