JP2012233914A - Light detection device and light detection system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily expand a variable range of selected wavelength without enlarging a size of a device.SOLUTION: A spectroscopic device 1 comprises: four band pass filters 11a-11d through which light L2 from a light source is selectively transmitted in a wavelength range in accordance with an incidence angle of the light L2; and a flat rotary table 10 on which the band pass filters 11a-11d are erected on a main face 10a and which are rotatable around a rotation center Calong the main face 10a. The four band pass filters 11a-11d are disposed so that light incidence faces 12 or light exit faces 13 are inclined relative to lines connecting the rotation center Con the main face 10a of the rotary table 10 and center points 15a-15d of the band pass filters 11a-11d on the main face 10a, respectively.

Description

  The present invention relates to a light detection device that spectrally detects light in a predetermined wavelength range and a light detection system including the same, and more particularly to a light detection device and a light detection system that incorporate 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 wavelength tunable filter including the plurality of filters described in Patent Document 2 described above, there is a tendency that the transmission wavelength variable range cannot be widened due to interference between the plurality of filters during rotation of the rotary table. This is because if the incident angle to a certain filter is set to be large, the incident light easily interferes with other filters, so that the range of the incident angle with respect to each filter is limited.

  Therefore, the present invention has been made in view of such problems, and provides a photodetection device and a photodetection system capable of easily expanding the variable range of the selected wavelength without increasing the size of the device. Objective.

  In order to solve the above-described problems, the photodetector of the present invention is configured to selectively transmit n light input from outside in a wavelength range corresponding to the incident angle of light (n is an integer of 3 or more). The thin-film interference filter, the dielectric thin-film interference filter are erected on the main surface, and are transmitted through the dielectric thin-film interference filter, a flat plate-shaped rotation support member that is rotatable around a predetermined point along the main surface. Each of the n dielectric thin film interference filters has an end face on the light incident side or light emitting side at a predetermined point on the surface of the rotation support member. And the dielectric thin film interference filter on the main surface are arranged so as to be inclined with respect to a line connecting the center point of the dielectric thin film interference filter. 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 photodetection device, light is incident from the outside along the main surface of the rotation support member, and the light is selectively dielectric within a wavelength range corresponding to the incident angle to the dielectric thin film interference filter. The light is transmitted through the thin film interference filter and output. At this time, 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. As a result, the transmission wavelength can be continuously changed. 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. As a result of the interference between the rotation angles being reduced, the variable range of the selected wavelength can be easily widened without increasing the rotation support member.

  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, each of the n dielectric thin film interference filters includes a rotation axis for adjusting an inclination angle with respect to a line connecting a predetermined point on the main surface and a center point of the dielectric thin film interference filter on the main surface. It is also suitable that the member is attached. By providing such a rotating shaft member, the range of the incident angle of light with respect to the dielectric thin film interference filter can be adjusted, so that the convenience of the photodetecting device when realizing a desired selection wavelength is improved.

  The light detection system of the present invention includes the above-described light detection device and a light source device that outputs light.

  According to the present invention, the variable range of the selected wavelength can be easily expanded without increasing the size of the apparatus.

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. It is a figure which shows the incident state of the light to the band pass filter of FIG. 1, (a) is an incident angle of 0 degree, (b) is an incident angle of 25 degree, (c) is an incident angle of 50. 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 filter rotary body of the light source device 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 two filter rotary bodies of the light source device of FIG. 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 graph which shows the wavelength characteristic of the light transmittance in two filter rotary bodies 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 which shows schematic structure of the photon detection apparatus which concerns on another embodiment of this invention. It is a schematic block diagram of the fluorescence detection system which is an application example 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.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of a light detection apparatus and a light detection system 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 FIG. 1 is a device used as a light source having a specific light emission wavelength region (for example, a near infrared 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 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 not directed toward the light conversion optical system 5 positioned in the + X axis direction. Polarized diffused light is emitted.

  First, the configuration of the light conversion optical system 5 will be described. The light conversion optical system 5 is provided with a collimating lens 6, a wavelength selection element 7, and a filter rotating body 8 in order from the vicinity of the light source 3 along the + X axis direction.

  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 filter rotating body 8 in the + X-axis direction, and unnecessary light of other wavelength components is unnecessary. The light is reflected in the −Y-axis direction and is lost by the beam damper 9. 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 to

  Here, the structure of the filter rotating body 8 will be described in detail with reference to FIG.

  The filter rotating body 8 includes a rotary table (rotary support member) 10 that is a disk-like member rotatably supported by a rotary mechanism 14 having a rotary axis along the Z axis, and a main surface 10 a of the rotary table 10. It is composed of four band-pass filters 11a, 11b, 11c, and 11d that are erected so as to be rotationally symmetric along the periphery.

  These band-pass filters 11a, 11b, 11c, and 11d are 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 12 and the light emitting surface 13. It is a filter. With such a structure, the band pass filters 11a, 11b, 11c, and 11d can selectively transmit light in a wavelength range corresponding to the incident angle of light with respect to the light incident surface 12. 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 11a-11d. For example, when the incident angle of light with respect to the light incident surface 12 is 0 degree, the band-pass filter 11a has characteristics of a transmission wavelength region having a center wavelength of about 700 nm and a half-value width of several nm, and increases the incident angle. Accordingly, the transmission wavelength region shifts to the short wavelength side, and when the incident angle is 50 degrees, the center wavelength is about 600 nm. The bandpass filters 11b, 11c, and 11d have transmission wavelength band characteristics different from those of the bandpass filter 11a having center wavelengths of about 610 nm, about 530 nm, and about 460 nm when the incident angle is 0 degree. FIG. 3 shows the incident angle dependence of the peak wavelength in the transmission wavelength region of the band-pass filters 11a to 11d with respect to incident light of S-polarized light and P-polarized light. Thus, the peak wavelength decreases as the absolute value of the incident angle increases with reference to the peak wavelength at an incident angle of 0 degree, and the rate of change increases as the absolute value of the incident angle increases.

Returning to FIG. 2, the bandpass filters 11 a to 11 d configured as described above are fixed so that the light incident surface 12 and the light emitting surface 13 are substantially perpendicular to the main surface 10 a of the turntable 10. In particular, a line connecting the rotational center _{C 1} of the center point 15a~15d the principal surface 10a on the principal surface 10a of the band-pass filter 11 a to 11 d, respectively, the light incident surface of the band-pass filter 11 a to 11 d 12 And the light exit surface 13 is inclined so that the inclination angles are equal to each other. Further, four intersecting lines 16a to 16d formed by the respective light emitting surfaces 13 and the main surface 10a are in contact with one virtual inscribed circle 17, and the center point 15a of the bandpass filters 11a to 11d. ˜15d is set to be located outside the inscribed circle 17. In addition, the band-pass filter 11 a to 11 d, 4 single line connecting the center point thereof 15a~15d the rotation center _{C 1} is arranged so as to form an equal angle, i.e. 90 degrees. That is, four bandpass filters 11a~11d will be arranged around the rotational center C ₁ on the main surface 10a so as to be 4-fold rotational symmetry.

Further, the band-pass filter 11a~11d is the inclination angle of the light incident surface 12 and the light emitting surface 13 against the vicinity of a line drawn between the center point 15a~15d the rotation center _{C 1} of the center point 15a~15d Rotating shaft members 18a to 18d such as shaft members and screw members may be attached for fine adjustment.

Filter rotating body 8 of the structure, the main surface 10a is parallel to the XY plane, it is arranged so that light L2 is incident between the peripheral portion of the rotation center C ₁ and the main surface 10a on the principal surface 10a. As a result, any one of the bandpass filters 11a to 11d can be rotated so as to be positioned on the optical path of the light L2, and the light L2 can be selectively incident, and the incident angle with respect to the bandpass filters 11a to 11d 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 width of the light L2, the number of bandpass filters, and the shape and arrangement of the bandpass filters.

  Returning to FIG. 1, the light conversion optical system 5 includes a beam sampler 21, a shutter 22, and a condenser lens 23 in order in the + X-axis direction along the optical axis of the light L <b> 3 transmitted by the filter rotator 8. It is arranged. A part of the light L3 is reflected by the beam sampler 21 and guided to the power monitor 24 to monitor its light intensity. On the other hand, the light L3 is irradiated to the outside by being guided to the optical fiber 4 through the beam sampler 21, the shutter 22, and the condenser lens 23.

  Next, the configuration of the control system 30 will be described. The control system 30 includes a light source power supply 31 that supplies power to the light source 3, a drive circuit 32 that rotationally drives the rotation mechanism 14, a light source power supply 31, a drive circuit 32, and The control circuit 33 is connected to the power monitor 24.

  A computer terminal 34 is connected to the control circuit 33 so that the light intensity value monitored by the power monitor 24 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 14 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 14 so that the incident angles with respect to the band-pass filters 11a to 11d 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. 4, the variable range of the incident angle of the band pass filter 11a is illustrated. In the figure, the beam diameter of the light L2 is 5 mm, the width and thickness along the main surface 10a of the band-pass filter 11a is 11 mm, 2 mm, the shortest distance R ₁ from the center of rotation C ₁ to band pass filter 11a 16.6 mm The incident state of the light L2 to the band pass filter 11a in the case of is shown. First, FIG. 4A shows a case where the incident angle of the band-pass filter 11a is 0 degree. At this time, no other band-pass filter is located on the optical path of the light L2. There is no interference between 11a-11d. 4B shows a state in which the bandpass filters 11a to 11d are rotated counterclockwise to set the incident angle to the bandpass filter 11a to 25 degrees, and FIG. 4C shows the bandpass filters. The state where the filters 11a to 11d are further rotated counterclockwise to set the incident angle to the band-pass filter 11a to 50 degrees is shown, and in either case, there is no interference between the band-pass filters 11a to 11d. . Further rotation from the state of FIG. 4C causes the bandpass filter 11b to enter the optical path of the light L2, so that the transmission characteristics of the two bandpass filters 11a and 11b interfere with each other and are stable. The emitted light wavelength cannot be obtained. Accordingly, in this case, the variable range of the incident angle of each of the bandpass filters 11a to 11d is 0 degree to 50 degrees.

FIG. 5 shows the wavelength characteristics of the light transmittance when the incident angle to the bandpass filters 11a to 11d is changed in the range of 0 degree to 50 degrees in the present embodiment. The characteristics G _A , G _B , G _C , and G _D correspond to the wavelength characteristics of the light transmittance corresponding to the change in the incident angle with respect to the band pass filters 11a, 11b, 11c, and 11d, respectively. In this way, it is understood that a wide range from 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 relating to the bandpass filters 11a to 11d while switching the band pass filters 11a to 11d.

According to the light source device 1 described above, the light L2 is incident along the main surface 10a of the turntable 10 from the light source 3, and the light L2 is in a wavelength range corresponding to the incident angles to the bandpass filters 11a to 11d. The light is selectively transmitted through the bandpass filters 11a to 11d and output. At this time, by rotating the rotary table 10 around the rotation center C ₁ of the main surface 10a, with the four band-pass filters 11a~11d light L2 is transmitted may be switched alternately, each of the bandpass The incident angle of the light L2 to the filters 11a to 11d can also be changed within a predetermined angle range, and as a result, the emission wavelength can be continuously changed.

In particular, the band-pass filter 11 a to 11 d, so that the light incident surface 12 is inclined with respect to a line connecting the center point 15a~15d of the rotation center _{C 1} and the bandpass filter 11 a to 11 d on the main surface 10a arranged As a result, interference between the plurality of band-pass filters 11a to 11d is reduced in a wide range of rotation angles (incident angles), and as a result, the light emission wavelength variable range can be easily widened without increasing the size of the rotary table 10. be able to.

  The four band pass filters 11a to 11d are mounted so that the intersecting lines 16a to 16d formed by the main surface 10a and the light incident surface 12 or the light emitting surface 13 are in contact with one inscribed circle 17. Therefore, the variable range of the incident angle of light of each of the bandpass filters 11a to 11d 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 10. I can do it.

  In addition, since the four band pass filters 11a to 11d are positioned outside the inscribed circle 17 on the main surface 10a, interference between the band pass filters 11a to 11d can be further reduced.

Furthermore, the four bandpass filters 11 a to 11 d, the line connecting the center point 15a~15d of the rotation center _{C 1} and the band-pass filter 11 a to 11 d are at an equal angle to each other, the rotation on the main surface 10a 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 11a~11d can be made uniform, limited turntable The variable range of the emission wavelength can be more efficiently expanded with respect to the area of 10.

  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. 17 and 18 are plan views showing the structure of a filter rotator as a comparative example of the present invention.

Filter rotating body 908A shown in FIG. 17, 10 mm width and thickness along the main surface 10a of the band-pass filter 11 a to 11 d, a 2 mm, band-pass filter 11 a to 11 d 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 12 are arranged such that 0 ° with respect to the line connecting the rotational center C ₁ and the center point 15 a to 15 d. When the filter rotator 908A is rotated, the variable range of the incident angle of the light L2 having a beam diameter of 5 mm is 0 degrees (indicated by the solid line in FIG. 17) in order to prevent interference between the bandpass filters 11a to 11d. The state is limited to 21 degrees (the state indicated by the dotted line in FIG. 17).

Further, the filter rotating body 908B shown in FIG. 18 (a) shows an example of a case where spread the shortest distance from the rotation center _{C 1} of the filter rotating body 908A to 5 mm. In this case, the variable range of the incident angle of the light L2 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 8 of the present embodiment.

Further, the filter rotating body 908C shown in FIG. 18 (b), the filter rotating body 908A, and change the width and thickness of the band-pass filter 11 a to 11 d 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 light L2 having a beam diameter of 5 mm is expanded to 0 degrees to 39 degrees, but is narrower than the filter rotating body 8 of the present embodiment. Nevertheless, the diameter of the rotary table 10 of the filter rotating body 908C needs to be considerably increased to about 102 mm as compared with the diameter of the rotary table 10 of the filter rotating body 8 being about 30 mm.

Thus, when placed along the line connecting the bandpass filter 11a~11d rotational center C ₁ and the center point 15 a to 15 d, the incident angle to be assigned per one filter by interference between adjacent filters Restrictions occur. In addition, since the incident angle to the bandpass filters 11a to 11d is in a range of positive and negative angles over 0 degrees (for example, in the case of the filter rotator 908A, 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 a bandpass filter 11a~11d the line connecting the rotational center C ₁ and the center point 15 a to 15 d, the incident angle to be assigned 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 8.

  Here, in FIG. 1, the wavelength component guided from the wavelength selection element 7 to the beam damper 9 is also provided with a wavelength selection mechanism having a similar configuration including a filter rotator and a rotation mechanism, so that 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. 6 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 the two filter rotators 8A and 8B having the same configuration as the filter rotator 8 are separated from the light L2. The two linearly polarized light components L4 and L5 are transmitted through the filter rotators 8A and 8B as P-polarized light, respectively.

  Specifically, in the light conversion optical system 105 of the light source device 101, the polarization separation element 25, the mirrors 26 and 27, the polarization combining element 28, the filter rotators 8A and 8B, and the two filter rotators 8A and 8B are rotated. Rotating mechanisms 14A and 14B are provided.

  The polarization separation element 25 is an optical element that receives the light L2 transmitted through the wavelength selection element 7 and separates the light L2 into two linearly polarized light components orthogonal to each other. For example, a cube-shaped polarization beam splitter (PBS) It is. Specifically, when the polarization separation element 25 separates a polarization component L4 having a polarization direction along the Y axis from the light L2 (hereinafter also referred to as “horizontal polarization component”) and transmits it in the + X axis direction. At the same time, a polarization component L5 having a polarization direction along the Z axis (hereinafter also referred to as “vertical polarization component”) is separated from the light L2 and reflected in the + Y axis direction.

  The filter rotators 8A and 8B are provided on the optical axes of the polarization components L4 and L5 transmitted or reflected by the polarization separation element 25, respectively. The bandpass filters 11a to 11d respectively mounted on the filter rotators 8A and 8B have the same transmission wavelength band characteristics with respect to the incident angles of P-polarized light and S-polarized light between the two filter rotators 8A and 8B. Yes. More specifically, the characteristics of the transmission wavelength region are the same between the bandpass filters 11a, the bandpass filters 11b, the bandpass filters 11c, and the bandpass filters 11d mounted on the two filter rotating bodies 8A and 8B. Has been.

Filter rotating body 8A is mounted so as to extend along the main surface 10a of the turntable 10 in the rotating mechanism 14A having an axis of rotation along the Z-axis in the XY plane, the rotation center C ₁ and the main surface on the main surface 10a It is positioned so that the horizontally polarized light component L4 is incident between the peripheral edge portion 10a (see FIG. 2). Thereby, the filter rotating body 8A can change the incident angle of the horizontal polarization component L4 with respect to the bandpass filters 11a to 11d by rotating the rotary table 10, and the horizontal polarization component L4 is changed to the bandpass filters 11a to 11a. It is always incident on 11d in the state of P-polarized light.

Filter rotating body 8B is mounted to the major surface 10a of the turntable 10 in the rotating mechanism 14B having a rotational axis along the Y-axis so as to extend along the ZX plane, the rotation of the main surface 10a center _{C 1} and the main surface 10a It is located so that the vertical polarization component L5 may be incident between the peripheral edge portions (see FIG. 2). A mirror 26 that totally reflects S-polarized light in the assumed wavelength range is disposed between the polarization separation element 25 and the filter rotator 8B, and reflects the vertical polarization component L5 emitted in the + Y-axis direction in the + X-axis direction. In this way, the light is incident on the filter rotating body 8B. Thereby, the filter rotating body 8B can change the incident angle of the vertical polarization component L5 with respect to the bandpass filters 11a to 11d by rotating the rotary table 10, and the vertical polarization component L5 is changed to the bandpass filters 11a to 11a. It is always incident on 11d in the state of P-polarized light.

  Here, the rotation axis of the rotary table 10 is orthogonal between the filter rotator 8A and the filter rotator 8B so as to be incident on the bandpass filters 11a to 11d as P-polarized light. The rotation axis may be the same direction, and the polarization plane may be rotated using a λ / 2 plate or the like so as to be incident on the bandpass filters 11a to 11d as P-polarized light. In addition, in the place where the λ / 2 plate is used, the λ / 2 plate is inserted before and after the band pass filter.

  The polarization combining element 28 is disposed in the + X-axis direction along the optical axis of the horizontal polarization component L4 that has passed through the filter rotating body 8A, and the mirror 27 is disposed between the polarization combining element 28 and the filter rotating body 8B. Has been. The mirror 27 has a role of totally reflecting S-polarized light in the assumed wavelength range and reflecting the vertically polarized component L5 transmitted through the filter rotating body 8B so as to be incident on the polarization combining element 28 along the −Y axis direction.

  The polarization beam combining element 28 is an optical element for combining two polarization components L4 and L5 that are orthogonal to each other. For example, a cube-shaped polarization beam splitter (PBS) is used. Specifically, the polarization beam combiner 28 combines the horizontal polarization component L4 incident along the X axis and the vertical polarization component L5 incident along the Y axis to generate the unpolarized combined light L3. , And emitted in the + X-axis direction. A part of the synthesized light L3 synthesized by the polarization synthesizing element 28 is guided to the power monitor 24, and at the same time, guided to the optical fiber 4 through the beam sampler 21, shutter 22, and condenser lens 23. , Irradiated outside.

  The control circuit 33 of the control system 30 is connected to any one of the bandpass filter 11a, the bandpass filter 11b, the bandpass filter 11c, and the bandpass filter 11d that are mounted on the filter rotators 8A and 8B and have the same light transmission characteristics. The rotation angles of the rotation mechanisms 14A and 14B are changed and controlled so that the polarization components L4 and L5 are incident and the incidence angles of the polarization components L4 and L5 with respect to the bandpass filters 11a to 11d are the same. In this way, if the incident angles of the two polarization components L4 and L5 are made the same, the filter rotators 8A and 8B are arranged so that the transmission wavelength regions of the polarization components L4 and L5 corresponding to the respective incident angles coincide. Will be. That is, the light components L4 and L5 after passing through the filter rotators 8A and 8B have the same spectral profile.

  According to such a light source device 101, the horizontal polarization component L4 separated by the polarization separation element 25 is incident on the filter rotator 8A as P-polarized light, and the vertical polarization component L5 separated by the polarization separation element 25 is the filter rotator. After being incident on the light 8B as P-polarized light at the same incident angle as the horizontal polarization component L4, the light transmitted through the two filter rotating bodies 8A and 8B is combined and emitted to the outside. Here, since the characteristics of the transmission wavelength region with respect to the incident angle with respect to the P-polarized light of the bandpass filters 11a to 11d mounted on the two filter rotators 8A and 8B are the same, the incident angle can be set appropriately. In addition, it is possible to narrow and stabilize the emission characteristics over the assumed wavelength range, and to efficiently emit light from the light source.

  Further, if the incident angles of the two polarization components L4 and L5 to the bandpass filters 11a to 11d are set to different angles, two different wavelength outputs can be obtained simultaneously. In this case, the polarization directions of the two wavelength outputs are vertical polarization and horizontal polarization, which are orthogonal to each other, but can be made non-polarized using a depolarizer or the like.

  FIG. 7 shows the wavelength characteristics of light transmittance when the incident angles of the two filter rotators 8A and 8B to the bandpass filters 11a to 11d in the present embodiment are changed in the range of 0 degrees to 50 degrees. Yes. In this way, the light emitted from the light source 3 is divided into two linearly polarized light components, and the incident angles of the respective components to the bandpass filters 11a to 11d are controlled, so that the emission intensity characteristics are stabilized in a wide variable wavelength range. It turns out that it becomes possible.

[Third Embodiment]
FIG. 8 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 101 according to the second embodiment is that the polarization components L4 and L5 are transmitted through the two filter rotators 8C and 8D as S-polarized light, respectively. is there.

Filter rotating body 8C is mounted so as to extend along the main surface 10a of the rotary table 10 to the ZX plane rotating mechanism 14C having a rotational axis along the Y-axis, the rotational center C ₁ and the main surface on the main surface 10a It is positioned so that the horizontally polarized light component L4 is incident between the peripheral edge portion 10a (see FIG. 2). Thereby, the filter rotating body 8C can change the incident angle of the horizontal polarization component L4 with respect to the bandpass filters 11a to 11d by rotating the rotary table 10, and the horizontal polarization component L4 is changed to the bandpass filters 11a to 11a. It is always incident on 11d in the state of S polarization.

Filter rotating body 8D is mounted so as to extend along the main surface 10a of the turntable 10 in the rotation mechanism 14D having an axis of rotation along the Z-axis in the XY plane, the rotation of the main surface 10a center _{C 1} and the main surface 10a It is located so that the vertical polarization component L5 may be incident between the peripheral edge portions (see FIG. 2). Thereby, the filter rotating body 8D can change the incident angle of the vertical polarization component L5 with respect to the bandpass filters 11a to 11d by rotating the rotary table 10, and the vertical polarization component L5 is changed to the bandpass filters 11a to 11a. It is always incident on 11d in the state of S polarization.

  Here, the rotation axis of the rotary table 10 is orthogonal between the filter rotary body 8C and the filter rotary body 8D so as to be incident on the bandpass filters 11a to 11d as S-polarized light. The rotation axis may be the same direction, and the polarization plane may be rotated using a λ / 2 plate or the like so as to be incident on the bandpass filters 11a to 11d as S-polarized light. In addition, in the place where the λ / 2 plate is used, the λ / 2 plate is inserted before and after the band pass filter.

  The control circuit 33 of the control system 30 is connected to any of the bandpass filter 11a, the bandpass filter 11b, the bandpass filter 11c, and the bandpass filter 11d that are mounted on the filter rotators 8C and 8D and have the same light transmission characteristics. The rotation angles of the rotation mechanisms 14C and 14D are changed and controlled so that the polarization components L4 and L5 are incident and the incidence angles of the polarization components L4 and L5 with respect to the bandpass filters 11a to 11d are the same.

  According to such a light source device 101, the horizontal polarization component L4 separated by the polarization separation element 25 is incident on the filter rotator 8C as S-polarized light, and the vertical polarization component L5 separated by the polarization separation element 25 is the filter rotator. After entering 8D as S-polarized light at the same incident angle as the horizontal polarization component L4, the light transmitted through the two filter rotators 8C and 8D is combined and emitted to the outside. Here, since the characteristics of the transmission wavelength region with respect to the incident angle with respect to the S-polarized light of the bandpass filters 11a to 11d mounted on the two filter rotators 8C and 8D are the same, the incident angle can be set appropriately. In addition, it is possible to narrow and stabilize the emission characteristics over the assumed wavelength range, and to efficiently emit light from the light source.

  Further, if the incident angles of the two polarization components L4 and L5 to the bandpass filters 11a to 11d are set to different angles, two different wavelength outputs can be obtained simultaneously. In this case, the polarization directions of the two wavelength outputs are vertical polarization and horizontal polarization, which are orthogonal to each other, but can be made non-polarized using a depolarizer or the like.

  FIG. 9 shows the wavelength characteristics of light transmittance when the incident angles of the two filter rotators 8C and 8D to the bandpass filters 11a to 11d in the present embodiment are changed in the range of 0 degrees to 50 degrees. Yes. In this case as well, the light intensity characteristics are stabilized in a wide variable wavelength range by dividing the light from the light source 3 into two linearly polarized light components and controlling the incident angles of the respective components to the bandpass filters 11a to 11d. It turns out that it becomes possible.

  In addition, this invention is not limited to embodiment mentioned above. For example, the number of band-pass filters mounted on the filter rotator 8 is not limited to a specific number, and an arbitrary number of three or more can be selected according to the assumed wavelength range and the area of the filter rotator 8. Good.

FIG. 10 shows the structure of the filter rotating body 108 having five band-pass filters 11a to 11e. In this case, the shortest distance of the beam diameter of the light L2 is 5 mm, the width and thickness along the main surface 10a of the band-pass filter 11 a to 11 e is 10 mm, 2 mm, from the center of rotation _{C 1} to bandpass filter 11 a to 11 e _{R 1} When the band-pass filters 11a to 11e are rotated counterclockwise, the variable range of the incident angle of each band-pass filter 11a to 11e is set to 0 degree to 45 degrees.

FIG. 11 shows the structure of a filter rotating body 208 having six band-pass filters 11a to 11f. In this case, the shortest distance of the beam diameter of the light L2 is 5 mm, the width and thickness along the main surface 10a of the band-pass filter 11a to 11f is 12 mm, 2 mm, from the center of rotation _{C 1} to bandpass filter 11a to 11f _{R 1} When the band-pass filters 11a to 11f are rotated counterclockwise, the variable range of the incident angle of each band-pass filter 11a to 11f is set to 0 degree to 45 degrees.

FIG. 12 shows a structure of a filter rotating body 308 having three band pass filters 11a to 11c. In this case, the shortest distance of the beam diameter of the light L2 is 10 mm, the width and thickness along the main surface 10a of the band-pass filter 11 a to 11 c is 18 mm, 2 mm, from the center of rotation _{C 1} to bandpass filter 11 a to 11 c _{R 1} When the band-pass filters 11a to 11c are rotated counterclockwise, the variable range of the incident angle of each band-pass filter 11a to 11c is set to 0 degree to 50 degrees.

On the other hand, the filter rotator 908D, which is a comparative example of the present invention shown in FIG. 19A, has a width and thickness along the main surface 10a of the bandpass filters 11a to 11e of 10 mm and 2 mm, bandpass filter 11a~11e 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 11a~11e becomes 0 degrees This is an example of the arrangement. When this filter rotator 908D is rotated, the variable range of the incident angle of the light L2 having a beam diameter of 5 mm is limited to 0 degrees to 9 degrees in order to prevent interference between the bandpass filters 11a to 11e. The Further, a filter rotator 908E as a comparative example of the present invention shown in FIG. 19B has a width and thickness along the main surface 10a of the bandpass filters 11a to 11e of 10 mm and 2 mm, and the bandpass filter 11a~11e 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 11a~11e becomes 0 degrees This is an example. When this filter rotator 908E is rotated, the variable range of the incident angle of the light L2 having a beam diameter of 5 mm is limited to 0 degree to 24 degrees. Furthermore, the filter rotator 908F, which is a comparative example of the present invention shown in FIG. 19C, has a width and thickness along the main surface 10a of the bandpass filters 11a to 11e of 12 mm and 2 mm, and the bandpass filter 11a~11e 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 11a~11e This is an example. When this filter rotator 908F is rotated, the variable range of the incident angle of the light L2 having a beam diameter of 5 mm is limited to 0 degree to 29 degrees, although the diameter of the rotary table 10 is increased. As described above, the variable range of the incident angle is greatly limited as compared with the filter rotating body 108 of FIG. 10 using the same number of band-pass filters.

Further, a filter rotator 908G, which is a comparative example of the present invention shown in FIG. 20, has a width and thickness of 12 mm and 2 mm along the main surface 10a of the bandpass filters 11a to 11f, and the bandpass filters 11a to 11f. 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 11a~11f is there. When the filter rotator 908G is rotated, the variable range of the incident angle of the light L2 having a beam diameter of 5 mm is limited to 0 degree to 23 degrees. As described above, the variable range of the incident angle is greatly limited as compared with the filter rotating body 108 of FIG. 11 using the same number of band-pass filters.

Further, a filter rotating body 908H as a comparative example of the present invention shown in FIG. 21A has a width and thickness along the main surface 10a of the bandpass filters 11a to 11c of 18 mm and 2 mm, and the bandpass filter 11a~11c 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 11a~11c becomes 0 degrees This is an example. When the filter rotator 908H is rotated, the variable range of the incident angle of the light L2 having a beam diameter of 10 mm is limited to 0 degree to 38 degrees. Compared with the filter rotator 308 in FIG. The variable range is greatly limited. Further, a filter rotating body 908I which is a comparative example of the present invention shown in FIG. 21B has a width and thickness along the main surface 10a of the bandpass filters 11a to 11c of 26 mm and 2 mm, and the bandpass filter 11a~11c 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 11a~11c becomes 0 degrees This is an example. When this filter rotator 908I is rotated, the variable range of the incident angle of the light L2 having a beam diameter of 10 mm is 0 degree to 50 degrees. The diameter becomes twice or more.

  The variable range of the incident angle with respect to the bandpass filters 11a to 11d of the filter rotating body 8 can be set to various ranges by changing the inclination angles of the bandpass filters 11a to 11d.

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. 13, a band-pass filter 11a to 11f, 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 11a to 11f on the main surface 10a May be set so that the variable range of the incident angle with respect to the band-pass filters 11a to 11f is, for example, 20 degrees to 50 degrees. In the figure, the width and thickness along the main surface 10a of the band-pass filter 11a~11f is 11 mm, a 2 mm, band pass filter 11a~11f is the shortest distance from the rotation center _{C 1} is 16.6mm In this example, the beam diameter of the light L2 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 11a 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 11a 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 11a to 11d built in the light source devices 1, 101, and 201 of the present embodiment have different center wavelengths in the transmission wavelength region for the same incident angle, but the center wavelengths are the same and the half-value width is the same. It may be configured differently. FIGS. 14A to 14D show examples of the characteristics of the transmission wavelength region when the incident angles are changed in the range of 0 to 50 degrees at intervals of 5 degrees in the band-pass filters 11a to 11d, respectively. ing. In this way, when the bandpass filters 11a to 11d having the same center wavelength are used, 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, a light detection device 301 as shown in FIG. 15 can be cited in addition to the light source device described above. This light detection device 301 is a device for spectrally detecting a predetermined wavelength component of light input from the outside, and includes a light conversion optical system 105 having the same configuration as the light source device 101 and light from the outside. An optical fiber 303 that guides light to the collimating lens 6 and a light detector 304 that detects light dispersed by the light conversion optical system 105 are provided. Also with such a light detection device 301, when spectrally detecting light from the outside, the variable range of the detection wavelength can be easily expanded without increasing the size of the device.

  As an application example of the present invention, a fluorescence detection system 401 in which a light source device 101 and a light detection device 301 are combined as shown in FIG. In this fluorescence detection system 401, the light output from the light source device 101 can be irradiated as excitation light to the sample A via the lens unit 402A, and the fluorescence emitted from the sample A accompanying this is transmitted via the lens unit 402B. Then, by inputting the light to the light detection device 301, it is possible to detect fluorescence in a predetermined wavelength region. By using such a fluorescence detection system 401, the wavelength range of excitation light to be emitted and the wavelength range of fluorescence to be detected can be freely adjusted in a wide range. Here, when the sample A limited to some extent is used as a measurement target, the light source device 101 may be replaced with a general light source such as a laser light source.

  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.

11a to 11f ... band pass filter, 15a to 15d ... center point, 1, 101, 201 ... light source device, 301 ... light detection device, 3 ... light source, 8, 8A, 8B, 8C, 8D, 108, 208, 308 ... Filter rotator, 10... Rotary table (rotation support member), 10a... Main surface, 12 .. light incident surface (end surface), 13 .. light exit surface (end surface), 17 .. inscribed circle, C ₁ . , L4, L5... Incident light.

Claims (7)

N pieces of dielectric thin film interference filters (n is an integer of 3 or more) for selectively transmitting light input from the outside in a wavelength range corresponding to the incident angle of the light;
The dielectric thin film interference filter is erected on a main surface, and is a flat plate-shaped rotation support member that is rotatable around a predetermined point along the main surface;
A photodetector for detecting light transmitted through the dielectric thin film interference filter,
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.
An optical detection device characterized by 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,
The photodetection device according to claim 1. 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 photodetection device according to claim 2. 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 photodetection device according to claim 1, wherein 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 photodetection device according to claim 4. Each of the n dielectric thin film interference filters has a rotation for adjusting an inclination angle with respect to a line connecting the predetermined point on the main surface and the center point of the dielectric thin film interference filter on the main surface. A shaft member is attached,
The photodetection device according to claim 1, wherein The light detection device according to claim 1 and a light source device that outputs the light.
An optical detection system characterized by that.