JP2013228322A - Spectral device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a spectral device for keeping a small loss of signal light even when the number of channels is large.SOLUTION: The wavelength band of the light transmitting through an optical filter 14 is ABC to travel to the right side in the figure. The light of a wavelength band DEF reflected by the optical filter 14 travels to the lower left side in the figure. Subsequently, for the light of transmitted light (band ABC) and reflected light (band DEF), a second optical filter that transmits only a wavelength band corresponding to a single channel is used.

Description

  The present invention relates to a spectroscopic device that outputs light in a plurality of wavelength bands.

  A spectroscopic device that inputs white light or light having a wide wavelength band and splits the light to output light of a desired wavelength band is used in various analysis apparatuses. For example, such a spectroscopic device is extremely effective in plasma diagnosis in nuclear fusion (Thomson scattering measurement) and absorbance measurement in blood and urine examinations.

  In the spectroscopic device, monochromatic light having a desired wavelength can be obtained by using, for example, a diffraction grating. However, when a plurality of desired wavelength bands desired as outputs are determined in advance, particularly good spectral characteristics (split light) can be obtained by using a spectroscopic device configured by combining a plurality of optical filters (interference filters). Of the spectrum). FIG. 13 is a diagram schematically showing the characteristics of the optical filter used in this case. Here, it is assumed that incident light having the spectrum of (a) enters the optical filter. In this case, the spectrum of the transmitted light is a narrow band having a band (wavelength band) I as shown in FIG. In the interference filter, the absorption of light inside the filter can be reduced, and most of light having a wavelength other than this wavelength band (light in band II) is reflected. For this reason, the spectrum of the reflected light is only in the band II as shown in (c). If the optical axis of the incident light is an angle deviated from direct incidence (when the optical axis is perpendicular to the reflecting surface), the reflected light can be extracted in a direction different from the incident light, and the transmitted light is the optical axis of the incident light. Can be taken out above. Thereby, the light of the band I can be separately output as the transmitted light, and the light of the band II can be separately output as the reflected light. Such an optical filter can be formed using, for example, a dielectric multilayer film, and the bands I and II can be appropriately set by adjusting the film configuration.

  A configuration of a spectroscopic device (polychromator) that combines a plurality of optical filters having such characteristics and outputs a multi-channel is described in Non-Patent Document 1 and Patent Document 1, for example. The configuration of the spectroscopic device 90 is schematically shown in FIG. Here, it is assumed that six types of light in the narrow bands A to F (outputs of six channels A to F) are obtained as output light. For this reason, it is assumed that the wavelength of the signal light incident first is over a wide band obtained by combining the bands A to F, and the output lights of the channels A to F can be obtained by separating the wavelength. Here, six types of optical filters 91a to 91f are used for this purpose, and the signal light 100 first enters the optical filter 91a. The reflected light from the optical filter 91a is to the optical filter 91b, the reflected light from the optical filter 91b is to the optical filter 91c, the reflected light from the optical filter 91c is to the optical filter 91d, and the reflected light from the optical filter 91d is to the optical filter 91e. It is set to enter. As shown in the figure, such a configuration can be realized by making light enter each optical filter at an angle deviated from the direct incidence by a predetermined incident angle (here, 10 °).

  Here, the optical filter 91a is only in the band A, the optical filter 91b is only in the band B, the optical filter 91c is only in the band C, the optical filter 91d is only in the band D, the optical filter 91e is only in the band E, and the optical filter 91f is only in the band F. , Are set so as to be transmitted (respective bands are assumed to be band I in FIG. 13), light after passing through the respective optical filters can be obtained as output light of the respective channels. That is, the detectors 92a to 92f that detect the transmitted light of the optical filters 91a to 91f detect the light in the bands A to F, respectively.

  That is, multichannel output light can be obtained by the spectroscopic device having the configuration of FIG. 14 in which a plurality of optical filters are combined.

International Publication No. WO2004 / 076997

“A Compact, Low Cost, Seven Channel Polychromator for Thomson Scattering Measurements”, T.A. N. Carlstrom, J.M. C. DeBoo, R.A. Evanko, C.I. M.M. Greenfield, C.I. L. Hsieh, R.H. T.A. Snider, and P.M. Trost, Review of Scientific Instruments, vol. 61 (10), p2858 (1990)

  However, the characteristics of the optical filter actually obtained are different from the ideal one shown in FIG. For example, the transmittance of the light of the wavelength in the band I in FIG. 13B is not actually 100%. Further, the reflectance of the light of the wavelength of the band II in FIG. 13C is not actually 100%, or the transmittance of the light of the wavelength of the band II in FIG. Absent. For this reason, when transmission and reflection by a plurality of optical filters are repeated, the loss of signal light by the optical filters increases, and the intensity of the output light greatly decreases. For this reason, in the configuration of FIG. 14, the intensity of the output light of channel A (light received by the detector 92a) is relatively high, but the loss increases toward the downstream side. Since the output light of the channel F taken out on the most downstream side is obtained five times of reflection and one time of transmission, the loss is the largest. Obviously, this trend becomes more pronounced as the number of channels increases.

  As described above, even when the number of channels is large, it is difficult to obtain a spectroscopic device that can keep the loss of signal light small.

  The present invention has been made in view of such problems, and an object thereof is to provide an invention that solves the above problems.

In order to solve the above problems, the present invention has the following configurations.
The spectroscopic device of the present invention is a spectroscopic device that splits signal light with a plurality of optical filters provided on the optical path thereof, and outputs output light having different wavelength bands to four or more channels. A first optical filter for splitting light into transmitted light having a wavelength band extending over two or more of the channels and reflected light having a wavelength band extending over two or more of the channels different from the wavelength band of the transmitted light; The second optical system that splits the incident light downstream of the first optical filter in the optical path with respect to the signal light into transmitted light or reflected light having a wavelength band corresponding to the single channel. And a filter.
In the spectroscopic device of the present invention, the signal light is set so that an optical axis of the signal light deviates from a direct incidence by a predetermined incident angle with respect to the first optical filter, and the signal light is the first optical filter. The second optical filter that is set to enter the filter so that the optical axis is at an angle deviated from the direct incident by a predetermined incident angle is transmitted light from the first optical filter, It is used for each reflected light.
In the spectroscopic device of the present invention, the incident angle of light incident on the first optical filter and the incident angle of light incident on the second optical filter are greater than 0 ° and not greater than 15 °. It is characterized by.
In the spectroscopic device of the present invention, the incident angle of light incident on the first optical filter and the incident angle of light incident on the second optical filter are greater than 0 ° and not greater than 45 °, The signal light has a divergence angle of 0.5 ° or less.
In the spectroscopic device of the present invention, the incident angle of the light incident on the first optical filter and the incident angle of the light incident on the plurality of second optical filters are each set to 45 °. In plan view, the output light of each of the plurality of channels is output in two directions perpendicular to the direction in which the signal light is input and in the same direction as the direction in which the signal light is incident. .
In the spectroscopic device of the present invention, the first optical filter and / or the second optical filter includes an incident-side surface and an exit-side surface formed so as not to be parallel to the incident-side surface. A first reflected light in which the incident light is reflected on the surface on the incident side, and a second light in which the light transmitted through the surface on the incident side is reflected on the surface on the output side. The reflected light and the light transmitted through the incident-side surface are further branched into three parts: transmitted light transmitted through the outgoing-side surface.

  Since the present invention is configured as described above, it is possible to obtain a spectroscopic device that can keep the loss of signal light small even when the number of channels is large.

It is a figure which shows the structure of the 1st example of the spectrometer which concerns on embodiment of this invention. It is an example of the transmission spectrum (a) and the reflection spectrum (b) of the 1st optical filter used in the 1st example of the spectrometer which concerns on embodiment of this invention. It is an example of the transmission spectrum of six 2nd optical filters used in the spectrometer which concerns on embodiment of this invention. It is a figure which shows the structure of the 2nd example of the spectrometer which concerns on embodiment of this invention. This is a result of comparing the channel number dependency of the total number of transmission / reflection required at maximum between the spectroscopic device according to the embodiment of the present invention and a conventional spectroscopic device. It is a figure which shows the structure of the 3rd example of the spectrometer which concerns on embodiment of this invention. It is the result of calculating the transmission spectrum in an optical filter having a wide transmission band when the set value of the incident angle is 45 ° with two types of divergence angles (0 °, 4 °). It is the result of having calculated the transmission spectrum with respect to the random polarization | polarized-light of the optical filter with a narrow transmission band when the setting value of an incident angle is 45 degrees about three types, p polarized light, s polarized light, and random polarized light. It is the result of having calculated the transmission spectrum with respect to the random polarization | polarized-light of the optical filter with a narrow transmission band when the setting value of an incident angle is 45 degrees about three types of divergence angles 0 degree, 2 degrees, and 4 degrees. It is the result of having calculated the transmission spectrum with respect to the random polarization | polarized-light of the optical filter with a narrow transmission band when the setting value of an incident angle is 10 degrees about two types of divergence angles of 0 degrees and 4 degrees. It is sectional drawing which shows the structure of the 3 branch optical filter which branches incident light into 3 parts. It is a figure which shows the structure of the 4th example (example using the optical filter which branches 3 incident light) of the spectrometer which concerns on embodiment of this invention. It is the figure which represented typically the relationship between the spectrum of the incident light in an optical filter, a transmission spectrum, and a reflection spectrum. It is a figure which shows the structure of the conventional spectroscopy apparatus.

  Hereinafter, a spectroscopic device according to an embodiment of the present invention will be described. This spectroscopic device outputs four or more channels by dispersing signal light using a plurality of optical filters. The optical filter used here is a first optical filter in which bands I and II in FIG. 13 are bands extending over a plurality of channels, respectively, and band I or II in FIG. 13 is a band corresponding to a single channel. And a second optical filter. The second optical filter is provided on the downstream side of the first optical filter when viewed from the signal light in the optical path. That is, the setting is such that the reflected light and transmitted light of the first optical filter enter the second optical filter and are dispersed.

  FIG. 1 is a diagram showing the configuration of the spectroscopic device 10 (first example). In the spectroscopic device 10, signal light 100 having a wide wavelength band is emitted from a light source 11 (for example, an optical fiber). The output of the spectroscopic apparatus 10 is 6 channels (channels A to F), and each wavelength band is A to F (the center wavelength of the band is A <B <C <D <E <F) and narrow. It is assumed that each wavelength band is not overlapped. The signal light 100 has a wide wavelength band including all of the bands A to F.

  The signal light 100 first enters the converging lens 12 and is adjusted so that the divergence angle θ shown in FIG. Thereafter, the light is incident on the optical filter (first optical filter) 14 so that the optical axis of the light deviates from the direct incidence by a predetermined incident angle. Here, the incident angle is 10 °.

  The optical filter 14 has the same transmission / reflection characteristics as in FIG. 13, but at this time, the band ABC is transmitted and the band DEF is reflected. That is, the band I in FIG. 13 is set to be a band that combines bands A, B, and C, and the band II in FIG. 13 is a band that combines bands D, E, and F. The reflected light is reflected to the opposite side with a reflection angle equal to the incident angle with respect to the optical axis of the incident light. However, the incident angle here is a set value of an angle formed by the optical axis of the incident light and the normal line of the surface of the optical filter 14. Actually, the incident light is not parallel light but is incident on the optical filter 14 with a certain divergence angle θ. Strictly speaking, there is a distribution in the incident angle and reflection angle of the light incident on the optical filter 14. Although this point will be described later, at least when the divergence angle θ is small, the optical path can be simplified as shown in FIG.

  For this reason, the wavelength band of the light transmitted through the optical filter 14 becomes ABC and proceeds to the right side in the figure. On the other hand, the light in the wavelength band DEF reflected by the optical filter 14 travels to the lower left side in the figure. Hereinafter, the same configuration as that of FIG. 14 is used for the transmitted light (band ABC) and the reflected light (band DEF). Here, a second optical filter that transmits only a wavelength band corresponding to a single channel is used.

  That is, the transmitted light (wavelength band ABC) of the optical filter 14 first enters the optical filter (second optical filter) 15c that transmits only the band C. The reflected light from the optical filter 15c enters the optical filter 15b (second optical filter) that transmits only the band B. The reflected light from the optical filter 15b enters the optical filter 15a (second optical filter) that transmits only the band A.

  Similarly, the reflected light (wavelength band DEF) from the optical filter 14 first enters an optical filter (second optical filter) 15d that transmits only the band D. The reflected light from the optical filter 15d enters an optical filter (second optical filter) 15e that transmits only the band E. The reflected light from the optical filter 15e is incident on an optical filter (second optical filter) 15f that transmits only the band F.

  The incident angle at which light rays enter each of the optical filters 15 a to 15 f is the same as that in the optical filter 14. Further, all of the components shown in FIG. 1 including the optical filter can be fixed to a common mount by using a positioning mechanism using protrusions, grooves, or the like. As a result, the accuracy of the mutual positional relationship can be maintained, and maintenance and replacement of these components can be easily performed.

  2A is an example (a) of the transmission spectrum of the optical filter 14, and FIG. 2B is an example (b) of the reflection spectrum. 3A is an example of a transmission spectrum (corresponding to the band A) of the optical filter 15a, FIG. 3B is an example of a transmission spectrum of the optical filter 15b (corresponding to the band B), and FIG. c) is an example of a transmission spectrum (corresponding to the band C) of the optical filter 15c, FIG. 3 (d) is an example of a transmission spectrum of the optical filter 15d (corresponding to the band D), and FIG. 3 (e) is a transmission of the optical filter 15e. An example of the spectrum (corresponding to the band E) and FIG. 3F show an example of the transmission spectrum (corresponding to the band F) of the optical filter 15f. In the interference filter, such setting is possible by adjusting the configuration of the multilayer film to be used.

  The transmitted light of each of the optical filters 15a to 15f passes through the condenser lenses 16a to 16f, and is collected and detected on the detection surfaces of the detectors 17a to 17f, respectively. Detectors 17a to 17f detect light in bands A to F, respectively. That is, the spectroscopic device 10 outputs six channels using the input light in the band ABCDEF as output light in the wavelength bands A to F. Since the incident angle at which the light beam enters each of the optical filters 15a to 15f is the same as that in the optical filter 14, the output of each channel can be obtained at different locations (locations of the detectors 17a to 17f). .

  In FIG. 1, the optical filter 15a is not necessary if the spectrum of the reflected light from the optical filter 15b already has a desired spectrum as output light having the band A. This also applies to the optical filter 15f or the conventional optical filter 91f in FIG.

  The second optical filters 15a to 15f used in this configuration and the optical filters 91a to 91f used in the conventional configuration of FIG. 14 have the same functions. Here, the light of the channel F which is the most downstream side in the configuration of FIG. 14 and undergoes the most transmission / reflection is reflected five times by the optical filters 91a, 91b, 91c, 91d and 91e, and 1 by the optical filter 91f. Through the transmission of times. That is, the total number of transmissions / reflections for the light of the channel F taken out at the most downstream is 6 times the total number of channels. The channel F is the channel with the greatest loss in the configuration of FIG.

  On the other hand, in the configuration of FIG. 1, channels A and F have the largest total number of transmissions and reflections. The light of the channel F is reflected three times by the optical filter (first optical filter) 14, the optical filters (second optical filter) 15d and 15e, and once by the optical filter (second optical filter) 15f. Through transmission. That is, the total number of transmissions / reflections for the light of the channel F is four. Similarly, the light of channel A is reflected twice by the optical filters (second optical filters) 15c and 15d, and by the optical filter (first optical filter) 14 and optical filter (second optical filter) 15a. Since the transmission is performed twice, the total number of transmissions / reflections for the light of channel A is four. For this reason, in the configuration of FIG. 1, when obtaining the same 6-channel output, the total transmission / reflection in the output light of the channel output on the most downstream side is compared with the configuration of FIG. The number of times can be reduced, and loss can be reduced.

  In the configuration of FIG. 1, a first optical filter 14 having a transmission band over a plurality of channels and a reflection band over a plurality of different channels is used, and two light beams (transmission light, The reflected light is dispersed using second optical filters 15a to 15f that are provided downstream thereof and each have a transmission band corresponding to a single channel. This reduces the total number of transmissions / reflections in the output light of the channel output on the most downstream side.

  Although the spectroscopic device 10 of FIG. 1 has an output of 6 channels, the above effect becomes more prominent when the number of output channels is large. In the case of FIG. 1, only one first optical filter (optical filter 14) having a transmission band and a reflection band over a plurality of channels is used, but many first optical filters may be used. it can. FIG. 4 shows an example of the configuration of the spectroscopic device 20 (second example) having outputs of 18 channels (A to R). Here, for the sake of simplicity, the description of the converging lens, the diaphragm, and each condenser lens is omitted. Further, it is assumed that the setting value of the incident angle of light with respect to each optical filter is 10 ° as in the case of FIG.

  In this configuration, optical filters (first optical filters) 21a to 21h having a transmission band over a plurality of channels and a reflection band over a plurality of different channels are used. Similarly to the above, when the wavelength band of incident light is represented as ABCDEFGHIJKLMNOPQR, the optical filter 21a that first enters this transmits IJKLMNOPQR and reflects ABCDEFGH. The optical filter 21b transmits EFGH out of ABCDEFGH and reflects ABCD. The optical filter 21c transmits EF out of EFGH and reflects GH. The optical filter 21d transmits AB of ABCD and reflects CD. The optical filter 21e transmits OPQR of IJKLMNOPQR and reflects IJKLMN. The optical filter 21f transmits KLMN out of IJKLMN and reflects IJ. The optical filter 21g transmits KL out of KLMN and reflects MN. The optical filter 21h transmits QR of OPQR and reflects OP.

  Similarly to the optical filter described in FIG. 14, optical filters (second optical filters) 22a to 22i that transmit only a band corresponding to a single channel are also used. The optical filter 22a transmits only A of AB and reflects B. The optical filter 22b transmits only D of the CD and reflects C. The optical filter 22c transmits only E of EF and reflects F. The optical filter 22d transmits only G of GH and reflects H. The optical filter 22e transmits only I out of IJ and reflects J. The optical filter 22f transmits only K of KL and reflects L. The optical filter 22g transmits only M of MN and reflects N. The optical filter 22h transmits only O of OP and reflects P. The optical filter 22i transmits only Q of the QR and reflects R.

  With this configuration, 18 channels of output light in the bands A to R are obtained at the locations of the detectors 23a to 23r, respectively. In this configuration, the total number of transmissions / reflections for the channels K, L, M, and N is five, and four for the other channels. On the other hand, in order to obtain the output of 18 channels with the configuration of FIG. 14 as well, the total number of transmissions / reflections for the most downstream channel is 18 times the number of channels. That is, the effect of the configuration of FIG. 4 having a larger number of channels is greater than that of the configuration of FIG.

FIG. 5 shows a case where only an optical filter having a transmission band corresponding to a single channel (corresponding to the second optical filter) is used as in the configuration of FIG. The relationship between the total number of transmission / reflection required and the number of channels in the case of combining the first optical filter and the second optical filter is shown. Thus, as the number of channels increases, the effect of combining the first optical filter and the second optical filter increases. When the first optical filter and the second optical filter are combined, the total number of transmission / reflection is about log ₂ (n), where n is the number of channels. Therefore, by using the above configuration, the total number of transmissions and reflections can be reduced, and the output light can be obtained while reducing the loss with respect to the signal light. This effect becomes more prominent as the number of channels increases.

  In the configuration of FIGS. 1 and 4, the incident angle of the light beam with respect to each optical filter is set to 10 °, but by reducing this angle, each of the optical filters near each of a plurality of locations along the optical path. Channel output can be obtained. However, when the incident angle is close to zero (direct incidence), the optical axis of the incident light and the optical axis of the reflected light overlap, making it difficult to secure an optical path and take out output light. For this reason, the incident angle is appropriately set within a non-zero range.

  FIG. 6 shows the configuration of a 16-channel (A to P) spectroscopic device 30 (third example) in which the setting value of the incident angle is 45 °. In this configuration, optical filters (first optical filters) 31a to 31g having a transmission band and a reflection band over a plurality of channels, and an optical filter (second optical filter) that transmits only a band corresponding to a single channel. ) 32a to 32h are used. A description of the function of each optical filter is omitted. Detectors 33a to 33p are arranged at the output destination of each channel.

  In this configuration, the optical paths in the spectroscopic device 30 are orthogonal to form a grating, and the detectors 33a to 33p can be arranged on rectangular sides. At this time, in plan view, there are a plurality of each in two directions perpendicular to the direction in which the signal light 100 is input (up and down direction in the figure) and the same direction as the direction in which the signal light 100 is incident (right direction in the figure) The output light of the channels is output. For this reason, it is particularly easy to take out the output of each channel after downsizing the entire spectroscopic device 30.

  In the above example, the transmitted light and reflected light from the second optical filter have wavelength bands corresponding to different single channels, but only one of the transmitted light and reflected light is transmitted. It is obvious that the spectroscopic device can be configured similarly even with a configuration having a wavelength band corresponding to a single channel.

  Next, the setting of the divergence angle (or divergence angle: θ in FIG. 1) of incident light in the configuration of FIGS. The transmission / reflection spectrum of each optical filter is dependent on the incident angle of light. On the other hand, when the divergence angle is not zero, that is, when the light is not strictly parallel light, a distribution also occurs in the incident angle of light with respect to each optical filter. For this reason, it is clear that the divergence angle is preferably close to 0 ° in order to obtain high wavelength resolution in the spectroscopic device. However, the divergence angle when the signal light 100 is emitted from the light emitting point is determined by various factors. As an index of the factor that determines the divergence angle, for example, the product of the divergence angle and the size of the light emitting point at this time can be considered, and this value is stored in the optical system. Here, for example, the F value of the imaging optical system can be reduced to increase the intensity of the signal light 100. In this case, however, the divergence angle increases, and in order to make this close to parallel light, a large size is required. A lens is required. In addition, for example, a bundle fiber composed of a plurality of strands can be used to increase the emission point to increase the intensity, but in this case as well, in order to reduce the divergence angle, a large lens with a long focal length is used. I need it. For this reason, in order to increase the intensity of the signal light 100 and reduce the divergence angle, a large optical system using a large lens is required. For this reason, it is preferable that sufficient characteristics can be obtained even when the divergence angle is not 0 °. The influence of the divergence angle on the spectral characteristics varies depending on the setting value of the incident angle.

  FIG. 7 shows the transmission spectrum of the optical filter 14 for parallel light (θ = 0 °) and light of θ = 4 ° when the incident angle setting value is 45 ° (configuration of FIG. 6). Here, as the transmission band, a wide wavelength range of about 500 nm to 640 nm is set. Here, since there is no significant difference depending on the deflection direction of the incident light, the polarization direction is arbitrary in this result. In this graph, the data of θ = 0 ° and θ = 4 ° substantially overlap. Therefore, for such an optical filter having a wide transmission band, even when the divergence angle θ is set to 4 °, substantially the same characteristics as when θ is 0 ° are obtained.

  On the other hand, when the transmission band is narrowed, first, the influence of the polarization of incident light increases. FIG. 8 shows the transmission when the narrow band optical filter with the incident angle set value of 45 ° and the transmission peak wavelength of 1050 nm is optimized for p-polarized light (polarized light whose electric field vector vibrates in the incident plane). It is an example of a spectrum. In this case, the transmittance of light of s-polarized light (the electric field vector vibrates in the direction perpendicular to the incident surface) is zero, and in the case of random polarized light mixed with these, the transmittance is half that of p-polarized light.

  On the other hand, FIG. 9 shows an example of a transmission spectrum when the set value of the incident angle is 45 °, and the divergence angle θ = 0 ° (parallel light), 2 °, and 4 °. Here, contrary to FIG. 8, the polarization dependence is optimized so as to be minimized, and the polarization dependence can be ignored. From this result, as the divergence angle increases, the transmittance decreases and the spread of the spectrum increases. For this reason, when the set value of the incident angle is 45 °, in order to increase the intensity of the output light and obtain a high wavelength resolution, the divergence angle may be close to zero, that is, close to parallel light. is necessary. Specifically, the divergence angle is preferably 0.5 ° or less, more preferably 0.2 ° or less. If the deflection direction of the signal light 100 is determined in advance from the results shown in FIG. 8, each optical filter can be optimized accordingly.

  On the other hand, FIG. 10 shows the same characteristics as FIG. 9 when the set value of the incident angle is 10 ° in the case of θ = 0 ° and 4 °. In this case, the two are almost overlapped, and a characteristic equivalent to that of parallel light is obtained even when the divergence angle θ is 4 °. For this reason, when the setting value of the incident angle is small, the intensity of the output light is high and the wavelength resolution is high even when used with a larger divergence angle than when the setting value of the incident angle is large. can do. For this reason, in order to obtain high wavelength resolution when it is difficult to make the divergence angle close to 0 °, the setting value of the incident angle is preferably 15 ° or less, and more preferably 10 ° or less.

  Next, a modified example of the spectroscopic device will be described. In any of the optical filters used in the spectroscopic devices 10 and 20 described above, incident light is branched into transmitted light and reflected light. However, it is also possible to branch (three branches) incident light into transmitted light and two reflected lights using one optical filter. FIG. 11 is a diagram showing a cross section of the three-branch optical filter (optical filter) 40 and paths of incident light, transmitted light, and reflected light when this is used.

  The upstream (left side) surface and downstream (right side) surface of light in the three-branch optical filter 40 are not parallel, and the cross-section thereof is trapezoidal as shown. For this reason, the incident light 200 is reflected by the upstream side surface (incident side surface) 41 and the first reflected light 201 is generated. In addition, the light beam that has not been reflected by the upstream side surface 41 passes through the inside of the three-branch optical filter 40 and reaches the downstream side surface (surface on the emission side) 42 where it is reflected again to generate the second reflected light 202. . Here too, the light that has not been reflected becomes transmitted light 203. In this setting, when the angle of the normal line of the upstream side surface 41 with respect to the optical axis and the angle of the normal line of the downstream side surface 42 with respect to the optical axis are φ, the incident angle with respect to both the upstream side surface 41 and the downstream side surface 42. Is φ, and the angle between the first reflected light 201 and the optical axis of the incident light 200 and the angle between the second reflected light 202 and the optical axis of the incident light 200 are both 2φ. The first reflected light 201 and the second reflected light 202 are reflected in opposite directions at the same angle with respect to the optical axis of the incident light 200.

  The spectrum of the transmitted light 203, the first reflected light 201, and the second reflected light 202 is determined by the structure of the three-branch optical filter 40, but the transmission band and the two reflection bands are set as in FIG. It is possible.

  FIG. 12 shows the configuration of a nine-channel (A to I) spectroscopic device 50 (fourth example) using a three-branch optical filter having this configuration. The signal light 100 emitted from the light source 11 enters an optical filter (first optical filter) 51 having the same configuration as the above-described three-branch optical filter, and as shown in FIG. The reflected light and the transmitted light are branched into three. Thereafter, the first and second reflected light and transmitted light are respectively incident on optical filters (second optical filters) 52a to 52c having the same configuration as the above-described three-branch optical filter, and detectors 53a to 53c. Each is detected as output light at the position 53i. Here, similarly to the configuration of FIGS. 1 and 4, the incident angle in each optical filter is set to 10 °. However, since the reflected light is reflected in the vertical direction at the same angle in each optical filter, the detectors 53a to 53i can be arranged in a form close to vertical symmetry.

  In this spectroscopic device, since light beams are branched into three in one optical filter, output light of many channels can be obtained using a small number of optical filters. In the configuration of FIG. 12, the output of 9 channels is realized by four optical filters in combination with the first and second optical filters. However, it is not necessary that all the optical filters are three-branch optical filters, and a conventional two-branch optical filter and a three-branch optical filter can be appropriately mixed and used. In this case, an optimum combination can be set by considering the transmission spectrum and reflection spectrum obtained by the two-branch optical filter and the three-branch optical filter. In this way, by using the three-branch optical filter as the first optical filter and / or the second optical filter, the total number of optical filters to be used (the number of parts constituting the spectroscopic device) is reduced. be able to.

  In the above example, the setting value of the incident angle is the same for all the optical filters (first and second optical filters), but this may be set differently for each optical filter.

  Further, the configuration other than the combination of the first optical filter and the second optical filter, for example, the form of the individual optical filters in FIG. 1, the converging lens 12, the diaphragm 13, and the condenser lenses 16a to 16f can realize their functions. Insofar as various configurations are possible. For example, in the above example, the surface (reflection surface) of each optical filter has a planar shape, but this can be a concave shape. In this case, it is also possible to finely adjust the divergence angle. However, alignment is easier when the surface of each optical filter is planar. Alternatively, a lens can be inserted between the two optical filters.

  The detectors 17a to 17f may be any detector that can detect light in a predetermined wavelength band, and a silicon photodiode, a photomultiplier tube, or the like can be used.

  Further, a condensing mirror such as a parabolic mirror can be used instead of the condensing lenses 16a to 16f.

  As described above, the spectroscopic device of the present invention can reduce the total number of transmissions and reflections by the optical filter, thereby reducing the loss of signal light due to transmission and reflection and increasing the intensity of output light. . Such a configuration is effective regardless of the wavelength of light in a spectroscopic device using an optical filter having a transmission spectrum and a reflection spectrum as shown in FIG. That is, the present invention is not limited to visible light, and is effective when an optical filter having similar characteristics is used for ultraviolet light, infrared light, and the like. At this time, as described above, the larger the number of output channels, the greater the effect.

  For this reason, this spectroscopic apparatus can be used for measurement in various fields such as plasma diagnosis in nuclear fusion (Thomson scattering measurement) and absorbance measurement in blood and urine examinations.

10, 20, 30, 50, 90 Spectrometer 11 Light source 12 Converging lens 13 Aperture 14, 21a to 21h, 31a to 31g, 51 First optical filter (optical filter)
15a-15f, 22a-22i, 32a-32h, 52a-52c 2nd optical filter (optical filter)
16a to 16f Condensing lenses 17a to 17f, 23a to 23r, 33a to 33p, 53a to 53i, 92a to 92f Detector 40 Three-branch optical filter (optical filter)
41 Upstream side (incident side surface)
42 Downstream side (outgoing surface)
91a to 91f Optical filter 100 Signal light 200 Incident light 201 First reflected light 202 Second reflected light 203 Transmitted light

Claims (6)

A spectroscopic device that splits signal light with a plurality of optical filters provided on an optical path thereof and outputs output light having different wavelength bands to four or more channels,
A first optical device that splits incident light into transmitted light having a wavelength band extending over two or more of the channels and reflected light having a wavelength band extending over two or more of the channels different from the wavelength band of the transmitted light. Filters,
A second optical filter that splits incident light downstream of the first optical filter in the optical path with respect to the signal light into transmitted or reflected light having a wavelength band corresponding to the single channel. When,
A spectroscopic device comprising: The optical axis of the signal light is set to be an angle deviated from the normal incidence by a predetermined incident angle with respect to the first optical filter, and the signal light is incident on the first optical filter,
The second optical filter, which is set so that light is incident so that the optical axis deviates from the direct incidence by a predetermined incident angle, is transmitted to each of the transmitted light and reflected light from the first optical filter. The spectroscopic device according to claim 1, wherein the spectroscopic device is used.   2. The incident angle of light incident on the first optical filter and the incident angle of light incident on the second optical filter are greater than 0 ° and 15 ° or less. Or the spectroscopic apparatus according to 2.   The incident angle of the light incident on the first optical filter and the incident angle of the light incident on the second optical filter are greater than 0 ° and not more than 45 °, and the divergence angle of the signal light is 0. The spectroscopic device according to claim 1, wherein the spectroscopic device is 5 ° or less. The incident angle of the light incident on the first optical filter and the incident angle of the light incident on the plurality of second optical filters are each set to be 45 °,
The output light of each of the plurality of channels is output in two directions perpendicular to the direction in which the signal light is input and in the same direction as the direction in which the signal light is incident in a plan view. Item 5. The spectroscopic device according to Item 4. The first optical filter and / or the second optical filter are:
An incident-side surface, and an exit-side surface formed so as not to be parallel to the incident-side surface,
Incident light
The incident light is reflected on the incident-side surface, the first reflected light is reflected on the incident-side surface, the second reflected light is reflected on the exit-side surface, and the incident-side light is reflected on the incident-side surface. The light transmitted through the surface is further branched into three: transmitted light transmitted through the surface on the emission side.
The spectroscopic device according to any one of claims 1 to 4, wherein the spectroscopic device is provided.

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