JP2014106111A - Spectroscopic device and fourier transformation spectroscopic analyzer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To acquire an interferogram with an inexpensive configuration.SOLUTION: Incident light is received by a plurality of light receiving elements of a detector array 16 via a polarizing plate 12A, a plurality of birefringence regions 14A having different lengths in an optical axis direction and formed inside a birefringent part 14, which is a transparent member, and a polarizing plate 12B. By the detector array 16, a signal output from the plurality of receiving elements is output as information showing an interferogram. By a computing unit 18, the interferogram expressed by the signal output from the detector array 16 is Fourier-transformed.

Description

  The present invention relates to a spectroscopic device and a Fourier transform spectroscopic analysis device, and more particularly to a spectroscopic device and a Fourier transform spectroscopic analysis device for obtaining an interferogram from incident light.

  2. Description of the Related Art Conventionally, a Fourier transform spectroscopic device that obtains an interferogram on a solid-state imaging device using a split birefringence element and a lens is known (Patent Document 1). In this Fourier transform spectroscopic device, using a birefringent crystal plate, the center of the interferogram (position of phase difference 0) is shifted, and the center of the interferogram is shifted to improve the measurement resolution.

  In addition, a spectroscopic device that uses a liquid crystal cell to create a phase difference between two orthogonal components of incident light and creates various phase difference states depending on the magnitude of the applied voltage is known (Patent Document 2). .

  In addition, the Fourier transform spectrometer has advantages such as a high signal-to-noise ratio due to its high light utilization efficiency and a wide wavelength band measurement, compared to a spectrometer using a diffraction grating. It has been put to practical use in analyzers and the like. In a general Fourier transform spectrometer, a Michelson interferometer is used to Fourier transform the waveform of the light intensity called “interferogram” that is generated when the optical path difference between the two optical paths is changed. A wavelength spectrum of light can be obtained. However, the assembly of the Michelson interferometer requires precision and requires a mechanically movable mechanism, which makes it large and expensive. On the other hand, a system using a birefringent prism having birefringence has been proposed as a small Fourier transform spectrometer having no mechanical movable part (Non-patent Document 1). In this method, a birefringent prism gives various amounts of phase difference between two orthogonally polarized light components of incident light, and a waveform of light intensity obtained by interference with an analyzer is used as an interferogram.

JP-A-7-27613 Japanese Patent Laid-Open No. 2005-31007

G. Boer, et. al. , “Compact static Fourier Transform Spectrometer with a large field of view based on liquid-technology”, Appl. Opt. , 41,1400 (2002)

  In the technique described in Patent Document 1, since a lens is used, the precision of optical axis adjustment is required, and it is difficult to center the interferogram at a predetermined position of the photodetector. is there. In addition, in order to match the size and number of image sensors with the scale of the interferogram on the surface on the solid-state image sensor, it is necessary to strictly match the specifications of each part, which reduces the degree of freedom in selecting parts. There is.

  Further, the technique described in Patent Document 2 requires power to drive the liquid crystal, and there is a problem that the assembly becomes complicated and expensive due to wiring to the liquid crystal cell.

  The present invention has been made to solve the above problems, and an object thereof is to provide a spectroscopic device and a Fourier transform spectroscopic analysis device that can obtain an interferogram with an inexpensive configuration.

  In order to achieve the above object, a spectroscopic device according to the present invention is arranged to transmit incident light polarized in the first direction and light polarized by the first polarizing plate. In addition, a plurality of birefringent regions having different lengths in the optical axis direction corresponding to the light incident direction are formed inside so as to be arranged one-dimensionally or two-dimensionally when viewed from the optical axis direction. The transparent member is disposed so that light transmitted through the transparent member is incident thereon, and is polarized by the second polarizing plate that polarizes the incident light in a second direction. A plurality of light receiving elements arranged corresponding to the plurality of regions exhibiting birefringence, and signals output from the plurality of light receiving elements as information representing an interferogram And an output light detection unit. To have.

  According to the spectroscopic device of the present invention, the incident light is formed in the first polarizing plate, the transparent member, the plurality of regions having different birefringence in the optical axis direction, and the second The light is received by the plurality of light receiving elements of the light detection unit through the polarizing plate, and the light detection unit outputs signals output by the plurality of light receiving elements as information representing the interferogram.

  In this way, since the information representing the interferogram can be obtained by using the transparent member in which a plurality of birefringent regions having different lengths in the optical axis direction are formed, the interferogram can be obtained with an inexpensive configuration. Can be obtained.

  The plurality of regions exhibiting birefringence according to the present invention may be arranged in a two-dimensional manner when viewed from the optical axis direction and formed inside the transparent member. Accordingly, the numerical aperture can be reduced without reducing the measurement resolution and the measurement wavelength range, and the influence of obliquely incident light can be reduced.

  The region exhibiting birefringence according to the present invention may be formed such that the direction of the optical principal axis is 45 degrees with respect to the transmission axis of the first polarizing plate.

  In the present invention, the plurality of waveguides extending in the optical axis direction are coupled at least to the incident side and the emission side from the birefringent region inside the transparent member so as to be optically coupled to the plurality of regions exhibiting birefringence. One can be formed. As a result, it is possible to reduce the influence of obliquely incident light and increase the light utilization efficiency.

  The transparent member according to the present invention is formed with a plurality of one-dimensionally or two-dimensionally arranged regions showing birefringence having different lengths in the optical axis direction as viewed from the optical axis direction. A plurality of regions having a birefringence different in length in the optical axis direction and a region having birefringence different from the optical principal axis by 90 degrees are arranged in one or two dimensions as viewed from the optical axis direction. Can be formed.

  In the transparent member according to the present invention, a plurality of regions having birefringence having different lengths in the optical axis direction are formed by being arranged in a one-dimensional or two-dimensional manner when viewed from the optical axis direction, The region showing the birefringence is different from the region showing the birefringence, and the region showing the birefringence differs from the direction of the optical principal axis by 90 degrees so as to optically couple with the plurality of regions showing birefringence. A plurality of one-dimensional or two-dimensional arrays can be formed as viewed from the optical axis direction.

  A Fourier transform spectroscopic analysis apparatus according to the present invention includes the spectroscopic apparatus described above, and an arithmetic unit that Fourier transforms an interferogram represented by a signal output from the light detection unit.

  As described above, according to the spectroscopic device and the Fourier transform spectroscopic analysis device of the present invention, an interferometer is formed using a transparent member in which a plurality of birefringent regions having different lengths in the optical axis direction are formed. Since information representing a gram can be obtained, an interferogram can be obtained with an inexpensive configuration.

It is a perspective view which shows the structure of the Fourier-transform spectroscopy analyzer which concerns on the 1st Embodiment of this invention. It is sectional drawing for demonstrating a birefringent area | region. It is a graph which shows the relationship between the standardized detection light quantity and phase difference. It is a perspective view which shows the structure of the birefringent component of the Fourier-transform spectroscopic analyzer which concerns on the 1st Embodiment of this invention. It is a graph which shows the relationship between a retardance and a detected light quantity. It is a figure which shows the transparent material at the time of (A) laser beam irradiation, and (B) is a figure which shows the transparent material after laser beam irradiation. (A) The figure which shows the transparent material at the time of laser beam irradiation, (B) The figure which shows the optical principal axis direction of a birefringent area | region. (A) It is a figure which shows a mode that a laser beam is scanned to an optical axis direction, (B) It is a figure which shows a mode that a laser beam is scanned to an XY plane direction. It is a perspective view which shows the structure of the birefringent component of the Fourier-transform spectroscopy analyzer which concerns on the 2nd Embodiment of this invention. It is a perspective view which shows the structure of the birefringent component of the Fourier-transform spectroscopy analyzer which concerns on the 3rd Embodiment of this invention. It is sectional drawing which shows a birefringent area | region and the birefringent area | region from which the direction of an optical principal axis differs 90 degree | times. It is a graph which shows the relationship between a retardance and a detected light quantity. It is a perspective view which shows the structure of the birefringent component of the Fourier-transform spectroscopy analyzer which concerns on the 4th Embodiment of this invention. It is a perspective view which shows the structure of the birefringent component of the Fourier-transform spectroscopy analyzer which concerns on the 5th Embodiment of this invention. It is a perspective view which shows the structure of the birefringent component of the Fourier-transform spectroscopic analyzer which concerns on the other example of the 5th Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  As shown in FIG. 1, the Fourier transform spectroscopic analysis apparatus 10 according to the first embodiment includes two polarizing plates 12A and 12B and a component in which a birefringent region 14A is formed (hereinafter referred to as “birefringent component”). 14), a detector array 16, and a calculator 18. In the figure, for the sake of explanation, each component is drawn apart in the direction of the optical axis (z direction), but in actuality, they are close to each other.

  The polarizing plate 12A polarizes incident light in a predetermined direction (first direction). The polarizing plate 12B is arranged so that the light transmitted through the birefringent component 14 is incident, and polarizes the incident light in a predetermined direction (second direction).

  As the polarizing plates 12A and 12B, commercially available polarizing filters may be used, as long as the necessary polarization characteristics (extinction ratio) are obtained with respect to the wavelength spectrum range of incident light to be measured. In FIG. 1, the transmission axes of the two polarizing plates 12A and 12B are made parallel, but the transmission axes of the polarizing plates 12A and 12B may be orthogonal.

  The birefringent component 14 is made of a transparent material, and is arranged so that light polarized by the polarizing plate 12A is transmitted. A plurality of birefringent regions 14A having different retardances are formed in the birefringent component 14 by changing the length (action length) in the optical axis direction corresponding to the incident direction of light, using a manufacturing method described later. The plurality of birefringent regions 14A are arranged in a direction crossing the optical axis direction.

  As a transparent material for the birefringent component 14, transparent acrylic or the like can be used in addition to various glasses such as quartz glass.

  The detector array 16 includes a plurality of light receiving elements that receive the light polarized by the polarizing plate 12B and are arranged corresponding to the plurality of birefringent regions 14A. As the detector array 16, a solid-state image sensor is preferably used, and an image sensor such as a CCD or CMOS can be used. In FIG. 1, for the sake of explanation, the number of birefringent regions 14A and the number of light receiving element arrays are shown as five. However, as will be described later, actually required measurement resolution and wavelength range to be measured are shown. It is necessary to increase according to. The cross-sectional size of the birefringent region may be made according to the size of each light receiving element, and a large region can be made by scanning the spot position as shown in FIG. 8B described later. However, as shown in FIG. 8A, which will be described later, it is convenient and preferable to produce one region only by scanning in the optical axis direction. At this time, the diameter of the birefringent region 14A can be controlled in the range of about 1 μm to 10 μm by adjusting the spot diameter of the laser beam. Therefore, the size of each light receiving element may be selected to this extent, and this size is common in commercially available solid-state image sensors. The birefringent region 14A is not necessarily separated as shown in the figure, and may be connected to an adjacent region when the region is formed by scanning the laser beam. When the incident light passes through the birefringent component 14, it is only necessary to obtain a necessary amount of retardance for each of the passing positions.

  As shown in the cross-sectional view of FIG. 2, the direction of the optical principal axis (the fast axis F and the slow axis S) of the birefringent region 14A is 45 degrees with respect to the transmission axis (y direction) of the incident side polarizing plate. Good. As a result, the two components in the fast axis direction and the slow axis direction of the birefringent region 14A have the same amount of light. The same applies to the other birefringent regions 14A in which the optical axis principal axis direction is not clearly shown in the drawing. Here, when a phase difference Δθ occurs between the two components of the light that has passed through the birefringent region 14A, the relationship with the normalized light amount I detected by the light receiving element is expressed by the following equation (1). The

I = cos ² (Δθ / 2) = (1 + cos Δθ) / 2 (1)

  The relationship between the retardance R and the phase difference Δθ is Δθ = 2π · R / λ, and λ is the wavelength. In other words, when light passes through a birefringent region where a certain amount of retardance (here, the optical path difference generated between the two components in the fast axis and slow axis directions of the light that has passed through the birefringent region) occurs, A shorter phase causes a larger phase difference. Temporarily, light of a single wavelength (referred to as a reference wavelength here) in a wavelength range to be measured passes through each birefringent region 14A in FIG. 2, and the phase difference Δθ generated in each region is shown in FIG. Thus, when it is 0 to 2π, the light quantity I detected by each light receiving element corresponds to the value indicated by a circle on the curve shown by the solid line in FIG. 3 according to the above equation (1). On the other hand, if light having a wavelength 2/3 times the reference wavelength passes through the birefringent region 14A, the value of the phase difference Δθ becomes 3/2 times once the influence of dispersion is ignored. This corresponds to the value indicated by the square mark on the curve indicated by the dotted line in FIG. Therefore, according to the wavelength of the light that has passed through each birefringent region 14A of the birefringent component 14, the distribution of the light quantity I detected by each light receiving element becomes a point on a sine wave (or cosine wave) having a different frequency, The original wavelength of the incident light can be obtained by subjecting these values to discrete Fourier transform by the calculator 18. When light including a plurality of wavelengths passes, the distribution of the respective light amounts I is superposed (interferogram), so that the wavelength spectrum can be obtained by performing Fourier transform by the calculator 18. The computing unit 18 that performs the Fourier transform processing is preferably integrated with the detector array 16. This can be easily realized in CMOS.

  Incidentally, as described above, it is actually necessary to increase the number of birefringent regions 14A and the array of light receiving elements. The resolution Δλ of the wavelength to be measured is expressed by the following equation (2).

Δλ = λ ² / R _max (2)

Here, λ is the wavelength, and R _max is the maximum retardance in the plurality of birefringent regions 14A. For example, when a spectrometer capable of measuring a wavelength of 400 nm to 800 nm is manufactured, R _max needs to be 45714 nm in order to achieve a resolution of 14 nm similar to that of a commercially available small-sized spectrometer at a maximum wavelength of 800 nm. As will be described later, in the birefringence region fabricated in quartz glass, a retardance of 300 nm is obtained when the optical path length is 100 μm. Therefore, in order to obtain the required R _max , the optical path length was 15.2 nm. A birefringent region may be prepared, and this is the longest birefringent region. Further, it is necessary to detect (sample) the amount of light at a frequency twice or more the frequency of the interferogram having the shortest wavelength of 400 nm (the sine wave waveform expressed by the above equation (1)). Accordingly, the retardance difference between the adjacent birefringent regions 14A is 200 nm, and is approximately 230 when the value of R _max is divided by 200 nm. That is, it is only necessary to produce about 230 birefringent regions where the retardance changes from 0 nm to 45714 nm at intervals of 200 nm. By the way, in the discrete Fourier transform, if the number of sampled data is 2 to the Nth power, high-speed processing is possible. In this case, it is preferable that N is 8 and 256 birefringence regions are produced. . In other words, in terms of the optical path length L of the birefringent region, as shown in FIG. 4, the birefringent region having an optical path length from 0 mm to 15.2 nm may be produced with the optical path length interval being about 60 μm. These are conditions that can be sufficiently produced. Note that even quartz glass has a large change in refractive index when irradiated with laser depending on the type, and such a material can further shorten the optical path length of the birefringent region.

  By the way, as described above, the refractive index has an influence of dispersion, and further, the sensitivity of the detector has a wavelength-dependent influence. These influences can be removed by correcting the result of Fourier transform. Can do.

  FIG. 5 shows a schematic diagram of an interferogram obtained when light having a certain wavelength distribution passes through each component. The interferogram is symmetric in the positive and negative directions around the position where the retardance is zero. The amount of light detected by the detector array 16 is schematically shown as a circle in FIG. 5, and the amount of light is detected by either the positive or negative retardance. .

  Here, a method for producing the birefringent component 14 will be described.

  In the automotive field, it is preferable if the spectroscope can be used, for example, for grasping the properties of fuel and oil, and for the color monitor of the display. Cost reduction was difficult. In the present embodiment, the problem of the prior art is solved by manufacturing an optical component having birefringence by laser processing.

  Among laser processing, a processing technique using an ultrashort pulse laser has a feature that processing can be performed inside a transparent material. For example, a structure such as an optical waveguide can be written inside glass. This is because the pulse has a high peak power, and when this pulse is condensed inside the glass with a lens (see FIG. 6A), the light intensity in the vicinity of the condensing point becomes extremely high, resulting in nonlinear absorption. This is because pulse energy is accumulated in the material and processing is performed (see FIG. 6B). At this time, the state of the processed part varies depending on the irradiation condition of the pulse. For example, by changing the fluence (energy per unit area on the condensing surface), a region showing an isotropic refractive index change or birefringence is shown. An area can be created.

References (M. Beresna, et.al., “Polarization sensitive elements fabricated by femtosecond laser nanostructure of glass”, 10 nm, Opt. It is known that a region exhibiting birefringence is produced by irradiating glass with an appropriate fluence, and a retardance of 300 nm or more is obtained. The retardance R is expressed by R = Δn · L with respect to the birefringence Δn (difference in refractive index between the fast axis direction and slow axis direction components) and the optical path length L (length in the optical axis direction of the birefringent region). since the quartz glass is an absolute value of about 3 × ^{10 -3} of the [Delta] n, L is about 100 [mu] m. This birefringence is an action of the nano-grating generated by the irradiation of the pulse, and the direction in which the nano-grating is generated is perpendicular to the optical axis of the irradiating pulse and the vibration direction of the electric field. Therefore, the irradiation pulse is made into linearly polarized light, the direction of polarization is rotated by a half-wave plate or the like, the direction of the nano-grating is changed, and the optical principal axis (fast axis and slow axis) direction of the birefringent region is changed. Control. As a result, as shown in FIGS. 7A and 7B, a birefringent region having an optical principal axis in an arbitrary direction can be produced in the transparent material. Further, as shown in FIG. 8A, the transparent material is moved in the optical axis direction (z direction) to change the irradiation position of the pulse, and the birefringence region 14A having a long optical path length is produced to increase the amount of retardance. Also, as shown in FIG. 8B, the birefringent regions 14A are distributed so that the transparent material is moved in the XY in-plane direction and arranged in a direction crossing the optical axis direction. It is also possible to adjust the amount of retardance by adjusting the energy of the pulse. That is, it is a great feature that a birefringent region of a necessary retardance can be produced with a necessary size and pitch, and it is a great advantage that a position where the retardance is zero can be determined with high accuracy. Note that the ultrashort pulse laser generally has a pulse time width of several picoseconds or less in general, but, for example, a nanosecond laser is similar if the light intensity at the focal point is sufficiently increased. Processing is possible.

  Next, the operation of the Fourier transform spectroscopic analyzer 10 according to the first embodiment will be described.

  First, when light to be measured enters the polarizing plate 12A, the light polarized by the polarizing plate 12A passes through each birefringent region 14A of the birefringent component 14, and the length of the optical path length of each birefringent region 14A. Light to which a phase difference corresponding to (retardance amount) is given is detected by each corresponding light receiving element of the detector array 16 via the polarizing plate 12B. An output signal of each light receiving element is output from the detector array 16, and an interferogram represented by the output signal of each light receiving element is obtained by the arithmetic unit 18, and discrete Fourier transform is performed on the waveform of the interferogram. Thus, the wavelength spectrum of the incident light is obtained.

  As described above, according to the Fourier transform spectroscopic analysis apparatus according to the first embodiment, a plurality of birefringent regions having different lengths in the optical axis direction are formed inside so as to be arranged one-dimensionally. Since information representing the interferogram can be obtained using the member, the interferogram can be obtained with an inexpensive configuration.

  In addition, a component in which a region showing birefringence is arranged on a transparent member can be manufactured by ultrashort pulse laser processing, and can be arranged one-dimensionally, and a region showing birefringence is arranged on a transparent member such as glass. By using these parts, a small and inexpensive Fourier transform spectrometer can be realized. On the other hand, the existing technology requires an expensive birefringent prism.

  Next, a Fourier transform spectroscopic analyzer according to a second embodiment will be described. In addition, about the part similar to 1st Embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  In the second embodiment, the point that a plurality of birefringent regions formed inside the birefringent component are two-dimensionally arranged as viewed from the optical axis direction is mainly different from the first embodiment. Is different.

  As shown in FIG. 9, the birefringent regions 14A formed inside the birefringent component 14 of the Fourier transform spectroscopic analyzer 10 according to the second embodiment are two-dimensionally arranged as viewed from the optical axis direction. Yes. As a result, the numerical aperture of the birefringent component 14 is reduced, so that the influence of obliquely incident light can be reduced.

  The light receiving elements of the detector array 16 are also two-dimensionally arranged corresponding to the arrangement of the birefringent regions 14A.

  The computing unit 18 obtains an interferogram represented by an output signal of each light receiving element of the detector array 16, and obtains a wavelength spectrum of incident light by performing a discrete Fourier transform on the waveform of the interferogram. .

  In addition, about the other structure and effect | action of the Fourier-transform spectroscopy analyzer 10 which concern on 2nd Embodiment, since it is the same as that of 1st Embodiment, description is abbreviate | omitted.

  In this way, a part in which a region showing birefringence is arranged on a transparent member can be manufactured by ultrashort pulse laser processing, and can be arranged two-dimensionally, and a region showing birefringence can be arranged two-dimensionally. Thus, since the numerical aperture of the spectrometer can be reduced, the influence of obliquely incident light can be reduced and high-accuracy measurement can be performed without reducing the measurement resolution and the measurement wavelength range.

  Next, a Fourier transform spectroscopic analyzer according to a third embodiment will be described. In addition, about the part similar to 1st Embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  In the third embodiment, the plurality of birefringent regions formed inside the birefringent component include both a birefringent region and both birefringent regions that are 90 degrees apart from the birefringent region and the direction of the optical principal axis. The point of inclusion is mainly different from the first embodiment.

  As shown in FIG. 10, a plurality of birefringent regions 14A formed inside the birefringent component 14 of the Fourier transform spectroscopic analyzer 10 according to the third embodiment are arranged in one dimension as viewed from the optical axis direction. In addition, a plurality of birefringent regions 14B that are 90 degrees different from the birefringent region 14A in the direction of the optical principal axis are arranged one-dimensionally as viewed from the optical axis direction.

  A plurality of birefringent regions 14A having different lengths in the optical axis direction are arranged on one side inside the birefringent component 14, and the lengths in the optical axis direction are different on the other side inside the birefringent component 14, respectively. A plurality of birefringent regions 14B that are 90 degrees different from the birefringent region 14A in the direction of the optical principal axis are arranged.

  Assuming that the retardance generated in the birefringent region 14A is positive, as shown in FIG. 11, the retardance is negative in the birefringent region 14B in which the direction of the optical principal axis is changed by 90 degrees.

  Further, the length in the optical axis direction of each birefringent region 14A is set so that the retardance at the position of the circle shown in FIG. 12 is obtained, and the retardance at the position of the triangle is obtained. The length in the optical axis direction of each of the birefringent regions 14B obtained by changing the birefringent region 14A and the direction of the optical principal axis by 90 degrees is set.

  The computing unit 18 folds back the array of light amounts detected on the negative side of the retardance to the positive side around the retardance 0, obtains an interferogram as shown in FIG. 5, and performs a discrete Fourier transform, The wavelength spectrum of the incident light is obtained.

  As described above, by using the positive and negative retardances, in the first embodiment, the optical path length of the birefringent region needs to be formed at intervals of about 60 μm, whereas the optical path of the birefringent region is required. It is sufficient to produce the length at intervals of about 120 μm, and the conditions during production are relaxed. Further, the arrangement of the amount of light detected on the negative side is the same as the original result when folded back to the positive side around the retardance 0, and the measurement resolution does not deteriorate.

  As in the second embodiment, a plurality of birefringent regions and a plurality of birefringent regions in which the direction of the birefringent region and the optical principal axis are changed by 90 degrees may be arranged two-dimensionally. Good.

  In addition, each birefringent region has a different length in the optical axis direction, and each birefringent region obtained by changing the direction of the plurality of refracted regions and the optical principal axis by 90 degrees has a different length in the optical axis direction. The length in the optical axis direction may be the same between the birefringent region and the birefringent region in which the direction of the optical main axis is changed by 90 degrees.

  Next, a Fourier transform spectroscopic analyzer according to a fourth embodiment will be described. In addition, about the part similar to 1st Embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  The fourth embodiment is mainly different from the first embodiment in that an optical waveguide is formed for each birefringent region inside the birefringent component.

  The birefringent region has a role as an optical waveguide because the refractive index is increased with respect to the surrounding unprocessed region. On the other hand, by adjusting the fluence of the laser beam to be irradiated as described above, it is possible to produce a region showing an isotropic refractive index change, which becomes an optical waveguide. Therefore, in the present embodiment, as shown in FIG. 13, isotropic non-birefringence as an optical path in a region where the optical path length of the birefringent region 14A is less than the length of the birefringent component 14 in the optical axis direction. A plurality of regions 14C are produced and optically coupled to the plurality of birefringent components 14.

  In addition, about the other structure and effect | action of the Fourier-transform spectroscopy analyzer 10 which concerns on 4th Embodiment, since it is the same as that of 1st Embodiment, description is abbreviate | omitted.

  In this way, by forming an optical waveguide structure that optically couples to each of the birefringent regions, it is possible to reduce the influence of obliquely incident light and increase the light utilization efficiency.

As in the second embodiment, a pair of optically coupled optical waveguides and birefringent regions may be arranged two-dimensionally. As a result, the influence of obliquely incident light can be further reduced.
In addition, the case where the optical waveguide is formed on the incident side of the birefringent region has been described as an example, but the present invention is not limited to this, and the optical path book of the birefringent region has a length in the optical axis direction of the birefringent component. If the optical waveguide is formed in a region that is less than that, it may be on either the incident side or the emission side.

  Next, a Fourier transform spectroscopic analyzer according to a fifth embodiment will be described. In addition, about the part similar to 1st Embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  In the fifth embodiment, a birefringent region that is optically coupled and a combination of the birefringent region and the birefringent region in which the direction of the optical principal axis is changed by 90 degrees are arranged in the birefringent component. This is mainly different from the first embodiment.

  As shown in FIG. 14, in the birefringent component 14 of the Fourier transform spectroscopic analyzer 10 according to the fifth embodiment, a birefringent region 14A aligned in the optical axis direction, the birefringent region 14A, and the optical axis principal axis. A plurality of pairs of birefringent regions 14B whose directions are changed by 90 degrees are optically coupled, and a plurality of pairs of optically coupled birefringent regions 14A and birefringent regions 14B are one-dimensionally viewed from the optical axis direction. It is arranged.

  The birefringent regions 14A have different lengths, and the birefringent regions 14A and the birefringent regions 14B obtained by changing the direction of the optical principal axis by 90 degrees are different.

    For a pair of optically coupled birefringent regions 14A and a birefringent region 14B in which the direction of the optical principal axis is changed by 90 degrees with the birefringent region 14A and the birefringent region 14A, the retardance is canceled and becomes zero. The longer the birefringent region 14A is, and the shorter the birefringent region 14B in which the birefringent region 14A and the direction of the optical principal axis are changed by 90 degrees is, the larger the retardance becomes.

  In addition, about the other structure and effect | action of the Fourier-transform spectroscopy analyzer 10 which concerns on 5th Embodiment, since it is the same as that of 1st Embodiment, description is abbreviate | omitted.

  Also, as shown in FIG. 15, as in the second embodiment, a pair of a birefringent region 14A that is optically coupled, a birefringent region 14B in which the direction of the optical axis principal axis is changed by 90 degrees, and the birefringent region 14A. May be arranged two-dimensionally. As a result, the influence of obliquely incident light can be reduced.

DESCRIPTION OF SYMBOLS 10 Fourier-transform spectroscopy analyzer 12A, 12B polarizing plate 14 Birefringent components 14A, 14B Birefringent area | region 14C Non-birefringent area | region 16 Detector array 18 Calculator

Claims (7)

A first polarizing plate that polarizes incident light in a first direction;
A plurality of regions that are arranged to transmit light polarized by the first polarizing plate and exhibit a plurality of birefringences having different lengths in the optical axis direction corresponding to the incident direction of the light are in the optical axis direction. Transparent members formed inside so as to be arranged in one or two dimensions when viewed from
A second polarizing plate disposed so that the light transmitted through the transparent member is incident thereon, and polarizing the incident light in a second direction;
A plurality of light receiving elements that receive light polarized by the second polarizing plate and that are arranged corresponding to the plurality of regions exhibiting birefringence, the information representing the interferogram, A light detection unit that outputs a signal output from the light receiving element;
Including spectroscopic apparatus.   The spectroscopic device according to claim 1, wherein the plurality of regions exhibiting birefringence are two-dimensionally arranged when viewed from the optical axis direction and are formed inside the transparent member.   The spectroscopic apparatus according to claim 1, wherein the birefringent region is formed so that an optical principal axis is oriented at 45 degrees with respect to a transmission axis of the first polarizing plate.   A plurality of waveguides extending in the optical axis direction are formed on at least one of the incident side and the emission side from the birefringent region inside the transparent member so as to be optically coupled to the plurality of regions exhibiting birefringence. The spectroscopic device according to any one of claims 1 to 3.   The transparent member is formed with a plurality of one-dimensional or two-dimensional arrays of birefringent regions having different lengths in the optical axis direction as viewed in the optical axis direction. A plurality of birefringent regions having different direction lengths and birefringent regions obtained by changing the direction of the optical principal axis by 90 degrees are arrayed in one or two dimensions as viewed from the optical axis direction. The spectroscopic device according to any one of claims 1 to 4.   In the transparent member, a plurality of birefringent regions having different lengths in the optical axis direction are formed in a one-dimensional or two-dimensional manner as viewed from the optical axis direction. The region showing the birefringence and the region showing the birefringence obtained by changing the direction of the optical principal axis by 90 degrees are different in the length of the optical axis direction so as to be optically coupled with the region showing the refractive property. The spectroscopic device according to any one of claims 1 to 4, wherein a plurality of one-dimensional or two-dimensional arrays are formed as viewed from a direction. The spectroscopic device according to any one of claims 1 to 6,
An arithmetic unit for Fourier transforming the interferogram represented by the signal output by the light detection unit;
Including Fourier transform spectroscopic analyzer.