JP2008191041A - Spectrometer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a spectrometer that can efficiently separate and remove the reflected light from a sample and Rayleigh-scattered light and obtain only the feeble signal light. <P>SOLUTION: The spectrometer for dividing the scattered light scattered by the sample, irradiated with excitation light, has a wavelength cut filter 130 for removing the wavelength components of the exciting light included in the scattered light, and a spectral element 140 for obtaining the spectrum of the light guided from the wavelength cut filter 130. The wavelength cut filter is a ring-type optical resonator 130 having a ring-like waveguide 102, or is a laminated type optical resonator, having a laminated structure of at least three layers and at least one air layer. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a spectroscope that separates input light. In particular, the present invention relates to a spectroscope that separates Raman scattered light of a measurement target or sample, and a spectroscopic analysis apparatus that includes the spectroscope and performs analysis using Raman scattered light of the measurement target or sample.

Traditionally, Raman spectra are known in molecular vibrational spectrum measurement methods for solids, liquids, gases and mixtures thereof and are used for the evaluation of materials. Since Raman scattered light is weak, a spectroscope that obtains a spectrum with little stray light is required. In particular, with the development of high-performance multi-channel photodetectors and lasers, it is necessary to develop spectrometers that detect only weak signal light (Raman scattered light) by separating and removing excitation light and Rayleigh scattered light with high efficiency. ing.

Until now, attempts have been made to separate and remove reflected light and Rayleigh scattered light from a sample light using a differential dispersion type double spectrometer or triple spectrometer. As an example of a spectroscopic analyzer using a triple spectrometer, an apparatus as shown in FIG. 9 has been proposed (see Patent Document 1).

In FIG. 9, 11 is a laser generator such as an argon ion laser, for example, which irradiates a sample 12 with laser light having a predetermined frequency via a half mirror HM. The sample 12 is subjected to Raman scattering when irradiated with laser light, and scattered light corresponding to the material characteristics of the sample 12 is emitted. The emitted scattered light is incident on the condensing optical system 13 via the half mirror HM and the prism P1. The condensing optical system 13 includes a Glan-Thompson prism, a depolarizing plate, a condensing lens, and the like. The condensing optical system 13 condenses the scattered light so as to match the F number of the spectroscope 14 described later, and the scattered light collected by the condensing optical system 13 is split through the prism P2. Is incident on the vessel 14. As the spectroscope 14, for example, a polychromator or a monochromator is used to split incident light. In this example, a triple polychromator is used as the spectrometer 14. The polychromator 14 includes an entrance slit S1, intermediate slits S2 and S3, diffraction gratings G1 to G3-5, concave mirrors M1 to M7, and the like. The incident scattered light enters the diffraction grating G1 through the prism P3 and the concave mirror M1, is dispersed by the diffraction grating G1, and forms an image on the slit S2. By setting the width of this slit appropriately, only light in a specific frequency region can be passed. The light that has passed through the slit S2 enters the diffraction grating G2 through the concave mirrors M3 and M4. The diffraction grating G2 has a differential arrangement that is arranged so as to face in the opposite direction to the diffraction grating G1.

The dispersed light diffracted by the diffraction grating G2 enters the slit S3 via the concave mirror M5, and after the frequency is specified, the light is incident on the light receiving surface of the CCD 15 via the concave mirror M6, the diffraction grating G3-5, and the concave mirror M7. Focus. The spectrometer 14 having the above configuration functions as a bandpass filter that extracts only the wavelength to be measured.
Japanese Patent Laid-Open No. 06-003271

In the spectroscope, as described above, it is desirable to separate and remove the reflected light and Rayleigh scattered light from the sample, and to obtain only weak signal light (Raman scattered light) with high efficiency. However, when the triple spectroscope is used to separate and remove the reflected light and Rayleigh scattered light from the signal light, the number of optical elements is large and the optical transmittance is considerably reduced. Therefore, since the light use efficiency is lowered, it is not easy to obtain only weak signal light (Raman scattered light) with high efficiency.

In view of the above problems, the spectroscope of the present invention that separates scattered light scattered by a sample irradiated with excitation light includes a wavelength cut filter that removes a wavelength component of excitation light contained in the scattered light, and a wavelength cut filter. A spectroscopic element for obtaining a spectrum of the guided light. Here, the wavelength cut filter is a ring type optical resonator having a ring-shaped waveguide, or a stacked type optical resonator having a laminated structure of at least three layers and having at least one air layer.

Moreover, in view of the said subject, the spectroscopic analyzer of this invention has an excitation light source, a condensing optical system, said spectroscope, and a detection processing system, It is characterized by the above-mentioned. The excitation light source irradiates the sample with light. The condensing optical system condenses the scattered light scattered by the sample. The spectroscope receives scattered light from a condensing optical system. The detection processing system detects and processes the spectral pattern emitted from the spectroscope.

According to the present invention, since the wavelength cut filter as described above is used, the reflected light and Rayleigh scattered light from the sample are separated and removed with high efficiency, and only weak signal light (Raman scattered light) is obtained with high efficiency. Can do.

An embodiment of a spectrometer according to the present invention will be described below with reference to FIG. FIG. 1 is a top view of the spectrometer of the present embodiment.

The spectroscope of this embodiment obtains a spectrum of the light by receiving the wavelength cut filter 130 for cutting the excitation light component of the scattered light from the sample or measurement object and the light from the filter 130 via the collimator 104. A spectroscopic element 140 is included. In the present embodiment, a ring-type optical resonator 130 including a ring-shaped waveguide 102 is used as the wavelength cut filter. In the ring-type optical resonator 130, the light 121 cut from the incident light 120 to the waveguide 101 is guided to the waveguide 121, and the light 122 from which unnecessary light is cut is emitted from the emission end of the waveguide 101. As the wavelength cut filter, as will be described later, a laminated optical resonator having a laminated structure of at least three layers and having at least one air layer can also be used.

In the present embodiment, the spectroscopic element 140 is a Michelson interferometer using Fourier transform. With this configuration, light can be detected in a batch without being decomposed for each wavelength, so that the light use efficiency can be improved (see Example 1 described later). The spectroscopic element may be a dispersive spectroscopic element as will be described later. An example of the dispersive spectroscopic element is a diffraction grating. With this configuration, it is possible to directly detect the wavelength of the spectrum without performing Fourier transform (see Example 4 described later).

The operation of the present embodiment will be described with reference to FIGS. FIG. 2 (a) shows the transmission characteristics of the wavelength cut filter 130, which is a feature of the present embodiment, and FIG. 2 (b) shows the light intensity distribution of the wavelength of light incident on the spectrometer, and FIG. ) Shows the light intensity distribution of the wavelength of the light after passing through the wavelength cut filter 130.

By irradiating a sample (not shown) with laser light having a predetermined wavelength λ0, reflected light or Rayleigh scattered light having a wavelength λ0 is emitted from the sample. Further, Raman scattered light having a wavelength λ0 ± Δλ is emitted corresponding to the material property of the sample (Δλ is a Raman shift). That is, as shown in FIG. 2B, the scattered light from the sample incident on the spectroscope of this embodiment includes reflected light, Rayleigh scattered light, and Raman scattered light from the sample. Raman scattered light is very weak compared to reflected light from a sample or Rayleigh scattered light. Therefore, in order to effectively detect Raman scattered light, it is necessary to separate and remove reflected light and Rayleigh scattered light from the sample.

In the ring-type optical resonator 130 that is a wavelength cut filter of this embodiment, a ring-shaped waveguide 102 is formed adjacent to the waveguides 101 and 103. In the ring-shaped waveguide 102, light can be extracted to the waveguide 103 at a constant wavelength interval due to a resonance phenomenon. Therefore, the light 120 incident on the waveguide 101 is coupled to the ring-shaped waveguide 102 and output from the waveguide 103 when the wavelength thereof is close to the resonance wavelength. On the other hand, when the wavelength is far from the resonance wavelength, the coupling with the waveguide 102 is weak and the light is output from the output end of the waveguide 101. Therefore, by setting the resonance wavelength of the wavelength cut filter 130 to the wavelength λ0 of the reflected light or Rayleigh scattered light from the sample, only the reflected light or Rayleigh scattered light from the sample can be selectively extracted from the waveguide 103. it can. Therefore, the Raman scattered light can be efficiently introduced into the spectroscopic element 140.

Since such a ring-shaped waveguide 102 can realize a Q value of about 1000 to 10,000, a narrow resonance peak of about 1 / Q of the resonance wavelength, that is, about 0.1 to 1 nm can be obtained. Accordingly, a spectrum (wavelength) component having a very narrow band can be removed from the light incident on the waveguide 101. Therefore, only the reflected light and Rayleigh scattered light from the sample can be separated and removed effectively.

As described above, FIG. 2A shows the characteristics of the wavelength cut filter 130 of the present embodiment. With the optical characteristics of the wavelength cut filter 130, a specific wavelength component can be cut with a half width of about 2 nm. The attenuation factor is about 40 db, and a specific wavelength component can be reduced to about 10 ⁻³ . By adjusting the wavelength cut by the wavelength cut filter 130 to the wavelength λ0 of the reflected light or Rayleigh scattered light from the sample, the intensity of the reflected light and Rayleigh scattered light from the sample as shown in FIG. Only can be reduced. Then, the Raman scattered light λ0 ± Δλ can be introduced into the spectroscopic element 140 with high efficiency. The light from the spectroscopic element 140 is guided to the detector 110 through the focusing optical system 109 and detected there.

As described above, the wavelength cut filter of the spectrometer can be a laminated optical resonator having a laminated structure of at least three layers and having at least one air layer. The operation in this case will be described. This laminated optical resonator has a structure in which films are alternately stacked, and transmits or reflects only light in a specific wavelength region by using interference of multiple reflected light generated at the boundary surface of each film. is there. As described above, the laminated optical resonator has a structure in which a high refractive index material film and a low refractive index material film are alternately repeated. If the optical film thickness nd, which is the product of the thickness d and the refractive index n of these films, is ½ of the wavelength λ to be cut, the light transmittance at the wavelength λ increases. On the other hand, if the optical film thickness is ¼ of the wavelength λ to be cut, the reflectance of light having the wavelength λ increases.

This laminated structure may be a Fabry-Perot structure (M-D-M) in which two highly reflective layers (M) are arranged in parallel and a D (dielectric) layer is arranged therebetween. If the optical film thickness nd, which is the product of the thickness d of the D layer and the refractive index n, is ½ of the wavelength λ to be cut, the transmittance of light having the wavelength λ increases due to the resonance phenomenon. On the other hand, if the optical film thickness nd is 1/4 of the wavelength λ to be cut, the reflectance of light having the wavelength λ increases due to the resonance phenomenon. The high reflection layer M may be a metal such as gold, silver, or aluminum, or a repeating structure of a high refractive index material and a low refractive material. The D layer may be air, which is a non-absorbing material.

Therefore, by using the laminated optical resonator as a wavelength cut filter, light having a spectrum (wavelength) having a very narrow band can be removed. Therefore, only the reflected light and Rayleigh scattered light from the sample can be effectively separated and removed from the incident light.

In the laminated optical resonator, at least one layer of the laminated structure is an air layer, and various materials can be used as the high refractive index material by using air as the low refractive index material film. In addition, since it is not necessary to use a plurality of materials, manufacturing is facilitated. Furthermore, since the air layer does not absorb light, only the reflected light and Rayleigh scattered light from the sample can be effectively separated and removed.

As described above, the laminated optical resonator can be configured to transmit light having a removal wavelength. With this configuration, it is possible to prevent leakage light having a high light intensity after removing reflected light or Rayleigh scattered light from the sample from entering the spectroscopic element 140 (see Example 2 described later).

On the other hand, the laminated optical resonator may be configured to reflect light having a removal wavelength. This configuration can be used without considering the difference in the polarization characteristics of the light incident on the optical resonator (see Example 3 described later).

It can also be set as the structure which has a some wavelength cut filter. With this configuration, reflected light and Rayleigh scattered light from the sample can be further reduced, so that weak signal light can be detected more efficiently (see Example 5 described later).

It can also be set as the structure which has the wavelength scanning part which changes the removal wavelength of a wavelength cut filter continuously. With this configuration, even when the wavelength of the excitation light applied to the sample changes, weak signal light can be detected by the same spectrometer (see Examples 4 and 6 described later).

Further, the wavelength cut filter 130 and the spectroscopic element 140 may be formed on the same substrate. With this configuration, the spectroscope can be miniaturized, and optical axis adjustment between optical elements is unnecessary or reduced (see Example 1 described later).

For example, the spectrometers may be stacked in a direction perpendicular to the paper surface of FIG. 1 and arranged in an array. With this configuration, more weak signal light can be collected in the plurality of detectors 110. The signals detected by the plurality of detectors 110 are added and appropriately processed by the processing system according to the purpose. For example, the detection signal can be compared with the molecular vibration spectra of various substances stored as a database in the processing system to identify the measurement object. In addition, the measurement object is scanned with excitation light, and in the processing system, mapping processing is performed by matching each scanning point with the detection signal of the Raman scattered light therefrom, and the stress distribution generated in the measurement object is imaged. You can also do it.

The spectroscope detects and processes a laser light source that irradiates a sample with excitation light, a condensing optical system that collects scattered light scattered by the sample, and a spectral pattern emitted from the spectroscope. A spectroscopic analyzer can be configured with a detection processing system including the detector 110. With this configuration, it is possible to realize a small spectroscopic analyzer that can remove reflected light and Rayleigh scattered light from a sample with high efficiency (see Example 7 described later).

Hereinafter, the present invention will be described in detail with reference to more specific examples.
(Example 1)
The spectroscope of Example 1 will be described with reference to FIG. Example 1 relates to a spectrometer corresponding to the above embodiment. The spectroscope of this embodiment includes a wavelength cut filter 130 that cuts an excitation light (near infrared light) component from incident light 120 and a spectroscopic element 140. In this embodiment, a ring-type optical resonator 130 having a high Q value including the ring-shaped waveguide 102 is used as the wavelength cut filter. The spectroscopic element 140 is a Michelson interferometer that uses Fourier transform.

The ring-type optical resonator 130 includes a waveguide 101, a waveguide 103, and a ring-shaped waveguide 102 that is adjacent to both the waveguides 101 and 103 and is coupled with a predetermined coupling length. The waveguides 101, 102, and 103 are formed of a core portion surrounded by a cladding portion. As will be described later, for example, the core portion is silicon, the lower clad portion is silicon oxide, and the upper clad portion is air. The core part should just be a material with a refractive index higher than a clad part.

In the ring type optical resonator 130 of this embodiment, light can be extracted from the waveguide 103 at a constant wavelength interval due to a resonance phenomenon. The resonance wavelength of the ring type optical resonator 130 is adjusted to the wavelengths of reflected light and Rayleigh scattered light from a sample (not shown). Therefore, in the light 120 incident from the waveguide 101, the reflected light and the Rayleigh scattered light from the sample whose wavelength is close to the resonance wavelength are coupled to the ring-type optical resonator 130, and the wavelength component is derived from the waveguide 103. Is output. On the other hand, in the case of Raman scattered light whose wavelength is far from the resonance wavelength, the coupling with the ring resonator 130 is weak, and the light is output from the output end of the waveguide 101. In this way, only the reflected light and the Rayleigh scattered light having the resonance wavelength can be effectively separated and removed from the waveguide 101.

As described in the above embodiment, the ring-type optical resonator 130 of this example has a Q value of about 1000. Therefore, it is possible to remove light having a spectrum having a narrow band of about 1 / Q of the resonance wavelength, that is, about 1 nm. Further, the transmission attenuation factor of the ring type optical resonator 130 of this embodiment is about 40 db, and the wavelength component of the reflected light or Rayleigh light from the sample can be reduced to about 10 ⁻³ .

The main structure of the Michelson interferometer 140 which is the spectroscopic element of the present embodiment is shown. The Michelson interferometer 140 includes a beam splitter 106 and two plane mirrors (a fixed mirror 105 and a movable mirror 107). The plane mirror 107 is connected to the spring 108 and can move parallel to the optical axis.

In this embodiment, the driving force of the actuator that drives the spring 108 is an electrostatic force. In FIG. 1, the black circle of the spring 108 represents a fixed point to the substrate 150, and other parts are movable. The spring 108 has fixed comb teeth 108a, 108b, 108c, 108d and movable comb teeth 108e, 108f, 108g, 108h. When an electrostatic force acts between the fixed comb teeth 108a and 108b and the movable comb teeth 108e and 108f and attracts them, the spring 108 moves to the left in FIG. Further, when an electrostatic force acts between the fixed comb teeth 108c and 108d and the movable comb teeth 108g and 108h and attracts them, the spring 108 can move to the right in FIG. The electrostatic force is generated by controlling the potential difference between the fixed comb teeth and the movable comb teeth by the control circuit. Thus, the movable mirror 107 can move parallel to the optical axis. The actuator may use a driving force such as electromagnetic force, piezoelectric energy, thermal expansion / contraction. In the case of electromagnetic force, instead of fixed comb teeth and movable comb teeth, for example, a planar coil and a magnet (magnetized in a direction perpendicular to the surface of the coil) are arranged, and the current to the coil is controlled. Driving force is generated by controlling with. In the case of piezoelectric energy, a driving force is generated by arranging a piezoelectric element instead of a fixed comb tooth and a movable comb tooth and controlling a voltage applied to the piezoelectric element by a control circuit. In the case of thermal expansion / contraction, a driving force is generated by arranging a heater and a thermal expansion / contraction material in place of the fixed comb teeth and the movable comb teeth and controlling the injection current to the heater by a control circuit.

Here, the Michelson interferometer 140 can be integrally formed from, for example, an SOI (Silicon on Insulator) substrate described later. On the plane mirrors 105 and 107, a metal film or the like is formed. As a result, the light 122 that has passed through the ring-type optical resonator 130 and entered the beam splitter 106 is partially transmitted as transmitted light in the direction of the movable mirror 107, and the rest is reflected as reflected light in the direction of the fixed mirror 105. To do. Thus, the light 122 is divided into two.

For example, when the distance from the beam splitter 106 to the moving mirror 107 is L1 and the distance from the fixed mirror 105 is L2, the two divided light beams are combined with the same phase in the state of L1 = L2. Therefore, they are strengthened and output to the detector 110 (photodiode) via the focusing optical system 109. Further, when the movable mirror 107 moves to reach the state of (L1−L2) = λ / 2, it is synthesized with an opposite phase. Therefore, the values are canceled out and the intensity becomes zero. Further, when the movable mirror 107 moves, it strengthens when the difference between L1 and L2 becomes a multiple of wavelength λ, and weakens when it becomes a multiple of λ / 2. Therefore, when the moving mirror 107 is continuously moved and the output light from the interferometer 140 is observed, the light and dark are periodically repeated.

Even if light of many wavelengths is introduced into the interferometer 140, a synthesized wave (interferogram) modulated for each wavelength component is output. Then, by analyzing the signal intensity of each frequency included in the interferogram, the intensity of light of each wavelength can be found.

In the present embodiment having the above-described configuration, the ring-type optical resonator 130 having a high Q value and a narrow resonance peak is used as a wavelength cut filter. Rayleigh scattered light can be separated and removed with high efficiency. Thereby, only signal light (Raman scattered light) can be detected. In this embodiment, the spectroscopic element is a Michelson interferometer 140. Therefore, since the light can be detected at once without being decomposed for each wavelength, the light use efficiency can be improved.

Furthermore, the spectroscope of the present embodiment can be integrally formed on the same substrate 150, for example. The spectroscope in this case can be manufactured using an SOI substrate. The SOI substrate is a substrate in which a SiO ₂ (silicon oxide) layer is inserted between a silicon substrate and a surface silicon layer. The SiO ₂ layer can act as a lower cladding layer of the waveguide of the ring optical resonator 130. A core part is produced by patterning and etching the surface silicon layer by photolithography. At this time, air is used for the upper cladding layer. Each element of the spectroscopic element 140 can also be produced by patterning and etching the surface silicon layer by photolithography. A reflective film such as metal is formed on the reflective surface of each element. With this manufacturing method, it is possible to reduce the size of the spectroscope and reduce the work of adjusting the optical axis. The movable movable mirror 107 and the movable portion of the spring 108 are also floated from the silicon substrate by etching the SiO ₂ layer.

According to this embodiment, since the wavelength cut filter as described above is used, the reflected light and the Rayleigh scattered light from the sample are separated and removed with high efficiency, and only extremely weak signal light (Raman scattered light) is efficiently obtained with high efficiency. It can be separated and detected. Further, as described above, the spectroscope can be reduced in size by being integrally formed on the same substrate.

(Example 2)
The spectroscope of Example 2 will be described with reference to FIG. FIG. 3 is a top view of the spectrometer of the present embodiment. The configuration and operational effects of the spectrometer of the second embodiment are substantially the same as those of the spectrometer of the first embodiment. The present embodiment is different in that a laminated optical resonator 330 having at least one air layer is used as a wavelength cut filter. The optical resonator 330 of this embodiment uses an air layer 301 as a low refractive index material film. Further, silicon 302 is used as the high refractive index material film.

The method of manufacturing the spectroscope of this example is substantially the same as the spectroscope of Example 1. The surface silicon layer of the SOI substrate is patterned by photolithography and dry-etched to produce a stacked optical resonator 330, a spectroscopic element 340, and the like.

In the optical resonator 330 of this embodiment, the optical film thickness is set to ½ of the wavelength λ to be cut. Therefore, the reflected light or Rayleigh scattered light contained in the incident light 320 from the sample having the wavelength λ is transmitted through the optical resonator 330 to become the transmitted light 321, and the light including the Raman scattered light is reflected, which is unnecessary. The reflected light 322 is cut from the light. Therefore, the reflected light and Rayleigh scattered light from the sample can be effectively separated and removed.

The fixed mirror 305, beam splitter 306, movable mirror 307, spring 308, focusing optical system 309, and detector 310 of this embodiment are the same as those of the first embodiment.

In this embodiment, the laminated optical resonator 330 having an air layer is used as a wavelength cut filter, and the reflected light 322 from the optical resonator 330 is introduced into the spectroscopic element 340. This makes it possible to separate and remove the reflected light and Rayleigh scattered light from the sample from weak Raman scattered light with high efficiency, and detect only the signal light. In the present embodiment, the leakage light after removing the reflected light or Rayleigh scattered light from the sample having a high light intensity is included in the transmitted light 321, so that the leakage light can be prevented from being introduced into the spectroscopic element 340.

(Example 3)
The spectroscope of Example 3 will be described with reference to FIG. FIG. 4 is a top view of the spectrometer of the present embodiment. The configuration and operational effects of the spectrometer of the third embodiment are substantially the same as those of the spectrometer of the second embodiment. Also in this embodiment, the laminated optical resonator 430 having at least one air layer is used as the wavelength cut filter. The feature of the optical resonator 430 of this embodiment is that an air layer 401 is used as a low refractive index material film and an oxide film 402 is used as a high refractive index material film.

The method for manufacturing the spectrometer of the present embodiment is also substantially the same as that of the spectrometer of the first embodiment. The surface silicon layer of the SOI substrate is patterned by photolithography and dry-etched to manufacture the stacked optical resonator 430, the spectroscopic element 440, and the like.

In the laminated optical resonator 430 of this embodiment, the optical film thickness is set to ¼ of the wavelength λ to be cut. Therefore, the reflected light or Rayleigh scattered light from the sample having the wavelength λ included in the incident light 420 is reflected by the optical resonator 430, and the light 422 including the Raman scattered light is transmitted. Therefore, the reflected light and Rayleigh scattered light from the sample can be separated and removed as reflected light 421.

The fixed mirror 405, the beam splitter 406, the moving mirror 407, the spring 408, the focusing optical system 409, and the detector 410 of this embodiment are the same as those of the first embodiment.

In this embodiment, a laminated optical resonator 430 having an air layer is used as a wavelength cut filter, and transmitted light 422 from the optical resonator 430 is introduced into the spectroscopic element 440. This makes it possible to separate and remove the reflected light and Rayleigh scattered light from the sample from weak Raman scattered light with high efficiency, and detect only the signal light. In this embodiment, the light 420 can be vertically incident on the optical resonator 430. Therefore, this configuration can be used without considering the difference in the polarization characteristics of the incident light 420 to the optical resonator 430.

(Example 4)
The spectroscope of Example 4 will be described with reference to FIG. FIG. 5 is a top view of the spectrometer of the present embodiment. The configuration and operational effects of the spectrometer of the fifth embodiment are substantially the same as those of the spectrometer of the first embodiment. In this embodiment, a rotatable diffraction grating 540 is used as a spectroscopic element, which has an aluminum film on the surface. A ring type optical resonator 530 is used as a wavelength cut filter.

The ring type optical resonator 530 of the present embodiment also has a Q value of about 1000, and can remove light having a spectrum having a narrow band of about 1 / Q of the resonance wavelength, that is, about 1 nm. Further, the transmission attenuation factor of the ring type optical resonator 530 of this embodiment is about 40 db. Therefore, the wavelength components of the reflected light and Rayleigh light from the sample can be reduced to about 10 ⁻³ .

The ring-type optical resonator 530 of this embodiment is also configured by a waveguide 501, a waveguide 503, and a ring-shaped waveguide 502 that is adjacent to both the waveguides 501 and 503 and is coupled with a predetermined coupling length. . The waveguides 501, 502, and 503 are formed of a core portion surrounded by a clad portion. For example, the core part is silicon, the lower clad part is silicon oxide, and the upper clad part is air. The ring-type optical resonator 530 of the present embodiment includes a wavelength scanning unit 550 including a heater provided on the back surface of the spectroscope substrate, for example. Thereby, the temperature of the ring-shaped waveguide 502 can be controlled, and the removal wavelength of the wavelength cut filter can be continuously changed. Therefore, even when the wavelength of the excitation light irradiated to the measurement object changes, weak signal light can be detected by the same spectrometer.

The principle of spectroscopy using a diffraction grating will be described. The diffraction grating can divide light mixed with various wavelengths for each wavelength. As the diffraction grating 540 of the present embodiment, a normal diffraction grating can be used. For example, the diffraction grating 540 has a structure in which a large number of grooves and slits are arranged (here, a large number of grooves are formed and the surface is formed). Are coated with aluminum film). When light 522 mixed with various wavelengths enters the diffraction grating 540, the light is strengthened at a certain angle determined for each wavelength, and the wavelength can be selected by taking out the strengthened light. Since the diffraction grating 540 is rotatable, light having various wavelengths can be introduced into the detection unit 510. The diffraction grating 540 can be fixed and used by arranging a large number of detectors.

Also in this embodiment, the ring type optical resonator 530 having a high Q value is used as a wavelength cut filter. This makes it possible to separate and remove the light 521 including the reflected light from the sample and the Rayleigh scattered light from the incident light 520 including the weak Raman scattered light with high efficiency, and detect only the signal light. Further, since the spectroscopic element is the diffraction grating 540, it is possible to directly detect the wavelength of the spectrum without performing Fourier transform.

(Example 5)
The configuration of the spectrometer of the fifth embodiment will be described with reference to FIG. FIG. 6 is a top view of the spectrometer of the present embodiment. The configuration and operational effects of the spectrometer of the fifth embodiment are substantially the same as those of the spectrometer of the first embodiment. This embodiment is different in that the two ring-type optical resonators 630 and 631 are arranged in series along the optical axis.

The two ring type optical resonators 630 and 631 of this embodiment each have a Q value of about 1000, and remove light having a spectrum with a narrow band of about 1 / Q of the resonance wavelength, that is, about 1 nm. Can do. Further, the transmission attenuation factor of the two ring type optical resonators 630 and 631 of the present embodiment is about 40 db. Therefore, by arranging the two ring-type optical resonators 630 and 631 in series as in the present embodiment, the wavelength component of the reflected light or Rayleigh light from the sample can be reduced to about 10 ⁻⁶ .

Waveguide 601a, b, waveguide 603a, b, ring-shaped waveguide 602a, b, collimator 604, fixed mirror 605, beam splitter 606, moving mirror 607, spring 608, focusing optical system 609, detector 610 These are the same as in Example 1. Also, the incident light 620, the cut light 621a, b, and the cut light 622 are the same as those in the first embodiment.

In this embodiment, ring type optical resonators having a high Q value and a narrow resonance peak are arranged in series and used as a wavelength cut filter. Thus, it is possible to separate and remove the reflected light and Rayleigh scattered light from the sample from the weak Raman scattered light, and detect only the signal light. The other points are the same as in the first embodiment. In Example 2 and Example 3 as well, a plurality of stacked optical resonators are arranged in series along the optical axis of the light guided to the spectroscopic element, and reflection from the sample from weak Raman scattered light. It may be configured to separate and remove light and Rayleigh scattered light with higher efficiency.

(Example 6)
A spectroscope according to Example 6 will be described with reference to FIG. FIG. 7 is a top view of the spectrometer of the present embodiment. The configuration and operational effects of the spectrometer of the sixth embodiment are substantially the same as those of the spectrometer of the second embodiment. The present embodiment is different in that the laminated optical resonator 730 having at least one air layer 701 has a movable structure. The highly reflective layers 702 and 703 are metal films (aluminum). As an actuator for translating at least one highly reflective layer of the wavelength scanning unit 750, an actuator utilizing the electrostatic force, electromagnetic force, piezoelectric energy, thermal expansion / contraction, or the like as described above can be used. The method of providing the moving mirror 107 may be provided in accordance with the actuator of the movable mirror 107 described in the first embodiment (which may be replaced with the high reflection layer).

The fixed mirror 705, the beam splitter 706, the movable mirror 707, the spring 708, the focusing optical system 709, the detector 710, and the spectroscopic element 740 of the present embodiment are the same as those in the first embodiment. Also, the incident light 720, the cut light 721, and the cut light 722 are the same as those in the first embodiment.

In the optical resonator 730 of this embodiment, since the gap between the metal film 702 and the metal film 703 is variable, the wavelength to be separated and removed can be changed. Therefore, even if the wavelength of the laser excitation light to the sample (not shown) changes, the reflected light and Rayleigh scattered light from the sample can be effectively separated and removed. The other points are the same as in the second embodiment.

(Example 7)
FIG. 8 is a diagram showing an embodiment of a spectroscopic analysis apparatus using the spectroscope. In FIG. 8, 803 is a beam splitter, and 805 is a spectrometer of the present invention. The spectroscopic analyzer of this embodiment detects the spectral pattern from the excitation light source 801 that irradiates the sample 802 with the light 810, the condensing optical system 804 that collects the scattered light from the sample 802, the spectrometer 805, and the spectrometer 805. And a detection processing system 806 for processing. The excitation light source 801 is a laser generator such as a semiconductor laser or an argon ion laser.

In the above configuration, the light emitted from the excitation light source 801 enters the sample 802 via the beam splitter 706. The light generated from the sample 802 includes reflected light, Rayleigh scattered light, Raman scattered light, and the like. The light generated from the sample 802 is condensed by the condensing optical system 804 and enters the spectroscope 805 of the present invention. A Raman shift can be detected by analyzing the result of spectroscopy by the spectroscope 805 by the detection processing system 806. By using the spectroscope of the present invention, it is possible to realize a small spectroscopic analyzer that can efficiently remove reflected light and Rayleigh scattered light from a sample.

FIG. 3 is a top view for explaining the spectrometer according to the first embodiment of the present invention. (A) is an example of the transmission characteristic of the optical resonator of the present invention, (b) is an example of the intensity distribution of light incident on the spectroscope of the present invention, and (c) is transmitted through the optical resonator of the present invention. It is an example of the intensity distribution of light. FIG. 6 is a top view for explaining a spectrometer according to a second embodiment of the present invention. FIG. 6 is a top view for explaining a spectrometer according to a third embodiment of the present invention. FIG. 6 is a top view for explaining a spectrometer according to a fourth embodiment of the present invention. FIG. 10 is a top view for explaining a spectrometer according to a fifth embodiment of the present invention. FIG. 10 is a top view for explaining a spectrometer according to a sixth embodiment of the present invention. FIG. 10 is a diagram for explaining a spectroscopic analyzer of Example 7 of the present invention. It is a figure which shows the structure of background art.

Explanation of symbols

101, 103, 501, 503, 601a, 601b, 603a, 603b waveguide
102, 502, 602a, 602b Ring-shaped waveguide
105, 305, 405, 605, 705 fixed mirror
107, 307, 407, 607, 707 Moving mirror
110, 310, 410, 510, 610, 710 Detection processing system (detector)
130, 530, 630, 631 Wavelength cut filter (ring type optical resonator)
140, 340, 440, 640, 740 Spectroscopic element (Michelson interferometer)
301, 401, 701 Air layer
330, 430, 730 wavelength cut filter (laminated optical resonator)
540 Spectroscopic element (diffraction grating)
550, 750 wavelength scanning section
801 Excitation light source (laser generator)
802 samples
804 Condensing optical system
805 Spectrometer
806 Detection processing system

Claims (9)

A spectroscope that scatters scattered light scattered by a sample irradiated with excitation light,
A wavelength cut filter for removing a wavelength component of the excitation light contained in the scattered light, and a spectroscopic element for obtaining a spectrum of light guided from the wavelength cut filter,
The wavelength cut filter is a ring type optical resonator having a ring-shaped waveguide. A spectroscope that scatters scattered light scattered by a sample irradiated with excitation light,
A wavelength cut filter that removes the excitation light component contained in the scattered light, and a spectroscopic element that obtains a spectrum of light guided from the wavelength cut filter,
The wavelength cut filter is a multilayer optical resonator having a laminated structure of at least three layers and having at least one air layer. The transmitted light of the stacked optical resonator has a wavelength component of the excitation light to be removed,
3. The spectroscope according to claim 2, wherein the reflected light of the laminated optical resonator is introduced into the spectroscopic element. The reflected light of the laminated optical resonator has a wavelength component of the excitation light to be removed,
3. The spectroscope according to claim 2, wherein the transmitted light of the laminated optical resonator is introduced into the spectroscopic element. 5. The spectrometer according to claim 1, wherein the spectrometer has a plurality of the wavelength cut filters provided in series along an optical axis. 6. The spectroscope according to claim 1, further comprising a wavelength scanning unit that continuously changes a wavelength of a wavelength component of the excitation light removed by the wavelength cut filter. 7. The spectroscope according to claim 1, wherein the spectroscopic element is a Michelson interferometer. 7. The spectroscope according to claim 1, wherein the spectroscopic element is a diffraction grating. An excitation light source that emits light toward the sample;
A condensing optical system for condensing the scattered light scattered by the sample;
The spectroscope according to any one of claims 1 to 8, which receives the scattered light from the condensing optical system,
A detection processing system for detecting and processing a spectral pattern emitted from the spectroscope;
A spectroscopic analyzer characterized by comprising:

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