Spectroscopic analysis device and light source position adjustment method for spectroscopic analysis device

Abstract

Provided is a spectroscopic analysis device that has a relatively simple configuration and can improve the light utilization efficiency (S / N) of a light source. The present invention is characterized by comprising a light source that emits light, a collection optical system unit that collects light from the light source, a first slit that extracts light of a prescribed region from the light collected by the collection optical system unit, an excitation-side diffraction element that disperses light from the collection optical system unit, a second slit that extracts monochromatic light of a prescribed wavelength from the light dispersed by the excitation-side diffraction element, and a detector that detects light from a sample irradiated with the monochromatic light, wherein the collection optical system unit includes a mirror that is disposed between the light source and the excitation-side diffraction element and has a reflection surface with non-axisymmetric free-form curved-surface shape.

Description

Spectroscopic analysis device and method for adjusting light source position of spectroscopic analysis device

[0001] The present invention relates to a configuration of a spectroscopic analyzer and a method for adjusting the position of its light source, and more particularly to a technique that is effective in improving the light utilization efficiency of a light source.

[0002] A spectroscopic analyzer is a device that analyzes a sample by detecting transmitted light, reflected light, fluorescence, and scattered light from the sample irradiated with monochromatic light. These spectroscopic analyzers are now being required to address new needs beyond the scope of traditional laboratory use, such as online measurements aimed at automating and advancing manufacturing processes. To improve throughput in online measurements, there is also a demand for improved light utilization efficiency (S / N) of the light source.

[0003] Background art in this technical field includes, for example, technology such as that disclosed in Patent Document 1. Patent Document 1 discloses "a spectrofluorometer that can correct positional fluctuations of the light-emitting point image due to electrode wear of the xenon lamp without requiring complicated operations by the user, thereby achieving stable measurement sensitivity over a long period of time."

[0004] JP 2010-112809 A

[0005] The optical system of a typical spectroscopic analyzer includes a focusing optical system for focusing light from a light source onto a slit, an excitation-side diffraction element for separating the light from the slit, a slit for extracting monochromatic light of a predetermined wavelength from the light separated by the excitation-side diffraction element, and a detector for detecting light from a sample illuminated with monochromatic light.

[0006] In the optical system of conventional spectroscopic analyzers, an elliptical mirror is placed behind the light source, and when light is collected by this elliptical mirror placed behind the light source, the light source itself blocks the reflected light collected by the elliptical mirror, reducing the light utilization efficiency.

[0007] In addition, a concave mirror is placed in front of the light source, and if a typical spherical or toroidal surface is used as this concave mirror, large aberrations will be generated, making it impossible to form a light spot of sufficient size relative to the slit opening width, resulting in a problem of reduced optical efficiency.

[0008] The technique of Patent Document 1 does not take these problems into consideration at all in improving the light utilization efficiency of the optical system.

[0009] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a spectroscopic analyzer and a method for adjusting the position of a light source thereof that can improve the light utilization efficiency (S / N) of the light source with a relatively simple configuration.

[0010] In order to solve the above problems, the present invention provides a light source that emits light, a collection optical system that collects light from the light source, a first slit that extracts light of a predetermined region from the light collected by the collection optical system, an excitation-side diffraction element that disperses the light from the collection optical system, a second slit that extracts monochromatic light of a predetermined wavelength from the light dispersed by the excitation-side diffraction element, and a detector that detects light from a sample irradiated with the monochromatic light, wherein the collection optical system includes a mirror that is disposed between the light source and the excitation-side diffraction element and has a reflective surface that is a non-axisymmetric free-form surface shape.

[0011] Furthermore, the present invention provides a method for adjusting the position of a light source in a spectroscopic analysis device having the above-mentioned characteristics, wherein the collection optical system further includes a concave mirror having a diameter smaller than that of the mirror, the mirror and the concave mirror are arranged to sandwich the light source, and the center of curvature of the concave mirror is arranged to approximately coincide with the position of the light source, and the mirror and the concave mirror are arranged by shifting the optical axis from approximately the center of the light-emitting region of the light source to an area with stronger light emission intensity.

[0012] According to the present invention, it is possible to realize a spectroscopic analyzer and a method for adjusting the light source position that can improve the light utilization efficiency (S / N) of the light source with a relatively simple configuration.

[0013] This makes it possible to improve the throughput of online measurements by a spectroscopic analyzer, for example.

[0014] Problems, configurations, and effects other than those described above will become apparent from the following description of the embodiments.

[0015] 7 is a functional block diagram showing a schematic configuration of a spectroscopic analysis device according to a first embodiment of the present invention. FIG. 7 is a diagram showing an example of the hardware functional configuration of the spectroscopic measurement unit 3 of FIG. 1. FIG. 7 is a diagram showing a modified example of FIG. 2A. FIG. 7 is a diagram showing an example of a conventional collection optical system. FIG. 7 is a diagram showing another example of a conventional collection optical system. FIG. 7 is a diagram showing an example of the collection optical system 10 of FIG. 2A or 2B. FIG. 7 is a diagram showing a schematic configuration of a light recycling mirror for returning light emitted toward the back surface of the light source. FIG. 7 is a diagram showing a schematic configuration of a light recycling mirror for returning light emitted toward the back surface of the light source. FIG. 7 is a diagram showing a schematic configuration of a light recycling mirror for returning light emitted toward the back surface of the light source. FIG. 7 is a diagram showing a state of light rays when light from a light source is incident at different angles on a collecting mirror having a reflective surface in a non-axisymmetric free-form shape. FIG. 7 is a diagram showing a state of light rays when light from a light source is incident at different angles on a collecting mirror having a reflective surface in a non-axisymmetric free-form shape. FIG. 7 is a diagram showing a state of light rays when light from a light source is incident at different angles on a collecting mirror having a reflective surface in a non-axisymmetric free-form shape. FIG. 7 is a diagram showing an example of the optical system configuration of a spectrofluorometer incorporating the collection optical system of the present invention. FIG. 7 is a diagram showing a modified example of FIG. Fig. 8 is a diagram showing another modified example of Fig. 7. Fig. 9 is a plan view showing the shape of a slit opening. Fig. 10 is a diagram showing the schematic structure of a flow cell for flowing a sample in liquid chromatography. Fig. 11 is a diagram showing the schematic structure of a sample cell of a general fluorometer.

[0016] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the drawings, the same components are designated by the same reference numerals, and detailed description of overlapping parts will be omitted.

[0017] A spectroscopic analyzer and a method for adjusting the light source position thereof according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 10C.

[0018] FIG. 1 is a functional block diagram showing a schematic configuration of a spectroscopic analyzer 1 according to this embodiment.

[0019] As shown in FIG. 1, the spectroscopic analysis device 1 of this embodiment mainly comprises a sample chamber section 2, a spectroscopic measurement section 3, a power supply section 4, a memory section 5, a control section 6, a communication section 7, and an input / output section 8.

[0020] The spectroscopic measurement unit 3 irradiates the dispersed light onto a sample placed in the sample chamber 2, detects the light from the sample, and measures various spectra.

[0021] The control unit 6 comprehensively controls the entire spectroscopic analysis device 1. The functions of the control unit 6 are realized by a calculation device such as a CPU.

[0022] The power supply unit 4 supplies power to each unit of the spectroscopic analyzer 1 .

[0023] The storage unit 5 stores information required for processing by each part of the spectroscopic analysis device 1 and information generated by each part of the spectroscopic analysis device 1. Furthermore, when the function of the control unit 6 is realized by a CPU, the storage unit 5 stores programs and data executed by the CPU. The storage unit 5 is configured with storage devices such as, for example, RAM (Random Access Memory), flash memory, HDD (Hard Disk Drive), SSD (Solid State Drive), etc.

[0024] The communication unit 7 communicates with an external information processing device via the input / output unit 8, which is a connector, by short-distance wireless communication, long-distance wireless communication, or wired communication.

[0025] The sample chamber 2 is an area for storing a sample. The sample may be placed in a space of a predetermined size, or a liquid sample may be placed in a sample cell or the like. If the spectrophotometer 1 is a spectrofluorometer used as a detector for liquid chromatography, the sample chamber 2 serves as a flow cell through which the sample flows after component separation.

[0026] The spectroscopic analysis device 1 is a spectrophotometer, a spectrofluorometer, etc. The spectroscopic analysis device 1 measures, as detection light from a sample, fluorescence, transmitted light, reflected light, scattered light, phosphorescence, emitted light via a nonlinear optical effect, etc., and generates a fluorescence spectrum, an absorption spectrum, a transmission spectrum, a reflection spectrum, a Raman spectrum, etc.

[0027] FIG. 2A is a diagram showing an example of the hardware functional configuration of the spectroscopic measurement unit 3 in FIG.

[0028] As shown in FIG. 2A, the spectroscopic measurement unit 3 is configured to include, for example, a light source unit 9, a collection optical system unit 10, an excitation side spectroscope unit 11, a sample unit 12, and a detection unit 13.

[0029] FIG. 2B is a diagram showing a variation of FIG. 2A.

[0030] As shown in FIG. 2B , the spectroscopic measurement unit 3 may be configured to include a light source unit 9, a collection optical system unit 10, an excitation-side spectroscope unit 11, a sample unit 12, a detection-side spectroscope unit 14, and a detection unit 13.

[0031] The light source unit 9 emits light in a predetermined wavelength range and is, for example, a Xe lamp, a deuterium (D2) lamp, a halogen lamp, or a solid-state light-emitting element (LED, laser, SLD: Super Luminescent Diode).

[0032] The collection optical system 10 collects the light emitted from the light source 9 and guides it to the excitation side spectroscope 11. The collection optical system 10 is configured to include, for example, one or more lenses, mirrors, prisms, etc.

[0033] The excitation side spectrometer section 11 is configured to have a slit (first slit) that extracts light of a predetermined region from the light collected by the collection optical system section 10, an excitation side diffraction element that disperses the light from the collection optical system section 10, and a slit (second slit) that extracts monochromatic light of a predetermined wavelength from the light dispersed by the excitation side diffraction element.

[0034] The sample section 12 stores a sample to be measured. The sample section 12 irradiates the sample with monochromatic light from the excitation side spectroscope section 11 and captures reflected light, transmitted light, fluorescence, and scattered light from the sample by a predetermined means. The sample section 12 may include a sample cell for storing a certain amount of liquid or powdered sample. It may also include a flow cell such as that used in liquid chromatography.

[0035] The detection side spectrometer section 14 is configured to have a slit (third slit) that extracts light of a predetermined region from the detection light from the sample, a detection side diffraction element that disperses the detection light from the sample, and a slit (fourth slit) that extracts monochromatic light of a predetermined wavelength from the light dispersed by the detection side diffraction element.

[0036] The detection unit 13 is a detector that detects light and has a function of converting light from the sample in the sample unit 12 or the detection-side spectroscope unit 14 into an electrical signal corresponding to the light intensity. The detection unit 13 is, for example, a photomultiplier tube, an avalanche photodiode, a photodiode, a phototube, a photoresistor, or the like.

[0037] 3A to 3C are diagrams showing specific configuration examples of the collection optical system section.

[0038] FIG. 3A shows an example of a conventional collecting optical system, in which the light source 15 is a Xe lamp.

[0039] 3A is a configuration in which a collecting mirror 16 is placed behind the light source 15 (Xe lamp) to reflect light. The light emitted from the light source 15 is collected by the axially symmetric collecting mirror 16 (elliptical mirror) placed behind the light source 15 (Xe lamp) and focused on a slit (first slit) 17 in the excitation-side spectroscope section 11.

[0040] However, because the light source 15 (Xe lamp) is arranged in the path of light reflected from the collecting mirror 16, there is a problem in that the light source 15 (Xe lamp) acts as an obstruction in the light path, causing a light defect area 20. Light is lost in the central part of the light path, making it impossible to illuminate the entire excitation-side diffraction element 18 efficiently, and reducing the light utilization efficiency.

[0041] FIG. 3B shows another example of a conventional collecting optical system, in which a collecting mirror 16 having an axially symmetric curved surface is placed in front of a light source 15 to collect light into a slit 17 in order to eliminate the light defect area.

[0042] The axisymmetric curved surface of the condenser mirror 16 is a spherical surface, an ellipsoidal surface, a toroidal surface, etc. The light from the light source 15 is reflected by the condenser mirror 16 at a predetermined reflection angle and reaches the slit 17, which causes aberration and makes it difficult to form a spot with a good shape on the slit 17, and it is difficult to obtain a light utilization efficiency higher than that of the configuration of FIG.

[0043] To correct aberrations, a toroidal surface with a spherical surface having different curvatures in the horizontal and vertical directions is sometimes used, but if a high NA mirror is used to improve light utilization efficiency, large aberrations occur in the spot on the slit, making it difficult to achieve sufficient efficiency.In addition, the area that can pass through the slit and illuminate the excitation-side diffraction element is limited, making it difficult to improve light utilization efficiency.

[0044] FIG. 3C is a diagram showing an example of the collection optics section 10 of FIG. 2A or 2B.

[0045] In order to solve this problem, the collection optical system 10 of the present invention shown in FIG. 3C has a configuration in which light is collected onto a slit 17 in the excitation side spectrometer 11 by a collecting mirror 16 having a reflective surface with a non-axisymmetric free-form shape.

[0046] 3C has the property of converging light emitted from one of two focal points to the other focal point. Therefore, this non-axisymmetric free-form reflecting surface is, for example, a shape obtained by cutting out a portion of an ellipsoid non-axisymmetrically or a shape equivalent thereto, and is placed between light source 15 and slit 17 so that the divergent light from light source 15 is reflected at a predetermined reflection angle and converged to slit 17.

[0047] This allows the emitted light from the light source 15 to be collected onto the slit 17 so that no light defect region 20 is formed, and even when the collecting mirror 16 has a high numerical aperture (NA), a spot with good aberration can be formed on the slit 17 surface, thereby significantly improving the light utilization efficiency.

[0048] 4A to 5 are diagrams showing a schematic configuration of a light recycling mirror 21 for returning light emitted in the direction of the rear surface of the light source 15. FIG.

[0049] As shown in Figures 4A and 4B, by placing a non-axisymmetric free-form surface mirror 22 (Figure 4A) or a collecting mirror 16 (Figure 4B) having a reflective surface with a non-axisymmetric free-form surface shape in front of the light source 15, the light reflected from the back surface by the light recycling mirror 21 can also be efficiently guided to the slit 17.

[0050] As shown in Figure 4A, for example, a Xe lamp (light source 15) has a predetermined gap between the anode 23 and cathode 24, creating a space. Therefore, a concave light recycling mirror 21 is placed behind the Xe lamp (light source 15). By folding back and reflecting the light emitted backward from the light source 15 in the same direction as the incident direction, the light is collected again by the light source 15, passes through the gap between the electrodes of the anode 23 and cathode 24, and is incident on the non-axisymmetric free-form surface mirror 22 placed in front, greatly improving efficiency.

[0051] The concave light recycling mirror 21 is a spherical mirror in which the position of the center of curvature of the reflective surface approximately coincides with the position between the electrodes of the light source 15, so that light reflected by the concave light recycling mirror 21 is collected at the position of the gap between the electrodes and emitted in the direction of the non-axisymmetric free-form surface mirror 22. The re-collected light from the rear light recycling mirror 21 is also collected onto the slit 17 plane by the non-axisymmetric free-form surface mirror 22, following the same path as the light emitted forward from the light source 15.

[0052] The rear light recycling mirror 21, which can generate retroreflected light without having to consider the optimum magnification, can be placed closer to the light source 15 and can be a smaller mirror, unlike the conventional collecting mirror 16 shown in Figures 3A and 3B. For the same reason, a smaller mirror than the non-axisymmetric free-form surface mirror 22 can be used.

[0053] 4A, by arranging the non-axisymmetric free-form surface mirror 22 and the light recycling mirror 21 on either side of the light source 15, it is possible to significantly improve the light utilization efficiency while miniaturizing the optical system. Furthermore, the light recycling mirror 21 on the back surface may be an aspherical mirror, taking into account the influence of subtle aberrations that occur in the sealing tube that encloses the optical system.

[0054] Typical examples of the light source 15, such as a Xe lamp, a deuterium lamp, a halogen lamp, and an LED, have a light-emitting area of ​​a predetermined size. Furthermore, the light-emitting intensity within the light-emitting area may not be constant. For example, as shown in FIG. 5 , a Xe lamp (light source 15) generates light by arc discharge between the anode 23 and the cathode 24, and therefore emits light in an area approximately the size of the space between the electrodes. Additionally, the light-emitting intensity is strong around the cathode 24.

[0055] Therefore, the light utilization efficiency can be further improved by arranging the non-axisymmetric free-form surface mirror 22 and the light recycling mirror 21 with their optical axes shifted from approximately the center of the light-emitting region of the Xe lamp (light source 15) to an area with stronger light emission intensity. For example, in the example of the Xe lamp (light source 15) in Figure 5, the non-axisymmetric free-form surface mirror 22 and the light recycling mirror 21 can be configured to be positioned closer to the cathode 24.

[0056] Next, the optimal positional relationship between light source 15, condenser mirror 16 having a reflective surface with a non-axisymmetric free-form shape, light recycling mirror 21, and slit 17 will be described with reference to FIGS. 6A to 6C.

[0057] 6A to 6C are diagrams showing the state of light rays when light from a light source 15 is incident at different angles on a collecting mirror 16 having a reflective surface in the shape of a non-axisymmetric free-form surface.

[0058] FIG. 6A shows a case where the reflection tilt angle θ, which is the angle between the optical axis a between the light source 15 and the collecting mirror 16 and the optical axis b between the collecting mirror 16 and the slit 17, is large, and FIGS. 6B and 6C show cases where the reflection tilt angle θ becomes smaller in this order.

[0059] As mentioned above, since the light source 15 has a predetermined size of light-emitting area, off-axis aberration performance is important in forming a spot on the slit 17 surface by the condenser mirror 16, which has a reflective surface with a non-axisymmetric free-form shape.

[0060] The smaller the off-axis aberration, the better the spot image can be formed on the slit 17 surface over the entire light-emitting area of ​​the light source 15, and the higher the light utilization efficiency. However, the collector mirror 16, which has a reflective surface with a non-axisymmetric free-form shape, has large off-axis aberration due to its poor symmetry, and when the reflection tilt angle θ is large, the effect of this cannot be ignored.

[0061] For example, as shown in Figure 6A, if the reflection tilt angle θ is large, the off-axis aberration performance deteriorates, the light source image formed on the slit 17 surface becomes blurred, and since the spot size is larger than the specified slit opening size, some of the light is blocked, resulting in a light defect area 20 in the excitation-side diffraction element 18 and a decrease in light utilization efficiency.

[0062] 6B, by reducing the reflection tilt angle θ, the off-axis aberration performance is improved, light can be transmitted through the slit opening, and the light defect area 20 can be reduced. In particular, by setting the reflection tilt angle to 40° or less, a spot of a sufficient size relative to the slit opening size can be obtained.

[0063] 6C , if the reflection tilt angle θ is set to a small angle such as less than 30°, the light reflected by the collecting mirror 16 is blocked by the Xe lamp (light source 15), resulting in a light defect region 20. Therefore, the light utilization efficiency decreases for reasons other than aberration.

[0064] Thus, there is an optimum reflection tilt angle θ, and it is desirable to set it between 30° and 40° in terms of maximizing light utilization efficiency. Furthermore, a light spot of sufficient size can be obtained relative to the opening size of the slit 17 surface, which has the effect of providing a robust configuration against misalignment of optical system components.

[0065] The NA of the collector mirror 16 and the light recycling mirror 21 having a reflective surface with a non-axisymmetric free-form shape as described above is just an example, and there is no problem in increasing the NA beyond that shown in the figure. By increasing the NA, a configuration is achieved in which a wider range of radiation is collected, improving the light utilization efficiency.

[0066] FIG. 7 is a diagram showing an example of the optical system configuration of a spectrofluorometer incorporating the collection optical system of the present invention.

[0067] In the configuration example shown in Figure 7, light collected by a light source 15, a light recycling mirror 21 on the back surface, and a collecting mirror 16 having a reflective surface with a non-axisymmetric free-form shape passes through the opening of a slit (first slit) 17 and illuminates an excitation-side diffraction element 18.

[0068] As shown in the figure, the excitation-side diffraction element 18 can be made compact by using a concave diffraction grating. In addition, by using a concave diffraction grating with irregularly spaced rulings and an optimized blaze angle depending on the location in order to correct aberrations, the light utilization efficiency and wavelength resolution can be improved.

[0069] Of the light λ1 to λ3 dispersed by excitation-side diffraction element 18, monochromatic light λ1 of a predetermined wavelength passes through slit (second slit) 25 and is extracted, and the extracted monochromatic light λ1 illuminates a sample cell or flow cell 26. Fluorescence emitted from the sample irradiated with monochromatic light λ1 passes through fluorescence-side slit (third slit) 27 and illuminates fluorescence-side diffraction element 28.

[0070] As shown in the figure, fluorescent-side diffraction element 28 can be made compact by using a concave diffraction grating. Furthermore, by using a concave diffraction grating with irregularly spaced rulings and an optimized blaze angle depending on the location in order to correct aberrations, light utilization efficiency and wavelength resolution can be improved.

[0071] Of the light separated by the fluorescent-side diffraction element 28 , monochromatic light of a predetermined wavelength is extracted by passing through a slit (fourth slit) 29 and is incident on a detector 30 .

[0072] FIG. 8 is a diagram showing a modification of FIG.

[0073] As in the modified example of the spectrofluorophotometer shown in FIG. 8, it is perfectly acceptable to include lenses or the like in the optical system to achieve miniaturization and high efficiency by increasing the NA.

[0074] 8 , light collected by light source 15, rear-side light recycling mirror 21, and collecting mirror 16 having a reflective surface with a non-axisymmetric free-form shape passes through lens 31 and the opening of slit (first slit) 17, and illuminates excitation-side diffraction element 18. Of the light dispersed by excitation-side diffraction element 18, monochromatic light of a predetermined wavelength may be extracted by passing through slit 32 and focused by lens 33, and the monochromatic light may be used to illuminate sample cell or flow cell 26.

[0075] The fluorescence emitted from the sample is passed through the fluorescence-side slit (third slit) 27 and slit 35 while the effective NA of the detection optical system is increased by lens 34 , and illuminates the fluorescence-side diffraction element 28 .

[0076] As shown in the figure, fluorescent-side diffraction element 28 can be made compact by using a concave diffraction grating. Furthermore, by using a concave diffraction grating with irregularly spaced rulings and an optimized blaze angle depending on the location in order to correct aberrations, light utilization efficiency and wavelength resolution can be improved.

[0077] Of the light dispersed by the fluorescent-side diffraction element 28, monochromatic light of a predetermined wavelength is extracted by passing it through a slit (fourth slit) 29, and the light is again collected by a lens 36 and enters the detector 30 via a slit 37.

[0078] FIG. 9 is a diagram showing another modified example of FIG.

[0079] 9, the modified spectrofluorometer or spectrophotometer has a simplified and compact detection-side spectroscope that detects the detected light from the sample. Light collected by a light source 15, a light recycling mirror 21 on the back surface, and a collecting mirror 16 having a reflective surface with a non-axisymmetric free-form shape passes through the opening of a slit (first slit) 17 and illuminates an excitation-side diffraction element 18.

[0080] Of the light dispersed by the excitation-side diffraction element 18, monochromatic light of a predetermined wavelength passes through the slit 32, the lens 33, and the slit (second slit) 25 and is extracted, and the extracted monochromatic light illuminates the sample in the sample chamber, sample cell, or flow cell 26.

[0081] The detection light emitted from the sample is incident on an integrating sphere 38 and homogenized, and then incident on a detector 30, which converts the light into an electrical signal and measures the light intensity.

[0082] From the viewpoint of imaging performance, the light-emitting region of the Xe lamp (light source 15) is elongated in the direction of the inter-electrode gap L, as shown in Fig. 5. Therefore, on the slit plane of the slit (first slit) 17, the direction corresponding to L is significantly affected by off-axis aberrations, and the spot tends to spread.

[0083] FIG. 10A is a plan view showing the opening shape of the slit 17. FIG.

[0084] The opening 39 of the slit surface of the slit (first slit) 17 is preferably arranged so that the long Ls direction (longitudinal direction) of the size is approximately aligned with the direction corresponding to the L0 of the inter-electrode gap, thereby improving the light utilization efficiency and the wavelength resolution of the spectroscopic analyzer 1.

[0085] Furthermore, from the viewpoint of improving the wavelength resolution, it is desirable that the Ls direction of the opening 39 approximately coincides with the spectral direction of the excitation-side diffraction element 18. If the excitation-side diffraction element 18 is a diffraction grating, the Ls direction of the slit 17 approximately coincides with the groove direction of the diffraction grating.

[0086] FIG. 10B is a diagram showing the schematic structure of a flow cell 40 for flowing a sample when performing spectrofluorometric measurement in liquid chromatography.

[0087] In liquid chromatography using a spectrofluorometer, in order to obtain good measurement results, the size (Wf) of the flow channel 41 of the flow cell 40 is determined to a predetermined size by taking into consideration a balance of multiple conditions, such as obtaining an appropriate component separation effect for the sample and obtaining sufficient fluorescence intensity from the sample, and the predetermined width (Wf) is generally about several millimeters to several tens of millimeters. Accordingly, the opening widths (Ws) of the exit slit and entrance slit are also about several millimeters.

[0088] FIG. 10C is a diagram showing a schematic structure of a sample cell 42 of a typical fluorometer.

[0089] The size of the flow path 41 of the transparent, rectangular sample cell 42 generally has a width (Wc) of several millimeters to several tens of millimeters. A sample such as a liquid is injected into the flow path 41 of the sample cell 42 to measure fluorescence and the like. As described with reference to FIGS. 5 and 10A , the longitudinal direction Lc of the sample cell 42 of the fluorometer may be approximately parallel to the direction corresponding to the inter-electrode gap Lo of the light source 15 and the Ls of the opening 39 of the slit 17.

[0090] On the other hand, there are cases where the advantage of a fluorometer is that it can perform measurements with a small amount of sample, and in this case, it may be possible to configure the direction perpendicular to Lc and the direction corresponding to Ls of the opening 39 of the slit 17 to be approximately parallel.

[0091] In a spectrofluorometer used in liquid chromatography, excitation light is applied to a flow path 41 of a flow cell 40 through which a sample flows, and the fluorescence is measured. The flow cell 40 has a configuration as shown in FIG. 10B , in which the flow path direction Lf is longer than the width Wf of the flow path 41. As with the opening 39 of the slit 17, from the perspective of improving light utilization efficiency and wavelength resolution, it is desirable that the flow path direction Lf of the flow cell 40 approximately coincide with the direction corresponding to the inter-electrode gap Lo of the Xe lamp (light source 15). For the same reason, it is desirable that the flow path direction Lf of the flow cell 40 be approximately parallel to an axis perpendicular to the rotation axis that forms the approximately ellipsoidal shape of the collector mirror 16, which has a reflective surface with a non-axisymmetric free-form shape.

[0092] The configuration of the collection optical system using the collector mirror 16 having a reflective surface with a non-axisymmetric free-form shape focuses the arc discharge between the electrodes of the Xe lamp (light source 15) at a predetermined magnification onto the opening 39 of the slit 17 via the collector mirror 16, so it is desirable to set the predetermined magnification so as not to exceed the opening width.

[0093] On the other hand, reducing the magnification increases the numerical aperture (NA) on the image side, and at the same time, a large-diameter diffraction element is required for excitation-side diffraction element 18 after passing through slit 17, resulting in a significant increase in the manufacturing cost of the device. Therefore, from the standpoints of cost and light utilization efficiency, it is desirable to use an ellipsoid that forms an image at a magnification that allows the light to pass through a predetermined aperture as the base shape of collector mirror 16 having a reflective surface with a non-axisymmetric free-form shape and non-axisymmetric free-form mirror 22.

[0094] By setting the two focal positions of the ellipsoid that forms the base of the non-axisymmetric free-form surface mirror to predetermined positions while taking into consideration the above-mentioned optimal reflection tilt angle θ, it is possible to create a spectrofluorometer that maximizes light utilization efficiency while suppressing costs.

[0095] For example, the ellipsoid that serves as the base of a non-axisymmetric free-form surface mirror may be a prolate ellipsoid that is shaped to rotate around the major axis of the ellipse, and it is desirable to use a shape obtained by cutting out a portion of the ellipsoid. Furthermore, the surface of the area that intersects with the major axis or minor axis of the ellipse is unnecessary because the reflected light returns to the light source, so the mirror may be a shape obtained by cutting out the surface of the area that does not intersect with the major axis or minor axis of the ellipse.

[0096] Furthermore, the distance between the two foci of the ellipsoid that forms the base of the non-axisymmetric free-form surface mirror is preferably in the range of 110 mm to 145 mm. Therefore, the distance between the light source 15 and the slit 17, which are respectively placed at positions corresponding to the foci of the ellipsoid, is also preferably 110 mm to 145 mm (dimension D in FIG. 6B ).

[0097] Furthermore, when using a light source having a light-emitting area of ​​a predetermined size and taking into account the effects of aberration due to misalignment of optical system components, and attempting to create a free-form surface mirror shape that is robust to component misalignment, the free-form surface mirror may be based on a shape obtained by cutting out a portion of a prolate ellipsoid non-axisymmetrically, but may be configured so that the sag amount is greater than that of the ellipsoid as it approaches the outer periphery of the mirror.

[0098] In addition, a non-axisymmetric free-form surface mirror may be configured by providing a metal film such as aluminum, silver, or gold as a reflective film on a base material, or a dielectric multilayer film. The metal reflective film generally has a silicon oxide film (SiO ２ However, protective films have the problem that the reflectivity is highly dependent on the angle of incidence of light, and the reflection angle of a non-axisymmetric free-form mirror changes significantly depending on the position within the reflection area, resulting in a deterioration in performance.

[0099] Therefore, the metal film used as the reflective film may be configured as a bare exposed metal film without a protective film, or in the case of a dielectric multilayer film, the configuration of the reflective film may be switched depending on the region within the reflective surface.

[0100] Regarding the direction of the grating grooves of the slit (third slit) 27, slit (fourth slit) 29, and fluorescence-side diffraction element 28 used in the detection-side optical system as exemplified in Figures 7 and 8, by making the longitudinal direction of the opening approximately parallel to the longitudinal direction of the light-emitting region of the light source 15 and the direction corresponding to the longitudinal direction Ls of the opening 39 of the slit (first slit) 17, which is the excitation-side slit, it is possible to improve the light utilization efficiency and wavelength resolution.

[0101] As described above, according to this embodiment, in a spectrophotometer, fluorometer, or other spectrophotometer that is required to meet new needs such as improved throughput in online measurements, it is possible to provide a miniaturized spectrophotometer while significantly improving the light utilization efficiency (S / N).

[0102] Although the present invention has been described above with reference to an embodiment, it is not limited to the above embodiment and includes various modifications. For example, the functional configuration of the spectroscopic analysis device and its collection optical system unit described above has been categorized according to the main processing content for ease of understanding. The present invention is not limited by the classification method or names of the components. The configuration of the spectroscopic analysis device and collection optical system unit can also be categorized into more components depending on the processing content. For example, it is perfectly acceptable to add or remove lenses in addition to mirrors. Furthermore, a single component can be categorized to perform even more processing.

[0103] Although the conditions for parallel axial directions have been described in some examples, there are cases where the optical axis rotates due to a reflecting mirror or prism in the optical path. In this case, it is sufficient that the directions of the corresponding axes are approximately parallel after correcting for the rotation of the optical axis and taking it into consideration.

[0104] Furthermore, it goes without saying that the present invention can be applied not only to spectroscopic analyzers but also to other optical devices having the configuration of the collecting optical system 10 described above.

[0105] Furthermore, the above-described configurations, functions, processing units, processing means, etc. may be partially or entirely implemented in hardware, for example, by designing them as integrated circuits. The above-described configurations, functions, etc. may also be implemented in software, with a processor interpreting and executing a program that implements each function. Information such as the programs, tables, and files that implement each function can be stored in a memory, a recording device such as a hard disk or SSD (Solid State Drive), or a recording medium such as an IC card, SD card, or DVD.

[0106] DESCRIPTION OF SYMBOLS 1...spectroscopic analysis device, 2...sample chamber section, 3...spectroscopic measurement section, 4...power supply section, 5...storage section, 6...control section, 7...communication section, 8...input / output section (connector), 9...light source section, 10...collecting optical system section, 11...excitation side spectroscope section, 12...sample section, 13...detection section, 14...detection side spectroscope section, 15...light source, 16...collecting mirror, 17...slit (first slit), 18...excitation side diffraction element, 19...irradiation area, 20...light defect area, 21...light recycling mirror 1. Mirror, 22...non-axisymmetric free-form surface mirror, 23...anode, 24...cathode, 25...slit (second slit), 26...sample cell or flow cell, 27...slit (third slit), 28...fluorescence side diffraction element, 29...slit (fourth slit), 30...detector, 31, 33, 34, 36...lenses, 32, 35, 37...slit, 38...integrating sphere, 39...aperture, 40...flow cell, 41...flow path, 42...sample cell.

Claims

1. A spectroscopic analysis device comprising: a light source that emits light; a collection optical system that collects light from said light source; a first slit that extracts light of a predetermined region from the light collected by said collection optical system; an excitation-side diffraction element that disperses the light from said collection optical system; a second slit that extracts monochromatic light of a predetermined wavelength from the light dispersed by said excitation-side diffraction element; and a detector that detects light from a sample irradiated with said monochromatic light, wherein said collection optical system is disposed between said light source and said excitation-side diffraction element and includes a mirror with a reflective surface having a non-axisymmetric free-form curved shape.

2. A spectroscopic analyzer according to claim 1, wherein the non-axisymmetric free-form surface shape corresponds to a shape obtained by cutting a portion of a prolate spheroid non-axisymmetrically.

3. A spectroscopic analysis device according to claim 1, wherein the non-axisymmetric free-form surface shape is a portion of a prolate spheroid, and corresponds to a shape obtained by cutting out a portion of the surface of a region that does not intersect with the major axis and minor axis of the prolate spheroid in a non-axisymmetric manner.

4. A spectroscopic analysis device according to claim 1, wherein the mirror has a shape equivalent to a portion of a prolate spheroid cut away non-axisymmetrically, and the sag amount is greater at the outer periphery than at the prolate spheroid.

5. A spectroscopic analyzer according to claim 1, characterized in that the angle formed between the optical axis between the light source and the mirror and the optical axis between the mirror and the opening of the first slit is between 30° and 40°.

6. A spectroscopic analysis device according to claim 1, wherein the collection optical system further comprises a concave mirror having a diameter smaller than that of the mirror, the mirror and the concave mirror are arranged to sandwich the light source, and the center of curvature of the concave mirror is arranged to approximately coincide with the position of the light source.

7. A spectroscopic analysis device according to claim 6, characterized in that the optical axis length between the first slit and the mirror is longer than the optical axis length between the light source and the mirror, and the optical axis length between the light source and the mirror is longer than the optical axis length between the light source and the concave mirror.

8. A spectroscopic analysis device according to claim 6, wherein the light source is a lamp that emits light by arc discharge between electrodes, the reflective surface of the concave mirror is spherical, and the concave mirror is positioned so that the center of curvature of the reflective spherical surface of the concave mirror approximately coincides with the gap between the electrodes of the light source.

9. A spectroscopic analysis device according to claim 2, characterized in that an axis perpendicular to the rotation axis of the ellipsoid, the long side direction of the opening of the first slit, and the longitudinal direction of the light emission distribution of the light source are all approximately parallel to each other.

10. A spectroscopic analyzer according to claim 6, characterized in that the center of the mirror and the center of the concave mirror are located at positions closer to the end face than the center of the longitudinal direction of the light-emitting region of the light source.

11. The spectroscopic analysis device according to claim 1, further comprising a spectroscope for separating light from the sample irradiated with the monochromatic light.

12. A spectroscopic analyzer according to claim 2, which is a fluorescence analyzer used in liquid chromatography, characterized in that an axis perpendicular to the rotation axis of the ellipsoid is approximately parallel to the flow direction of a flow cell through which a sample flows within the fluorescence analyzer.

13. A spectroscopic analyzer according to claim 3, wherein the light source and the first slit are disposed at a distance of 110 mm or more and 145 mm or less.

14. A spectroscopic analysis device according to claim 1, wherein the mirror is formed by coating a base material with a thin reflective film, and the reflective film is a film in which a pure metal film without a protective film is exposed or a dielectric multilayer film formed by dividing the area of ​​the reflective surface.

15. A method for adjusting the position of a light source in a spectroscopic analysis device as described in claim 6, characterized in that the mirror and the concave mirror are positioned by shifting the optical axis from approximately the center of the light-emitting area of ​​the light source to an area with stronger light emission intensity.

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