WO2018070469A1

WO2018070469A1 - Spectroscope, and microscope provided with same

Info

Publication number: WO2018070469A1
Application number: PCT/JP2017/036966
Authority: WO
Inventors: 世智佐藤
Original assignee: 株式会社堀場製作所
Priority date: 2016-10-14
Filing date: 2017-10-12
Publication date: 2018-04-19
Also published as: JPWO2018070469A1; JP6847973B2

Abstract

The objective of the present invention is to provide a spectroscope with which it is possible to improve spectral resolution over a wide wavelength range while suppressing a deterioration in light reception efficiency and suppressing the generation of stray light. To this end, this spectroscope is provided with: a refracting lens 3 equipped with a first surface 31 upon which light emitted from a light source is incident, and a second surface 32 in the shape of a convex curved surface from which the light that has entered from the first surface 31 is emitted; a reflection-type diffraction grating 4 in the shape of a concave curved surface which reflects and diffracts incident light that is the light emitted from the second surface 32 of the refracting lens 3; a detector 6 provided in a position in which light that has been reflected by the reflection-type diffraction grating 4, has entered from the second surface 32 of the refracting lens 3 and has been emitted from the first surface 31 forms an image; and a compensating element 5 provided between the first surface 31 of the refracting lens 3 and the detector 6.

Description

Spectroscope and microscope equipped with the same

The present invention relates to a spectroscope used for spectroscopic analysis, for example.

For example, a Dyson type spectrometer is known as one of the spectrometers with excellent imaging performance. This Dyson type spectroscope includes an entrance slit, a refractive lens having a convex curved surface, a reflective diffraction grating having a concave curved surface, and a detector. The convex curved surface of the refractive lens and the concave curved surface of the reflective diffraction grating are concentric. Are arranged in a shape.

The Dyson spectroscope 100A described in Patent Document 1 compensates for the influence of the aberration of the refractive lens 3A and improves the spectral resolution, as shown in FIG. A compensating lens 5A is provided between the concave curved surface 4A.

US Pat. No. 6,181,418

However, when the compensation lens 5A is provided as in Patent Document 1, the following problems occur.

First, since the compensation lens 5A is provided between the refractive lens 3A and the reflective diffraction grating 4A, when light enters the reflective diffraction grating 4A from the refractive lens 4A, it is reflected by the reflective diffraction grating 4A. When returning to the refractive lens 3A, the compensation lens 5A is passed twice. For this reason, when the compensation lens 5A is designed so that the position and angle of the light that passes through the refractive lens 3A and enters the reflective diffraction grating 4A is optimized, the light reflected by the reflective diffraction grating 4A is compensated for. The light is refracted by 5A and cannot enter the refraction lens 3A at an optimum position. This is a cause of hindering further improvement in spectral resolution.

Further, since the light path is an optical path that passes through the compensation lens 5A twice, the number of times of passage through the interface serving as a reflection surface is increased four times as compared with the conventional Dyson spectroscope. The amount of light that can be reached decreases and efficiency decreases, or stray light increases.

The present invention has been made in view of the above-described problems, and a spectroscope capable of improving spectral resolution in a wide wavelength range while suppressing a decrease in light receiving efficiency and generation of stray light, and the use thereof. An object of the present invention is to provide a conventional microscope.

That is, the spectroscope according to the present invention includes a refractive lens including a first surface on which light emitted from a light source is incident, and a convexly curved second surface on which light incident from the first surface is emitted. A reflection-type diffraction grating having a concave curved surface that reflects and diffracts incident light that is emitted from the second surface of the refractive lens, and is reflected by the reflection-type diffraction grating and is reflected by the first of the refractive lens. Provided between a detector provided at a position where light incident from two surfaces and emitted from the first surface forms an image, the first surface of the refractive lens, and the detector, and the refraction And a compensation element for compensating for the aberration of the lens.

In such a case, since the compensation element is provided between the first surface of the refractive lens and the detector, light can pass through the compensation element only once. Therefore, it is possible to form an image of light on the detector after compensating and optimizing the influence of coma aberration, chromatic aberration and the like in the refractive lens.

In addition, since there is no optical element that is affected by the change of the optical path by providing this compensation element, optimization design is easier than in the prior art.

Furthermore, since the light passes only once through the compensation element, the number of interfaces through which the light passes can be minimized, and a decrease in efficiency and an increase in stray light can be suppressed.

In order to compensate for the influence of the aberration of the refractive lens in a wide wavelength range and improve the spectral resolution, the compensation element is a combination of a plurality of lenses formed of a light-transmitting material having different refractive indexes. Any configuration may be used. If this is the case, it is easy to design optimal compensation for each wavelength.

Specific examples of the above-described combination lens include one in which each surface of the combination lens constituting the compensation element is a spherical surface.

In order to improve the manufacturability while realizing the desired performance while enabling the compensation element to be manufactured at low cost, either the light incident surface or the light exit surface of the combination lens constituting the compensation element is flat. If it is.

In order to further increase the ability to compensate for the influence of the aberration of the refractive lens, it is sufficient that the compensation element is composed of an aspheric lens.

In order to improve the imaging performance, the convex curved surface of the second surface of the refractive lens and the concave curved surface of the reflective diffraction grating may be arranged concentrically.

The detector and the entrance slit can be separated from each other, and in order to make it easy to attach even a large device, a reflection element provided between the light source and the first surface of the refractive lens is provided. The light source is provided so that the optical axis direction of the light source intersects the optical axis direction of the refractive lens, and the light that has passed through the entrance slit is reflected by the reflective element and What is necessary is just to be comprised so that it may inject into 1 surface.

In order to prevent the generation of interference fringes when light enters the first surface of the refractive lens from the reflective element, and to prevent a part of the wavelength component of the light from being transmitted, the reflective element is a reflective prism. Yes, it suffices if the light exit surface of the reflecting prism and the first surface of the refractive lens are separated from each other.

In order to prevent stray light from being generated by the light emitted from the light source being reflected by the second surface of the refractive lens or the reflective diffraction grating and returning to the light source again, the light sources are arranged concentrically. The center of the convex surface of the second surface and the concave surface of the reflective diffraction grating may be arranged so as to be shifted from the point to be surfaced with respect to the reflective surface of the reflective element.

A microscope equipped with a separation instrument according to the present invention can realize high-resolution spectroscopic analysis in a wide wavelength range.

The spectroscope according to the present invention compensates for the influence of the aberration of the refractive lens to improve the spectral resolution, while reducing the number of times the light passes through the compensation element only once, thereby reducing the light receiving efficiency and increasing the stray light. Can be suppressed.

The schematic diagram which shows the structure of the spectrometer which concerns on one Embodiment of this invention. The simulation result which shows the difference in the spectral resolution of the spectrometer in the same embodiment and the conventional spectrometer. The schematic diagram which shows the compensation element in the 1st modification of this invention. The schematic diagram which shows the compensation element in the 2nd modification of this invention. The schematic diagram which shows the compensation element in the 3rd modification of this invention. The schematic diagram which shows the reflective element and refractive lens in the 4th modification of this invention. The schematic diagram which shows the spectrometer in the 5th modification of this invention. The schematic diagram which shows the course of the reflected light from the 2nd surface in a 5th modification. The schematic diagram which shows the structure of the conventional spectrometer.

DESCRIPTION OF SYMBOLS 100 ... Spectroscope 1 ... Incident slit 2 ... Reflective element 3 ... Refractive lens 31 ... 1st surface 32 ... 2nd surface 4 ... Reflective diffraction grating 5 ... Compensation element 6 ... Detector

A spectroscope 100 according to an embodiment of the present invention will be described with reference to FIG. The spectroscope 100 is used for a spectroscopic microscope, for example, and is a so-called Dyson spectroscope further provided with a compensation element 5.

More specifically, the spectroscope 100 is provided with an incident slit 1, a reflecting element 2, a refractive lens 3, a reflecting diffraction grating 4, a compensating element 5, and a detector 6 which are light sources in the order of the optical path. Each part will be described in detail below.

The entrance slit 1 has a predetermined rectangular slit width. In the present embodiment, the entrance slit 1 has a rectangular slit of 10 μm × 100 μm. Reflected light or transmitted light from a measurement object measured with a microscope is incident on the entrance slit 1, and the beam cross section is emitted in a substantially rectangular shape. As shown in FIG. 1, the opening direction of the entrance slit 1 is provided to be perpendicular to the optical axis direction of the refractive lens 3.

The reflection element 2 is a reflection prism made of glass, for example, and reflects the light that has passed through the entrance slit 1 to enter the refractive lens 3. The reflecting surface of the reflecting element 2 is inclined at an angle of about 45 degrees with respect to the opening direction of the entrance slit 1. That is, the center of the convex curved surface of the refractive lens 3 is arranged at a position where the reflecting surface of the reflecting element 2 and the surface object are in relation to the point where the incident slit 1 is provided.

The refractive lens 3 is a lens having a substantially plano-convex shape, and a first surface 31 that is a plane on which light passing through the entrance slit 1 is incident, and light incident from the first surface 31 passes through the inside. And a convex curved second surface 32 that is ejected to the outside. As shown in FIG. 1, in this embodiment, light that has passed through the incident slit 1 is reflected by the reflecting element 2 so that its traveling direction is bent by 90 degrees and then enters the first surface 31. It is configured. The position of the incident point of the light incident on the first surface 31 is outside the center line of the first surface 31.

The reflection type diffraction grating 4 has a concave curved surface formed with a grating at an interval of 100 to 1000 lines / mm. The concave curved surface and the second surface 32 of the refractive lens 3 are concentric, and the light is dispersed in the light width direction. Most of the light diffracted and reflected by the reflective diffraction grating 4 is a part different from the part where the light is emitted on the second surface 32, and is incident on the upper half part on the paper surface. is there.

The compensation element 5 is opposite to a portion where the light reflected by the reflective diffraction grating 4 enters the second surface 32 of the refractive lens 3, passes through the inside, and exits from the first surface 31. The other is opposed to the detector 6. The compensation element 5 is a combination lens made up of two lenses having different refractive indexes from the refractive lens 3, and the three boundary surfaces formed by the two lenses each form a spherical surface. The compensation element 5 compensates for an error caused by the aberration of the refractive lens 3 and is configured to act more strongly on the light on the long wavelength side than on the light on the short wavelength side.

The detector 6 is provided at a position where each of the dispersed light beams that have passed through the compensation element 5 forms an image, and the light receiving surface thereof is provided so as to be substantially parallel to the first surface 31 of the refractive lens 3. .

With respect to the simulation result regarding the slit image of each wavelength detected by the detector 6 by the spectroscope 100 configured in this way, the slit image of each wavelength detected by the conventional spectroscope 100 configured as shown in FIG. This will be described in comparison with a simulation result relating to the detection result.

Figure 2 shows the simulation results.

According to the spectroscope 100 of this embodiment, the slit shape is detected on the longer wavelength side as compared with the conventional spectroscope 100, and the minimum unit that can be distinguished from adjacent wavelengths is more You can see that it is small.

Thus, in the spectroscope 100 of the present embodiment, the compensation element 5 is provided between the first surface 31 of the refractive lens 3 and the detector 6 and passes only once. Even if the optimum design is performed in order to compensate for the influence of the third aberration, the action can hardly cause another influence on other optical systems. For this reason, compared with the conventional spectroscope 100, a more accurate spectral resolution can be obtained.

In addition, since light passes through the compensation element 5 only once, the increase in the number of boundary surfaces and reflection surfaces on the optical path can be minimized with respect to a typical Dyson spectrometer 100. For this reason, it is possible to suppress a decrease in light receiving efficiency due to a decrease in the amount of light and generation of stray light, and it is possible to increase spectral resolution and imaging ability.

Furthermore, since the incident slit 1 does not have to be opposed to the first surface 31 of the refractive lens 3 by the reflecting element 2, the incident slit 1 and the detector 6 can be provided apart from each other. Therefore, the detector 6 having a high resolution and a large size can be easily used, and the handling of the entrance slit 1 and the detector 6 can be improved.

Other embodiments will be described.

The compensation element is not limited to a combination lens, and for example, a single lens may be used for compensation. Conversely, a compensation element may be constituted by a combination lens composed of three or more lenses so that the aberration of the refractive lens can be compensated with higher accuracy.

Further, it is not necessary to make all surfaces of the combination lens constituting the compensation element curved, and the light incident surface facing the first surface 31 of the refractive lens 3 in the combination lens constituting the compensation element 5 as shown in FIG. May be formed as a plane. Alternatively, as shown in FIG. 4, in the combination lens constituting the compensation element 5, the light exit surface facing the detector 6 may be formed as a plane. If these are used, the compensation element 5 can be easily processed and the manufacturing cost can be easily reduced while the aberration of the refractive lens 3 can be compensated. In addition, in order to compensate the aberration of the refractive lens 3 with higher accuracy, the compensation element 5 may be formed of an aspheric lens as shown in FIG.

Further, as the compensation element 5, a DO lens or a DO element using a diffraction phenomenon may be used. Further, an aberration correction plate may be used as the correction element 5, or a distributed refractive index lens (GRIN lens) may be used.

As shown in FIG. 6, a gap may be formed between the first surface 31 of the refractive lens 3 and the light exit surface of the reflecting element 2 constituted by the reflecting prism so as to be separated by a predetermined distance. Note that the gap between the reflecting element 2 and the refractive lens 3 can be increased by making the gap larger than the wavelength of the light passing therethrough or by making the gap larger than the coherence length when the light source is a broadband light source such as a halogen lamp or SLD. Interference fringes can be suppressed when light passes between them. Further, by leaving the gap without being filled with an adhesive or the like, it is possible to prevent a part of the light passing therethrough from being attenuated by being absorbed or irregularly reflected by the adhesive. Therefore, a wide range of wavelengths can be guided to the detector 6.

Further, as shown in FIG. 7, the position of the entrance slit 1 that is a light source with respect to the reflection element 2 may be shifted from the first embodiment to the first surface 31 side of the refractive lens 3. That is, when the convex curved surface of the second surface 32 of the refractive lens 3 and the concave curved surface of the reflective diffraction grating 4 are arranged so as to be concentric, the position of the entrance slit 1 is relative to the reflective surface of the reflective element 2. However, they may not be aligned with the center of the concentric circles and may be arranged in a shifted state. For example, when the light source is arranged at a position corresponding to the center of the concentric circle as in the above embodiment, the light reflected by the second surface 32 of the refractive lens 3 or the reflective diffraction grating 4 is as shown in FIG. May return to the light source and become stray light. On the other hand, by arranging the light source as shown in FIG. 8, the reflected light generated by the second surface 32 or the reflective diffraction grating 4 can be prevented from returning to the light source and stray light can be prevented from being generated. .

The reflection element may be omitted, and the opening direction of the entrance slit may be arranged to face the first surface of the refractive lens as in the conventional case. The light source is not limited to the line light formed by the entrance slit, and for example, a light source in which optical fibers are arranged in one or a plurality of rows may be used as the light source for emitting the line light.

The spectroscope according to the present invention is not used only for a microscope, but may be used for a camera or other purposes.

Besides, various modifications and combinations of the embodiments may be made without departing from the spirit of the present invention.

According to the present invention, a spectroscope capable of improving the spectral resolution by compensating for the influence of the aberration of the refractive lens and suppressing the decrease in the light receiving efficiency and the increase in stray light by reducing the number of times the light passes through the compensation element. Can provide.

Claims

A refraction lens comprising a first surface on which light emitted from a light source is incident, and a convexly curved second surface on which light incident from the first surface is emitted;
A concave curved reflective grating that reflects and diffracts incident light emitted from the second surface of the refractive lens;
A detector provided at a position where light reflected by the reflective diffraction grating and incident from the second surface of the refractive lens and emitted from the first surface forms an image;
A spectroscope comprising: a compensation element that is provided between the first surface of the refractive lens and the detector and compensates for an aberration of the refractive lens.
The spectroscope according to claim 1, wherein the compensation element is configured by combining a plurality of lenses formed of translucent materials having different refractive indexes.
The spectroscope according to claim 2, wherein each surface through which light passes in the plurality of lenses constituting the compensation element is a spherical surface.
3. The spectroscope according to claim 2, wherein either one of the light incident surface and the light exit surface of at least one lens constituting the compensation element is a flat surface.
The spectroscope according to claim 1, wherein the compensation element comprises an aspheric lens.
The spectroscope according to claim 1, wherein the convex curved surface of the second surface of the refractive lens and the concave curved surface of the reflective diffraction grating are arranged concentrically.
The light source and a reflective element provided between the first surface of the refractive lens,
The optical axis direction of the light source is provided so as to intersect the optical axis direction of the refractive lens, and light that has passed through the incident slit is reflected by the reflective element and is reflected on the first surface of the refractive lens. The spectrometer according to claim 1, wherein the spectrometer is configured to be incident.
The spectroscope according to claim 7, wherein the reflecting element is a reflecting prism, and a light exit surface of the reflecting prism and the first surface of the refractive lens are separated from each other.
The light source is arranged so that the center of the convex curved surface of the second surface and the concave curved surface of the reflective diffraction grating arranged concentrically is shifted from the point to be a surface object with respect to the reflective surface of the reflective element. The spectroscope according to claim 6.
A microscope comprising the spectroscope according to claim 1.