JP2011164014A

JP2011164014A - Polychromator

Info

Publication number: JP2011164014A
Application number: JP2010028769A
Authority: JP
Inventors: Makoto Sato; 佐藤　　誠
Original assignee: Shimadzu Corp
Current assignee: Shimadzu Corp
Priority date: 2010-02-12
Filing date: 2010-02-12
Publication date: 2011-08-25

Abstract

<P>PROBLEM TO BE SOLVED: To supply a polychromator having a high wavelength resolution over the entire wavelength region. <P>SOLUTION: The polychromator includes an inlet slit 1 for introducing measuring light, a recessed surface diffraction lattice 2 that disperses the introduced light for each wavelength and forms an image of light of each wavelength, and an array detector 3 for simultaneously measuring intensity of the light of each wavelength. The array detector 3 includes a photoelectric conversion element string 3a and a light-transmitting plate 3b. The light-transmitting plate 3b is made of BK7 glass whose thickness varies in the direction of wavelength dispersion. For example, the image forming positions of lights with the lengths of 440 nm, 550 nm, and 650 nm are adjusted with the thickness of the light-transmitting plate 3b. All the positions exist on a light-receiving surface of the photoelectric conversion element string 3a, and the wavelength resolution is high iver the entire wavelength region. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

本発明は、ポリクロメータ形分光器に関し、特には波長分解能を向上するための構成に関する。 The present invention relates to a polychromator-type spectrometer, and more particularly to a configuration for improving wavelength resolution.

ポリクロメータは、測定光を波長毎に回折格子（グレーティング）で分散し、この分散された各波長の光の像をアレイ検出器の検出面上に結像し、各波長の光の強度を同時に測定するように構成されている。ポリクロメータを構成する回折格子（波長分散手段）には、凹面回折格子と平面回折格子がある。凹面回折格子は、平面回折格子と異なり、凹面鏡などの結像素子を用いずに分光光学系を構成できる。 The polychromator disperses measurement light with a diffraction grating (grating) for each wavelength, forms an image of the dispersed light of each wavelength on the detection surface of the array detector, and simultaneously adjusts the intensity of light of each wavelength. It is configured to measure. The diffraction grating (wavelength dispersion means) constituting the polychromator includes a concave diffraction grating and a planar diffraction grating. Unlike a plane diffraction grating, a concave diffraction grating can constitute a spectroscopic optical system without using an imaging element such as a concave mirror.

測定光を波長毎に凹面回折格子で分散する形式のポリクロメータは、図２に示すとおり、測定光を導入する入口スリット１と、該導入された光を各波長毎に分散するとともに各波長の光の像を結像する凹面回折格子２と、該各波長の光を電気信号に変換し各波長の光の強度を同時に測定するアレイ検出器２３で構成されている。 As shown in FIG. 2, the polychromator of the type in which the measurement light is dispersed by the concave diffraction grating for each wavelength, the entrance slit 1 for introducing the measurement light, the introduced light is dispersed for each wavelength and each wavelength is dispersed. A concave diffraction grating 2 that forms an image of light and an array detector 23 that converts the light of each wavelength into an electrical signal and simultaneously measures the intensity of the light of each wavelength.

アレイ検出器２３は、平面状に光電変換素子を波長分散方向に配列した光電変換素子列２３ａと、光電変換素子列２３ａへの光の入射側に配設され透明で厚さが一定な平板状の透光板２３ｂと、光電変換素子列２３ａと透光板２３ｂとを支持するケースで構成されている。 The array detector 23 includes a photoelectric conversion element array 23a in which photoelectric conversion elements are arranged in a plane in a wavelength dispersion direction, and a flat plate shape that is disposed on the light incident side of the photoelectric conversion element array 23a and has a constant thickness. The translucent plate 23b, the photoelectric conversion element array 23a, and the translucent plate 23b are configured to support the case.

ポリクロメータの波長校正法として次の方法が提案されている。モノクロメータから出射する単色光を校正しようとするポリクロメータに入射させ、モノクロメータの波長走査を行って、ポリクロメータの検出面を構成する光電変換素子の各単位素子毎にその単位素子の出力が最大となるモノクロメータの波長値を検出し、その単位素子の波長とする（特許文献１参照）。 The following methods have been proposed as wavelength calibration methods for polychromators. The monochromatic light emitted from the monochromator is incident on the polychromator to be calibrated, the wavelength of the monochromator is scanned, and the output of the unit element is output for each unit element of the photoelectric conversion element constituting the detection surface of the polychromator. The maximum wavelength value of the monochromator is detected and set as the wavelength of the unit element (see Patent Document 1).

特開平５−７９９４６号公報JP-A-5-79946

ポリクロメータにおいては、図２に示すとおり、各波長の光の結像位置は、収差補正形回折格子を用いたとしても、必ずピントずれｄが生起する。例えば、凹面回折格子２の溝本数を１２８６本／ｍｍ、凹面回折格子２の曲率半径を１００ｍｍ、入射距離を７０．７ｍｍ、入射角度を４５°とし、５５０ｎｍの光軸と光電変換素子列２３ａの受光面を直交させ、透光板２３ｂが厚さ２ｍｍのＢＫ７ガラスで構成されている場合、５５０ｎｍの光は受光面で結像するが、４４０ｎｍの光は受光面の２．０ｍｍ手前、６５０ｎｍの光は受光面の１．７ｍｍ手前で結像し、ピントずれｄが生起する。 In the polychromator, as shown in FIG. 2, a focus shift d always occurs at the imaging position of light of each wavelength even if an aberration correction type diffraction grating is used. For example, assuming that the number of grooves of the concave diffraction grating 2 is 1286 / mm, the radius of curvature of the concave diffraction grating 2 is 100 mm, the incident distance is 70.7 mm, the incident angle is 45 °, the optical axis of 550 nm and the photoelectric conversion element array 23a When the light receiving surfaces are orthogonal to each other and the translucent plate 23b is made of BK7 glass having a thickness of 2 mm, 550 nm light forms an image on the light receiving surface, but 440 nm light is 2.0 mm before the light receiving surface and 650 nm. Light forms an image 1.7 mm before the light receiving surface, and a focus shift d occurs.

本発明は、測定光を導入する入口スリットと、前記導入された測定光を波長毎に分散させる波長分散手段と、前記波長分散手段により分散された光を検出面に入射させて、各波長毎の光の強度を同時に測定する平面状のアレイ検出器を備えたポリクロメータにおいて、前記波長分散手段により分散された光のそれぞれが、前記アレイ検出器の検出面上で結像するように前記アレイ検出器への光入射側に厚さを変化させた透光板を配設するものである。したがって透光板の厚い部分を透過した波長の光の結像位置は、屈折の影響で、薄い部分を透過した波長の光の結像位置より、波長分散手段から遠ざかる。 The present invention includes an entrance slit for introducing measurement light, wavelength dispersion means for dispersing the introduced measurement light for each wavelength, and making the light dispersed by the wavelength dispersion means incident on a detection surface, for each wavelength. In a polychromator having a planar array detector for simultaneously measuring the light intensity of the light, the array dispersed so that each of the light dispersed by the wavelength dispersion means forms an image on the detection surface of the array detector. A light-transmitting plate with a varying thickness is disposed on the light incident side to the detector. Therefore, the imaging position of the light having the wavelength transmitted through the thick part of the light transmitting plate is farther from the wavelength dispersion means than the imaging position of the light having the wavelength transmitted through the thin part due to the influence of refraction.

透光板の厚さを変化させることで、各波長の光の結像位置を光電変換素子列の受光面上とすることが可能であり、全波長域で波長分解能が良好なポリクロメータを供給可能である。 By changing the thickness of the translucent plate, it is possible to set the imaging position of light of each wavelength on the light receiving surface of the photoelectric conversion element array, and supply a polychromator with good wavelength resolution in all wavelength regions Is possible.

本発明の実施例によるポリクロメータの概略構成を示す図である。It is a figure which shows schematic structure of the polychromator by the Example of this invention. 従来のポリクロメータの概略構成を示す図である。It is a figure which shows schematic structure of the conventional polychromator.

本発明の実施例によるポリクロメータは、測定光を導入する入口スリットと、導入された測定光を各波長毎に分散するとともに各波長毎に結像する凹面回折格子と、各波長毎に結像した光を電気信号に変換するアレイ検出器とで構成され、該アレイ検出器への光入射側に配設された透光板の厚さは波長分散方向で変化している。 A polychromator according to an embodiment of the present invention includes an entrance slit for introducing measurement light, a concave diffraction grating that disperses the introduced measurement light for each wavelength and forms an image for each wavelength, and forms an image for each wavelength. The thickness of the light transmitting plate arranged on the light incident side to the array detector changes in the wavelength dispersion direction.

本発明の実施例について図１を参照して説明する。図１は、本発明の実施例によるポリクロメータの概略構成を示す図である。本発明の実施例によるポリクロメータは、図１に示すとおり、測定光を導入する入口スリット１と、該導入された光を各波長毎に分散するとともに各波長の光の像を結像する凹面回折格子２と、該各波長の光を電気信号に変換し各波長の光の強度を同時に測定するアレイ検出器３で構成されている。本実施例の凹面回折格子２は、本件発明の波長分散手段に相当する。 An embodiment of the present invention will be described with reference to FIG. FIG. 1 is a diagram showing a schematic configuration of a polychromator according to an embodiment of the present invention. As shown in FIG. 1, a polychromator according to an embodiment of the present invention includes an entrance slit 1 for introducing measurement light, and a concave surface that disperses the introduced light for each wavelength and forms an image of light of each wavelength. It comprises a diffraction grating 2 and an array detector 3 that converts the light of each wavelength into an electrical signal and simultaneously measures the intensity of the light of each wavelength. The concave diffraction grating 2 of the present embodiment corresponds to the wavelength dispersion means of the present invention.

アレイ検出器３は、平面状に光電変換素子を波長分散方向に配列した光電変換素子列３ａと、透光板３ｂと、光電変換素子列３ａと透光板３ｂとを支持するケースで構成されている。透光板３ｂは、厚さが波長分散方向で変化する例えばＢＫ７ガラスで構成される。 The array detector 3 includes a photoelectric conversion element array 3a in which photoelectric conversion elements are arranged in a wavelength dispersion direction, a translucent plate 3b, and a case that supports the photoelectric conversion element array 3a and the translucent plate 3b. ing. The translucent plate 3b is made of, for example, BK7 glass whose thickness changes in the wavelength dispersion direction.

本発明は以上の構成であるから、凹面回折格子２を出射し結像する各波長毎の光は透光板３ｂを透過する際、屈折し結像位置が凹面回折格子２から遠ざかることはよく知られており、該遠ざかる長さは、透光板３ｂの厚さと屈折率に応じて長くなる。 Since the present invention has the above-described configuration, the light for each wavelength that is emitted from the concave diffraction grating 2 and forms an image is refracted when passing through the light transmitting plate 3b, so that the image formation position is far from the concave diffraction grating 2. It is known that the length of the distance increases depending on the thickness and refractive index of the light transmitting plate 3b.

例えば、凹面回折格子２の溝本数を１２８６本／ｍｍ、凹面回折格子２の曲率半径を１００ｍｍ、入射距離を７０．７ｍｍ、入射角度を４５°とし、５５０ｎｍの光軸と光電変換素子列３ａの受光面を直交させ、５５０ｎｍ近傍の透光板３ｂの厚さを２ｍｍとし、５５０ｎｍの光が受光面に結像している場合、４４０ｎｍ近傍の透光板３ｂの厚さを７．９ｍｍ、６５０ｎｍ近傍の透光板３ｂの厚さを６．９ｍｍとすることにより、４４０ｎｍと６５０ｎｍの光はともに受光面で結像する。 For example, assuming that the number of grooves of the concave diffraction grating 2 is 1286 / mm, the radius of curvature of the concave diffraction grating 2 is 100 mm, the incident distance is 70.7 mm, the incident angle is 45 °, the optical axis of 550 nm and the photoelectric conversion element array 3a When the light receiving surfaces are orthogonal, the thickness of the light transmitting plate 3b near 550 nm is 2 mm, and light of 550 nm is imaged on the light receiving surface, the thickness of the light transmitting plate 3b near 440 nm is 7.9 mm and 650 nm. By setting the thickness of the nearby translucent plate 3b to 6.9 mm, both light of 440 nm and 650 nm is imaged on the light receiving surface.

したがって、図２で示す従来のポリクロメータではピントずれｄが生起するが、図１で示すとおり厚さが部分的に厚くなった透光板３ｂによりピントずれｄは改善される。ピントずれｄの解消により全波長域で波長分解能が良好なポリクロメータを供給可能である。 Therefore, although the focus shift d occurs in the conventional polychromator shown in FIG. 2, the focus shift d is improved by the translucent plate 3b whose thickness is partially increased as shown in FIG. By eliminating the focus shift d, it is possible to supply a polychromator with good wavelength resolution in the entire wavelength region.

図に示す実施例においては、透光板３ｂはＢＫ７ガラスで構成されているが、代わりに色ガラスフィルタや、蒸着膜の付いたガラスあるいはプラスチック等でもよい。また、透光板３ｂは３波長に対応して両端が厚い３段階構造となっているが、結像の状態によって、３波長より多くの波長に対応して厚さが多段階構造になることもある。また、実施例では、透光板３ｂはアレイ検出器３の窓板の機能を備えているが、平板ガラスで構成される窓板を備えたアレイ検出器の光入射側に厚さを変えたガラス板を配設する構成でもよい。 In the embodiment shown in the figure, the translucent plate 3b is made of BK7 glass, but it may instead be a colored glass filter, glass with a deposited film, plastic, or the like. In addition, the translucent plate 3b has a three-stage structure that is thick at both ends corresponding to three wavelengths. However, depending on the state of image formation, the translucent plate 3b has a multi-stage structure corresponding to a wavelength greater than three wavelengths. There is also. In the embodiment, the translucent plate 3b has the function of the window plate of the array detector 3, but the thickness is changed to the light incident side of the array detector having the window plate made of flat glass. The structure which arrange | positions a glass plate may be sufficient.

なお、実施例においては、凹面回折格子２だけで波長の分散と結像を行い、凹面鏡などの結像素子を用いない形式のポリクロメータの説明をしたが、凹面鏡と凹面回折格子を組み合わせたモンクギリーソン形ポリクロメータ、あるいは凹面鏡と平面回折格子を組み合わせたツェルニターナ形ポリクロメータにおいても本発明は適用可能である。またプリズムその他入射した光を複数の光に分散させる機能を有する光学素子であれば本発明は適用可能である。上述のとおり本発明は図示例に限定されるものではなく種々の変形例を包含する。 In the embodiment, the description has been given of the polychromator that performs wavelength dispersion and image formation using only the concave diffraction grating 2 and does not use an imaging element such as a concave mirror. However, a monk that combines a concave mirror and a concave diffraction grating is described. The present invention can also be applied to a Gilleyson type polychromator or a Zellnitana type polychromator that combines a concave mirror and a planar diffraction grating. Further, the present invention is applicable to any optical element having a function of dispersing incident light into a plurality of lights such as a prism. As described above, the present invention is not limited to the illustrated examples and includes various modifications.

本発明は、ポリクロメータ形分光器に関し、特には波長分解能を向上するための構成に利用の可能性がある。 The present invention relates to a polychromator-type spectrometer, and in particular, may be used for a configuration for improving wavelength resolution.

１入口スリット
２凹面回折格子
３アレイ検出器
３ａ光電変換素子列
３ｂ透光板
２３アレイ検出器
２３ａ光電変換素子列
２３ｂ透光板
ｄピントずれ 1 Entrance slit 2 Concave diffraction grating 3 Array detector 3a Photoelectric conversion element array 3b Translucent plate 23 Array detector 23a Photoelectric conversion element array 23b Translucent plate d Focus shift

Claims

測定光を導入する入口スリットと、前記導入された測定光を波長毎に分散させる波長分散手段と、前記波長分散手段により分散された光を検出面に入射させて、各波長毎の光の強度を同時に測定する平面状のアレイ検出器を備えたポリクロメータにおいて、前記波長分散手段により分散された光のそれぞれが、前記アレイ検出器の検出面上で結像するように前記アレイ検出器への光入射側に厚さを変化させた透光板を配設したことを特徴とするポリクロメータ。 An entrance slit for introducing measurement light, wavelength dispersion means for dispersing the introduced measurement light for each wavelength, and light dispersed by the wavelength dispersion means is incident on the detection surface, and the light intensity for each wavelength. In a polychromator having a planar array detector for simultaneously measuring the wavelength, the light dispersed by the wavelength dispersion means forms an image on the detection surface of the array detector. A polychromator characterized in that a translucent plate having a changed thickness is disposed on the light incident side.