JP5811956B2 - Spectrometer calibration apparatus and calibration method - Google Patents

Spectrometer calibration apparatus and calibration method Download PDF

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JP5811956B2
JP5811956B2 JP2012128654A JP2012128654A JP5811956B2 JP 5811956 B2 JP5811956 B2 JP 5811956B2 JP 2012128654 A JP2012128654 A JP 2012128654A JP 2012128654 A JP2012128654 A JP 2012128654A JP 5811956 B2 JP5811956 B2 JP 5811956B2
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敦子 田村
敦子 田村
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本発明は、分光器から取り出される光の波長を校正するための校正装置及び校正方法に関する。   The present invention relates to a calibration apparatus and calibration method for calibrating the wavelength of light extracted from a spectrometer.

紫外可視光分光光度計や原子吸光分光光度計等の分光光度計では、所定波長の光を被測定物に照射したときの透過光量を検出し、その波長における吸光度を求めて被測定物の定性・定量分析を行う。分光光度計では、所定波長の単色光を得るために分光器（モノクロメータ）が用いられる。分光器は一般的に、入口スリット、回折格子（波長分散素子）及び出口スリットと、入口スリットからの入射光に対する該回折格子の角度を変えるための回転駆動機構とを備えており、入口スリットから入射した光を回折格子に照射し、回折格子で波長分散させた光のうち、特定の波長の光（単色光）のみを出口スリットから取り出す。そして、該回転駆動機構により回折格子の回転位置を調整することにより、任意の波長の光（単色光）を取り出すことができる。また、回折格子を連続的に回転させることにより入射光のスペクトルを得ることができる。   A spectrophotometer such as an ultraviolet-visible light spectrophotometer or an atomic absorption spectrophotometer detects the amount of light transmitted when the object to be measured is irradiated with light of a predetermined wavelength, determines the absorbance at that wavelength, and qualifies the object to be measured.・ Perform quantitative analysis. In a spectrophotometer, a spectroscope (monochromator) is used to obtain monochromatic light having a predetermined wavelength. A spectroscope generally includes an entrance slit, a diffraction grating (wavelength dispersion element), an exit slit, and a rotational drive mechanism for changing the angle of the diffraction grating with respect to incident light from the entrance slit. The incident light is irradiated onto the diffraction grating, and only light having a specific wavelength (monochromatic light) is extracted from the exit slit out of the light wavelength-dispersed by the diffraction grating. Then, by adjusting the rotational position of the diffraction grating by the rotation driving mechanism, light of any wavelength (monochromatic light) can be extracted. Further, the spectrum of incident light can be obtained by continuously rotating the diffraction grating.

このように、分光器により取り出される光の波長は、入口スリットと出口スリットの間に配置された回折格子の回転角度位置により決まる。分光器により取り出される単色光の波長が目的波長と異なると、該分光器が組み込まれる分光光度計において、被測定物に含まれる物質の種類や量を正確に測定することができない。このため、通常、製品を工場から出荷する前に、分光器から取り出される単色光の波長を目的波長に合わせるための波長校正が行われる。   Thus, the wavelength of the light extracted by the spectroscope is determined by the rotational angle position of the diffraction grating disposed between the entrance slit and the exit slit. When the wavelength of the monochromatic light extracted by the spectroscope is different from the target wavelength, the type and amount of the substance contained in the object to be measured cannot be accurately measured in the spectrophotometer in which the spectroscope is incorporated. For this reason, normally, before the product is shipped from the factory, wavelength calibration for adjusting the wavelength of the monochromatic light extracted from the spectroscope to the target wavelength is performed.

分光器の波長校正方法の一つに水銀ランプや重水素ランプのような既知の波長の輝線を含む光を用いた方法がある。この方法では、例えば、校正しようとする波長範囲内に輝線を含む光（校正光）を入口スリットから分光器に導入する。そして、出口スリットから出射する光の強度を測定しつつ回折格子を回転させることにより、校正光のスペクトルを得、このスペクトルの中の前記既知の輝線の波長とそのときの回折格子の角度に対応する波長を求めることにより分光器を校正する。しかしながら、この方法で、水銀ランプや重水素ランプのような特殊な光源を用いなければならず、また、光源の出力調整が面倒であるという欠点がある。   One of the wavelength calibration methods of a spectroscope is a method using light including an emission line with a known wavelength, such as a mercury lamp or a deuterium lamp. In this method, for example, light (calibration light) including a bright line within the wavelength range to be calibrated is introduced into the spectroscope from the entrance slit. Then, the spectrum of the calibration light is obtained by rotating the diffraction grating while measuring the intensity of the light emitted from the exit slit, and corresponds to the wavelength of the known emission line in the spectrum and the angle of the diffraction grating at that time. The spectrometer is calibrated by determining the wavelength to perform. However, this method has a disadvantage that a special light source such as a mercury lamp or a deuterium lamp has to be used, and the output adjustment of the light source is troublesome.

これに対して、特定の吸収波長帯を有する光学フィルタの透過光を用いて分光器の波長校正を行う方法がある。この方法では、光源から分光器までの光路上に光学フィルタを配置して該光学フィルタの透過光強度を各波長で測定し、透過率が最小となる波長を前記光学フィルタの材料の物性値である既知の最大吸収波長と比較することにより分光器を校正する。光学フィルタを用いた波長校正方法では広く一般的に用いられている光源を用いることができる。
On the other hand, there is a method of performing wavelength calibration of a spectrometer using light transmitted through an optical filter having a specific absorption wavelength band. In this method, an optical filter is arranged on the optical path from the light source to the spectroscope, the transmitted light intensity of the optical filter is measured at each wavelength, and the wavelength at which the transmittance is minimized is the physical property value of the material of the optical filter. Calibrate the spectrometer by comparing it to some known maximum absorption wavelength. In a wavelength calibration method using an optical filter, a widely used light source can be used.

Standard Reference Material 2009 "Dynamic Glass Filter for Checking the Wavelength Scale of Spectrophotometers", National Bureau of Standards, pp. 104-111Standard Reference Material 2009 "Dynamic Glass Filter for Checking the Wavelength Scale of Spectrophotometers", National Bureau of Standards, pp. 104-111 HOYA CANDEO OPTRONICS株式会社ホームページ、[平成24年2月20日検索],インターネット＜URL:http://www.hoyacandeo.co.jp/japanese/products/eo_color_10.html＞HOYA CANDEO OPTRONICS Co., Ltd. homepage, [Search February 20, 2012], Internet <URL: http://www.hoyacandeo.co.jp/english/products/eo_color_10.html>

ところが、光学フィルタを用いて分光器の校正を行った場合、該分光器から取り出される光の波長と目的波長との間に大きな誤差が生じることがあり、特に、分光器の波長分解能が低い場合に誤差が大きくなる傾向があった。   However, when the spectrometer is calibrated using an optical filter, a large error may occur between the wavelength of the light extracted from the spectrometer and the target wavelength, especially when the wavelength resolution of the spectrometer is low. There was a tendency for errors to increase.

本発明が解決しようとする課題は、分光器の波長分解能に関係なく正確度の高い波長校正を行うための校正装置及び校正方法を提供することである。   The problem to be solved by the present invention is to provide a calibration apparatus and calibration method for performing wavelength calibration with high accuracy regardless of the wavelength resolution of the spectrometer.

上記課題を解決するために成された本発明は、波長分散素子と、該波長分散素子の位置を変える駆動装置とを備える分光器の波長校正を行うための校正装置であって、
a) 光源から放射される光の波長範囲に含まれる吸収波長帯を有する光学フィルタとを備え、前記光源からの光を前記光学フィルタを通して前記分光器に入射させる光学系と、
b) 前記分光器の波長分散素子の位置を変えつつ、該分光器から出射される光の強度を求め、前記吸収波長帯において強度が最小となる波長であるディップ波長を求めるディップ波長検出手段と、
c) 分光器の波長分解能を変化させた場合の、該波長分解能と、該波長分解能における前記ディップ波長と前記光学フィルタの前記吸収波長帯における既知の最大吸収波長との差分値との関係を表す関係式を記憶する記憶手段と、
d) 校正対象分光器の波長分解能に対応する前記差分値を前記関係式から求め、当該差分値と、前記光源からの光を前記光学フィルタを通して前記校正対象分光器に入射させて得られたディップ波長と前記既知の最大吸収波長との差分値とが、許容範囲内で一致するように前記分光器を校正する校正手段と
を備えることを特徴とする。
The present invention made to solve the above problems is a calibration apparatus for performing wavelength calibration of a spectroscope comprising a wavelength dispersion element and a drive device that changes the position of the wavelength dispersion element,
an optical filter having an absorption wavelength band included in a wavelength range of light emitted from a light source, and an optical system that causes the light from the light source to enter the spectroscope through the optical filter;
b) Dip wavelength detecting means for obtaining the dip wavelength which is the wavelength with the minimum intensity in the absorption wavelength band while obtaining the intensity of the light emitted from the spectrometer while changing the position of the wavelength dispersion element of the spectrometer. ,
c) Represents the relationship between the wavelength resolution when the wavelength resolution of the spectrometer is changed and the difference value between the dip wavelength at the wavelength resolution and the known maximum absorption wavelength in the absorption wavelength band of the optical filter. Storage means for storing the relational expression;
d) The difference value corresponding to the wavelength resolution of the calibration target spectrometer is obtained from the relational expression, and the difference value and the dip obtained by causing the light from the light source to enter the calibration target spectrometer through the optical filter. And calibrating means for calibrating the spectrometer so that a difference value between a wavelength and the known maximum absorption wavelength matches within an allowable range .

また、上記課題を解決するために成された本発明は、波長分散素子と、該波長分散素子の位置を変える駆動装置とを備える分光器の波長校正を行うための校正方法であって、
a) 光源からの光を、該光源から放射される光の波長範囲に含まれる吸収波長帯を有する光学フィルタを通して前記分光器に入射させ、
b) 前記分光器の波長分散素子の位置を変えつつ、該分光器から出射される光の強度を求め、前記吸収波長帯において強度が最小となる波長であるディップ波長を求め、
c) 分光器の波長分解能を変化させた場合の、該波長分解能と、該波長分解能における前記ディップ波長と前記光学フィルタの前記吸収波長帯における既知の最大吸収波長との差分値との関係を表す関係式を記憶し、
d) 校正対象分光器の波長分解能に対応する前記差分値を前記関係式から求め、当該差分値と、前記光源からの光を前記光学フィルタを通して前記校正対象分光器に入射させて得られたディップ波長と前記既知の最大吸収波長との差分値とが、許容範囲内で一致するように前記分光器を校正する
ことを特徴とする。
Further, the present invention made to solve the above problems is a calibration method for performing wavelength calibration of a spectroscope comprising a wavelength dispersion element and a drive device that changes the position of the wavelength dispersion element,
a) the light from the light source is incident on the spectrometer through an optical filter having an absorption wavelength band included in the wavelength range of the light emitted from the light source;
b) While changing the position of the wavelength dispersive element of the spectrometer, obtain the intensity of the light emitted from the spectrometer, find the dip wavelength that is the minimum intensity in the absorption wavelength band,
c) Represents the relationship between the wavelength resolution when the wavelength resolution of the spectrometer is changed and the difference value between the dip wavelength at the wavelength resolution and the known maximum absorption wavelength in the absorption wavelength band of the optical filter. Memorize the relational expression,
d) The difference value corresponding to the wavelength resolution of the calibration target spectrometer is obtained from the relational expression, and the difference value and the dip obtained by causing the light from the light source to enter the calibration target spectrometer through the optical filter. The spectroscope is calibrated so that a difference value between a wavelength and the known maximum absorption wavelength is within an allowable range .

なお、波長分散素子の「位置」には、波長分散素子の回転角が対応する。また、光源からの光を光学フィルタを通して分光器に入射させた時に得られる透過スペクトルに含まれる１ないし複数の吸収波長帯のそれぞれにおいて、透過率が最小となる波長を、該吸収波長帯のディップ波長と呼ぶ。   The “position” of the wavelength dispersion element corresponds to the rotation angle of the wavelength dispersion element. In addition, in each of one or a plurality of absorption wavelength bands included in the transmission spectrum obtained when the light from the light source is incident on the spectroscope through the optical filter, the wavelength with the minimum transmittance is dip of the absorption wavelength band. Called wavelength.

図１は、585.34nmという既知の最大吸収波長を有する材料を用いた光学フィルタに光源からの光を入射させた時に得られる透過スペクトルを示しており、実線は分光器の波長分解能を1.5nmとした場合の透過スペクトルであり、破線は分光器の波長分解能を10.5nmとした場合の透過スペクトルである（非特許文献１）。図１に示すように、この光学フィルタの透過スペクトルは複数の吸収波長帯を含み、各吸収波長帯において透過率が最小となる波長がディップ波長であり、特に、符合Ａ１を付した吸収波長帯のディップ波長が、該光学フィルタの既知の最大吸収波長に相当する。
本来は、各吸収波長帯のディップ波長は不変であるが、実際は分光器の波長分解能によってディップ波長が変化する場合がある。 FIG. 1 shows a transmission spectrum obtained when light from a light source is incident on an optical filter using a material having a known maximum absorption wavelength of 585.34 nm, and the solid line indicates the wavelength resolution of the spectrometer as 1.5 nm. The broken line is the transmission spectrum when the wavelength resolution of the spectrometer is 10.5 nm (Non-patent Document 1). As shown in FIG. 1, the transmission spectrum of this optical filter includes a plurality of absorption wavelength bands, and the wavelength at which the transmittance is minimum in each absorption wavelength band is the dip wavelength, and in particular, the absorption wavelength band denoted by reference numeral A1. Of the optical filter corresponds to the known maximum absorption wavelength of the optical filter.
Originally, the dip wavelength of each absorption wavelength band is not changed, but actually the dip wavelength may change depending on the wavelength resolution of the spectrometer.

例えば、波長分解能が1.5nmのときの透過スペクトルでは、吸収波長帯Ａ１には２個のディップが含まれており、そのうちの一方のディップ波長が光学フィルタの既知の最大吸収波長に相当する。これに対して、波長分解能が10.5nmのときの透過スペクトルでは、吸収波長帯Ａ１には１個のディップしか含まれていない。これは、波長分解能が低いと急峻なディップを検出できないため、波長分解能が10.5nmのときは、波長分解能が1.5nmのときに検出された２個のディップが見かけ上、１個のディップとして検出されるからである。この結果、波長分解能が1.5nmのときと波長分解能が10.5nmのときでディップ波長が異なるという現象が生じる場合がある。このような現象は、吸収波長帯に複数のディップが含まれる場合や吸収波長帯の形状が最大吸収波長を中心として長波長側と短波長側で非対称である場合、等に見られる。   For example, in the transmission spectrum when the wavelength resolution is 1.5 nm, the absorption wavelength band A1 includes two dips, and one of the dips corresponds to the known maximum absorption wavelength of the optical filter. On the other hand, in the transmission spectrum when the wavelength resolution is 10.5 nm, the absorption wavelength band A1 includes only one dip. This is because if the wavelength resolution is low, a steep dip cannot be detected. Therefore, when the wavelength resolution is 10.5 nm, two dip detected when the wavelength resolution is 1.5 nm are apparently detected as one dip. Because it is done. As a result, there may be a phenomenon in which the dip wavelength differs between the wavelength resolution of 1.5 nm and the wavelength resolution of 10.5 nm. Such a phenomenon is seen when the absorption wavelength band includes a plurality of dips, or when the shape of the absorption wavelength band is asymmetric between the long wavelength side and the short wavelength side with the maximum absorption wavelength as the center.

ところが、上述したように、従来は分光器の波長分解能によるディップ波長の変化を考慮せず、光学フィルタの材料固有の物性値である最大吸収波長を用いて分光器の波長校正を行っていた。このため、分光器の波長校正を行った場合でも該分光器から取り出される光の波長と目的波長の間に誤差が生じる場合があった。本発明は、このような知見に基づきなし得たものである。   However, as described above, the wavelength calibration of the spectrometer is conventionally performed using the maximum absorption wavelength, which is a physical property value specific to the material of the optical filter, without considering the change in the dip wavelength due to the wavelength resolution of the spectrometer. For this reason, even when the wavelength of the spectrometer is calibrated, an error may occur between the wavelength of light extracted from the spectrometer and the target wavelength. The present invention has been achieved based on such knowledge.

例えば図２は、445.7nmという既知の最大吸収波長を有する光学フィルタ（HOYA CANDEO OPTRONICS株式会社製、製品番号：ＨＹ−１）を通して光源からの光を分光器に入射させたときに得られる、理論上の透過スペクトルを示している。図２の透過スペクトルから分かるように、該光学フィルタの最大吸収波長帯（矢印Ａ２で示す。）は複数のディップを含み、且つ、最大吸収波長帯Ａ２のスペクトル形状は、最大吸収波長445.7nmを中心として長波長側及び短波長側で非対称となっている。
一方、図３は、上記光学フィルタの最大吸収波長付近の透過スペクトルを分光器の波長分解能別に示した図である。図２及び図３中、横軸は波長（nm）、縦軸は強度（透過率（％）を示しており、これら図２及び図３では、光の強度を、光源から出射された光の強度を100％としたときの相対値（透過率（％））で表している。 For example, FIG. 2 is a theoretical view obtained when light from a light source is incident on a spectroscope through an optical filter having a known maximum absorption wavelength of 445.7 nm (manufactured by HOYA CANDEO OPTRONICS, product number: HY-1). The upper transmission spectrum is shown. As can be seen from the transmission spectrum of FIG. 2, the maximum absorption wavelength band (indicated by arrow A2) of the optical filter includes a plurality of dips, and the spectrum shape of the maximum absorption wavelength band A2 has a maximum absorption wavelength of 445.7 nm. The center is asymmetric on the long wavelength side and the short wavelength side.
On the other hand, FIG. 3 is a diagram showing a transmission spectrum in the vicinity of the maximum absorption wavelength of the optical filter for each wavelength resolution of the spectrometer. 2 and 3, the horizontal axis indicates the wavelength (nm) and the vertical axis indicates the intensity (transmittance (%). In these FIGS. 2 and 3, the light intensity is represented by the light emitted from the light source. Expressed as a relative value (transmittance (%)) when the intensity is 100%.

図３に示すように、分光器の波長分解能が2nmから8nmと変化するにつれて、得られる透過スペクトルの最大吸収波長帯のディップ波長が、光学フィルタの最大吸収波長445.7nmよりも徐々に長くなる。従来は、このような波長分解能によるディップ波長の変化は考慮されておらず、波長分解能に関係なく一定の校正値を用いて分光器の波長校正を行っていた。これに対して本発明では、このような、ディップ波長と光学フィルタの既知の最大吸収波長との差分値と、分光器の波長分解能との関係を表す関係式を予め記憶し、この関係式から、校正対象の分光器の波長分解能に応じた差分値を用いて該分光器を校正するようにしたため、波長分解能に起因する波長誤差を小さくすることができる。   As shown in FIG. 3, as the wavelength resolution of the spectroscope changes from 2 nm to 8 nm, the dip wavelength in the maximum absorption wavelength band of the obtained transmission spectrum gradually becomes longer than the maximum absorption wavelength 445.7 nm of the optical filter. Conventionally, such a change in the dip wavelength due to the wavelength resolution is not taken into consideration, and the wavelength calibration of the spectrometer is performed using a constant calibration value regardless of the wavelength resolution. On the other hand, in the present invention, a relational expression representing the relationship between the difference value between the dip wavelength and the known maximum absorption wavelength of the optical filter and the wavelength resolution of the spectroscope is stored in advance. Since the spectroscope is calibrated using the difference value corresponding to the wavelength resolution of the spectroscope to be calibrated, the wavelength error caused by the wavelength resolution can be reduced.

このように、上記構成の本発明によれば、分光器の波長分解能に起因する波長誤差を考慮し、分光器の波長分解能に応じた校正用差分値を用いて該分光器を校正するため、いずれの波長分解能であっても正確度の高い波長校正を行うことができる。   Thus, according to the present invention having the above configuration, in order to calibrate the spectroscope using the calibration difference value according to the wavelength resolution of the spectroscope, considering the wavelength error due to the wavelength resolution of the spectroscope, Wavelength calibration with high accuracy can be performed at any wavelength resolution.

波長分解能の違いによる光学フィルタの透過スペクトルの変化を示す図。The figure which shows the change of the transmission spectrum of an optical filter by the difference in wavelength resolution. 445.7nmという既知の最大吸収波長を有する光学フィルタの透過スペクトル。Transmission spectrum of an optical filter with a known maximum absorption wavelength of 445.7 nm. 図２の透過スペクトルを有する光学フィルタの、各波長分解能における透過スペクトルの変化を示す図。The figure which shows the change of the transmission spectrum in each wavelength resolution of the optical filter which has the transmission spectrum of FIG. 本発明の一実施例に係る分光器の校正装置を示す図。The figure which shows the calibration apparatus of the spectrometer which concerns on one Example of this invention. 最大吸収波長が445.7nmである光学フィルタの、分光器の波長分解能別の透過率曲線。Transmittance curve according to wavelength resolution of spectroscope of optical filter whose maximum absorption wavelength is 445.7nm.

以下、図４及び図５を参照して本発明の一実施例について説明する。図４は本実施例に係る校正装置の概略構成図である。該校正装置は、白色光を出射する光源１０と、この光源１０の光路上に配置された光学フィルタ１２と、この光学フィルタ１２の後段に配置された、該光学フィルタ１２の透過光を２つに分岐するビームスプリッタ１４と、該ビームスプリッタ１４による分岐光の一方が入射する標準分光器１６とを有する。ビームスプリッタ１４による他方の分岐光は、校正対象の分光器１８（以下、「校正対象分光器１８」という）に入射される。   Hereinafter, an embodiment of the present invention will be described with reference to FIGS. FIG. 4 is a schematic configuration diagram of a calibration apparatus according to the present embodiment. The calibration device includes a light source 10 that emits white light, an optical filter 12 that is disposed on the optical path of the light source 10, and two transmitted light beams of the optical filter 12 that are disposed at the subsequent stage of the optical filter 12. And a standard spectrometer 16 into which one of the branched lights from the beam splitter 14 enters. The other branched light from the beam splitter 14 is incident on a spectrometer 18 to be calibrated (hereinafter referred to as “calibrator to be calibrated 18”).

標準分光器１６は、入口スリット１６１及び出口スリット１６２、これら両スリットの間に配置された回折格子１６３、回折格子１６３を回転することにより該回折格子１６３の位置を変える駆動装置１６４を有する。駆動装置１６４は、モータと該モータの回転を減速するための減速機構等を備えて構成されている。図示しないが、入口スリット１６１及び出口スリット１６２は開口幅が変更可能に構成されており、駆動装置１６４による回折格子１６３の最小駆動角度の大きさや入口スリット１６１及び出口スリット１６２の開口幅等を変化させることにより標準分光器１６の波長分解能（nm）が変更可能となっている。 Standard spectroscope 16 has a drive device 164 for changing the position of the diffraction grating 163 by an entrance slit 161 and the outlet slit 162, the both slits diffraction grating 163 disposed between the diffraction grating 163 is rotated. The driving device 164 includes a motor and a reduction mechanism for reducing the rotation of the motor. Although not shown, the opening width of the entrance slit 161 and the exit slit 162 can be changed, and the size of the minimum driving angle of the diffraction grating 163 by the driving device 164 and the opening width of the entrance slit 161 and the exit slit 162 are changed. By doing so, the wavelength resolution (nm) of the standard spectrometer 16 can be changed.

光学フィルタ１２には、例えばHOYA CANDEO OPTRONICS株式会社製の光学フィルタ（品番：ＨＹ−１）が用いられている。図２はこの光学フィルタの透過スペクトルであり、最大吸収波長は445.7nmである。図２の透過スペクトルに示すように、最大吸収波長445.7nmの吸収波長帯（以下、「最大吸収波長帯」という。）は、そのスペクトル形状が当該最大吸収波長よりも短波長側及び長波長側で非対称となっている。   As the optical filter 12, for example, an optical filter (product number: HY-1) manufactured by HOYA CANDEO OPTRONICS Co., Ltd. is used. FIG. 2 is a transmission spectrum of this optical filter, and the maximum absorption wavelength is 445.7 nm. As shown in the transmission spectrum of FIG. 2, the absorption wavelength band having a maximum absorption wavelength of 445.7 nm (hereinafter referred to as “maximum absorption wavelength band”) has a spectrum shape shorter and longer than the maximum absorption wavelength. It is asymmetric.

上記の校正装置においては、光源１０からの光のうち光学フィルタ１２を透過した光の一部はビームスプリッタ１４で透過されて標準分光器１６に入射し、残りは反射されて校正対象分光器１８に入射する。標準分光器１６に入射した光は回折格子１６３によって分散され、分散した光のうち所定波長の単色光が出口スリット１６２を通過して検出器２０に入射する。駆動装置１６４は標準分光器１６の回折格子１６３を所定のピッチで回転移動させ、このとき標準分光器１６から取り出された単色光は検出器２０に導入され、その光強度に応じた検出信号が出力される。   In the calibration apparatus described above, a part of the light transmitted from the light source 10 that has passed through the optical filter 12 is transmitted by the beam splitter 14 and is incident on the standard spectrometer 16, and the rest is reflected to be the calibration target spectrometer 18. Is incident on. The light incident on the standard spectroscope 16 is dispersed by the diffraction grating 163, and monochromatic light having a predetermined wavelength among the dispersed light passes through the exit slit 162 and enters the detector 20. The driving device 164 rotates and moves the diffraction grating 163 of the standard spectroscope 16 at a predetermined pitch. At this time, the monochromatic light extracted from the standard spectroscope 16 is introduced into the detector 20, and a detection signal corresponding to the light intensity is generated. Is output.

この検出信号は処理・制御部２２に入力され、ここで所定の演算処理が行われることによって透過率が計算され、波長と透過率との関係を表す透過スペクトルが作成される。さらに、処理・制御部２２は、光学フィルタ１２の透過スペクトルから、前記最大吸収波長帯に対応する吸収波長帯において、透過率が最小となる波長であるディップ波長を求め、このディップ波長と光学フィルタ１２の最大吸収波長との差分値を求める。この差分値は標準分光器１６の波長分解能別に求められ、差分値と波長分解能との関係を表す関係式が関係式記憶部２４に記憶される。関係式は、例えば予め作成しておいた近似モデル式に求めた差分値と波長分解能を代入して、その近似モデル式に含まれる定数を決定して関係式を完成させることができる。もちろんその他の方法を用いて関係式を完成させても良い。図５にディップ波長と光学フィルタ１２の最大吸収波長の差分値と、波長分解能との関係を表す図を示す。   This detection signal is input to the processing / control unit 22 where a predetermined calculation process is performed to calculate the transmittance and create a transmission spectrum representing the relationship between the wavelength and the transmittance. Further, the processing / control unit 22 obtains a dip wavelength, which is a wavelength that minimizes the transmittance, in the absorption wavelength band corresponding to the maximum absorption wavelength band from the transmission spectrum of the optical filter 12, and the dip wavelength and the optical filter. A difference value from the maximum absorption wavelength of 12 is obtained. The difference value is obtained for each wavelength resolution of the standard spectrometer 16, and a relational expression representing the relationship between the difference value and the wavelength resolution is stored in the relational expression storage unit 24. The relational expression can be completed by substituting the obtained difference value and wavelength resolution into an approximate model expression prepared in advance, for example, and determining a constant included in the approximate model expression. Of course, the relational expression may be completed using other methods. FIG. 5 shows a relationship between the difference between the dip wavelength and the maximum absorption wavelength of the optical filter 12 and the wavelength resolution.

なお、処理・制御部２２は上記のような信号の演算処理機能の他に分光器制御部２６を含む。分光器制御部２６は、モータ駆動部２８を介して駆動装置１６４を駆動する。   The processing / control unit 22 includes a spectroscope control unit 26 in addition to the above-described signal processing function. The spectroscope control unit 26 drives the driving device 164 via the motor driving unit 28.

一方、校正対象分光器１８に入射した光は、標準分光器１６と同様に回折格子によって分散され、分散した光のうち所定波長の単色光が出口スリットを通過して検出器３０に導入されて光強度に応じた検出信号が出力される。この検出信号は処理・制御部２２に入力され、所定の演算処理が行われることによって透過率が計算されて波長と透過率の関係を表す透過スペクトルが作成される。   On the other hand, the light incident on the calibration target spectroscope 18 is dispersed by the diffraction grating in the same manner as the standard spectroscope 16, and monochromatic light having a predetermined wavelength out of the dispersed light passes through the exit slit and is introduced into the detector 30. A detection signal corresponding to the light intensity is output. This detection signal is input to the processing / control unit 22, and a predetermined calculation process is performed to calculate the transmittance and create a transmission spectrum representing the relationship between the wavelength and the transmittance.

これと同時に、処理・制御部２２は関係式記憶部２４に記憶されている関係式から、校正対象分光器１８の分解能に対応する差分値（Ａ）を求めると共に、校正対象分光器１８について得られた透過率スペクトルのディップ波長（最小透過率の波長）と前記光学フィルタ１２のピーク波長との差分値（Ｂ）（以下、「測定差分値（Ｂ）」という。）を求める。これら差分値（Ａ）及び測定差分値（Ｂ）はディスプレイモニタ３２に表示されるため、作業者は、これら差分値（Ａ）と測定差分値（Ｂ）を比較し、これら差分値の差（Ａ−Ｂ）が目的値になるように校正対象分光器１８を適宜調整すれば良い。差分値の差の目的値は「０」が望ましいが、構造上避けられない誤差を考慮して適宜の値に設定するとよい。また、波長分解能の高低に応じて目的値を設定しても良い。例えば、波長分解能が低い場合よりも高い場合の方が目的値を小さくする。   At the same time, the processing / control unit 22 obtains a difference value (A) corresponding to the resolution of the calibration target spectrometer 18 from the relational expression stored in the relational expression storage unit 24 and obtains the calibration target spectrometer 18. A difference value (B) between the dip wavelength (minimum transmittance wavelength) of the obtained transmittance spectrum and the peak wavelength of the optical filter 12 (hereinafter referred to as “measurement difference value (B)”) is obtained. Since the difference value (A) and the measurement difference value (B) are displayed on the display monitor 32, the operator compares the difference value (A) with the measurement difference value (B), and the difference between these difference values ( What is necessary is just to adjust the calibration object spectrometer 18 suitably so that A-B) may become a target value. The target value of the difference value is preferably “0”, but it may be set to an appropriate value in consideration of errors that are unavoidable due to the structure. The target value may be set according to the wavelength resolution. For example, the target value is made smaller when the wavelength resolution is higher than when the wavelength resolution is low.

このように本実施例に係る校正装置及び校正方法によれば、光学フィルタ１２を含む光学系を用いて分光器を構成する場合に、分光器の波長分解能により生じる、分光器から取り出される波長と目的波長との間の差を考慮して分光器を校正することため、波長分解能に関係なく正確度の高い波長校正を行うことができる。   As described above, according to the calibration apparatus and the calibration method according to the present embodiment, when the spectroscope is configured using the optical system including the optical filter 12, the wavelength extracted from the spectroscope caused by the wavelength resolution of the spectroscope Since the spectrometer is calibrated in consideration of the difference from the target wavelength, wavelength calibration with high accuracy can be performed regardless of the wavelength resolution.

なお、上記実施例では光学フィルタを通して光源からの光を標準分光器に導入し、そのとき得られた透過スペクトルから求められたディップ波長に基づき関係式を算出し、記憶するようにしたが、予め関係式を記憶しておいても良い。また、光学フィルタの複数の吸収波長帯の各最大吸収波長を用いて、或いは、複数の光学フィルタの最大吸収波長を用いて分光器の波長校正を行うようにしても良い。さらに、波長処理・制御部２２が差分値の差（Ａ−Ｂ）と目的値の比較を行い、その比較結果を出力して分光器の調整作業の要否を知らせるようにしても良い。その他、本発明の趣旨の範囲で適宜の変形や修正、追加を行っても良いことは明らかである。   In the above embodiment, the light from the light source is introduced into the standard spectrometer through the optical filter, and the relational expression is calculated and stored based on the dip wavelength obtained from the transmission spectrum obtained at that time. The relational expression may be stored. Further, the wavelength calibration of the spectrometer may be performed using the maximum absorption wavelengths of the plurality of absorption wavelength bands of the optical filter or using the maximum absorption wavelengths of the plurality of optical filters. Further, the wavelength processing / control unit 22 may compare the difference value difference (A−B) with the target value, and output the comparison result to notify the necessity of the adjustment work of the spectrometer. In addition, it is apparent that appropriate changes, modifications, and additions may be made within the scope of the present invention.

１０…光源
１２…光学フィルタ
１４…ビームスプリッタ
１６…標準分光器
１６１…入口スリット
１６２…出口スリット
１６３…回折格子
１８…校正対象分光器
２０、３０…検出器
２２…処理・制御部
２４…関係式記憶部
２６…分光器制御部
２８…モータ駆動部
３２…ディスプレイモニタ DESCRIPTION OF SYMBOLS 10 ... Light source 12 ... Optical filter 14 ... Beam splitter 16 ... Standard spectrometer 161 ... Entrance slit 162 ... Exit slit 163 ... Diffraction grating 18 ... Calibration object spectrometer 20, 30 ... Detector 22 ... Processing / control part 24 ... Relational expression Storage unit 26 ... Spectrometer control unit 28 ... Motor drive unit 32 ... Display monitor

Claims (2)

波長分散素子と、該波長分散素子の位置を変える駆動装置とを備える分光器の波長校正を行うための校正装置であって、
a) 光源から放射される光の波長範囲に含まれる吸収波長帯を有する光学フィルタを備え、前記光源からの光を前記光学フィルタを通して分光器に入射させる光学系と、
b) 前記分光器の波長分散素子の位置を変えつつ、該分光器から出射される光の強度を求め、前記吸収波長帯における強度が最小値となる波長であるディップ波長を求めるディップ波長検出手段と、
c) 分光器の波長分解能を変化させた場合の、該波長分解能と、該波長分解能における前記ディップ波長と前記光学フィルタの前記吸収波長帯における既知の最大吸収波長との差分値との関係を表す関係式を記憶する記憶手段と、
d) 校正対象分光器の波長分解能に対応する前記差分値を前記関係式から求め、当該差分値と、前記光源からの光を前記光学フィルタを通して前記校正対象分光器に入射させて得られたディップ波長と前記既知の最大吸収波長との差分値とが、許容範囲内で一致するように前記分光器を校正する校正手段と
を備えることを特徴とする校正装置。 A calibration device for performing wavelength calibration of a spectroscope comprising a wavelength dispersion element and a drive device that changes the position of the wavelength dispersion element,
an optical system comprising an optical filter having an absorption wavelength band included in a wavelength range of light emitted from a light source; and an optical system that causes light from the light source to enter a spectroscope through the optical filter;
b) Dip wavelength detection means for obtaining the dip wavelength which is the wavelength at which the intensity in the absorption wavelength band is the minimum value while obtaining the intensity of the light emitted from the spectrometer while changing the position of the wavelength dispersion element of the spectrometer. When,
c) Represents the relationship between the wavelength resolution when the wavelength resolution of the spectrometer is changed and the difference value between the dip wavelength at the wavelength resolution and the known maximum absorption wavelength in the absorption wavelength band of the optical filter. Storage means for storing the relational expression;
d) The difference value corresponding to the wavelength resolution of the calibration target spectrometer is obtained from the relational expression, and the difference value and the dip obtained by causing the light from the light source to enter the calibration target spectrometer through the optical filter. A calibration apparatus comprising: calibration means for calibrating the spectrometer so that a difference value between a wavelength and the known maximum absorption wavelength is within an allowable range . 波長分散素子と、該波長分散素子の位置を変える駆動装置とを備える分光器の波長校正を行うための校正方法であって、
a) 光源からの光を、該光源から放射される光の波長範囲に含まれる吸収波長帯を有する光学フィルタを通して前記分光器に入射させ、
b) 前記分光器の波長分散素子の位置を変えつつ、該分光器から出射される光の強度を求め、前記吸収波長帯において強度が最小となる波長であるディップ波長を求め、
c) 分光器の波長分解能を変化させた場合の、該波長分解能と、該波長分解能における前記ディップ波長と前記光学フィルタの前記吸収波長帯における既知の最大吸収波長との差分値との関係を表す関係式を記憶し、
d) 校正対象分光器の波長分解能に対応する前記差分値を前記関係式から求め、当該差分値と、前記光源からの光を前記光学フィルタを通して前記校正対象分光器に入射させて得られたディップ波長と前記既知の最大吸収波長との差分値とが、許容範囲内で一致するように前記分光器を校正する
ことを特徴とする校正方法。 A calibration method for performing wavelength calibration of a spectroscope comprising a wavelength dispersion element and a drive device that changes the position of the wavelength dispersion element,
a) the light from the light source is incident on the spectrometer through an optical filter having an absorption wavelength band included in the wavelength range of the light emitted from the light source;
b) While changing the position of the wavelength dispersive element of the spectrometer, obtain the intensity of the light emitted from the spectrometer, find the dip wavelength that is the minimum intensity in the absorption wavelength band,
c) Represents the relationship between the wavelength resolution when the wavelength resolution of the spectrometer is changed and the difference value between the dip wavelength at the wavelength resolution and the known maximum absorption wavelength in the absorption wavelength band of the optical filter. Memorize the relational expression,
d) The difference value corresponding to the wavelength resolution of the calibration target spectrometer is obtained from the relational expression, and the difference value and the dip obtained by causing the light from the light source to enter the calibration target spectrometer through the optical filter. A calibration method , wherein the spectroscope is calibrated so that a difference value between a wavelength and the known maximum absorption wavelength is within an allowable range .
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