JP6917824B2 - Spectral measuring device and spectroscopic measuring method - Google Patents

Spectral measuring device and spectroscopic measuring method Download PDF

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JP6917824B2
JP6917824B2 JP2017154203A JP2017154203A JP6917824B2 JP 6917824 B2 JP6917824 B2 JP 6917824B2 JP 2017154203 A JP2017154203 A JP 2017154203A JP 2017154203 A JP2017154203 A JP 2017154203A JP 6917824 B2 JP6917824 B2 JP 6917824B2
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鈴太郎 高橋
鈴太郎 高橋
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Citizen Electronics Co Ltd
Citizen Watch Co Ltd
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Description

本発明は、LEDを光源とする分光測定装置及び分光測定方法に関する。 The present invention relates to a spectroscopic measuring device and a spectroscopic measuring method using an LED as a light source.

光源、分光器、検出器を主要な構成要素とし、少なくとも2つの波長帯域を使って反射率や透過率を測定する分光測定装置が知られている。通常、分光測定装置は、光源から得た光を分光器で単色化し、この単色した光(以下「単色光」という)で試料の透過光又は反射光を測る。また、光源から得た光を試料に当て、その反射光や透過光について分光分析しても良い。光源には、スペクトルが比較的平坦で連続的な重水素放電管やタングステンランプが用いられる。分光器には、プリズムや回折格子など、検出器には、光電子倍増管やホトダイオードなどが利用される。 There are known spectroscopic measuring devices that measure reflectance and transmittance using at least two wavelength bands, with a light source, a spectroscope, and a detector as main components. Usually, the spectroscopic measuring device monochromaticizes the light obtained from the light source with a spectroscope, and measures the transmitted light or the reflected light of the sample with the monochromatic light (hereinafter referred to as "monochromatic light"). Alternatively, the light obtained from the light source may be applied to the sample, and the reflected light or transmitted light may be spectroscopically analyzed. As the light source, a deuterium discharge tube or a tungsten lamp having a relatively flat spectrum and being continuous is used. A prism or a diffraction grating is used for the spectroscope, and a photomultiplier tube or a photodiode is used for the detector.

例えば、特許文献1には、トマト等の試料の内部で反射した拡散反射光から得た分光スペクトルに基づいて、成分を分析する分光分析装置(分光測定装置)が記載されている。特許文献1に記載された分光測定装置では、第1の光ファイバーを介して光源から放射される赤外線光(連続スペクトル)を試料に照射し、第2の光ファイバーを介して拡散反射光を凹面回折格子(分光器)に導き、リニアイメージセンサ(検出器)で分光スペクトルを得ている。 For example, Patent Document 1 describes a spectroscopic analyzer (spectral measurement device) that analyzes components based on a spectroscopic spectrum obtained from diffusely reflected light reflected inside a sample such as tomato. In the spectroscopic measuring apparatus described in Patent Document 1, the sample is irradiated with infrared light (continuous spectrum) radiated from a light source via the first optical fiber, and diffused reflected light is emitted through a second optical fiber into a concave diffraction lattice. It is guided to (spectrometer) and the spectroscopic spectrum is obtained by the linear image sensor (detector).

特開2000−206037号公報(図1)Japanese Unexamined Patent Publication No. 2000-2060337 (Fig. 1)

特許文献1に記載された分光測定装置は、光源にタングステン−ハロゲンランプを使用していた。タングステン−ハロゲンランプは、ガラス管や口金が必要なため分光測定装置の小型化の障害となる。これに対し、光源をLED化すれば、容易に分光測定装置の小型化が図れると思われる。 The spectroscopic measuring apparatus described in Patent Document 1 uses a tungsten-halogen lamp as a light source. Tungsten-halogen lamps require a glass tube and a base, which hinders the miniaturization of spectroscopic measuring devices. On the other hand, if the light source is changed to LED, it seems that the spectroscopic measuring device can be easily miniaturized.

しかしながら、LEDは、半値幅の狭い釣鐘状のスペクトルを示すことが多い。このようなLEDから広い帯域で平坦な特性を持つ光源を得ようとすると、ピーク波長が少しずつずれた多数のLEDを準備すれば実現できる。ところが、装置を小型化しようとすることと、多数のLEDを準備することとは相反する。 However, LEDs often exhibit a bell-shaped spectrum with a narrow full width at half maximum. An attempt to obtain a light source having flat characteristics in a wide band from such an LED can be realized by preparing a large number of LEDs whose peak wavelengths are slightly deviated from each other. However, trying to miniaturize the device conflicts with preparing a large number of LEDs.

このため、やむを得ず、ピーク波長が離れた少数のLEDで光源を構成すると、1つのLEDのピーク波長と他方のLEDのピーク波長との間に強度の弱い帯域が現れる。この強度が弱い帯域は、強度が強い帯域に比べ測定誤差が大きくなってしまう。すなわち、少数のLEDで構成した光源では全帯域に亘って一定の精度が得られない。 Therefore, if the light source is unavoidably composed of a small number of LEDs having peak wavelengths separated from each other, a band having a weak intensity appears between the peak wavelength of one LED and the peak wavelength of the other LED. In this band with low intensity, the measurement error becomes larger than in the band with high intensity. That is, a light source composed of a small number of LEDs cannot obtain a constant accuracy over the entire band.

そこで、本発明は、上記課題に鑑みてなされたものであり、ピーク波長が離れた少数のLEDで光源を構成しても、広い帯域で一定の精度を維持できる分光測定装置及び分光測定方法を提供することを目的とする。 Therefore, the present invention has been made in view of the above problems, and a spectroscopic measuring device and a spectroscopic measuring method capable of maintaining a constant accuracy in a wide band even if a light source is composed of a small number of LEDs having peak wavelengths separated from each other. The purpose is to provide.

上記目的を達成するため、本発明の分光測定方法は、ピーク波長が離れた赤外線発光型の第1LED及び第2LEDからなる光源と、複数のフィルターと、を備えた分光測定方法において、少なくとも2つの帯域で分光測定を行い、前記2つの帯域のうちの一方の帯域は、前記第1LED又は前記第2LEDのピーク波長の周辺の帯域であり、前記2つの帯域のうちの他方の帯域は、前記第1LEDのピーク波長と前記第2LEDのピーク波長との間の帯域であり、前記複数のフィルターを通した光の強度が等しくなるように、予め前記第1LED及び第2LEDへの電流供給量を調整した後に、前記一方の帯域で分光測定する第1測定ステップと、前記第1LED又は前記第2LEDへの電流供給量を前記第1測定ステップの時より増加してから前記他方の帯域で分光測定する第2測定ステップと、を有する。 In order to achieve the above object, the spectroscopic measurement method of the present invention is a spectroscopic measurement method including a light source composed of an infrared emitting type first LED and a second LED having different peak wavelengths and a plurality of filters. Spectroscopic measurement is performed in the bands, one of the two bands is a band around the peak wavelength of the first LED or the second LED, and the other band of the two bands is the first LED. The amount of current supplied to the first LED and the second LED is adjusted in advance so that the peak wavelength of the 1 LED and the peak wavelength of the second LED are the bands and the intensities of the light passing through the plurality of filters are equal. Later, the first measurement step of spectroscopic measurement in the one band and the second measurement in which the current supply amount to the first LED or the second LED is increased from the time of the first measurement step and then spectroscopic measurement is performed in the other band. It has two measurement steps .

本発明の分光測定方法において、光源は、ピーク波長が離れた第1LEDと第2LEDとを備えている。このため、第1LED及び第2LEDのピーク波長の周辺の帯域で強度が強く、第1LED及び第2LEDのピーク波長の間の帯域で強度が弱くなる。そこで、本発明の分光測定方法では、照射強度の強いピーク波長周辺の帯域について透過率や反射率を測定する第1測定ステップと、ピーク波長の間の谷間となる帯域で透過率や反射率を測定する第2測定ステップとを準備する。第1測定ステップでは、あらかじめ設定した条件で第1及び第2LEDを発光させる。第2測定ステップでは、前記条件に対し第1又は第2LEDへの電流供給量を増加し、光源の発光強度を強くする。 In the spectroscopic measurement method of the present invention, the light source includes a first LED and a second LED having different peak wavelengths. Therefore, the intensity is high in the band around the peak wavelengths of the first LED and the second LED, and weak in the band between the peak wavelengths of the first LED and the second LED. Therefore, in the spectroscopic measurement method of the present invention, the transmittance and the reflectance are measured in the first measurement step of measuring the transmittance and the reflectance in the band around the peak wavelength where the irradiation intensity is strong, and in the band which is the valley between the peak wavelengths. Prepare a second measurement step to be measured. In the first measurement step, the first and second LEDs are made to emit light under preset conditions. In the second measurement step, the amount of current supplied to the first or second LED is increased with respect to the above conditions, and the emission intensity of the light source is increased.

上記目的を達成するため、本発明の分光測定装置は、ピーク波長が離れた赤外線発光型の第1LED及び第2LEDからなる光源と、前記第1LED及び第2LEDにそれぞれ直列接続する第1可変定電流源及び第2可変定電流源と、前記第1可変定電流源及び前記第2可変定電流源に流れる電流値を制御する制御回路と、複数のフィルターと、を備え、前記制御回路は、前記複数のフィルターを通した光の強度が等しくなるように、予め前記第1LED及び第2LEDへの電流供給量が調整され、分光測定する前記帯域に応じて前記第1可変定電流源及び前記第2可変定電流源に流す電流切り換えられる。 In order to achieve the above object, the spectroscopic measuring device of the present invention has a light source composed of infrared light emitting type first LED and second LED having peak wavelengths separated from each other, and a first variable constant current connected in series to the first LED and the second LED, respectively. comprising a source and a second variable constant-current source, a control circuit for controlling the current flowing through the first variable constant current source and said second variable constant-current source, and a plurality of filters, wherein the control circuit comprises as the intensity of light through a plurality of filters is equal, the current supply amount is adjusted to advance the first 1LED and second 2LED, the first variable constant-current source in response to said band spectroscopic measurement and the second The current flowing through the variable constant current source is switched .

本発明の分光測定装置は、光源と分光器と検出器とを備えている。光源にはピーク波長が離れている第1LED及び第2LEDが含まれ、第1LED及び第2LEDにはそれぞれ第1可変定電流源及び第2可変定電流源が直列接続している。第1可変定電流源及び第2可変定電流源を流れる電流は、測定帯域により異なった値に設定される。 The spectroscopic measuring device of the present invention includes a light source, a spectroscope, and a detector. The light source includes a first LED and a second LED having peak wavelengths separated from each other, and a first variable constant current source and a second variable constant current source are connected in series to the first LED and the second LED, respectively. The currents flowing through the first variable constant current source and the second variable constant current source are set to different values depending on the measurement band.

前記分光器は、複数のバンドパスフィルターを備えていても良い。 The spectroscope may include a plurality of bandpass filters.

本発明の分光測定装置及び分光測定方法は、ピーク波長が離れた少数のLEDで光源を構成しても、それぞれのピーク波長の間の帯域のデータを取得するとき、LEDに流す電流を増加し、光源の強度を強くしている。この結果、本発明の分光測定装置及び分光測定方法は、広い帯域で一定の精度を維持できる。 The spectroscopic measuring device and the spectroscopic measuring method of the present invention increase the current flowing through the LEDs when acquiring data in the band between the peak wavelengths even if the light source is composed of a small number of LEDs having different peak wavelengths. , The intensity of the light source is increased. As a result, the spectroscopic measuring device and the spectroscopic measuring method of the present invention can maintain a constant accuracy in a wide band.

本発明の実施形態として示す分光測定装置において主要部品の配置関係を示す図である。It is a figure which shows the arrangement relation of the main parts in the spectroscopic measuring apparatus shown as the embodiment of this invention. 図1に示す分光測定装置のブロック図である。It is a block diagram of the spectroscopic measuring apparatus shown in FIG. 図1に示す分光測定装置に含まれる光源のスペクトル図である。It is a spectrum diagram of the light source included in the spectroscopic measuring apparatus shown in FIG. 図1に示す分光測定装置に含まれる光源のスペクトル図である。It is a spectrum diagram of the light source included in the spectroscopic measuring apparatus shown in FIG.

以下、添付図1〜図4を参照して本発明の好適な実施形態について詳細に説明する。なお、()に特許請求の範囲で示す発明特定事項を記載する。 Hereinafter, preferred embodiments of the present invention will be described in detail with reference to FIGS. 1 to 4. In addition, the matters specifying the invention shown in the claims are described in parentheses.

図1は、本発明の実施形態として示す分光測定装置10の主要な部品の配置関係を示す図である。図1に示すように、分光測定装置10は、主要な部品として、光源11、分光器12、検出器13を備えている。分光器12は、ホイール12a、フィルター12b(バンドパスフィルター)、モーター12cからなっている。ホイール12aは、円盤であ
り、8枚のフィルター12bが環状に取り付けられている。なお、ホイール12aは、フィルター12bの取り付け部が開口している。モーター12cの軸は、ホイール12aの中心を貫いている。光源11は、検出器13とともにフィルター12bの背面部に設置され、試料20は、ホイール12aの前面側に配置される。
FIG. 1 is a diagram showing an arrangement relationship of main parts of the spectroscopic measuring device 10 shown as an embodiment of the present invention. As shown in FIG. 1, the spectroscopic measuring device 10 includes a light source 11, a spectroscope 12, and a detector 13 as main components. The spectroscope 12 includes a wheel 12a, a filter 12b (bandpass filter), and a motor 12c. The wheel 12a is a disk, and eight filters 12b are attached in an annular shape. The wheel 12a has an opening for attaching the filter 12b. The shaft of the motor 12c runs through the center of the wheel 12a. The light source 11 is installed on the back surface of the filter 12b together with the detector 13, and the sample 20 is arranged on the front surface side of the wheel 12a.

光源11を発した光は、1つのフィルター12bを抜け、試料20に照射される。この試料20を照射する光(以下「照射光」という)は、試料20で反射する。この反射した光(以下「反射光」という)は、再びフィルター12bを通り、検出器13に入射する。 The light emitted from the light source 11 passes through one filter 12b and irradiates the sample 20. The light that irradiates the sample 20 (hereinafter referred to as “irradiation light”) is reflected by the sample 20. This reflected light (hereinafter referred to as "reflected light") passes through the filter 12b again and is incident on the detector 13.

ホイール12aに取り付けられた8枚のフィルター12bは、5〜10nmの通過帯域をもつバンドパスフィルターであり、それぞれの通過帯域が異なっている。なお、農産物等の品質評価としては、既知の物質の分量等が分れば良いので、特定の帯域における反射率を測定するだけで済むことが多い。このため、分光器12として構造が簡単で光線の強度を強くできるバンドパスフィルターを使用することができる。 The eight filters 12b attached to the wheel 12a are bandpass filters having a pass band of 5 to 10 nm, and each pass band is different. For quality evaluation of agricultural products and the like, it is only necessary to know the amount of known substances and the like, so it is often sufficient to measure the reflectance in a specific band. Therefore, as the spectroscope 12, a bandpass filter having a simple structure and capable of increasing the intensity of light rays can be used.

なお、光源11の発光及び試料20からの反射光はできるだけフィルター12bに垂直入射させる必要がある。このときフィルター12bの反射光が検出器13に入射してしまう場合は、検出器13をバンドパスフィルターの前面側(試料20側)に配置すれば良い。しかしながら、以後の説明では、フィルター12bの反射は無視し、光源11と検出器13をフィルター12bの背面側に併設させておく。 It is necessary that the light emitted from the light source 11 and the reflected light from the sample 20 are vertically incident on the filter 12b as much as possible. At this time, if the reflected light of the filter 12b is incident on the detector 13, the detector 13 may be arranged on the front side (sample 20 side) of the bandpass filter. However, in the following description, the reflection of the filter 12b is ignored, and the light source 11 and the detector 13 are provided side by side on the back side of the filter 12b.

反射率の分光測定は、以下のように行う。まず、分光測定装置10では、1つのフィルター12bを選択したときの照射光と、他のフィルター12bを選択したときの照射光の強度が概ね等しくなるよう、フィルター12bごとに予め光源11に流す電流を決めておく。すなわち、Au又はAlからなる基準板と検出器13を使用し、基準板による反射光が各フィルター12bごとに等しくなるよう電流調整する。 Spectral measurement of reflectance is performed as follows. First, in the spectroscopic measuring device 10, the current to be passed through the light source 11 in advance for each filter 12b so that the intensity of the irradiation light when one filter 12b is selected and the intensity of the irradiation light when the other filter 12b is selected are substantially equal. Decide. That is, the reference plate made of Au or Al and the detector 13 are used, and the current is adjusted so that the light reflected by the reference plate becomes equal for each filter 12b.

次に、試料20と、1つのフィルター12bをセットし、光源11を点灯させ、当該1つのフィルターによって決まる帯域の反射光を測定する。続いて、ホイール12aを45°回転し、他のフィルター12bに切換え、光源11を点灯させ、当該他のフィルター12bによって決まる帯域の反射光を測定する。なお、前述したように、電源には個々のフィルター12bごとに決まった電流を流す。この過程について全てのフィルター12bについて実施し、各フィルター12bで決まる帯域の反射光を測定する。 Next, the sample 20 and one filter 12b are set, the light source 11 is turned on, and the reflected light in the band determined by the one filter is measured. Subsequently, the wheel 12a is rotated by 45 °, switched to another filter 12b, the light source 11 is turned on, and the reflected light in the band determined by the other filter 12b is measured. As described above, a current determined for each filter 12b is passed through the power supply. This process is carried out for all filters 12b, and the reflected light in the band determined by each filter 12b is measured.

最後に、試料20から得られた反射光と、基準板で測定しておいた反射光について、各フィルター12bごとに比をとる(正確には、基準板の反射率で補正する)と、それぞれの帯域の反射率が得られる。 Finally, the reflected light obtained from the sample 20 and the reflected light measured by the reference plate are compared for each filter 12b (corrected by the reflectance of the reference plate to be exact). The reflectance of the band of is obtained.

図2は、分光測定装置10のブロック図である。なお、図2では、モーター12cやホイール12aなど分光器12の駆動に係る部材については図示していない。図2に示すように、分光測定装置10には、光源11、分光器12、検出器13に加え、制御回路14、2つの可変定電流源15、16(第1可変定電流源、第2可変定電流源)、電源17が書き加えられている。 FIG. 2 is a block diagram of the spectroscopic measuring device 10. Note that FIG. 2 does not show members related to driving the spectroscope 12, such as the motor 12c and the wheel 12a. As shown in FIG. 2, the spectrophotometer 10 includes a light source 11, a spectroscope 12, a detector 13, a control circuit 14, and two variable constant current sources 15 and 16 (first variable constant current source, second). Variable constant current source) and power supply 17 have been added.

光源11は、2つのLED11a、11b(第1LED、第2LED)からなる。LED11a、11bは、赤外線発光型LEDであり、ピーク波長がそれぞれ800nmと850nmであり(図3参照)、可変定電流源15、16と直列接続している。可変定電流源15、16は、制御回路14から出力される制御信号15a、16aに基づいてLED11a、11bに流す電流を調整する。電源17は、LED11a、11bに電力を供給する。 The light source 11 is composed of two LEDs 11a and 11b (first LED and second LED). The LEDs 11a and 11b are infrared light emitting LEDs having peak wavelengths of 800 nm and 850 nm, respectively (see FIG. 3), and are connected in series with the variable constant current sources 15 and 16. The variable constant current sources 15 and 16 adjust the current flowing through the LEDs 11a and 11b based on the control signals 15a and 16a output from the control circuit 14. The power supply 17 supplies electric power to the LEDs 11a and 11b.

光源12から発した光線L1は、分光器12に含まれる1つのフィルター12b(図1参照)を通り、試料20で反射する。この反射した光からなる光線L2は、再びフィルター12bを通り検出器13に入射する。検出器13は、ホトダイオードであり、入射した光に応じた電流値を測定データ13aとして制御回路14に出力する。 The light beam L1 emitted from the light source 12 passes through one filter 12b (see FIG. 1) included in the spectroscope 12 and is reflected by the sample 20. The light ray L2 composed of the reflected light passes through the filter 12b again and is incident on the detector 13. The detector 13 is a photodiode, and outputs a current value corresponding to the incident light to the control circuit 14 as measurement data 13a.

なお、前述のように1つのフィルター12bがセットされているとき、制御回路14は、LED11a、11bに予め決めておいた電流が流れるように、可変定電流源15、16を設定する。すなわち、どのフィルター12bがセットされているか、信号12dを介して分光器12と制御回路14との間で、どのフィルター12bが選択されているかについて情報がやりとりされる。 When one filter 12b is set as described above, the control circuit 14 sets the variable constant current sources 15 and 16 so that a predetermined current flows through the LEDs 11a and 11b. That is, information is exchanged between the spectroscope 12 and the control circuit 14 via the signal 12d as to which filter 12b is set and which filter 12b is selected.

図3は、分光測定器10に含まれる光源11の発光スペクトル30(実線)を示すスペクトル図である。図3に示すように光源11の発光スペクトル30は、λ=800nm付近にピークを有するLED11aのスペクトル31(破線)と、λ=850nm付近にピークを有するLED11bのスペクトル32(破線)とを合算したものである。発光スペクトル30は、λ=820nm付近に谷が存在する。 FIG. 3 is a spectrum diagram showing an emission spectrum 30 (solid line) of the light source 11 included in the spectroscopic measuring instrument 10. As shown in FIG. 3, the emission spectrum 30 of the light source 11 is the sum of the spectrum 31 (broken line) of the LED 11a having a peak near λ = 800 nm and the spectrum 32 (broken line) of the LED 11b having a peak near λ = 850 nm. It is a thing. The emission spectrum 30 has a valley near λ = 820 nm.

図4は、図3で示したスペクトル図にフィルター12b(図1参照)の通過帯域を書き加えた光源11のスペクトル図である。図中、ハッチングの掛った帯域に付された符号fn(nは整数)は、この帯域がn番目のフィルター12bの通過帯域であることを示している。各通過帯域f1〜f8は、幅が5〜10nmであり、全体としては離散した状態で780〜870nmに亘って分散している。 FIG. 4 is a spectrum diagram of the light source 11 in which the pass band of the filter 12b (see FIG. 1) is added to the spectrum diagram shown in FIG. In the figure, the code fn (n is an integer) attached to the hatched band indicates that this band is the pass band of the nth filter 12b. Each pass band f1 to f8 has a width of 5 to 10 nm, and is dispersed over 780 to 870 nm in a discrete state as a whole.

前述のように、農産物の選定では、既知の物質についてその分量が分れば良い場合が多い。すなわち、予め必要とする波長帯の反射率だけ分かれば良く、分析すべき帯域はとびとびとなっても良い。この結果、分光測定装置10は、分光器12をバンドパスフィルター12bで構成でき、光学系が簡単化し、試料20(図1参照)を照射する光の強度も強くできる。 As mentioned above, when selecting agricultural products, it is often sufficient to know the amount of known substances. That is, it is only necessary to know the reflectance of the required wavelength band in advance, and the bands to be analyzed may be discrete. As a result, in the spectroscopic measurement device 10, the spectroscope 12 can be configured by the bandpass filter 12b, the optical system can be simplified, and the intensity of the light irradiating the sample 20 (see FIG. 1) can be increased.

反射率は、(反射光の強度)/(照射光の強度)であるから、各帯域f1〜f2の間で反射率の精度を均一にするには、測定しようとする帯域ごとに照射光の強度が略一定であることが望ましい。前述したように、分光測定装置10では、第n番目のフィルター12bから第(n+1)番目のフィルター12bに切り替えるとき、可変定電流回路15、16に流す電流を設定し直している。この結果、分光測定装置10では、フィルター12bごとに照射光の強度は概ね等しくなる。 Since the reflectance is (intensity of reflected light) / (intensity of irradiation light), in order to make the accuracy of the reflectance uniform between the bands f1 to f2, the irradiation light of each band to be measured is used. It is desirable that the strength is substantially constant. As described above, in the spectroscopic measuring device 10, when switching from the nth filter 12b to the (n + 1) th filter 12b, the current flowing through the variable constant current circuits 15 and 16 is reset. As a result, in the spectroscopic measuring device 10, the intensity of the irradiation light becomes substantially equal for each filter 12b.

以上のようにして、分光測定装置10は、フィルター12bごとに、試料20(図1参照)を照射する光の強度を概ね等しくできるため、全測定帯域で測定精度が略等しくなる。 As described above, since the spectroscopic measurement device 10 can make the intensity of the light irradiating the sample 20 (see FIG. 1) substantially equal for each filter 12b, the measurement accuracy becomes substantially the same in all measurement bands.

分光測定装置10における分光測定方法の特徴をまとめると以下の通りになる。ピーク波長が離れたLED11a(第1LED)とLED11b(第2LED)とを有する分光測定装置10は、少なくとも2つの帯域で測定を行う。2つの帯域のうち一方の帯域は、例えば、LED11aのピーク波長の周辺の帯域f3(又は帯域f7)であり、他方の帯域は、LED11aのピーク波長とLED11bのピーク波長との間の帯域f4(又は帯域f5)である(図4参照)。そして、分光測定装置10は、一方の帯域で反射率を測定する第1測定ステップと、LED11a又はLED11bへの電流供給量を増加してから他方の帯域で反射率を測定する第2測定ステップとを有している。 The features of the spectroscopic measurement method in the spectroscopic measurement device 10 are summarized below. The spectroscopic measuring device 10 having the LED 11a (first LED) and the LED 11b (second LED) having peak wavelengths separated from each other performs measurement in at least two bands. One of the two bands is, for example, band f3 (or band f7) around the peak wavelength of LED11a, and the other band is band f4 (or band f4) between the peak wavelength of LED11a and the peak wavelength of LED11b. Or the band f5) (see FIG. 4). Then, the spectroscopic measuring device 10 has a first measurement step of measuring the reflectance in one band, and a second measurement step of increasing the amount of current supplied to the LED 11a or the LED 11b and then measuring the reflectance in the other band. have.

すなわち、第1測定ステップでは第3番目のフィルター12bを用いてピーク波長周辺の帯域f3で反射率を測定し、第2測定ステップでは第4番目のフィルター12bを用い、LED11a,11bへの電流供給量を増加してからピーク波長間の帯域f4で反射率を測定する。なお、光源11のスペクトルがピークを示す波長と谷を示す波長の中間となる帯域(例えば、f6帯域)では、第1ステップで流す電流と第2ステップで流す電流の中間の電流をLED11a、11bに流す(帯域f2、f8も同様に電流を増加させる)。 That is, in the first measurement step, the third filter 12b is used to measure the reflectance in the band f3 around the peak wavelength, and in the second measurement step, the fourth filter 12b is used to supply current to the LEDs 11a and 11b. After increasing the amount, the reflectance is measured in the band f4 between the peak wavelengths. In a band (for example, the f6 band) in which the spectrum of the light source 11 is intermediate between the wavelength indicating the peak and the wavelength indicating the valley, the currents intermediate between the current flowing in the first step and the current flowing in the second step are the LEDs 11a and 11b. (Bands f2 and f8 also increase the current).

分光測定装置10に含まれる分光器12は、複数のバンドパスフィルター12bからなっていた。本発明の分光測定装置では、分光器は複数のバンドパスフィルター12bからなるものに限られない。例えば、分光器は、良く知られたプリズムや回折格子であっても良い。しかしながら、これらの分光器に比べ、複数のバンドパスフィルターからなる分光器は、光線群を平行化する度合いが低くてよく、照射強度も強くできる。 The spectroscope 12 included in the spectroscopic measuring device 10 was composed of a plurality of bandpass filters 12b. In the spectroscopic measuring apparatus of the present invention, the spectroscope is not limited to the one including a plurality of bandpass filters 12b. For example, the spectroscope may be a well-known prism or diffraction grating. However, compared to these spectroscopes, a spectroscope composed of a plurality of bandpass filters may have a lower degree of parallelization of light rays and can have a stronger irradiation intensity.

分光器12が回折格子やプリズムである場合、測定する帯域は連続的になる。この場合でも、分光測定装置10は、光源11に供給する電流が異なる少なくとも2つのステップで反射率を測定する。つまり、分光測定装置10は、ピーク波長周辺の帯域で測定する第1測定ステップと、ピーク波長の間の帯域(谷となる帯域)で測定する第2測定ステップとを有する。第1ステップでは予め定めておいた電流をLED11a、11bに流す。第2ステップでは当該電流よりも供給量を増やす。 When the spectroscope 12 is a diffraction grating or a prism, the measurement band is continuous. Even in this case, the spectroscopic measuring device 10 measures the reflectance in at least two steps in which the currents supplied to the light source 11 are different. That is, the spectroscopic measurement device 10 has a first measurement step of measuring in a band around the peak wavelength and a second measurement step of measuring in a band between peak wavelengths (a band forming a valley). In the first step, a predetermined current is passed through the LEDs 11a and 11b. In the second step, the supply amount is increased more than the current.

また、図3に示した帯域より広い測定帯域を必要とする場合は、LED11a、11bとはピーク波長の異なる第3LEDを追加すれば良い。分光測定装置10は、試料20(図1参照)からの反射光を測定していたが、透過光を測定しても良い。光源11に使用するLED11a、11bは、温度特性を持つので、制御回路14は温度補償機能を備えると良い。 If a measurement band wider than the band shown in FIG. 3 is required, a third LED having a peak wavelength different from that of the LEDs 11a and 11b may be added. Although the spectroscopic measuring device 10 has measured the reflected light from the sample 20 (see FIG. 1), the transmitted light may be measured. Since the LEDs 11a and 11b used for the light source 11 have temperature characteristics, it is preferable that the control circuit 14 has a temperature compensation function.

10…分光測定装置、
11…光源、
11a、11b…LED(第1LED、第2LED)、
12…分光器、
12a…ホイール、
12b…フィルター(バンドパスフィルター)、
12c…モーター、
13…検出器、
13a…測定テータ、
14…制御回路、
15、16…可変定電流源(第1可変定電流源、第2可変定電流源)、
15a、16a…制御信号、
17…電源、
20…試料、
L1、L2…光線。
10 ... Spectroscopic measuring device,
11 ... Light source,
11a, 11b ... LEDs (first LED, second LED),
12 ... Spectrometer,
12a ... Wheel,
12b ... Filter (bandpass filter),
12c ... Motor,
13 ... Detector,
13a ... Measurement data,
14 ... Control circuit,
15, 16 ... Variable constant current source (first variable constant current source, second variable constant current source),
15a, 16a ... Control signal,
17 ... Power supply,
20 ... Sample,
L1, L2 ... Rays.

Claims (5)

ピーク波長が離れた赤外線発光型の第1LED及び第2LEDからなる光源と、複数のフィルターと、を備えた分光測定方法において、
少なくとも2つの帯域で分光測定を行い、
前記2つの帯域のうちの一方の帯域は、前記第1LED又は前記第2LEDのピーク波長の周辺の帯域であり、
前記2つの帯域のうちの他方の帯域は、前記第1LEDのピーク波長と前記第2LEDのピーク波長との間の帯域であり、
前記複数のフィルターを通した光の強度が等しくなるように、予め前記第1LED及び第2LEDへの電流供給量を調整した後に、
前記一方の帯域で分光測定する第1測定ステップと、
前記第1LED又は前記第2LEDへの電流供給量を前記第1測定ステップの時より増加してから前記他方の帯域で分光測定する第2測定ステップと、を有する分光測定方法。
In a spectroscopic measurement method including a light source composed of an infrared emitting type first LED and a second LED having different peak wavelengths and a plurality of filters.
Take spectroscopic measurements in at least two bands
One of the two bands is a band around the peak wavelength of the first LED or the second LED.
The other band of the two bands is a band between the peak wavelength of the first LED and the peak wavelength of the second LED.
After adjusting the amount of current supplied to the first LED and the second LED in advance so that the intensities of the light passing through the plurality of filters are equal,
The first measurement step of spectroscopic measurement in one of the bands and
A spectroscopic measurement method comprising a second measurement step in which a current supply amount to the first LED or the second LED is increased from the time of the first measurement step and then spectroscopic measurement is performed in the other band.
前記第1LEDはピーク波長が800nmの発光スペクトルを有し、前記第2LEDはピーク波長が850nmの発光スペクトルを有し、前記第1LED及び第2LEDの合算後の発光スペクトルの相対強度が等しい請求項1に記載の分光測定方法。The first LED has an emission spectrum having a peak wavelength of 800 nm, the second LED has an emission spectrum having a peak wavelength of 850 nm, and the relative intensities of the combined emission spectra of the first LED and the second LED are equal. The spectroscopic measurement method according to. 前記2つの帯域は、一方が波長800nmもしくは850nmの周辺の帯域であり、他方が波長820nmの周辺の帯域であり、前記他方の帯域は、前記一方の帯域に対して発光スペクトルの相対強度が30%以上である請求項1に記載の分光測定方法。One of the two bands is a band around a wavelength of 800 nm or 850 nm, the other is a band around a wavelength of 820 nm, and the other band has a relative intensity of emission spectrum of 30 with respect to the one band. The spectroscopic measurement method according to claim 1, which is% or more. ピーク波長が離れた赤外線発光型の第1LED及び第2LEDからなる光源と、
前記第1LED及び第2LEDにそれぞれ直列接続する第1可変定電流源及び第2可変定電流源と、
前記第1可変定電流源及び前記第2可変定電流源に流れる電流値を制御する制御回路と、
複数のフィルターと、を備え、
前記制御回路は、前記複数のフィルターを通した光の強度が等しくなるように、予め前記第1LED及び第2LEDへの電流供給量が調整され、
分光測定する前記帯域に応じて前記第1可変定電流源及び前記第2可変定電流源に流す電流切り換えられる分光測定装置。
A light source consisting of an infrared emitting type first LED and a second LED having peak wavelengths separated from each other,
A first variable constant current source and a second variable constant current source connected in series to the first LED and the second LED, respectively.
A control circuit that controls the current value flowing through the first variable constant current source and the second variable constant current source, and
With multiple filters,
In the control circuit, the amount of current supplied to the first LED and the second LED is adjusted in advance so that the intensities of the light passing through the plurality of filters are equal.
Spectroscopic said first variable constant-current source in response to the band to be measured and the second variable constant-current source spectrometer which current is switched to flow in.
前記複数のフィルターは、帯域の異なる複数のバンドパスフィルターによって構成され、前記第1LED及び第2LEDのそれぞれのピーク波長の発光スペクトルの相対強度に対して50%となる半値幅の範囲内で配置される請求項4に記載の分光測定装置。The plurality of filters are composed of a plurality of bandpass filters having different bands, and are arranged within a half-value width range of 50% with respect to the relative intensity of the emission spectra of the peak wavelengths of the first LED and the second LED. The spectroscopic measuring apparatus according to claim 4.
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