JPH08201278A - Spectrum measuring device - Google Patents

Abstract

PURPOSE: To provide the spectrum measuring device using a compact ATR (Attenuated Total Reflectance measurement) prism, which has the few number of constituent parts and does not require an adjusting mechanism. CONSTITUTION: An ATR prism 11 has the pairs of a plurality of incident surfaces and outgoing surfaces. Light sources 12a and 12b, which emit the lights having the specified wavelengths are attached to the respective incident surfaces in tight contact. Detectors 13a and 13b, which receive the measuring lights that are emitted from the light sources 12a and 12b attached to the incident surface for forming the pairs and reflected from the reflecting surfaces, are attached to the outgoing surfaces in tight contact. the measurement of a plurality of wavelengths is performed by the respective pairs.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spectrum measuring apparatus, and more particularly to a spectrum measuring apparatus used for on-line measurement of a structure of a substance based on the principle of infrared and near-infrared spectrum measurement.

[0002]

2. Description of the Related Art There is known a method of spectrum analysis by total reflection absorption measurement (hereinafter referred to as ATR) in which an absorption spectrum of the sample surface is obtained by measuring light totally reflected on the sample surface to measure a substance.

A conventional ATR spectrum measuring apparatus uses a condensing optical system using a reflecting mirror or the like as shown in FIG. 9 to measure on a side surface of an incident side cut out at a predetermined angle of a flat plate-shaped ATR prism. After the light was incident and the sample to be measured was repeatedly reflected between the parallel reflecting surfaces of the ATR prism to which the sample was adhered, the output light from the side surface on the exit side of the ATR prism was guided to a detector for measurement. A device like this
In the case of TR measurement, there are optical and mechanical restrictions of the optical components arranged around the ATR prism, so that the output light from the spectroscope 1 interferometer is made incident from one point, and wavelength scanning is performed, so that many We are measuring at the wavelength. Even in an application in which a plurality of monochromatic light sources are used, it is necessary to use a complicated light beam combiner outside the prism.

[0004]

The above ATR measurement requires a focusing optical system around the ATR prism and an adjusting mechanism for adjusting this optical system. Therefore, the number of constituent parts is increased and the optical system becomes complicated. Also, adjustment of these optical systems is complicated. The present invention solves the above problems, reduces the number of components of the optical system, achieves cost reduction, high productivity, and downsizing of the device. Furthermore, the adjustment mechanism is unnecessary, and stability and operation are achieved. The purpose is to improve sex.

[0005]

The spectrum measuring apparatus of the present invention made to solve the above-mentioned problems is such that the incident surface on which the measurement light is incident and the surface of the sample to be measured are in close contact with each other, and In a spectrum measuring apparatus for measuring using an ATR prism having a reflection surface for reflecting light and an emission surface for emitting the measurement light after being reflected by the reflection surface, the ATR prism is composed of a plurality of incidence surfaces and an emission surface. A light source that emits light of a specific wavelength is attached to each incident surface in close contact with this incident surface, and each exit surface is emitted from the light source attached to the incident surface to be paired and reflected by the reflection surface. It is characterized in that a detector for receiving the measured light thus measured is attached to the emission surface so as to be in close contact therewith, thereby performing total reflection absorption measurement of a plurality of wavelengths. Hereinafter, how this spectrum measuring device works will be described.

[0006]

In the spectrum measuring apparatus of the present invention, since the light source and the detector are closely attached to the ATR prism, the conventional ATR prism is used.
The condensing optical system such as the reflecting mirror and the lens, which was necessary for the measurement, is not required, and the device configuration becomes simple. In the measurement, one wavelength is measured for each of the plurality of pairs of the entrance surface and the exit surface, so that the plurality of pairs perform the measurements at the plurality of wavelengths. Here, necessary information can be obtained by selecting a combination of wavelengths to be measured according to the sample to be measured. Particularly, in the online measurement of the process, the present apparatus is effective because it is sufficient to measure a specific wavelength without continuously scanning and measuring the wavelength.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an overall configuration diagram of a spectrum measuring apparatus showing an embodiment of the present invention. 2 is a plan view of an ATR prism portion of a spectrum measuring apparatus showing an embodiment of the present invention, FIG. 3 is a sectional view taken along line 3-3 ′ of FIG. 2, and FIG.
4'shows a cross section. This spectrum measuring device 10 is
TR prism 11, semiconductor laser 12a as a light source,
12b, photodiodes 13a and 13 as detectors
b, semiconductor laser power supplies 14a and 14b, photodiode output signal amplifiers 15a and 15b, and a control unit 16 that controls and calculates the apparatus.

The ATR prism 11 has the shape of a regular quadrangular pyramid having an upper surface and a lower surface which are parallel to each other, and four side surfaces cut off at an angle of 45 degrees with respect to these surfaces. The sample to be measured is attached to the upper and lower surfaces of the ATR prism so as to be in close contact with each other (these surfaces serve as reflecting surfaces). Adjacent two of the four sides of the ATR prism
The semiconductor lasers 12a and 12b are attached to one surface so as to be in direct contact with this surface (these surfaces are incident surfaces). Photodiodes 13a and 13b are attached so as to be in direct contact with the surface opposite to the surface to which the semiconductor lasers 12a and 12b are attached (these surfaces become emission surfaces). The light emitted from the semiconductor laser 12a reaches the photodiode 13a after being repeatedly reflected by the reflecting surface, and similarly, the light emitted from the semiconductor laser 12b reaches the photodiode 13b.

As the semiconductor lasers 12a and 12b, those having appropriate emission wavelengths λ1 and λ2 are selected according to the sample to be measured. If a variable wavelength laser whose wavelength can be arbitrarily changed is used, it is possible to easily perform measurement under optimum conditions for each sample to be measured. It should be noted that the light source is not limited to the semiconductor laser, in short, it can be brought into close contact with the ATR prism, can emit light of a specific wavelength, and can realize the property of projecting totally reflected light on the prism facing surface. If Further, the detector is not limited to the photodiode, and any detector can be used as long as it can be in close contact with the ATR prism and can detect the measurement light.

FIG. 5 shows the principle of dual wavelength measurement. In the figure, λ2 is a specific absorption wavelength to be measured by the sample to be measured, and λ1 is a background, that is, an absorption wavelength due to inclusions outside the object to be measured of the sample to be measured. Therefore,
The abundance of the sample to be measured is determined by the B / A ratio.
In this embodiment, for example, λ1 is selected as the emission wavelength of the semiconductor laser 12a and λ is selected as the semiconductor laser 12b.
If 2 is selected, the photodiodes 13a and 13a
Measurement based on this principle can be performed by obtaining the ratio of the outputs of b.

The material of the ATR prism 11 may be selected from the same standard as that of the conventional ATR prism.

At the time of measurement, the power supplies 14a and 14b are turned on to drive the semiconductor lasers 12a and 12b. Lights of wavelengths λ1 and λ2 are emitted from the semiconductor lasers 12a and 12b respectively, and travel through the ATR prism as shown by arrows in FIGS. 3 and 4, and are repeatedly totally reflected on the sample surface. The reflected measurement light will eventually come to the photodiode 13
a, 13b, the measurement signal is sent to the control unit 16 of the spectrum measuring apparatus via the amplifiers 15a, 15b and is calculated. The control unit calculates and outputs the ratio of each signal. In this way, the sample can be measured by the two-wavelength measurement.

In the above embodiment, the two semiconductor lasers are continuously oscillated simultaneously. However, when the sample or the prism includes a particle-like scattering element, only one of them is alternately oscillated by pulse oscillation. The influence of stray light due to scattering can be suppressed. Further, when there is an influence of outside light through the sample, it is possible to remove the influence of outside light by providing an OFF cycle for both the two semiconductor lasers.

Although the cut-off angle of the side surface is set to 45 degrees in the above-mentioned embodiment, the cut-off angle is not limited to this, and it is not limited to this.
It may be selected according to the relationship with the sample to be measured, such as 60 degrees or 60 degrees. Further, if the number of side surfaces is 6, three pairs of entrance and exit surfaces can be formed, and measurement at three wavelengths can be performed. Similarly, 8
The number may be increased to 10 faces.

FIGS. 6, 7 and 8 show another embodiment according to the present invention. FIG. 6 is a plan view and FIG.
7'is a sectional view, and FIG. 8 is an 8-8 'sectional view in FIG. This one utilizes the straightness of a laser, and a polygonal surface such as a square surface cut off at 45 degrees is provided on the upper surface (tip portion) of a columnar prism having a parallel upper surface and a lower surface. The sample to be measured is brought into close contact with the outer surface of the polygonal surface. The semiconductor lasers 22a and 22b and the photodiodes 23a and 23 are provided on the lower surface (the surface on the other end side).
Attach b. At this time, after the light emitted from the semiconductor laser 22a is reflected by the polygonal surface of the tip, the semiconductor laser 22 reaches the paired photodiodes 23a.
a and the photodiode 23a are attached. The same applies to the semiconductor laser 22b and the photodiode 23b. In this case, since the semiconductor laser and the photodiode are mounted on the same surface, the entrance surface and the exit surface have the same surface.

The manner in which the present invention is applied will be summarized below.

(1) An incident surface on which the measurement light is incident, a reflection surface on which the surface of the sample to be measured is closely attached and the measurement light is reflected by the surface of the sample to be measured, and the measurement light after being reflected by the reflection surface is emitted. In a spectrum measuring apparatus for measuring using an ATR prism having an output surface, the ATR prism has a plurality of pairs of an entrance surface and an exit surface, and each entrance surface is provided with a light source that emits light of a specific wavelength. Each detector is attached in close contact with the entrance surface, and each exit surface is attached in close contact with this exit surface by a detector that receives the measurement light emitted from the light source attached to the pair of entrance surfaces and reflected by the reflection surface. A spectrum measuring apparatus characterized in that control means for turning on a light source at different timings is provided, and total reflection absorption measurement of a plurality of wavelengths is performed at different timings.

(2) An incident surface on which the measurement light is incident, a reflection surface on which the surface of the sample to be measured is closely attached and the measurement light is reflected by the surface of the sample to be measured, and the measurement light after being reflected on the reflection surface is emitted. In a spectrum measuring apparatus that measures using an ATR prism having an emission surface, the ATR prism has a columnar shape, a light source emitting a specific wavelength on the lower surface thereof, and a reflection surface formed on the upper surface of the light source emitting from the light source. A plurality of pairs consisting of a detector that detects reflected measurement light that is reflected from the bottom surface and emitted again from the bottom surface,
A spectrum measuring device characterized in that total reflection absorption measurements of a plurality of wavelengths are measured by individual pairs.

[0019]

As described above, according to the present invention,
The ATR prism is provided with a plurality of pairs of an entrance surface and an exit surface, and a light source that emits light of a specific wavelength is attached to each entrance surface in close contact with the entrance surface. Each exit surface forms a pair of entrance surfaces. Since a detector for receiving the measurement light emitted from the light source attached to and reflected by the reflection surface is attached in close contact with this emission surface, it is possible to use A without using a complicated optical system.
TR measurement can be performed. Therefore, the number of components is reduced, the adjustment of the optical system is not necessary, and the device can be downsized. In particular, the compact and stable spectrum measuring apparatus of the present invention is effective for continuous monitoring of several specific wavelengths in the on-line measurement of the process.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a spectrum measuring apparatus that is an embodiment of the present invention.

FIG. 2 is a plan view of an ATR prism portion of a spectrum measuring apparatus which is an embodiment of the present invention.

3 is a sectional view taken along line 3-3 'in FIG.

4 is a cross-sectional view taken along line 4-4 'of FIG.

FIG. 5 is a diagram showing the principle of dual wavelength measurement.

FIG. 6 is a plan view (bottom view) of an ATR prism portion of a spectrum measuring apparatus which is another embodiment of the present invention.

7 is a sectional view taken along line 7-7 'of FIG.

8 is a sectional view taken along line 8-8 'of FIG.

FIG. 9 is a principle diagram of spectrum measurement using a conventional ATR prism.

[Explanation of symbols]

 10: spectrum measuring device 11: ATR prism 12a, 12b: semiconductor laser 13a, 13b: photodiode 16: control unit

Claims (1)

[Claims] 1. An incident surface on which measurement light is incident, a reflection surface on which the surface of the sample to be measured is in close contact and the measurement light is reflected by the surface of the sample to be measured, and the measurement light after being reflected by the reflection surface is emitted. In a spectrum measuring apparatus that measures using an ATR prism having an exit surface, the ATR prism has a plurality of pairs of entrance surfaces and exit surfaces, and each entrance surface is provided with a light source that emits light of a specific wavelength. By closely attaching to the surface, by attaching to each emission surface a detector that receives the measurement light emitted from the light source attached to the pair of incident surfaces and reflected by the reflection surface is closely attached to the emission surface, A spectrum measuring apparatus, characterized in that total reflection absorption measurement of a plurality of wavelengths is performed.