JP2003121361A - Method and apparatus for measuring micro constituent using laser beam - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a micro constituent-measuring method and a micro constituent-measuring apparatus using laser beams that can simultaneously and accurately detect a constituent having a different wavelength in plasma beams and constituents having high and low signal light intensity in a wide wavelength range by inhibiting noise, and at the same time easily analyze detection data and adjust the apparatus. SOLUTION: When micro constituents in the substance to be measured are to be changed into plasma by laser beams and the plasma beams are to be dispersed for detecting micro constituents, the plasma beams are passed through a plurality of filters where a transmission wavelength region is limited for applying to a plurality of optical fibers, and the plasma light from the optical fibers is dispersed for each wavelength and is detected by such detection means as a CCD camera.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to the detection of heavy metals in exhaust gas and water and impurities (Si, A) in cement.
It is used for the detection of l) and the like, and collects a laser beam to turn trace components such as heavy metals in the substance to be measured into plasma, and then spectrally analyzes the plasma light to detect the trace components in the substance to be measured. The present invention relates to a method and an apparatus for measuring a trace component using laser light.

[0002]

2. Description of the Related Art Heavy metals (Na,
Hg, Cu) detection, or impurities (S in cement)
A laser-induced breakdown method (hereinafter referred to as LIBS method) is provided as one of the methods for detecting (i, Al).

FIG. 4 is a schematic configuration diagram of a trace component measuring device in a substance to be measured by the LIBS method. In the figure, 50 is a laser device, and a laser beam 20 emitted from the laser device 50 is a lens 2 and a hole. It is condensed through the open beam splitter 3 and is irradiated to the substance 8 to be measured. The temperature rise of the substance 8 to be measured by such irradiation (10,000 to 20)
(000 ° C.) generates plasma light 21, and part of the plasma light 21 is generated by the beam splitter 3 and the lens 4.
To the photodetector 51. And the photodetector 51
At this point, the plasma light 21 is dispersed and input to a computer 52, and a heavy metal waveform to be detected as shown in FIGS. 5A and 5B (Hg in FIG. 5A and Cd in FIG. 5B). The concentration of the heavy metal is detected from the signal intensity of the heavy metal appearing in the plasma waveform in which a plasma waveform is shown).

In the LIBS method, since a plurality of trace components emit plasma light at different wavelengths at the same time,
Usually, the plasma light is dispersed by a spectroscope to obtain signal light. In this case, in order to simultaneously measure other components, it is necessary to detect signal lights of a plurality of wavelengths with high wavelength resolution. An Eschel spectroscope is available as a method for detecting signal light of a plurality of wavelengths with high wavelength resolution as described above.

FIG. 6 is an explanatory diagram of a spectroscopic method using a diffraction grating for high-order light (hereinafter referred to as a grating) that reflects and disperses high-order light in plasma light in such an Eschel type spectroscope. , 61 is a second grating, and the first and second gratings are
The gratings 60 and 61 have a large number of light reflecting grooves 60a and 61a formed on their surfaces. The grooves 60a and 61a are constructed so that the reflection angles differ depending on the wavelength of the light that reflects them. Further, the groove 61 a of the second grating 61 is formed in the first grating 60.
The groove 60a is provided in a direction of 90 °.

In the spectroscopic method using the grating in such an Eschel type spectroscope, the measured substance 8
Plasma light from the first grating groove 60.
It is incident on a and is reflected at a reflection angle that differs depending on its wavelength. That is, in the figure, for example, wavelengths 200, 300, 4
00, 800 nm ··· primary light, 200, 400 nm ·
・ Secondary light, 200 nm, third light, etc.
The light from the next light to the higher light is reflected at different reflection angles for each wavelength. The plasma light reflected by the first grating 60 is incident on the groove 61 a of the second grating 61. Since the groove 61a is provided in the direction of 90 ° with respect to the groove 60a of the first grating 60, the groove 6a
The plasma light reflected by 1a spreads in the direction at right angles, and as shown by the arrow in the figure, a signal having a waveform arranged in a band for each wavelength is obtained. By capturing an image of this waveform signal with the CCD camera 31, a spectral signal for each waveform of plasma light is obtained.

[0007]

However, the spectroscopic method using the grating in the Eschel type spectroscope has the following problems. That is, in such a spectroscopic method, the plasma light 21 having different wavelengths reflected by the two gratings 60 and 61 in which the directions of the grooves 60a and 61a intersect at 90 ° is different from the signal light (plasma light) on the screen of the CCD camera 31. Since a high-intensity component and a low-intensity component are detected at the same time, it is difficult to match the dynamic range of the CCD camera 31 with the required detection target component, and it is difficult to perform accurate spectroscopy, and noise with high signal light intensity can be removed. Have difficulty. Furthermore, as described above, since components having different intensities are detected at the same time, it is difficult to analyze the detection data and adjust the device.

That is, in such a spectroscopic method, a component having a different wavelength and a component having a high signal light intensity and a component having a low signal light intensity are simultaneously detected, so that noise is generated when the detection signal of the CCD camera 31 is obtained in a wide wavelength range. It becomes large, and when trying to obtain the detection signal finely, the wavelength range becomes narrower,
Furthermore, when trying to obtain a multi-component detection signal by widening the wavelength range, the resolution of the spectroscopic device including the CCD camera 31 is lowered and overlapping signals are detected, which are contradictory problems.

In view of the above problems of the prior art, the present invention can detect a component having different wavelengths of plasma light, a component having high signal light intensity and a component having low signal light intensity simultaneously in a wide wavelength range and with high accuracy while suppressing noise. In addition, it is an object of the present invention to provide a trace component measuring method using a laser beam and an apparatus thereof, which facilitates analysis of detection data and adjustment of the apparatus.

[0010]

In order to solve the above problems, the present invention provides an invention as set forth in claim 1, in which a trace amount of heavy metals and the like in a substance to be measured is converted into plasma by condensing laser light. In a trace component measuring method for detecting a trace component in the substance to be measured by dispersing the plasma light, the plasma light is incident on a plurality of optical fibers through a plurality of filters having a limited transmission wavelength region, There is proposed a method for measuring a trace amount component using a laser beam, which is characterized in that the plasma light from the optical fiber is spectrally separated by wavelength and detected by a detecting means such as a CCD camera.

In the first aspect of the present invention, preferably, as in the second aspect, the plasma light from the optical fiber is incident on the diffraction grating for the higher-order light and reflected by the diffraction grating for each wavelength.

The invention according to claims 3 to 5 is defined by claim 1.
According to the invention of an apparatus for carrying out the invention of claim 3, the invention of claim 3 condenses the laser light emitted from the laser light irradiating means to turn trace components such as heavy metals in the substance to be measured into plasma, and the plasma In a trace component measuring device using a laser beam configured to detect a trace component in the substance to be measured by dispersing light with a spectrometer, a plurality of transmission wavelength regions of the plasma light are limited. A filter and a plurality of optical fibers for propagating the plasma light passing through the filter are provided, and the spectroscopic device is configured to detect the plasma light from the optical fiber by spectrally separating it by wavelength. To do.

According to a fourth aspect of the present invention, in the third aspect, the spectroscopic device is provided with a diffraction grating for high-order light that reflects the plasma light to disperse the light into wavelengths.

According to a fifth aspect of the present invention, in the third aspect, the plurality of filters are vapor-deposited on the plurality of optical fibers, respectively, and the filters and the optical fibers are integrated for each transmission wavelength region.

According to the first to fifth aspects of the present invention, a plurality of filters having a limited transmission wavelength region of the plasma light, which emits the plasma light emitted by converting the trace components in the substance to be measured into plasma by the laser light, are provided. By separating each wavelength by each wavelength and making it incident on a plurality of optical fibers connected to each filter, and reflecting the plasma light from the optical fibers from the first-order light to the higher-order light by the diffraction grating for higher-order light according to claim 2. Disperse. That is, according to such an invention, the signal light separated for each wavelength by the plurality of filters is further separated by the diffraction grating for higher-order light from the first-order light to the higher-order light, so that the detection device such as the CCD camera can be configured as described above. It becomes possible to clearly separate and detect the signal light that has been spectrally separated for each wavelength.

Therefore, according to the present invention, it is possible to finely and precisely obtain plasma light (signal light) in a detection device such as a CCD camera while suppressing noise in a wide wavelength range, and to disperse multi-component plasma light into a spectrum. Also, it is possible to clearly separate and detect without generating overlapping signals due to deterioration of resolution in the detection device, and thus it is possible to measure many kinds of components with one detection device Is reduced.

Further, the signal light is separated into wavelengths by a plurality of filters, and the signal light is further separated into higher order light by a diffraction grating for higher order light. Since the signal light is clearly separated for each wavelength and detected, it is easy to analyze the detection data from the detection device and adjust the device for analysis, and it is possible to measure trace components in the substance to be measured with high efficiency. You can do the work.

According to the fifth aspect of the present invention, the filter and the optical fiber are compactly combined by integrating the plurality of filters and the optical fiber for each transmission wavelength region, and the light passing through the filter is also combined. The structure for simplifying the structure is not required because a mirror for making the light incident on the optical fiber is unnecessary.

According to a sixth aspect of the present invention, the trace amount of heavy metal or the like in the substance to be measured is converted into plasma by condensing the laser beam emitted from the laser beam irradiating means, and the plasma beam is analyzed by the spectroscopic device. In a trace component measuring device using a laser beam configured to detect a trace component in the substance to be measured by spectroscopy, a plurality of mirrors in which the reflection wavelength region of the plasma light is limited, and the mirror And a plurality of optical fibers that propagate the reflected plasma light, and the spectroscopic device is configured to disperse and detect the plasma light from the optical fibers for each wavelength.

According to the invention, since the plasma light is detected by spectrally splitting the plasma light according to the wavelength by using the plurality of mirrors in which the reflection wavelength region of the plasma light is limited, the plasma light is reflected and deflected. The mirror for this can also have the function of a spectroscope that separates plasma light by wavelength, and a filter is not required, and the device is simplified.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below with reference to the embodiments shown in the drawings. However, the dimensions, materials, shapes, relative positions, etc. of the components described in this embodiment are not intended to limit the scope of the present invention thereto, unless there is a specific description, and are merely illustrative examples. Nothing more.

FIG. 1 is a schematic configuration diagram on the filter side in a heavy metal measuring apparatus for exhaust gas using laser light according to the first embodiment of the present invention, and FIG. 2 is a schematic configuration diagram on the spectroscopic apparatus side in the first embodiment. Is. FIG. 3 is an external perspective view of a main part showing a second embodiment of the present invention. FIG. 4 is a configuration diagram of a trace component measuring apparatus by the LIBS method to which the present invention is applied, and FIG. 5 is a diagram showing an example of a plasma optical signal.

In FIG. 4 showing a LIBS method trace amount measuring apparatus to which the present invention is applied, a laser device 50 is provided, and a laser beam 20 emitted from the laser device 50 passes through a lens 2 and a beam splitter 3 having a hole. Then, the substance to be measured 8 is condensed and irradiated. A part of the plasma light generated by the temperature rise of the substance 8 to be measured due to such irradiation is detected by the beam splitter 3 and the lens 4 by the photodetector 51.
To transmit. Then, the photodetector 51 disperses the plasma light and inputs it into a computer 52, as shown in FIG.
The heavy metal waveform to be detected as shown in FIG.
The concentration of the heavy metal is detected from the signal intensity of the heavy metal appearing in the plasma waveform in which (A) shows Hg and (B) shows Cd plasma waveform).

The present invention relates to a method and an apparatus for spectrally dispersing the plasma light in the trace component measurement by the LIBS method. 1 and 2 showing the first embodiment, 50 is a laser device, 2 is a lens for condensing the laser beam 20 and transmitting the plasma beam 21, 3 is a beam splitter with a hole, and 4 is an optical path of the laser beam 20. It is a lens that is arranged in the right-angled direction. Reference numerals 6a, 6b, and 6c are filters (1), (2), and (3), and are configured so that the transmission wavelength regions of the plasma light 21 are different. 7a, 7
b and 7c are the filters (1) 6a, (2) 6b,
(3) Optical fibers (1), (2), and (3) that are incident upon and propagate the plasma light 21 that has passed through 6c.

The filter (1) 6a is the lens 4
The filter (2) 6b and the filter (3) 6c are arranged in the direction perpendicular to the transmission line. Reference numeral 5 is a perforated beam splitter arranged on the transmission line of the lens 4, and transmits the plasma light 21 passing through the lens 4 through the central hole to the filter (1) 6a on the transmission line of the lens 4. With
A filter (2) 6b and a filter (3) 6 which reflect the plasma light 21 and are arranged in a direction perpendicular to the transmission line.
It is incident on c. A plurality of filters (1) 6a, (2) 6b, (3) 6c and optical fibers (1) 7a, (2) 7b, (3) 7c are provided.

In FIG. 2, reference numeral 07 is an optical fiber, which is constructed as in the second embodiment shown in FIG. 3 (details will be described later).
The optical fibers (1) 7a, (2) 7b, (3) 7c
And the filters (1) 6a, (2) 6b, and (3) 6c are integrated. 30 is the optical fiber (1)
An imaging spectroscope that disperses the plasma light (signal light) 21 that has passed through 7a, (2) 7b, and (3) 7c, and is configured as follows.

10a and 10b are first mirrors, 11a,
11b is a second mirror, 33 is a grating for high-order light (diffraction grating), 31 is a CCD camera, and the plasma light 21 incident from the optical fiber 07 is reflected by the first mirror 1.
0a, the second mirror 11a reflects the plasma light 21 reflected by the second mirror 11a, and the high-order light grating 33 separates the plasma light 21 into wavelengths, which are incident on the second mirror 11b. The second spectroscopic plasma light 21 received by the second mirror 11b is received by the first mirror 10b and CC
The light is incident on the D camera 31.

In the trace component measuring device having such a structure, the laser light 20 emitted from the laser device 50 is used.
Is condensed through the lens 2 and the perforated beam splitter 3 and irradiated on the substance 8 to be measured, plasma 021 is generated, and a part of the plasma light 21 is transmitted through the lens 4. The plasma light 21 transmitted through the lens 4 reaches the filter (1) 6a through the hole of the beam splitter 5, and is reflected by the beam splitter 5 to reach the filter (2) 6b, and further, the beam splitter 5.
It is reflected by and reaches the filter (3) 6c.

Since the filters (1) 6a, the filters (2) 6b, and the filters (3) 6c have different transmission wavelength regions, as described above,
The plasma light 21 is spectrally separated for each wavelength by the filters (1) 6a, the filters (2) 6b, and the filters (3) 6c, and the filters (1) 6a, the filters (2) 6b, and the filters (3) are separated. ) The plasma light 21 having different wavelengths separated by 6c is an optical fiber (1) 7 connected to each of the filters 6a, 6b, 6c.
a, (2) 7b, (3) 7c, is propagated through the optical fibers (1) 7a, (2) 7b, (3) 7c, and is incident on the first mirror 10a in FIG.

The plasma light 21 received and reflected by the first mirror 10a is reflected by the second mirror 11a and is incident on the high-order light grating 33. The high-order light grating 33 has the same structure and function as the grating 60 shown in FIG. 6, and the plasma light 21 incident on the high-order light grating 33 receives the groove (see FIG. 6) of the high-order light grating 33. 60a), the light from the primary light to the high-order light is reflected with a reflection angle that differs depending on the wavelength.

The plasma light 21 spectrally separated for each wavelength in the filter (1) 6a, the filter (2) 6b, and the filter (3) 6c is subjected to the second-stage spectral action in the high-order light grating 33. Fine signal light in which noise is suppressed is clearly separated for each wavelength and is incident on the second mirror 11b. The separated plasma light 21 received by the second mirror 11b is received by the first mirror 10b and is incident on the CCD camera 31. In the CCD camera 31, 32 in FIG.
A signal light image clearly separated for each wavelength as shown in a, 32b, and 32c is obtained.

Therefore, according to such an embodiment, a plurality of plasma lights 21 which emit light when the trace components in the substance 8 to be measured are made into plasma by the laser light are transmitted in a limited wavelength range of the plasma light 21. In the example, three filters 6a, 6b, 6c are separated for each wavelength and incident on a plurality of optical fibers 7a, 7b, 7c connected to the respective filters 6a, 6b, 6c, and the optical fibers 7a,
Further spectroscopic plasma light from 7b and 7c is reflected by the high-order light grating 33 from the primary light to the high-order light to perform further spectroscopic analysis, and is spectrally separated for each wavelength by a plurality of filters 6a, 6b and 6c. The signal light is further dispersed by the high-order light grating 33 from the primary light to the higher-order light, so that the signal light dispersed in the CCD camera 31 as described above is separated by wavelength as shown in FIG. It is possible to clearly separate and detect.

As a result, the plasma light (signal light) 21 can be finely and accurately obtained in the CCD camera 31 while suppressing noise in a wide wavelength range, and the multi-component plasma 21 light can be resolved in a spectroscopic and detection device. Can be clearly separated and detected without the generation of overlapping signals due to the decrease of the signal. Therefore, one CCD camera 31 can measure many kinds of components.

In the second embodiment of the present invention shown in FIG. 3, a plurality of filters 6a, 6b and 6c configured to have different transmission wavelength regions are provided to a plurality of optical fibers 7a and 7a.
b and 7c are vapor-deposited on the end portions of the filters 6a and 6c, respectively.
b and 6c and the optical fibers 7a, 7b and 7c are integrated for each transmission wavelength region. Other configurations are the same as the first
This is the same as the embodiment, and the same members are designated by the same reference numerals.

In this embodiment, since the plurality of filters 6a, 6b, 6c and the optical fibers 7a, 7b, 7c are integrated for each transmission wavelength region, the filters 6a, 6b, 6c and the optical fibers 7a, 7b, 7c is compactly combined. In addition, the filter 6a,
The optical fiber 7 receives the plasma light 21 that has passed through 6b and 6c.
A mirror for making the light incident on a, 7b, and 7c unnecessary, the number of parts is reduced, and the structure is simplified.

Further, in the third embodiment of the present invention, although not shown, in FIG.
a, filter (2) 6b, and filter (3) 6c
Is omitted, and the plasma light 2 is transmitted to the plurality of beam splitters 5.
Ones having different reflection wavelength regions are used. This allows
The beam splitter 5 for reflecting and diverting the plasma light 21 can also have the function of a spectroscope for separating the plasma light by wavelength, and the filters as in the first and second embodiments are not necessary. The device is simplified.

[0037]

As described above, according to the first to fifth aspects of the present invention, the signal light dispersed for each wavelength by the plurality of filters is further dispersed by the diffraction grating for higher order light from the first order light to the higher order light. By performing the two-step spectroscopy of
It is possible to clearly separate the signal light separated by a detection device such as a CCD camera for each wavelength for detection.

Therefore, according to the present invention, plasma light (signal light) can be finely and accurately obtained while suppressing noise in a wide wavelength range in a detection device such as a CCD camera, and multi-component plasma light can be spectrally separated. Also, it is possible to clearly separate and detect without generating overlapping signals due to deterioration of resolution in the detection device, and thus it is possible to measure many kinds of components with one detection device Is reduced.

Further, since the signal light is split into two stages as described above, the split signal light can be clearly separated and detected by the detection device such as a CCD camera. It becomes easy to analyze the detection data from and to adjust the device for analysis.

According to the present invention, the filter and the optical fiber are integrated in each transmission wavelength region by integrating the plurality of filters and the optical fiber, whereby the filter and the optical fiber are compactly coupled and the light passing through the filter is integrated. A mirror for making the light incident on the optical fiber is unnecessary, the number of parts is reduced, and the structure is simplified.

Further, according to the sixth aspect, since the plasma light is detected by spectrally splitting the plasma light according to the wavelength using a plurality of mirrors having a limited reflection wavelength region of the plasma light, the plasma light is reflected. The mirror for changing the direction can also have the function of a spectroscope that separates the plasma light according to wavelength, and a filter is not required, so that the number of parts can be reduced and the apparatus can be simplified.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram on a filter side in a heavy metal measuring apparatus for exhaust gas using a laser beam according to a first embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of a spectroscopic device side in the first embodiment.

FIG. 3 is an external perspective view of a main part showing a second embodiment of the present invention.

FIG. 4 is a configuration diagram of a trace component measuring device according to the LIBS method to which the present invention is applied.

FIG. 5 is a diagram showing an example of a plasma optical signal.

FIG. 6 is a trace component measuring device by the LIBS method.

[Explanation of symbols]

2, 4 lens 3, 5 beam splitter 6a, 6b, 6c filters (1), (2), (3) 7a, 7b, 7c optical fibers (1), (2), (3) 8 Substance to be measured 10a, 10b First mirror 11a, 11b Second mirror 20 laser light 21 Plasma light 30 Imaging Spectrometer 31 CCD camera 33 Higher-order light grating 50 laser device 51 Photodetector

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 2G020 AA03 AA04 AA05 BA12 BA14                       CA01 CB23 CC02 CC26 CC47                       CD24 CD51                 2G043 AA01 BA01 CA06 EA10 FA05                       FA06 GA02 GA04 GB01 HA01                       HA02 HA05 HA09 JA03 JA04                       KA02 KA03 LA03

Claims (6)

[Claims] 1. A trace component such as a heavy metal in a substance to be measured is turned into plasma by condensing laser light, and the trace component in the substance to be measured is detected by spectrally dispersing the plasma light. In the trace component measuring method, the plasma light is made incident on a plurality of optical fibers through a plurality of filters having a limited transmission wavelength region, and the plasma light from the optical fibers is spectrally separated by wavelength and detected by a detection means such as a CCD camera. A method for measuring trace components using laser light, which is characterized in that 2. The trace component measuring method using laser light according to claim 1, wherein the plasma light from the optical fiber is made incident on and reflected by a diffraction grating for higher-order light to be spectrally separated for each wavelength. 3. The laser light emitted from the laser light irradiating means is condensed to turn trace components such as heavy metals in the substance to be measured into plasma, and the plasma light is dispersed by a spectroscopic device to obtain the spectrum. In a trace component measuring device using a laser beam configured to detect a trace component in a substance to be measured, a plurality of filters having a limited transmission wavelength region of the plasma light, and the plasma light passed through the filter. With multiple propagating optical fibers,
The spectroscopic device is configured to detect the plasma light from the optical fiber by spectrally separating the plasma light according to wavelength, and the trace component measuring device using laser light. 4. The trace component measuring device using a laser beam according to claim 3, wherein the spectroscopic device includes a diffraction grating for high-order light that is spectroscopically separated into wavelengths to reflect the plasma light. 5. The laser beam according to claim 3, wherein the plurality of filters are vapor-deposited on the plurality of optical fibers, respectively, and the filters and the optical fibers are integrated for each transmission wavelength region. Trace component measuring device. 6. The laser light emitted from the laser light irradiating means is condensed to turn trace components such as heavy metals in the substance to be measured into plasma, and the plasma light is dispersed by a spectroscopic device to obtain the plasma light. In a trace component measuring device using a laser beam configured to detect a trace component in a substance to be measured, a plurality of mirrors in which the reflection wavelength region of the plasma light is limited, and plasma reflected by the mirrors A plurality of optical fibers for propagating light, and the spectroscopic device is configured to detect the plasma light from the optical fibers by spectrally separating it by wavelength, and measure a trace component using laser light. apparatus.