KR20160091187A - laser-induced plazma spectroscopy and laser induced plazma spectroscopic analyzer - Google Patents

Abstract

The present invention relates to a laser induced plasma spectrometry capable of securing data with high reliability by analyzing a spectrum of ambient light including more emission lines generated from a target material after focusing light emitted from the plasma, And a spectral analysis apparatus.
The laser induced plasma spectrometry improved the light receiving method of the present invention includes a laser irradiation step of irradiating a sample with a laser to generate a plasma, a focusing step of focusing the light emitted from the plasma in a predetermined direction, A light receiving step of excluding ambient light, and an analysis step of analyzing the spectrum of ambient light.

Description

[0001] The present invention relates to a laser-induced plasma spectrometer and a laser-induced plasma spectroscopic analyzer using the same,

[0001] The present invention relates to a laser induced plasma spectrometer and a laser induced plasma spectrometer using the same. More particularly, the present invention relates to a laser induced plasma spectrometer which improves the light receiving method and more specifically, And more particularly, to a laser induced plasma spectrometry capable of securing reliable data by analyzing a spectrum of ambient light.

Environmentally hazardous substances in soil have a wide range of species, and most of them are present in trace amounts in the environment and therefore involve considerable difficulty in the analysis process.

Chemical analysis methods such as Inductively Coupled Plasma Mass Spectrometry (ICP-MS) or Atomic Absorption Spectrometry (AAS) are used as methods for analyzing trace amounts of environmentally harmful substances such as heavy metals in soil Respectively.

The above methods require a lot of time, effort, and high cost through sampling, extraction, and complicated refining processes that are representative of the area to be contaminated. They also require expensive analytical instruments and skilled personnel. Therefore, there is a need for a technique capable of real-time monitoring of heavy metal substances harmful to the environment in a simple and quick manner while overcoming such shortcomings and ensuring analysis accuracy and rapid analysis speed.

One such technique is laser-induced breakdown spectroscopy (LIBS) or laser-induced plasma spectroscopy (LIPS), which focuses a laser beam onto a sample to excite a plasma generated by light energy, It is a spectrophotometric method used as a circle.

In this method, a laser pulse is irradiated onto a soil sample, and light emitted from the laser induced plasma, which is generated when intense pulse energy is transmitted to the material, is detected from the spectrum shape measured through the optical measuring system and the spectral unit, And the amount or type of a specific substance is analyzed. At high temperature, an emission line is generated from a specific material (the target material to be analyzed), and this emission line forms a peak in the intrinsic wavelength region in the spectrum analysis.

When analyzing using a spectrum, as shown in FIG. 1, a peak corresponding to a wavelength range of a target material such as a heavy metal, and a base continuous line base not corresponding to the wavelength range of the target material Can exist. Such basecontinuous lines may be light scattered by the nature of the soil medium itself, rather than by heavy metals. Thus, these background continuous bands can cause the reliability of the analysis to be reduced.

Korean Patent Registration No. 10-1084766 discloses a method of obtaining data including peaks and background continuous lines corresponding to a wavelength range of a target material in order to minimize influence of a medium and improve reliability of analysis Discloses a heavy metal analysis method capable of securing only a peak corresponding to a wavelength range of a target material by removing continuous bases from the background.

However, the above-mentioned patent has a problem in that data must be additionally processed in that data including only a background continuous line is first acquired and then processed to secure only a peak corresponding to a wavelength range of a target material.

Korean Patent No. 10-1084766: Method for analyzing heavy metals

The present invention has been made in order to solve the above problems, and it is an object of the present invention to provide a laser induced plasma spectrometry method capable of directly obtaining data in which a background continuous line is removed without processing additional data by improving the light receiving method of light emitted from the plasma And an object of the present invention is to provide a laser induced plasma spectrometer using the same.

According to an aspect of the present invention, there is provided a laser-induced plasma spectrometry including: a laser irradiation step of irradiating a sample with a laser to generate a plasma; A focusing step of focusing the light emitted from the plasma in a predetermined direction; A light receiving step of excluding the central portion of the focused light to obtain ambient light; And analyzing the spectrum of the ambient light.

Wherein the light receiving step is performed by disposing an optical fiber outside the central portion of the focused light to obtain the ambient light.

The spectral data obtained in the analysis step is characterized in that the background base line is reduced or eliminated.

In order to accomplish the above object, the present invention provides a laser induced plasma spectrometer comprising: a laser generator for emitting a laser toward a sample; A light focusing unit for focusing the light emitted from the plasma derived from the sample in a predetermined direction; A light receiving unit which excludes a central portion of the light focused by the light focusing unit to obtain ambient light; And an analysis unit for analyzing the spectrum of the ambient light obtained through the light receiving unit.

The light-receiving unit includes a light-receiving case having an irradiation surface to which the light converged by the light focusing unit is irradiated, and an optical fiber supported at the light-receiving case and having an end located in an area off the center of the irradiation surface.

As described above, according to the present invention, only the ambient light including more emission lines generated from the target material after focusing the light emitted from the plasma is received and analyzed. Thus, the background continuous line is removed Data can be obtained.

Therefore, the present invention has an advantage of securing data with enhanced reliability of analysis.

1 is a graph of spectroscopic data obtained by a conventional laser induced plasma spectrometry,
2 is a perspective view schematically showing a laser induced plasma spectrometer according to an embodiment of the present invention,
FIG. 3 is a diagram showing the operation of the laser induced plasma spectrometer of FIG. 2,
FIG. 4 is a perspective view showing a principal part of a light receiving unit applied to FIG. 2,
5 is a view for showing ambient light in the light focused by the light focusing unit,
FIG. 6 is a view showing an arrangement state of the optical fiber seen from the front of the light receiving portion of FIG. 4,
FIG. 7 is a view showing an arrangement state of the optical fiber seen from the rear side of the light receiving portion of FIG. 4,
8 is a view showing an arrangement state of the optical fiber seen from the front face of the light receiving unit applied to another embodiment,
FIG. 9 is a view showing an arrangement state of the optical fiber seen from the rear side of the light receiving portion of FIG. 8,
10 is a view showing an arrangement state of the optical fiber seen from the front face of the light receiving unit applied to another embodiment,
FIG. 11 is a view showing an arrangement state of the optical fiber seen from the rear side of the light receiving portion of FIG. 10,
12 is a photograph of light emitted from a plasma generated by irradiating a sample with a laser,
13 and 14 are comparative data and experimental data of copper, zinc and cadmium,
15 and 16 are lead comparison data and experimental data.

Hereinafter, a laser induced plasma spectrometry method and a laser induced plasma spectrometer using the same according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

2 to 4, a laser induced plasma spectrometer according to an embodiment of the present invention includes a laser generating unit for emitting a laser 41 toward a sample 10 to induce a plasma to a sample 10 A light focusing unit 50 for focusing the light emitted from the plasma generated in the sample 10 in a predetermined direction and a light source 40 for generating ambient light by excluding the central part of the light focused by the light focusing unit 50 A light receiving section 60 and an analyzing section 80 for analyzing the spectrum of the ambient light obtained through the light receiving section 60.

The sample 10 is mounted on the sample stage 31 and is mounted on the sample mounting portion 30. [ The sample mounting portion 30 is provided at an upper portion of the frame portion 20.

The frame portion 20 has a plate bottom plate 21 and a plate-like vertical plate 25 disposed at one side edge of the bottom plate 21 so as to be perpendicular to the bottom plate 21. [

The sample mounting portion 30 is provided on the bottom plate 21 and includes a sample table 31, a first body 32, an elastic portion 33, a pressure cover 34, Two bodies 36, and a rotation driving unit.

The sample stage 31 is formed in a cylindrical shape having an opening at the top and a closed structure at the bottom so that the sample 10 can be placed thereon.

The first body 32 has a lead groove 32a having a diameter corresponding to the diameter of the sample table 31 and drawn downward to a predetermined depth so as to be able to insert and withdraw the sample table 31 from the upper side downward, And is formed in a cylindrical shape. The first body 32 has a hollow structure. The inlet 32a of the first body 32 is further provided with an inlet groove 32b formed in a tapered shape so that a flange 34a of a pressing cover 34, which will be described later, And a lower end is seated in a seating groove 36a provided at the upper end of the second body 36. [

The elastic part 33 is inserted into the inlet groove 32a so as to be interposed between the sample table 31 and the first body 32 to urge the sample table 31 upwardly against the first body 32, And a spring is applied.

The pressurizing cover 34 is installed on the first body 32 so as to surround the sample stage 31 and presses the sample stage 31 downward and the sample 10 placed on the sample stage 31 And has an opening portion having a size corresponding to the opening of the sample table 31 so as to be exposed to the outside.

The upper portion of the pressure cover 34 is formed so as to be able to press down the sample table 31 in a state of being in contact with the upper end of the sample table 31, A flange 34a is provided and can be restrained or released from the first body 32 by a coupling portion described later. The flange 34a of the pressure cover 34 is seated in the entry groove 32b provided in the first body 32. [

The sample holder 31 is moved upward and downward by the external force generated when the pulse laser emitted from the laser generator 40 reaches the sample 10 mounted on the sample holder 31 on the side surface of the pressure cover 34 And a fastening hole 38 for fastening the position fixing member 39 for holding the initial setting position of the sample table 31 is formed on the outer circumferential surface of the sample table 31, A fastening hole 31a into which the position fixing member 39 can be inserted is formed at a position corresponding to the hole 38. [

The position fixing member 39 applies bolts or set screws that can be screwed into the fastening holes 31a.

The engaging portion is provided on the first body 32 and separates the pressurizing cover 34 from the first body 32 by restraining or releasing the first cover 32. The engaging portion is formed to partially occupy the upper portion of the first body 32 And a fixing bolt 35b for fixing the pair of pressing plates 35a and the pressing plate 35a to the upper end of the first body 32, respectively.

The pressing plate 35a is in contact with the upper surface of the flange 34a of the pressing cover 34 in a state of being seated on the upper end of the first body 32 and is fixed to the pressing body 34 by fastening the fixing bolt to the first body 32 Is not detached from the first body (32). The pressing plate 35a is formed with an insertion hole 35c into which the fixing bolt 35b can be inserted. The insertion hole 35c has a long hole formed in the left-right direction. Therefore, when the fixing bolt 35b is loosened, the pressing plate 35a can be moved in the left-right direction. When the fixing bolt 35b is tightened, the pressing plate 35a is fixed at a specific position.

The rotary drive unit rotates the first body 32 so as to rotate the sample 10 and has a seating groove 36a in which the lower end of the first body 32 is seated in an upper portion thereof, A worm wheel 37 having gear teeth formed in the lower part of the second body 36 along the circumferential direction of the second body 36, A worm 38 having gear teeth meshingly engaged with the wheel 37, and a drive motor 39 for rotating the worm 38.

The sample 10 placed on the sample stage 31 can be rotated through the configuration of the rotation driving unit as described above so that the pulse laser 41 emitted from the laser generating unit 40 have.

As an example of the sample, soil may be applied. In this case, contaminants such as heavy metals contained in the soil are quantitatively or qualitatively analyzed using the present invention. Here, a contaminant such as heavy metals means a target material to be analyzed.

The laser generator 40 is installed on the upper portion of the vertical plate 25 and emits the pulsed laser 41 downward. The laser generation unit 40 is designed to repeat oscillation and stop at a predetermined time interval, and applies a pulse-type laser emission. At this time, the energy of the pulse laser 41 can be increased as the ratio of the stop time to the oscillation time is increased. The laser generating part 40 may be a solid laser Nd: YAG, and may have a wavelength of 1064 nm or 532 nm.

A first optical lens 45 for converging the pulsed laser 41 emitted from the laser generating portion 40 and causing the pulsed laser 41 to be incident on the sample 10 is provided on the vertical plate 25 below the laser generating portion 40 have.

The light focusing unit 50 is provided on the path of the pulse laser 41 emitted from the laser generating unit 40, that is, between the laser generating unit 40 and the sample stage 31, And comprises a reflection plate 51 and a second optical lens 55 for focusing the light emitted from the plasma induced in the sample 10 by the passing and pulsed laser 41 in a predetermined direction.

The reflection plate 51 is formed with a through hole 52 on the inner side so as to allow the pulse laser 41 emitted from the laser generation unit 40 to pass therethrough and has a through hole 52 in the direction corresponding to the advancing direction of the pulse laser 41 A reflecting surface 53 for reflecting the light emitted from the plasma generated from the sample 10 to be parallel light is provided on one surface. The reflection plate 51 reflects the light emitted from the plasma in a direction perpendicular to the direction in which the pulsed laser 41 advances.

The second optical lens 55 focuses the light reflected by the reflection plate 51 and enters the light receiving unit 60, and a focusing lens having a predetermined magnification is used.

The light receiving unit 60 is disposed on the rear side of the second optical lens 55 and receives the light converged by the second optical lens 55 and transmits the light to the light separating unit 70.

In the present invention, the light receiving portion 60 excludes the central portion of the light focused by the light focusing portion 50 to obtain only the ambient light. 5, the light focused by the light focusing unit 50, that is, the focused light, is shown in FIG. 5. Light located on the center of the surface is referred to as a center light A, (B). When the shape of the focusing light is circular as shown in the figure, the central light A may be a region corresponding to 1/10 to 1/3 of the radius of the focusing light from the center C of the focusing light.

The present invention excludes the central light A through the light receiving unit 60 and acquires only the ambient light B and then analyzes the spectrum of the ambient light to obtain information of the target material.

As shown in FIG. 12, the central portion of the light emitted from the plasma is white, but the edge portions are red and blue. This seems to be due to the concentration of the emission line generated from the target material at the edge portion of the light emitted from the plasma. Accordingly, the central portion of the light emitted from the plasma is excluded, only the ambient light is obtained, and the spectral data is analyzed from the central portion, thereby obtaining the spectral data from which the background continuous line is removed.

The light receiving unit 60 includes a light receiving case 61 and a plurality of optical fibers 67 supported by the light receiving case 61.

The light receiving box 61 is provided in the support bracket 69. On the front surface of the light receiving case 61, an irradiation surface 63 to which the light focused by the light focusing unit 50 is irradiated is formed. Preferably, the light converging unit 50 converges the light to the same size as the irradiation surface 63 and irradiates the light onto the irradiation surface 63.

A plurality of optical fibers 67 are inserted into the light receiving case 61 in a state of being inserted therein. The end of the optical fiber 67 into which the light is incident is installed so as to be exposed to the irradiation surface 63. For example, an insertion hole may be formed at regular intervals along the edge of the irradiation surface 67, and a single optical fiber 67 may be inserted into each insertion hole.

The end of the optical fiber 67 into which the light is incident is located in an area off the center of the irradiation surface 63. In the illustrated example, the ends of the plurality of optical fibers 67 are arranged circularly along the edge of the irradiation surface 63. The arrangement of the optical fibers 67 is shown in Fig. 6 is a diagram schematically showing the arrangement state of the optical fiber 67 seen from the front face of the light receiving unit. The end of the optical fiber 67 is disposed outside the center C of the irradiation surface 63. [

The other end of the optical fiber 67 inserted into and supported by the light receiving case 61 extends to the later-described light separating unit 70. At this time, the optical fibers 67 extending to the light-distributing unit 70 through the rear surface of the light-receiving box 61 extend in a line-aligned state to transmit light as shown in FIG. 7 is a view schematically showing an arrangement state of the optical fibers viewed from the rear side of the light receiving unit.

8 and 9 illustrate a light receiving unit that can be applied to another embodiment of the present invention. FIG. 8 is a view schematically showing the arrangement state of the optical fibers viewed from the front of the light receiving unit, and FIG. 9 is a view showing the arrangement state of the optical fibers viewed from the rear side of the light receiving unit.

Fig. 8 shows that the optical fibers 67 of smaller diameter as compared to Fig. 6 are arranged in a circle spaced apart from the irradiation surface 63 of the light receiving box 61 at regular intervals. The end of the optical fiber 67 into which the light is incident in FIG. 8 is located between the edge C of the irradiation surface 63 and the edge of the irradiation surface 63.

10 and 11 illustrate a light-receiving portion that can be applied to another embodiment of the present invention. FIG. 10 is a view schematically showing the arrangement state of the optical fibers viewed from the front of the light receiving unit, and FIG. 11 is a view showing an arrangement state of the optical fibers viewed from the rear side of the light receiving unit.

Fig. 10 shows that the optical fibers 67 of smaller diameter are arranged in a circular shape on the irradiation surface 63 of the light receiving box 61, as compared with Fig. 10, the end of the optical fiber 67 into which the light is incident is positioned between the edges of the irradiation surface 63 at the center C of the irradiation surface 630.

With the structure of the light receiving portion as described above, the center light is excluded from the light focused by the light focusing portion, and only the surrounding light corresponding to the end portion of the optical fiber is transmitted through the optical fiber.

Referring to FIG. 2, the spectroscopic unit 70 is for spectrally separating ambient light transmitted through the light receiving unit 60, and separates the components included in the ambient light into respective wavelength ranges. The spectroscopic unit 70 typically employs a spectrometer used to separate light by wavelength. For example, the spectroscopic unit 70 may be a product capable of detecting a band of 200 to 780 nm.

The analysis unit 80 is a computing device that quantitatively and qualitatively analyzes the spectrum of light output from the spectroscopic unit 70. The spectroscopic analysis unit 80 detects a spectrum inherent to a substance emitted from a substance contained in the sample 10, Identify the substances contained in.

Hereinafter, an analysis method using the laser induced plasma spectrometer shown in FIG. 2 to FIG. 4 will be described.

First, a laser is irradiated to the sample 10 to generate a plasma.

After the prepared sample 10 is mounted on the sample stage 31, a pressurizing cover 34 is provided to fix the pressurizing cover 34 and the sample stage 31. Then, the presser plate 35a is moved in the direction of the sample table 31, and then the presser cover 34 is fixed by tightening the fixing bolts 35b.

Power is supplied to the laser generation unit 40 located above the sample 10 to generate a plasma by irradiating a pulsed laser to the sample 10 from the laser generation unit 40. The pulsed laser generated in the laser generating unit 40 is converged while passing through the first optical lens 45 and passes through the through hole 52 of the reflecting plate 51 to be incident on the sample 10. At this time, the plasma is induced in the sample 10 by the energy of the pulse laser 41.

Next, the light emitted from the plasma is focused in a predetermined direction.

The light emitted from the plasma is reflected in a direction set by the reflection plate 51 provided on the path of the laser. In the illustrated example, light is reflected to the second optical lens 55 side by the reflection curved surface 53 of the reflection plate 51 provided on the sample 10. As described above, the reflection plate 51 is provided between the sample 10 and the laser generating unit 40 to analyze the light emitted in the direction of the laser propagation path among the light radiated from the plasma, so that the improved signal intensity can be obtained, Have the ability.

The light reflected by the reflection plate 51 is focused through the second optical lens 55 and irradiated to the light receiving unit 60. [

Next, the light receiving portion 60 excludes the central portion of the converged light to obtain ambient light. This is because only the ambient light can be obtained by disposing the optical fiber 67 outside the central portion of the converged light as described above.

The ambient light transmitted through the optical fiber 67 of the light receiving unit 60 to the light splitting unit 70 is provided to the analyzing unit 80 in a spectrum form separated by wavelengths. The analyzing unit 80 can quantitatively or qualitatively detect a specific substance contained in the sample 10 by analyzing the spectrum provided.

As described above, according to the present invention, only the ambient light including more emission lines generated from the target material after focusing the light emitted from the plasma is received and analyzed, so that the background continuous line is reduced or eliminated without processing additional data Spectral data can be obtained. Therefore, it is possible to secure data that increases the reliability of the analysis.

<Experimental Example>

The comparison data obtained by transmitting all of the collected light to the analyzer using the same soil sample and the experimental data obtained after receiving only the ambient light among the collected light using the light receiving unit as shown in FIG.

FIG. 6 shows comparative data of copper, zinc and cadmium, and FIG. 7 shows experimental data of copper, zinc and cadmium.

FIG. 7 shows that the background continuous lines are removed much in comparison with FIG. Therefore, FIG. 7 shows that the shape of the peak is clear and the intensity is higher.

In FIG. 6, the area of the peak is about 2.43, whereas in FIG. 7, the area of the peak is about 6.86, which is about 2.8 times that of the peak.

Fig. 8 is comparative data of lead, and Fig. 9 is experimental data of lead.

Comparing FIG. 8 and FIG. 9, it can be seen that FIG. 9 shows that the base line is removed much more than in FIG. 8, and the shape and strength of the peak are more pronounced and higher.

In FIG. 8, the peak area value is about 0.94, whereas in FIG. 9, the peak area value is about 4.22, which is quantitatively increased by about 4.5 times.

From these experimental results, it was confirmed that the reliability of the analysis can be improved by extracting and analyzing only the ambient light after focusing the light emitted from the plasma.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the scope of the invention. . Accordingly, the true scope of protection of the present invention should be determined only by the appended claims.

10: Sample
20: frame part 30: sample mounting part
40: laser generating unit 50: light focusing unit
60: light receiving section 70:
80: Analytical Department

Claims (5)

A laser irradiation step of irradiating the sample with a laser to generate plasma;
A focusing step of focusing the light emitted from the plasma in a predetermined direction;
A light receiving step of excluding the central portion of the focused light to obtain ambient light;
And analyzing the spectrum of the ambient light by using a laser beam. The laser induced plasma spectrometry method according to claim 1, wherein the light receiving step is performed by arranging an optical fiber outside a central portion of the focused light to obtain the ambient light. [3] The laser induced plasma spectrometry according to claim 2, wherein the spectral data obtained in the analysis step is reduced or eliminated from the background base line. A laser generating unit for emitting a laser toward the sample;
A light focusing unit for focusing the light emitted from the plasma derived from the sample in a predetermined direction;
A light receiving unit which excludes a central portion of the light focused by the light focusing unit to obtain ambient light;
And an analyzer for analyzing the spectrum of the ambient light obtained through the light receiving unit. The optical pickup apparatus according to claim 4, wherein the light-receiving unit includes a light-receiving case having an irradiation surface to which the light converged at the light focusing unit is irradiated, and an optical fiber supported at the light-receiving case and having an end located in an area off- Wherein the laser beam is irradiated by the laser beam.

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