JP2001165857A - Icp emission spectroscopic analyzer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ICP emission spectroscopic analyzer which can easily perform observation from the lateral direction and/or the axial direction with a spectroscope and a plasma torch fixed, especially can perform observation under the condition with larger quantity of light from the lateral direction. SOLUTION: This ICP emission spectroscopic analyzer has a mirror ring 11 which is provided between a plasma torch 1 and a light transmission part 7 for a spectroscope 4 and whose inner surface serves as a mirror, and both the plasma light emitted to any direction of the ambience and the plasma light to the axial direction onto the spectroscope via the light conduction part 7. Switching between the lateral direction and the axial direction is implemented by placing an annular mask 16 and a disk-shaped mask in front of the light transmission part 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an ICP emission spectrometer, and more particularly, to an ICP emission spectrometer capable of easily switching an observation direction of a plasma emission portion of the ICP emission spectrometer. Also, when observing plasma light from the lateral direction, I
The present invention relates to a CP emission spectrometer.

[0002]

2. Description of the Related Art In an ICP emission spectrometer (hereinafter abbreviated as ICP), there are two methods for observing plasma light. One is the case of lateral observation in which light from the plasma is guided to the spectroscope from the lateral direction as shown in FIGS. 1 and 2, and the other is the central axis of the plasma as shown in FIGS. 3 and 4. This is a case of axial observation in which light is guided from a direction to a spectroscope and analyzed. In these figures, reference numeral 1 denotes a plasma torch to which a sample gas formed by an atomizer (not shown) is supplied. Reference numeral 2 denotes a coil. When high-frequency power is applied to the coil, a gas containing the sample is ionized to generate a plasma 3. Reference numeral 4 denotes a spectroscope for analyzing plasma. In order to guide the measurement light from the plasma 3 to the spectroscope, a light guide unit 7 using a converging lens 5 and a mirror 6 for changing the optical path direction is attached according to each observation direction. The light guide 7 has at least one lens 5 for guiding the plasma light to the spectroscope 4. Reference numeral 8 denotes a well-known motor-driven plasma torch moving mechanism for changing an observation position (observation height) in a lateral observation.

[0003] The lateral observation and the axial observation each have characteristics. That is, in the whole plasma light, the “analysis light by the sample” (not including the light emission by Ar as a carrier gas) used for analysis mainly emits near the central axis of the plasma light, so that it is observed in the lateral direction. In this method, only a part of the analysis light from the sample existing linearly along the central axis is used in the analysis, and as a result, the absolute amount of the analysis light from the sample guided to the spectrometer is small, resulting in high sensitivity. Measurement is not suitable. On the other hand, lateral observation is suitable for analysis of relatively high-concentration samples because it is less affected by self-absorption and coexisting elements. On the other hand, in the axial observation, the plasma light near the central axis used for analysis is observed along the axial direction, so it is possible to take in the analysis light from a larger number of samples, enabling high-sensitivity measurement and plasma noise Measurement with less noise is possible. On the other hand, it is susceptible to self-absorption, and the effect of coexisting substances in the sample is greater than the other.

[0004] Therefore, it is rational to use the observation in the lateral direction and the observation in the axial direction according to the purpose of the sample to be analyzed, and the ICP often has a mechanism for switching the observation direction. As a specific switching mechanism, a mechanism for manually or automatically moving the position of the plasma torch with respect to the spectroscope, or a method of inserting an optical system combining a mirror and a lens into the optical path and bending the optical path by 90 degrees is used. The observation direction can be changed. And
When switching between the lateral observation and the axial observation, operations such as moving the plasma torch are involved, so the plasma is turned off once and these switching operations are performed.

[0005]

In the lateral observation in the prior art, light emitted in one direction among light emitted in 360-degree directions is guided to a spectroscope for analysis. I have. In the lateral observation, as described above, only a part of the analysis light by the sample in the plasma existing linearly along the central axis is used for analysis, but all of the light Only light emitted in one of the surrounding directions will be used. For this reason, the amount of light introduced into the spectrometer is only a small part of the light useful for analysis. In addition, in the case of lateral observation, the observation position (observation height) of the plasma light affects the analysis result. However, in general, the spectroscope itself is fixed because of the configuration of the apparatus. Since it cannot be moved, it is necessary to move the plasma torch portion, which is the plasma light emitting portion, in the axial direction. In addition, to switch the observation direction from the horizontal direction to the axial direction, it is necessary to rotate the plasma emission unit by 90 degrees, or to provide a mechanism to insert a mirror or lens into the optical path to bend the light and guide it to the spectroscope. If the mechanism for adjusting the observation position and the mechanism for switching between the horizontal observation and the axial observation are simultaneously provided, a very complicated moving mechanism is required. Furthermore, if the operation of switching between the horizontal direction and the axial direction is performed after the plasma is once turned off, and the operation is waited until the operation is stabilized again, a waiting time is required until the apparatus is again stabilized. Therefore, an object of the present invention is to make it possible to use plasma light efficiently in lateral observation. In addition, the present invention provides an ICP that can adjust the observation height and switch between observation in the lateral direction and the axial direction without moving the plasma torch itself by moving the optical system. Aim. A further object of the present invention is to provide an ICP that can switch between lateral observation and axial observation without turning off the plasma.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, an ICP emission spectrometer according to the present invention is directed to an ICP emission spectrometer for guiding light generated by a plasma torch to a spectroscope for analysis. A light guide portion including at least one lens for guiding light from the light source to the spectroscope, and coaxially with the plasma torch at a position intermediate between the plasma torch and the light guide portion, near the periphery of the plasma torch, or on the rear side of the plasma torch. And a mirror ring whose inner surface is a mirror surface and which reflects light emitted from the plasma in an arbitrary surrounding direction and guides the light to the light guide. In addition, in an ICP emission spectrometer that conducts analysis by guiding light generated by a plasma torch to a spectroscope, a light guide unit including at least one lens for guiding light from plasma to the spectroscope; It is provided coaxially with the plasma torch at an intermediate position with the light guide or near the periphery of the plasma torch or at the rear side of the plasma torch, and has an inner surface serving as a mirror surface that reflects light emitted from the plasma in any direction around the plasma torch. And a mirroring driving means for moving the mirroring in the axial direction, and focusing the lens of the light guide according to the position of the mirroring so that the light reflected by the mirroring can be introduced into the spectroscope. And a light-guiding unit lens adjusting means. Also,
In an ICP emission spectrometer for conducting analysis by guiding light generated by a plasma torch to a spectroscope, a light guide section including at least one lens for guiding light emitted in an axial direction from plasma to the spectroscope; It is provided coaxially with the plasma torch at an intermediate position between the torch and the light guide section or near the periphery of the plasma torch or on the rear side of the plasma torch, and the inner surface is a mirror surface and is emitted from the plasma light in any direction around the plasma torch. A mirror ring that reflects light and guides the light to the light guide, and a mask for introducing one or both of the light emitted in the axial direction of the plasma torch and the light reflected by the mirror ring to the light guide. It is characterized by comprising a mask portion to be attached and detached and a drive means for switching or attaching / detaching a mask used in the mask portion.

According to the present invention, the plasma light emitted in the lateral direction is reflected by the mirror ring, collected by the lens of the light guide, and introduced into the spectroscope, so that a larger amount of light can be used for analysis. Further, the observation in the axial direction and the lateral direction can be performed while the plasma torch, the light guide unit and the spectroscope are fixed. In particular, in the observation in the lateral direction, the analysis can be performed using light from an oblique direction within an angle range that does not hinder the analysis. Furthermore, by making an angle to the mirror surface of the mirroring, it is possible to perform analysis from a direction perpendicular to the axis (right side), or place the mirror on the rear side of the plasma (plasma torch side) where it is not affected by heat. Analysis can also be performed. In short, analysis can be performed by reflecting light emitted at an arbitrary angle by mirroring, and in this case, increasing the amount of light because light emitted in all directions is collected using mirroring. Even if the light is slightly oblique, the analysis will not be affected. Furthermore, the observation position (observation height) can be made variable by providing a mechanism for moving the mirror ring and the lens of the light guide section in the axial direction and changing the position of the ring with respect to the plasma. In that case, by moving the focal position of the lens of the light guide in conjunction with the position of the ring, plasma light can be introduced into the spectroscope. When only observation in the axial direction is performed, the plasma light in the horizontal direction may be shielded by the mask portion, and the setting may be made so that only the light in the axial direction can be introduced into the light guide portion. On the other hand, in the case of observing in the lateral direction, the setting may be made so that only light reflected by mirroring by the mask unit can be introduced into the light guide unit. This allows the light guide and the spectroscope to be fixed and the plasma torch to remain fixed, while allowing light not only in the axial direction but also in the horizontal direction to be introduced into the spectrometer via mirroring, And the axial direction can be added to observe.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments. FIG. 5 is a diagram showing a configuration of an ICP according to one embodiment of the present invention. In the figure, the same components as those in the conventional example are denoted by the same reference numerals, and description thereof will be omitted. In the present embodiment, the basic configuration of the measuring optical system is such that axial observation can be performed, and a light guide 7 is disposed on an extension of the plasma torch 1 in the axial direction. The lens 5 and the torch 1 are arranged so as to be adjusted so that light in the axial direction of the plasma torch 1 can be introduced into the spectroscope 4. The lens 5 need not be a single lens, but may be a lens group whose focal length can be changed. If the focal length can be changed, a motor drive mechanism for focus adjustment is required. Further, a mirror ring 11 is coaxially arranged in a space between the light guide 7 and the plasma torch 1. The mirror ring 11 has a mirror 12 on the inner surface side of the ring, and the ring diameter is larger than that of the plasma torch 1. Thus, light emitted from the plasma 3 in an arbitrary surrounding direction is introduced into the spectroscope 4 from the lens 5 of the light guide 7. A drive unit 20 including a well-known motor drive mechanism is provided so that the mirror ring 11 can move in the axial direction in order to change the position (observation height) when performing lateral observation. Since the mirror ring 11 can be moved in the axial direction, it is necessary to adjust the focus according to the position of the ring. Therefore, the light guide 7 is provided with a lens 5b for focus adjustment.
The motor drive unit 20 is also provided so that it can move in the axial direction in conjunction with the movement of the mirroring 11. As a result, the mirror ring 11 can be moved along the axial direction, and the focus position can be adjusted by moving the lens 5b according to the position of the mirror ring 11. Note that the mirror ring 11 and the lens 5b may only be movable in the axial direction. In that case, the measurer manually adjusts the mirroring 11 and the lens 5b separately. Alternatively, the ring 11 and the lens 5b may be moved integrally, and the focus may be adjusted by the lens 5. Further, by attaching a lens to the mirror surface of the mirror ring so as to focus on a specific portion (for example, the center of the plasma) of the plasma light, it is possible to increase the amount of required plasma light.
That is, glass is formed on the surface of the mirror 12 of the mirror ring 11 from the convex lenses 14 and 15 and the plane 13. At this time, the paint 30 may be applied to the glass surface other than the lenses 14 and 15 for light shielding. Further, when it is desired to move the mirror ring 11 closer to or farther from the plasma torch side, as shown in FIG.
What is necessary is just to change the angle of one mirror 12. By setting the angle of the mirror 12 to an appropriate angle, even light emitted in the lateral direction of the plasma 3 can be easily introduced into the light guide 7. Furthermore, the mirror ring 11 can be arranged around the plasma torch 1 behind the plasma 3 to reflect the light going toward the plasma torch 1 and introduce it into the light guide unit 7.

Next, the operation of the apparatus of this embodiment will be described. A high frequency power is applied to the coil 2 in the plasma torch 1 to generate a plasma 3. Light containing a lateral component emitted from the plasma 3 in any surrounding direction is reflected by the ring 11 and sent to the light guide 7. The light sent to the light guide 7 is collected by the lens 5 and guided to the spectroscope 4 for analysis. Therefore, the light reflected from the entire circumference of the mirror ring 11 is sent to the spectroscope 4, so that even in the lateral observation, the analysis is performed with a larger light amount.

Next, a case where the lateral observation position (observation height) is changed will be described. By changing the angle of the mirror surface of the mirroring as in the example shown in FIG. 6 earlier, the observation position can be changed. In this case, however, mirroring with a different mirror surface angle for each observation position is required. Will be needed. As another method, the observation position can be changed by providing a position adjusting mechanism between the mirror ring 11 and the lens 5b as shown in FIGS. That is, first, the mirroring 11 is moved to a desired observation position, and the lens 5b is also moved and focused in accordance with the movement, thereby enabling observation in the lateral direction in which the observation position is changed. This adjustment is preferably performed automatically by providing a well-known automatic focus adjustment mechanism. Alternatively, the focus position may be manually searched.

Next, the case of switching between the axial observation and the lateral observation will be described. As shown in FIGS. 8 (a) and 8 (b), an annular mask 16 or a disk mask 17 having a central opening at the entrance of the light guide 7 is replaceably arranged. In consideration of the ease of attachment of the drive mechanism for attaching and detaching the mask, it is preferable to attach the mask section to the entrance of the light guide section 7 as shown in the figure. In FIG. 8, a focal point before the lens 5b) may be used. In short, if the optical path for each of the axial observation and the lateral observation is provided at a position where light can be shielded, it can function as a mask section. (A) for axial observation
An annular mask 16 is used as shown in FIG. Accordingly, light that is reflected by the mirror ring 11 and reaches the light guide portion 7 at a wide angle is shielded, so that axial observation can be performed. In this case, by further providing a lens 18 on the optical path between the mask 16 and the plasma 3, only light from a specific point on the axis of the plasma 3 (the focal position of the lens 18) is concentrated.
Can be introduced. On the other hand, in the case of horizontal observation, a disk mask 17 is used as shown in FIG. Accordingly, the light from the axial direction is shielded by the mask 17 while the light reflected by the mirror ring 11 and introduced into the light guide 7 at a wide angle is condensed by the lens 5 and sent to the spectroscope. When adjusting the position (observation height) of the mirror ring 11, the mirror unit 11, the lens 5b, and the lens 18 are adjusted by the drive unit 20 in the same manner as described above. In addition, mirroring 11, lens 5b, lens 18
May be moved together, and the focus may be adjusted by a lens 5 composed of a plurality of lens groups.

[0012]

As described above, mirroring is used in the ICP of the present invention, so that observation can be performed with a stronger light amount even in the case of lateral observation. Further, when switching between the lateral observation and the axial observation, the positional relationship between the spectroscope and the plasma torch can be switched without moving at all. Therefore, switching can be performed without turning off the plasma. Furthermore, the observation position can be easily moved in the lateral observation.

[Brief description of the drawings]

FIG. 1 is a diagram showing conventional lateral observation of ICP.

FIG. 2 is a diagram showing a conventional lateral observation of another ICP.

FIG. 3 is a diagram showing conventional axial observation of ICP.

FIG. 4 is a diagram showing another conventional ICP axial observation.

FIG. 5 is a diagram showing a configuration of an ICP according to an embodiment of the present invention.

FIG. 6 is a sectional view of a mirroring portion of an ICP according to another embodiment of the present invention.

FIG. 7 is a diagram showing a state where an observation position is changed at the time of lateral observation in the present invention.

FIG. 8 is a diagram showing a state of switching between axial observation and lateral observation in the present invention.

[Explanation of symbols]

 1: Plasma torch 3: Plasma 4: Spectroscope 5: Lens 5b: Lens 7: Light guide 8: Driver 11: Mirroring 12: Mirror 14, 15: Lens 16: Annular mask 17: Disk mask 20: Driver

Claims (3)

[Claims] An ICP emission spectrometer for guiding light generated by a plasma torch to a spectroscope for analysis, comprising: a light guide unit including at least one lens for guiding light from the plasma to the spectroscope; It is provided coaxially with the plasma torch at an intermediate position between the torch and the light guide or near the periphery of the plasma torch or at the rear side of the plasma torch. An ICP emission spectrometer comprising: a mirror ring that reflects and guides the light to the light guide. 2. An ICP emission spectrometer for guiding light generated by a plasma torch to a spectroscope for analysis, comprising: a light guide unit including at least one lens for guiding light from the plasma to the spectroscope; It is provided coaxially with the plasma torch at an intermediate position between the torch and the light guide or near the periphery of the plasma torch or at the rear side of the plasma torch. A mirror ring that reflects the light and guides the light to the light guide unit, a mirroring driving unit that moves the mirror ring in the axial direction, and a focal point of a lens of the light guide unit according to the position of the mirror ring so that light reflected by the mirror ring can be introduced into the spectroscope. An ICP emission spectrometer comprising: a light guide lens adjusting means for adjusting the wavelength of light. 3. An ICP emission spectrometer for guiding light generated by a plasma torch to a spectroscope for analysis, comprising: at least one lens for guiding light emitted in an axial direction from the plasma to the spectroscope. A light portion, an intermediate position between the plasma torch and the light guide portion, or the vicinity of the periphery of the plasma torch or at the rear side of the plasma torch, provided coaxially with the plasma torch, the inner surface of which is a mirror surface and has an arbitrary direction around the plasma light. Mirror light for guiding the light emitted to the light guide to the light guide, and introducing one or both of the light emitted in the axial direction of the plasma torch and the light reflected by the mirror ring to the light guide. And a drive unit for switching or attaching / detaching a mask used in the mask unit. CP emission spectrometer.