Optical emission spectrometer and optical emission spectroscopy

Abstract

An optical emission spectrometer is provided. The optical emission spectrometer includes a plasma source, an optical assembly, a reference light source, and a first mirror. The plasma source is arranged to emit light. The optical assembly includes a plurality of optical components arranged to direct light traveling in a first direction from the plasma source along a first optical path to an entrance slit of the optical emission spectrometer. The reference light source is used for calibrating the spectrometer, wherein the reference light source is arranged to output reference light along a reference light path. The first reflector is arranged to selectively switch the reference light to the first light path, thereby guiding the reference light to the entrance slit for calibrating the optical emission spectrometer.

Description

Technical Field

[0001] This disclosure relates to optical spectroscopy methods. Specifically, this disclosure relates to optical emission spectroscopy methods. Background Technology

[0002] Optical emission spectroscopy involves analyzing the light emitted by sample molecules when electrons transition from higher to lower energy levels. Typically, an energy source (such as a plasma source) is used to excite the electrons of the sample molecules to a higher energy level.

[0003] Optical emission spectrometers are designed to capture emitted light and analyze its wavelength to determine information about the composition of a sample. To accurately characterize sample molecules, optical emission spectrometers typically include an optical system that directs light from a plasma source to the spectrometer's detector.

[0004] For optical emission spectrometers, it is necessary to be able to accurately determine the wavelength of light emitted from a plasma source. US-B-7,319,519 discloses a method for calibrating an Escher spectrum, wherein the wavelengths are distributed across multiple orders. The method includes recording a line-rich reference spectrum with known wavelengths and multiple spectral lines, and determining the positions of multiple peaks of the reference spectrum within the recorded spectrum.

[0005] In this context, it is desirable to provide an improved, or at least commercially relevant, alternative optical emission spectrometer and optical emission spectroscopy method. Summary of the Invention

[0006] According to a first aspect of this disclosure, an optical emission spectrometer is provided. The optical emission spectrometer includes a plasma source, optical components, a reference light source, and a first mirror. The plasma source is configured to emit light. The optical components include a plurality of optical elements configured to guide light traveling from the plasma source along a first direction along a first optical path to an entrance slit of the optical emission spectrometer. The reference light source is used to calibrate the spectrometer, wherein the reference light source is configured to output reference light along a reference optical path. The first mirror is configured to selectively switch the reference light onto the first optical path, thereby guiding the reference light to the entrance slit for calibrating the optical emission spectrometer.

[0007] Therefore, the optical emission spectrometer of the first aspect is configured to measure light emitted from a plasma source and traveling in a first direction. The optical components of the optical emission spectrometer provide a first optical path to guide the light from the plasma source to the entrance slit of the optical emission spectrometer. Calibration of the optical emission spectrometer is advantageous to improve its accuracy.

[0008] The optical emission spectrometer of the first aspect can be calibrated using a reference light source integrated with it. Therefore, the first optical path of the optical emission spectrometer can be reliably calibrated without any external light source or calibration sample. Specifically, the reference light source is easily switched to the first optical path using a first mirror, allowing calibration to be performed in real time. That is, the optical emission spectrometer does not require any external adjustments (e.g., the use of calibration samples or internal standards) for calibration. Accordingly, the first optical path can be calibrated repeatedly or in real time during a series of measurements performed using the optical emission spectrometer.

[0009] To perform calibration, the optical emission spectrometer of the first aspect includes a first mirror configured to selectively switch reference light onto a first optical path, thereby imaged the reference light on the entrance slit of the optical emission spectrometer. Therefore, the reference light can be imaged on the first optical path without adjusting any components of the optical assembly defining the first optical path. Thus, calibration measurements can be performed without requiring any adjustments to the optical components, thereby further improving the accuracy of the optical spectrometer.

[0010] In some implementations, the first reflector is movable between a first position and a second position, wherein the first position is away from the first optical path, and the second position is configured to reflect reference light from the reference optical path back onto the first optical path. Therefore, the first reflector can be moved between the first and second positions to selectively switch the reference light onto the first optical path. Accordingly, calibration of the optical emission spectrometer can be triggered by moving the first reflector, rather than by any adjustment to the optical components providing the first optical path.

[0011] In some implementations, the reference optical path may intersect with the first optical path. Furthermore, in some implementations, the first reflector may be positioned along the reference optical path, for example, at the intersection of the reference optical path and the first optical path, to selectively switch the reference light.

[0012] In some embodiments, the plasma source can be configured to generate axial light in the axial direction and radial light in the radial direction. In some embodiments, the first direction of light emitted by the plasma source can be either the axial direction of the plasma source or the radial direction of the plasma source. According to this disclosure, the axial direction of the plasma source is understood as the direction aligned with the main axis of the plasma source. The radial direction is understood as the direction transverse to the axial direction. Therefore, the axial and radial directions of the plasma source can be two directions of light emission, which are transverse to each other.

[0013] In some embodiments, the optical assembly includes multiple optical components configured to radially guide radial light from the plasma source along a second optical path to the entrance slit of the optical emission spectrometer; and the optical emission spectrometer includes a second mirror configured to selectively switch reference light to the second optical path for calibration of the optical emission spectrometer. Therefore, in some embodiments, the optical emission spectrometer can be configured to perform measurements using light emitted radially or axially from the plasma source. By providing a first and a second mirror, a reference light source can be used to calibrate both the first and second optical paths without requiring any further adjustments to the optical assembly. Furthermore, the same reference light source can be used to calibrate both the first and second optical paths. Therefore, the calibration accuracy of the optical emission spectrometer can be further improved.

[0014] In some embodiments, the second mirror may be movable between a first position and a second position away from the second optical path. In the second position, the second mirror is configured to reflect reference light from the reference optical path onto the second optical path, thereby guiding the reference light to the entrance slit of the optical emission spectrometer. Therefore, in some embodiments, the second mirror can be moved between two positions to switch the reference light onto the second optical path.

[0015] In some embodiments, the first reflector may include a reflective portion and a transmissive portion. When the first reflector is in the second position, the reflective portion may be configured to reflect reference light incident on the reflective portion onto the first optical path, and the transmissive portion may be configured to transmit reference light incident on the transmissive portion, thereby intersecting with the second optical path. Therefore, the first reflector can be positioned in the second position so that some reference light is reflected by the reflective portion of the first reflector onto the first optical path. Reference light incident on the transmissive portion can be transmitted to the second reflector / second optical path. Therefore, in some embodiments, both the first and second reflectors can be positioned in the second position to allow calibration of the first and second optical paths without requiring any further adjustment to the reflector positions.

[0016] In some embodiments, the second reflector may include a complementary reflective portion, such that when the second reflector is in the second position, the complementary reflective portion is configured to reflect reference light transmitted by the transmission portion of the first reflector. Therefore, the first and second reflectors can be provided in a complementary manner.

[0017] In some embodiments, the transmissive portion (of the first reflector) may define a first shape on the first reflector. In some embodiments, the complementary reflective portion (of the second reflector) may define a complementary first shape on the second reflector, wherein the first shape and the complementary first shape may be aligned along the reference optical path. Therefore, light transmitted through the first reflector can be reflected by the first reflector onto the second optical path. Thus, when the first and second reflectors are each in their respective second positions, reference light can exist on both the first and second optical paths.

[0018] In some embodiments, the first shape and the complementary first shape may each be defined as one or more of the following: a circle, a regular polygon, an irregular polygon, and an ellipse. In some embodiments, the transmissive portion of the first reflector may include various shapes. For example, the transmissive portion may include a first shape and a second shape. The first shape and the second shape may be the same shape or different shapes. Therefore, it should be understood that the transmissive portion of the first reflector can have any two-dimensional pattern, while the complementary reflective portion of the second reflector has a complementary two-dimensional pattern.

[0019] In some embodiments, the first reflector may include an optically transparent plate having a reflective coating that partially covers the main surface of the optically transparent plate, wherein the reflective coating provides a reflective portion of the first reflector. In some embodiments, the second reflector may include an optically transparent plate having a reflective coating that partially covers the main surface of the optically transparent plate, wherein the reflective coating provides a complementary reflective portion of the second reflector.

[0020] In some implementations, when in the first position, the first reflector may intersect with the reference optical path. Therefore, when in the first position, the transmission portion of the first reflector may be configured to allow the reference light to be transmitted to the second reflector.

[0021] In some embodiments, the optical emission spectrometer may further include optical fibers. The optical fibers may be configured to guide reference light from a reference source to a first and a second reflecting mirror. Therefore, the optical emission spectrometer can be configured to spatially efficiently accommodate the reference source and the reference optical path. For example, the optical fibers may be configured to receive the reference light from the reference source along a first reference direction and output the reference light along the reference optical path to the first and second reflecting mirrors, wherein the direction of the reference optical path differs from the direction of the reference light. For example, in some embodiments, the direction of the reference optical path may not intersect with the direction of the reference light.

[0022] In some embodiments, the optical component may include an adjustable mirror. The adjustable mirror may be configured to be adjustable between a first position and a second position, wherein in the first position, the adjustable mirror reflects light from a first optical path to the entrance slit of the spectrometer; and in the second position, the adjustable mirror reflects light from a second optical path to the entrance slit of the spectrometer. In some embodiments, the optical component may include a first focusing mirror provided in the first optical path. The first focusing mirror may be configured to receive axial light from a plasma source and reference light from the first mirror, and focus the axial light and reference light onto the adjustable mirror of the optical component. In some embodiments, the optical component may include a second focusing mirror provided in the second optical path. The second focusing mirror may be configured to receive radial light from a plasma source and reference light from the second mirror, and focus the radial light and reference light onto the adjustable mirror of the optical component. Therefore, the optical component can be spatially efficient in its configuration to focus light from a plasma source and a reference source onto the entrance slit of the optical emission spectrometer.

[0023] In some implementations, the reference light source may include one or more of the following: a hollow cathode lamp, a glow discharge lamp, a spectral lamp, a laser, an LED (preferably a narrowband LED), etc. Therefore, it should be understood that the reference light source can be provided by any light source with one or more sufficiently defined spectral lines of known output wavelength (i.e., bandwidth less than 1 nm). Preferably, the reference light source can emit multiple spectral lines spanning a wavelength range, thereby enabling calibration of the optical emission spectrometer across the desired wavelength range or across the desired detector location range.

[0024] In some embodiments, an optical emission spectrometer may include one or more of the following: a reference shutter configured to block a reference source from entering the reference optical path; an axial shutter configured to block a plasma source from entering the first optical path; and a radial shutter configured to block the plasma source from entering the second optical path. Therefore, the optical emission spectrometer may be equipped with a reference shutter that allows the optical emission spectrometer to continuously operate the reference source while in use. For example, in some embodiments, it is not necessary to repeatedly turn the reference source on and off each time a calibration measurement is performed. Therefore, a reference shutter can be used to keep the reference source continuously on without interfering with other measurements of the optical emission spectrometer. Similarly, the axial and / or radial shutters can be configured to allow continuous operation of the plasma source while performing calibration measurements.

[0025] In some embodiments, the optical emission spectrometer may include a detector. In some embodiments, the optical emission spectrometer may include an Escher grating configured to receive light from an entrance slit and guide the light to the detector, where multiple orders of Escher spectra are imaged on the detector. In some embodiments, the detector may be a two-dimensional detector (i.e., an array detector). In some embodiments, the optical emission spectrometer may include a concave grating configured to receive light from an entrance slit and guide the light to the detector, where a linear spectrum is imaged on the detector. Therefore, in some embodiments, the entrance slit may be the entrance slit of a polychromator (or an Escher polychromator). In such a polychromator, the light incident on the polychromator entrance slit, depending on the wavelength of the incident light, may be distributed across a two-dimensional detector.

[0026] According to a second aspect of this disclosure, an optical emission spectrometry method using the optical emission spectrometer of the first aspect is provided. The method includes performing a calibration measurement, wherein a first mirror is positioned to guide reference light from a reference source along a first optical path to the entrance slit of the spectrometer, wherein the optical emission spectrometer detects a known wavelength of the reference source.

[0027] Therefore, the second approach uses an integrated reference light source to perform calibration measurements on the optical emission spectrometer. The calibration of the optical emission spectrometer can be determined based on the correlation between a known wavelength and the position of a spectral peak at a known wavelength incident on the spectrometer's detector. Thus, the optical emission spectrometer of the first approach can be calibrated quickly, accurately, and reliably.

[0028] In some embodiments, the method may further include performing sample measurements, wherein a first reflector is positioned to guide light from the plasma source along a first optical path to the entrance slit of the optical emission spectrometer. Therefore, the method may include performing calibration measurements and sample measurements. In some embodiments, calibration measurements may be repeated or interleaved throughout multiple sample measurements performed using the first optical path.

[0029] In some embodiments, the method may further include: performing an axial sample measurement, wherein a first reflector is positioned to guide axial light from the plasma source to the entrance slit of the optical emission spectrometer; and / or performing a radial sample measurement, wherein a second reflector is positioned to guide radial light from the plasma source to the entrance slit of the optical emission spectrometer. Therefore, the method of the first aspect allows for the measurement of a sample present in the plasma source by changing the positions of the first and / or second reflectors. Thus, the optical emission spectrometer can efficiently switch between performing sample measurements and calibration measurements.

[0030] In some embodiments, an optical emission spectroscopy method may be provided in which multiple axial sample measurements and / or multiple radial sample measurements are performed. As part of this method, at least one axial calibration measurement and / or at least one radial calibration measurement may be performed during the multiple sample measurements. For example, the axial calibration measurements and / or radial calibration measurements may be interleaved with the multiple sample measurements. Therefore, the calibration of the optical emission spectrometer can be checked (and recalibrated) in real time. Thus, according to the method of the second aspect, small real-time fluctuations in the operating conditions of the optical emission spectrometer can be compensated for by performing repeated calibrations of the optical emission spectrometer in real time. Attached Figure Description

[0031] Embodiments of this disclosure will now be described with reference to the following non-limiting drawings, in which: Figure 1 is a block diagram of an optical emission spectrometer according to the present disclosure; Figure 2 is a schematic diagram of an optical emission spectrometer for performing axial light measurement according to an embodiment of the present disclosure; Figure 3 is a schematic diagram of an optical emission spectrometer performing a first optical path calibration measurement according to an embodiment of the present disclosure; Figure 4 is a schematic diagram of an optical emission spectrometer for performing radial light measurement according to an embodiment of the present disclosure; Figure 5 is a schematic diagram of an optical emission spectrometer performing a second optical path calibration measurement according to an embodiment of the present disclosure; Figure 6 is a schematic diagram of the first reflecting mirror; Figure 7 is a schematic diagram of the second reflecting mirror; - Figure 8 Figures 8a, 8b, 8c, 8d, 8e and 8f show schematic diagrams of a first and a second reflector according to other embodiments of the present disclosure; Figure 9 is a schematic diagram of an optical emission spectrometer containing multiple shutters; Figure 10 is a block diagram of the optical emission spectroscopy measurement method according to this disclosure; and Figure 11 is a block diagram of another optical emission spectroscopy method according to the present disclosure. Detailed Implementation

[0032] According to one embodiment of the present disclosure, an optical emission spectrometer is provided. Figure 1 is a block diagram of the optical emission spectrometer 1 according to the present disclosure. As shown in Figure 1, the optical emission spectrometer 1 includes: a plasma source 10, an optical component 20, a reference light source 30, a first reflector 40, a second reflector 50, an entrance slit 60, a diffraction optical component 70, and a detector 80.

[0033] Figure 2 is another simplified diagram of the plasma source 10, optical component 20, reference light source 30, first reflector 40, second reflector 50 and entrance slit 60.

[0034] Plasma source 10 is configured to emit light. Plasma source 10 may be configured to generate axial light in the axial direction and radial light in the radial direction. Plasma source 10 may be an inductively coupled plasma (ICP) source. In such embodiments, optical emission spectrometer 1 may be an inductively coupled plasma optical emission spectrometer (ICP-OES).

[0035] As shown in Figure 2, the optical assembly 20 is configured to receive and guide axial and radial light to the entrance slit 60. The optical assembly 20 includes multiple optical components 21, 22, 23, and 24. Figure 2 shows an example of the optical assembly 20. The optical assembly 20 of Figure 2 includes a (planar) radial reflector 21, an axial focusing reflector 22, a radial focusing reflector 23, and a slit focusing reflector 24. It should be understood, of course, that in other embodiments, other combinations of planar reflectors, focusing reflectors (e.g., convex reflectors), lenses, and / or any other optical components may be used to guide light from the plasma source 10 to the entrance slit 60.

[0036] Optical assembly 20 is configured to guide light traveling axially (i.e., in the first direction) from plasma source 10 along a first optical path to the entrance slit 60 of optical emission spectrometer 1. As shown in FIG2, the first optical path extends axially from plasma source 10 to axial focusing mirror 22. Axial focusing mirror 22 is configured to receive axial light and reflect it to slit focusing mirror 24. Slit focusing mirror 24 is configured to reflect axial light from the axial focusing mirror to the entrance slit 60. Slit focusing mirror 24 is configured to focus the axial light onto the entrance slit 60 of optical emission spectrometer 1. Therefore, axial light is guided along the first optical path defined by optical components 22, 24 of optical assembly 20.

[0037] Reference light source 30 is a light source suitable for calibrating spectrometer 1. Therefore, reference light source 30 can be configured to output light with a wavelength or wavelength range that spectrometer 1 can measure. As shown in FIG2, reference light source 30 is configured to output reference light along a reference optical path. In some embodiments, the reference light output in the reference optical path can be collimated, for example, by providing a collimating lens (not shown) as part of reference light source 30. As shown in FIG2, the reference optical path intersects with the first and second optical paths of optical assembly 20. In some embodiments, reference light source 30 can be one or more of the following: a hollow cathode lamp, a narrowband LED, a laser, a glow discharge lamp, and a spectral lamp. Therefore, it should be understood that reference light source 30 can be used to calibrate optical emission spectrometer 1 across a wavelength range.

[0038] According to this disclosure, the reference light source 30 is configured to output light for calibrating the optical emission spectrometer 1. Specifically, the reference light source 30 outputs light for calibrating the position of spectral peaks on the detector 80 of the optical emission spectrometer. By determining the position of the spectral peaks (or peaks) of the reference light source 30 (having a known wavelength), the optical emission spectrometer 1 can determine its position calibration.

[0039] In some embodiments, the reference light source 30 may be configured to output reference light directly along a reference optical path (e.g., as shown in FIG2). In some embodiments, one or more reference optical components (not shown in FIG2) may be provided to guide the light output from the reference light source to the reference optical path. For example, in some embodiments, an optical fiber (not shown) may be provided, configured to guide the reference light from the reference light source to the first reflector 40 and the second reflector 50. One or more focusing lenses or reflectors may be provided to focus the light from the reference light source 30 into the optical fiber and focus the light output from the optical fiber onto the first and second reflectors. By utilizing an optical fiber to guide the reference light, the optical components 20 and the reference light source 30 can be arranged in a more spatially efficient manner.

[0040] A diffractive optical component 70 (e.g., as shown in FIG. 1) can be configured to guide light from the entrance slit 60 to the detector 80 of the optical emission spectrometer 1 (e.g., as shown in FIG. 1). The diffractive optical component 70 may include one or more diffractive elements configured to diffract light so that different wavelengths of light are distributed in space. For example, the diffractive optical component 70 may include an Escher grating (not shown in FIG. 1). The Escher grating can be configured to receive light from the entrance slit 60 and guide the light to the detector 80, wherein multiple orders of Escher spectra are imaged on the detector 80. Alternatively, the diffractive element may be a concave grating (not shown in FIG. 1). The concave grating can be configured to receive light from the entrance slit 60 and guide the light to the detector 80, wherein a linear spectrum is imaged on the detector 80. Therefore, it should be understood that light from the plasma source 10 or the reference source 30 can be imaged on the detector 80 as a spatially distributed spectrum.

[0041] Detector 80 can be configured to receive light from the diffractive optics component and generate a signal indicating the spectrum incident on detector 80. For example, in some embodiments, the optical spectrum incident on detector 80 can be a two-dimensional spectrum. In such embodiments, detector 80 can be a CCD (charge-coupled device) array. A typical CCD array can have at least approximately 1024 x 1024 pixels (i.e., 1 megapixel). The CCD array can be arranged to generate spectral intensity values ​​corresponding to the measured spectral light quantity and to transmit the spectral values ​​to a processor (not shown) for further analysis. In the case where the diffractive optics component 70 includes an escher grating, the order of the escher spectrum can be distributed across the entire CCD array. Therefore, detector 80 can be a multichannel detector configured to detect multiple different wavelengths. Detector 80 (as shown in the embodiment of Figure 1) can be configured to detect a two-dimensional spectrum. In other embodiments, detector 80 can be a complementary metal-oxide-semiconductor (CMOS) detector or a charge-injection device (CID) detector. The optical emission spectrometer 1 can be calibrated by correlating the known wavelength spectral peak of the reference light source 30 with the position (location) of the detector 80 on which the spectral peak is incident. It should be understood that the combination of the entrance slit 60, the diffraction optics assembly 70, and the detector 80 (e.g., an Escher grating) can be configured to distribute light of different wavelengths onto a two-dimensional detector (e.g., an array detector). Therefore, in some embodiments, the entrance slit 60 can be the entrance slit 60 of a polychromator (or an Escher polychromator). In such a polychromator, light of different wavelengths can be distributed onto a two-dimensional detector (e.g., a CCD array).

[0042] In the embodiments shown in Figures 2 and 3, the reference optical path extends in a direction intersecting the axial direction of the axial light. Therefore, the reference optical path can intersect the axial optical path orthogonally.

[0043] The first reflector 40 is configured to be movable between a first position and a second position. As shown in Figure 2, when the first reflector 40 is in the first position, it is positioned away from the first optical path. That is, in the first position, the first reflector 40 does not block the first optical path. Therefore, when the first reflector 40 is in the first position, substantially all of the available axial light is guided through the optical assembly 20 to the entrance slit 60.

[0044] As shown in Figure 3, the first reflecting mirror 40 can be moved to a second position, in which it is configured to reflect reference light from the reference optical path back onto the first optical path. Therefore, when the first reflecting mirror 40 is in the second position, the reference light can be reflected by the first reflecting mirror 40, thereby aligning with the first optical path. Correspondingly, the first reflecting mirror 40 is configured to selectively switch the reference light to the first optical path, thereby guiding the reference light to the entrance slit 60 for calibration of the optical emission spectrometer 1. That is, when the first reflecting mirror 40 is in the first position, the plasma source 10 can be operated to perform sample measurements using the optical emission spectrometer 1. When the first reflecting mirror 40 is in the second position, the reference light source 30 can be operated to perform calibration measurements using the optical emission spectrometer 1.

[0045] As shown in Figures 2 and 3, the first reflector 40 can be switched between a first position and a second position by rotating the first reflector 40 about one end of the first reflector 40. In other embodiments, the first reflector 40 can be moved between the first position and the second position by translational movement (e.g., sliding the reflector) or a combination of rotational and translational movements.

[0046] The first reflecting mirror 40 shown in Figures 2 and 3 is a plane reflecting mirror. It should be understood that when the first reflecting mirror 40 is in the second position, the first reflecting mirror 40 can be any reflecting mirror suitable for guiding the reference light onto the axial optical path. For example, in some embodiments, the first reflecting mirror 40 can be a curved reflecting mirror.

[0047] When the first reflecting mirror 40 is in the second position, the reference light can be received by the axial focusing mirror 22 and reflected to the slit focusing mirror 24. Therefore, when performing calibration measurements, the reference light can be guided to the entrance slit 60 by the same optical components 22, 24 of the optical assembly 20, wherein the optical components are used to guide the axial light of the plasma source 10 when performing sample measurements using axial light.

[0048] Although the embodiments of Figures 2 and 3 include a first optical path and a second optical path, it should be understood that in some embodiments, the optical emission spectrometer 1 may be equipped with only a single reflector 40 and a first optical path (i.e., without a second optical path and a second reflector 50). The first reflector 40 may be adjustable between two positions to allow the optical emission spectrometer 1 to perform sample measurements using the plasma source 10 and reference measurements using the reference light source 30. It should be understood that the single optical path may receive radial and / or axial light from the plasma source 10.

[0049] The optical emission spectrometer 1 in Figures 2 and 3 can also be configured to use radial light from the plasma source 10 to perform sample measurement and calibration measurements. Therefore, the optical emission spectrometer 1 in Figures 2-5 includes a first optical path and a second optical path. Figures 4 and 5 are schematic diagrams of the optical emission spectrometer 1 performing sample measurement and calibration measurements using the radial optical path of the optical component 20, respectively.

[0050] As shown in Figures 4 and 5, the planar reflector 21, radial focusing reflector 23, and slit focusing reflector 24 of the optical assembly 20 are arranged to guide radial light from the plasma source 10 to the entrance slit 60. The radial light is guided along a second optical path defined by the optical components 21, 23, and 24 of the optical assembly 20.

[0051] The second reflector 50 is configured to be movable between a first position and a second position. As shown in FIG4, when the second reflector 50 is in the first position, the second reflector 50 is positioned away from the second optical path. That is, in the first position, the second reflector 50 does not block the second optical path. Therefore, when the second reflector 40 is in the first position, substantially all radial light reflected by the plane reflector 21 can be guided through the optical assembly 20 to the entrance slit 60.

[0052] As shown in Figure 5, the second reflector 50 can be moved to a second position, in which it is configured to reflect reference light from the reference optical path onto the second optical path. Therefore, when the second reflector 50 is in the second position, the reference light can be reflected by the second reflector 50, thereby aligning with the second optical path. Correspondingly, the second reflector 50 is configured to selectively switch the reference light onto the second optical path, thereby guiding the reference light to the entrance slit 60 for calibration of the optical emission spectrometer 1. That is, when the second reflector 50 is in the first position, the plasma source 10 can be operated to perform sample measurements using the optical emission spectrometer 1. When the second reflector 50 is in the second position, the reference light source 30 can be operated to perform calibration measurements using the optical emission spectrometer 1.

[0053] As shown in Figures 4 and 5, the second reflector 50 can be switched between a first position and a second position by rotating the second reflector 50 about one end of the second reflector 50. In other embodiments, the first reflector 50 can be moved between the first position and the second position by translational movement (e.g., sliding the reflector) or a combination of rotational and translational movements.

[0054] The second reflector 50 shown in Figures 4 and 5 is a plane reflector. It should be understood that when the second reflector 50 is in the second position, it can be any reflector suitable for guiding the reference light into the second optical path. For example, in some embodiments, the second reflector 50 can be a curved reflector.

[0055] When the second reflector 50 is in the second position, the reference light can be received by the radial focusing reflector 23 and reflected to the slit focusing reflector 24. Therefore, when performing calibration measurements, the reference light can be guided to the entrance slit 60 by the optical components 23, 24 of the optical assembly 20, wherein the optical components are also used to guide the radial light of the plasma source 10 when performing sample measurements using axial light.

[0056] In some implementations, a first reflector 40 and a second reflector 50 may be arranged to perform calibration measurements with improved accuracy. As shown in FIG3, the first reflector 40 may include a transmission portion 42 and a reflection portion 44. Figure 6 A plan view of one possible design for the first reflecting mirror 40.

[0057] The transmission portion 42 of the first reflecting mirror 40 is configured to allow light incident on the first reflecting mirror 40 to be transmitted through the first reflecting mirror 40 (i.e., through the thickness of the first reflecting mirror 40). Through transmission, it should be understood that the transmission portion 42 is configured to allow at least certain wavelengths of visible light to be substantially transmitted through the thickness of the first reflecting mirror 40. Therefore, when the first reflecting mirror 40 is in the second position, the transmission portion can be configured to allow at least some reference light from the reference light source to be transmitted through the first reflecting mirror 40 and to the second reflecting mirror 50. The transmission portion 42 of the first reflecting mirror can also be configured to allow at least some axial light in the first optical path to be transmitted through the first reflecting mirror 40 and to the axial focusing reflecting mirror 22.

[0058] The reflecting portion 44 can be configured to reflect the reference light incident on the reflecting portion 44 onto the first optical path.

[0059] In some embodiments, the first reflector 40 includes an optically transparent plate having a reflective coating that partially covers the main surface of the optically transparent plate, wherein the reflective coating provides a reflective portion 44 of the first reflector 40. In the embodiment of FIG. 6, the reflective portion 44 of the first reflector 40 may be provided by a thin metal film (e.g., aluminum film, silver film, etc.) provided on the surface of the glass substrate. The transmissive portion 42 may define an area on the surface of the glass substrate where the reflective portion 44 is not provided. In the embodiment of FIG. 6, the first reflector 40 includes a generally rectangular glass substrate. The transmissive portion 42 is a circular or elliptical region generally located at the center of the surface of the first reflector 40. The reflective portion 44 covers the remaining surface of the first reflector 40, surrounding the transmissive portion 42.

[0060] As shown in Figure 2, the first reflector 40 can be aligned relative to the reference optical path, such that when the first reflector 40 is in a first position, the reference optical path extends through the transmission portion 42 of the first reflector 40. As shown in Figure 3, the first reflector 40 can also (or optionally) be aligned relative to the reference optical path, such that when the first reflector 40 is in a second position, the reference optical path extends through the transmission portion 42 of the first reflector 40. Therefore, in the embodiments of Figures 2 and 3, when the first reflector 40 is in the first or second position, the reference light source can illuminate at least a portion of the second reflector 50.

[0061] In some embodiments, for example, as shown in Figures 4 and 5, the second reflector 50 may include a complementary reflective portion 52, such that when the second reflector 50 is in the second position, the complementary reflective portion 52 is configured to reflect the reference light transmitted by the transmission portion 42 of the first reflector 40. Figure 7 is a design plan view of the second reflector 50. In embodiments where the reference light is collimated in the reference optical path, the complementary reflective portion 52 may have a design with substantially the same shape and size as the transmission portion 42. Therefore, the design of the second reflector 50 in Figure 7 complements the design of the first reflector 40 shown in Figure 6.

[0062] As shown in Figure 4, when the second reflector 50 is in the first position, the second reflector 50 does not block the second optical path. The first position ensures that any reference light incident on the second reflector 50 (i.e., the reference light transmitted through the transmission portion 42 of the first reflector 40) is not reflected onto the first or second optical path.

[0063] As shown in Figure 5, when the second reflector 50 is in the second position, the complementary reflection portion 52 of the second reflector 50 is configured to reflect the reference light incident on the complementary reflection portion 52 onto the second optical path. Therefore, at least from Figure 6 As can be seen from Figure 7, the transmission portion 42 of the first reflector can define a first shape on the first reflector 40. The complementary reflection portion 52 of the second reflector can define a complementary first shape on the second reflector 50, wherein the first shape and the complementary first shape are aligned along the reference optical path.

[0064] In some embodiments, such as the one shown in FIG. 7, the second reflector 50 may further include a complementary transmission portion 54. The complementary transmission portion 54 may be configured to allow light to transmit through the thickness of the second reflector 50. Therefore, at least as shown in FIG. 5, when the second reflector 50 is in the second position, the second reflector 50 may allow at least some radial light to reach the entrance slit via the complementary transmission portion 54 of the second reflector 50. In some embodiments, the second reflector 50 includes an optically transparent plate having a reflective coating that partially covers the main surface of the optically transparent plate, wherein the reflective coating provides the complementary reflective portion 52 of the second reflector. For example, the optically transparent plate may be a glass substrate similar to the glass substrate of the first reflector 40 in FIG. 6. The reflective coating may be provided by a thin metal film similar to the reflective portion 44 of the first reflector 40 in FIG. 6.

[0065] Although the embodiments shown in Figures 2-7 indicate that the first reflector 40 and the second reflector 50 have a first shape that is generally circular and a complementary first shape, it should be understood that the first reflector 40 and the second reflector 50 may use other patterns.

[0066] In some embodiments, the first reflector 40 may include multiple shapes, while the second reflector 50 may include multiple complementary shapes. Figures 8a and 8b show examples of first reflector 40a and second reflector 50a having multiple shapes. Thus, the first reflector 40a of Figure 8a includes multiple transmissive portions 42a, and the second reflector 50a of Figure 8b includes multiple complementary reflective portions 52a. Although the first reflector 40a of Figure 8a includes a single continuous reflective portion 44a, in other embodiments, multiple reflective portions 44a may be provided. The second reflector 50a of Figure 8b includes complementary transmissive portions 54a, the shapes of which correspond to the reflective portions 44a.

[0067] In some embodiments, the first shape and the complementary first shape may each define one or more of the following: circular, regular polygonal, irregular polygonal, and elliptical. For example, the first reflector 40b of FIG. 8c includes a transmissive portion 42b having a generally rectangular first shape; and the second reflector 50b of FIG. 8d includes a complementary reflective portion 52b having a rectangular complementary first shape. The first reflector 40b includes a reflective portion 44b surrounding the rectangular transmissive portion 42b. The second reflector 50b of FIG. 8d includes a complementary transmissive portion 54b, the shape of which corresponds to the reflective portion 44b. The first reflector 40c of FIG. 8e includes a transmissive portion 42c having a generally elliptical first shape; and the second reflector 50c of FIG. 8f includes a complementary reflective portion 52c having an elliptical complementary first shape. The first reflector 40c includes a reflective portion 44c surrounding the elliptical transmissive portion 42c. The second reflector 50c in Figure 8f includes a complementary transmission portion 54c, the shape of which corresponds to that of the reflection portion 44c.

[0068] As can be seen at least from Figures 2-5, the entrance slit 60 can receive light from both the first and second optical paths of the optical assembly 20. To select whether to focus light from the first or second optical path onto the entrance slit, the slit focusing mirror 24 can be an adjustable mirror. Therefore, in some embodiments, the slit focusing mirror 24 can be configured to be adjustable between a first position and a second position, wherein in the first position, the slit focusing mirror 24 reflects light from the first optical path to the entrance slit 60; and in the second position, the slit focusing mirror 24 reflects light from the second optical path to the entrance slit 60. Thus, in some embodiments, the slit focusing mirror 24 can be used to select the light incident on the entrance slit 60.

[0069] In the embodiments of Figures 2-5, the slit-focusing mirror 24 is rotatable about an axis extending perpendicularly to a plane defined by the radial and axial directions of the light. In a first position, the slit-focusing mirror 24 is configured to reflect light from a first optical path to the entrance slit 60. In the embodiments of Figures 2-5, the slit-focusing mirror 24 is configured to rotate clockwise from the first position to a second position, wherein the slit-focusing mirror is configured to reflect light from a second optical path to the entrance slit 60. It should be understood that the slit-focusing mirror 24 is one example of an optical component that can be used to focus light from both the first and second optical paths onto the entrance slit 60. In other embodiments, other combinations of optical components may be provided as part of the optical assembly 20 to provide similar functionality.

[0070] In some implementations, the selection of light incident on the entrance slit 60 can also be controlled by one or more shutters. For example, as shown in FIG9, the optical emission spectrometer 1 may include a reference light shutter 34. The reference light shutter 34 may be configured to block the reference light source 30 from entering the reference optical path. For example, the reference light shutter 34 may be located in front of the reference light source 30. In a first position (shown in FIG9), the reference light shutter 34 may block the reference optical path, so that the reference light does not incident on the first mirror and / or the second mirror 40, 50. In a second position (indicated schematically by dashed lines in FIG9), the reference light shutter 34 may allow the reference light to incident on the first mirror 40 and / or the second mirror 50. Therefore, the reference light shutter 34 can be used to control the transmission of reference light into the optical assembly 20 while maintaining the operation of the reference light source 30. That is, the use of the reference light shutter 34 can avoid repeatedly opening and then closing the reference light source 30 each time a calibration measurement is performed. By using the reference shutter 34 to reduce the number of times the reference light source is turned on and / or off, the lifetime of the reference light source 30 can be extended. Furthermore, when the reference light source 30 is turned on, some reference light sources 30 may have a warm-up period. During this warm-up period, the spectral characteristics of the reference light source 30 may change. Therefore, by reducing the number of times the reference light source 30 is turned on and / or off, the accuracy of calibration measurements can be improved.

[0071] In some embodiments, a plasma optical shutter can be provided. The plasma optical shutter can be configured to block the plasma source 10 from entering the optical assembly 20. In some embodiments, a single plasma optical shutter can be provided, which can block the plasma source 10 from entering the first and second optical paths. In the embodiment of FIG. 9, the plasma source 10 is provided with an axial optical shutter 26 and a radial optical shutter 28. In a first position (shown in FIG. 9), the axial optical shutter 26 can block the first optical path, so that axial light does not incident on the first reflecting mirror 40 and / or the axial focusing mirror 22. In a second position (schematically indicated by dashed lines in FIG. 9), the axial shutter 26 can allow axial light to incident on the first reflecting mirror 40 and / or the axial focusing mirror 22. In the first position (shown in FIG. 9), the reference optical shutter 28 can block the second optical path, so that axial light does not incident on the second reflecting mirror 50 and / or the radial focusing mirror 23. In the second position (indicated schematically by dashed lines in Figure 9), the radial shutter 28 can allow radial light to be incident on the second mirror 50 and / or the radial focusing mirror 23.

[0072] The optical emission spectroscopy method 100 using an optical emission spectrometer 1 will be described next. Figure 10 is a block diagram of method 100.

[0073] In step 101, the method includes performing a calibration measurement using an optical emission spectrometer 1. The calibration measurement performed can be a radial calibration measurement or an axial calibration measurement. To perform an axial calibration measurement, a first reflector 40 can be positioned in a second position to guide reference light from a reference source 30 along a first optical path to the entrance slit 60, wherein the optical emission spectrometer 1 detects a known wavelength of the reference source. In the embodiments shown in Figures 2-7, a slit-focusing reflector 24 can also be positioned in a first position to guide light along the first optical path to the entrance slit 60.

[0074] To perform radial calibration measurements, the first reflector 40 can be positioned in either a first or second position to guide reference light from the reference source 30 to the second reflector 50. Positioning the second reflector in the second position guides the reference light along a second optical path to the entrance slit 60, where the optical emission spectrometer 1 detects the known wavelength of the reference source. In the embodiments shown in Figures 2-7, the slit focusing reflector 24 can also be positioned in the second position to guide light along the second optical path to the entrance slit 60.

[0075] The data generated by detector 80 (as shown in Figure 1) during calibration measurements can be used to calibrate optical emission spectrometer 1. For example, when detector 80 is an array detector, multiple spectral peaks of the reference light can be imaged on detector 80 during calibration measurements. One or more spectral peaks of the reference light source may have known wavelengths. Therefore, optical emission spectrometer 1 can associate one or more detector positions with corresponding wavelengths based on the positions of the spectral peaks of the reference light imaged on the detector.

[0076] When performing calibration measurements using an optical emission spectrometer 1 that includes one or more shutters, the shutters can be operated to block light sources not used during the calibration measurements. For example, in the embodiment of FIG9, during calibration measurements, the axial shutter 26 and the radial shutter 28 can be moved into their respective first positions. The reference shutter 26 can be in a second position during calibration measurements.

[0077] In embodiments where one or more shutters are not provided to plasma source 10, the plasma source may be briefly shut off while performing calibration measurements in some embodiments.

[0078] Therefore, the optical emission spectrometer 1 can be calibrated (or recalibrated) using the reference light source 30 integrated within it. Thus, the calibration process can be performed automatically by the optical emission spectrometer 1 without any user intervention or input. Consequently, the optical emission spectrometer 1 can switch between performing sample measurements and calibration measurements in a relatively rapid manner. For example, while performing a sample measurement, the optical emission spectrometer 1 can repeatedly perform calibration measurements. Performing such calibration measurements (within a relatively short time) allows the optical emission spectrometer 1 to perform sample measurements with improved accuracy without requiring repeated manual recalibration by the user.

[0079] In step 102, the method may include performing a sample measurement using an optical emission spectrometer 1. The sample measurement performed may be an axial sample measurement or a radial sample measurement.

[0080] To perform axial sample measurements, a first reflecting mirror 40 and a slit focusing mirror 24 can be positioned in a first position to guide light from the plasma source 10 along a first optical path to the entrance slit 60 of the optical emission spectrometer 1. The light incident on the entrance slit is then imaged by the detector 80.

[0081] To perform radial sample measurements, the second reflector 50 can be positioned in the first position to guide light from the plasma source 10 along the second optical path to the entrance slit 60 of the optical emission spectrometer 1. In the embodiments shown in Figures 2-7, the slit focusing reflector 24 can also be positioned in the second position to guide light along the second optical path to the entrance slit 60. The light incident on the entrance slit is then imaged by the detector 80.

[0082] When performing sample measurements (e.g., radial or axial sample measurements), the optical emission spectrometer 1 can utilize data from calibration measurements (e.g., radial and / or axial calibration measurements) when assigning wavelengths to the data generated by the detector 80. For example, the optical emission spectrometer 1 can calibrate radial sample measurements using radial calibration information from radial calibration measurements. The optical emission spectrometer 1 can also calibrate axial sample measurements using axial calibration information from axial calibration measurements.

[0083] When performing sample measurements using an optical emission spectrometer 1 containing one or more shutters, the shutters can be operated to block light sources not used during the sample measurement. For example, in the embodiment of FIG9, the reference light shutter 26 can be moved into a first position during sample measurement. For sample measurement, the slit focusing mirror 24 can be used to select whether light from the first optical path or light from the second optical path is imaged on the slit. Therefore, when performing sample measurement, both the axial shutter 26 and the radial shutter 28 can be in the second position.

[0084] By calibrating the optical emission spectrometer 1 using the reference light source 30, the optical emission spectrometer 1 can switch between performing calibration measurements and sample measurements in a straightforward manner (e.g., by moving the first reflecting mirror 40). Therefore, the optical emission spectrometer 1 may not require any changes to the sample being measured (e.g., measuring a calibration mixture or internal standard) for the spectrometer calibration. Thus, the optical emission spectrometer 1 can be calibrated reliably and robustly. Furthermore, calibration measurements can be performed in real time to correct for spectrometer drift during a series of sample measurements.

[0085] In some embodiments, one or more calibration measurements can be performed on the optical emission spectrometer 1 before performing sample measurements (e.g., as shown in method 100 of Figure 10). In some embodiments, when multiple sample measurements are to be performed, calibration measurements can be performed alternately throughout the sample measurements. Thus, each sample measurement performed can use the calibration information already obtained in real time for the optical emission spectrometer 1. Figure 11 shows an example of optical emission spectroscopy method 200. In Figure 11, axial calibration measurement 201 and radial calibration measurement 202 are performed first. Then, multiple axial sample measurements 203 and multiple radial sample measurements 204 are performed. In the embodiment of Figure 11, using the optical emission spectrometer 1, sample measurements are performed alternately between radial sample measurements and axial sample measurements 203, 204. After performing multiple radial and axial sample measurements 203, 204 (e.g., at least 3, 5, 7, 10, 15, or 20 times), the optical emission spectrometer 1 can repeat the axial calibration measurement 201a and the radial calibration measurement 202a, followed by further radial and axial sample measurements 203a, 204a. The further radial and axial sample measurements 203a, 204a can utilize calibration information from the most recently performed calibration measurements 201a, 202a. By performing calibration measurements in real-time staggered, the optical emission spectrometer 1 can perform multiple sample measurements with improved accuracy. Specifically, by repeating the calibration process throughout a set of sample measurements, the optical emission spectrometer can compensate for any measurement drift that may occur during the experiment.

[0086] For example, in some embodiments, the optical emission spectrometer 1 can perform multiple sample measurements 203, 204, each with a duration not exceeding 2000 ms, 1000 ms, 500 ms, or 250 ms. A switching time of not more than 2000 ms, 1000 ms, or 500 ms can be provided to switch from performing one sample measurement to performing another calibration measurement. The optical emission spectrometer can then perform one or more calibration measurements, each with a duration not exceeding 2000 ms, 1000 ms, 500 ms, or 250 ms. A switching time of not more than 2000 ms, 1000 ms, or 500 ms can be provided to switch from performing one calibration measurement to performing another sample measurement. Therefore, when performing a series of sample measurements, interspersing calibration measurements between consecutive sample measurements may introduce a delay of not more than 6000 ms, 4000 ms, 2000 ms, or 1000 ms. Therefore, it should be understood that optical emission spectrometers can switch between calibration measurements and sample measurements without excessive delay between sample measurements performed before and after calibration measurements.

[0087] Therefore, in some embodiments, the optical emission spectrometer 1 can perform multiple sample measurements. For example, multiple sample measurements can be performed at least at the following frequencies: 0.5 Hz, 1 Hz, 2 Hz, or 4 Hz. During the performance of multiple sample measurements, the optical emission spectrometer 1 can perform calibration measurements interleaved. Calibration measurements can be repeated during sample measurements to correct any drift of the optical emission spectrometer 1. For example, the optical emission spectrometer 1 can perform calibration measurements at least at frequencies of 0.01 Hz, 0.02 Hz, 0.05 Hz, 0.1 Hz, or 0.2 Hz. In some embodiments, the optical emission spectrometer 1 can perform calibration measurements after performing no more than 100, 50, 30, 20, or 10 sample measurements. Therefore, the optical emission spectrometer 1 can automatically perform repeated calibration measurements during the duration of multiple sample measurements to maintain a relatively high level of measurement accuracy / confidence during the duration of the sample measurements.

[0088] Therefore, according to embodiments of this disclosure, an optical emission spectrometer 1 and an optical emission spectroscopy measurement method 100, 200 are provided. It should be understood that the above disclosure is not limited to the embodiments discussed above, and various modifications will be apparent to those skilled in the art. The scope of the invention is defined by the following claims.

Claims

1. An optical emission spectrometer, comprising: Configured as a plasma source that emits light; An optical assembly comprising multiple optical components, the optical assembly being configured to guide light traveling from a plasma source in a first direction along a first optical path to the entrance slit of an optical emission spectrometer; A reference light source for calibrating a spectrometer, the reference light source being configured to output reference light along a reference optical path; A first reflecting mirror is configured to selectively switch reference light to a first optical path, thereby guiding the reference light to the entrance slit for calibrating an optical emission spectrometer.

2. The optical emission spectrometer according to claim 1, wherein... The first reflector is configured to be movable between a first position and a second position. The first position is farthest from the first optical path. In the second position, the first reflector is configured to reflect reference light from the reference optical path back onto the first optical path.

3. The optical emission spectrometer according to claim 1 or claim 2, wherein... The reference optical path intersects with the first optical path.

4. The optical emission spectrometer according to any one of claims 1 to 3, wherein The plasma source is configured to generate axial light in the axial direction and radial light in the radial direction, wherein the axial direction is the first direction.

5. The optical emission spectrometer according to any one of claims 1 to 3, wherein... The plasma source is configured to generate axial light in the axial direction and radial light in the radial direction, wherein the radial direction is the first direction.

6. The optical emission spectrometer according to claim 4, wherein... The optical assembly includes multiple optical components configured to guide radial light from the plasma source radially along a second optical path to the entrance slit of the optical emission spectrometer; and Optical emission spectrometers include: A second reflector is configured to selectively switch the reference light to a second optical path for calibrating an optical emission spectrometer.

7. The optical emission spectrometer according to claim 6, wherein... The second reflector is configured to be movable between the first position and the second position. The first position is far from the second optical path. In the second position, the second mirror is configured to reflect reference light from the reference optical path onto the second optical path, thereby guiding the reference light to the entrance slit of the optical emission spectrometer.

8. The optical emission spectrometer according to claim 7, wherein... The first reflector includes a reflecting portion and a transmitting portion. When the first reflector is in the second position, the reflecting portion is configured to reflect reference light incident on the reflecting portion onto the first optical path, and the transmitting portion is configured to transmit reference light incident on the transmitting portion to the second reflector.

9. The optical emission spectrometer according to claim 8, wherein... The second mirror includes a complementary reflective portion, such that when the second mirror is in the second position, the complementary reflective portion is configured to reflect reference light transmitted by the transmission portion of the first mirror.

10. The optical emission spectrometer according to claim 9, wherein... The transmissive portion defines a first shape on the first reflector, and the complementary reflective portion defines a complementary first shape on the second reflector, wherein the first shape and the complementary first shape are aligned along the reference optical path.

11. The optical emission spectrometer according to claim 10, wherein... The first shape and the complementary first shape can each be defined as one or more of the following: circle, regular polygon, irregular polygon and ellipse.

12. The optical emission spectrometer according to any one of claims 8 to 11, wherein The first reflector includes an optically transparent plate having a reflective coating that partially covers the main surface of the optically transparent plate, wherein the reflective coating provides the reflective portion of the first reflector.

13. The optical emission spectrometer according to any one of claims 8 to 12, wherein The second reflector includes an optically transparent plate having a reflective coating that partially covers the main surface of the optically transparent plate, wherein the reflective coating provides a complementary reflective portion of the second reflector.

14. The optical emission spectrometer according to any one of claims 2 to 13, wherein When in the first position, the first reflecting mirror intersects with the reference optical path.

15. The optical emission spectrometer according to any one of claims 1 to 14, further comprising: An optical fiber configured to guide reference light from a reference light source to a first reflector and a second reflector.

16. The optical emission spectrometer according to any one of claims 6 to 15, wherein Optical components include: Adjustable reflector; A first focusing mirror is provided in the first optical path, and the first focusing mirror is configured as follows: It receives axial light from the plasma source and reference light from the first reflecting mirror, and Focusing axial light and reference light onto an adjustable mirror of the optical component; and A second focusing mirror is provided in the second optical path, and the second focusing mirror is configured as follows: It receives radial light from the plasma source and reference light from the second mirror, and The radial light and reference light are focused onto the adjustable mirror of the optical component. The adjustable reflector is configured to be adjustable between a first position and a second position. In the first position, the adjustable reflector reflects light from the first optical path to the entrance slit of the spectrometer. In the second position, the adjustable reflector reflects light from the second optical path to the entrance slit of the spectrometer.

17. The optical emission spectrometer according to any one of claims 1 to 16, wherein Reference light sources include one or more of the following: hollow cathode lamps, narrowband LEDs, lasers, glow discharge lamps, and spectral lamps.

18. The optical emission spectrometer according to any one of claims 1 to 17, further comprising one or more of the following: It can be set as a reference light shutter to block the reference light source from entering the reference light path; It can be configured to block the plasma source from entering the optical components of the plasma shutter.

19. The optical emission spectrometer according to any one of claims 1 to 18, further comprising: detector; and An Eichel grating is configured to receive light from the entrance slit and guide the light to the detector, containing multiple orders of Eichel spectra for imaging on the detector.

20. The optical emission spectrometer according to any one of claims 1 to 18, further comprising: detector; and Configured to receive light from the entrance slit and guide the light to a concave grating on the detector, where a linear spectrum is imaged on the detector.

21. A method for measuring optical emission spectrometry using an optical emission spectrometer according to any one of claims 1 to 20, the method comprising: A calibration measurement is performed, wherein a first reflector is positioned to guide reference light from a reference source along a first optical path to the entrance slit of the spectrometer, wherein the optical emission spectrometer detects a known wavelength of the reference source.

22. The optical emission spectroscopy method according to claim 20, further comprising: Sample measurements are performed, wherein a first reflector is positioned to guide light from the plasma source along a first optical path to the entrance slit of the optical emission spectrometer.

23. A method for measuring optical emission spectrometry using the optical emission spectrometer according to any one of claims 6 to 20, the method comprising: An axial calibration measurement is performed, wherein a first reflector is positioned to guide reference light from a reference source along a first optical path to the entrance slit of the spectrometer, wherein the optical emission spectrometer detects a known wavelength of the reference source. as well as A radial calibration measurement is performed, wherein a second reflector is positioned to guide reference light from a reference source along a second optical path to the entrance slit of the spectrometer, wherein the optical emission spectrometer detects a known wavelength of the reference source.

24. The method of claim 23, further comprising: Perform axial sample measurements, wherein a first reflecting mirror is positioned to guide axial light from the plasma source to the entrance slit of the optical emission spectrometer; and / or Radial sample measurements are performed, in which a second reflector is placed to guide radial light from the plasma source to the entrance slit of the optical emission spectrometer.

25. The method of claim 24, wherein Perform multiple axial sample measurements and / or multiple radial sample measurements, and Perform at least one axial calibration measurement and / or at least one radial calibration measurement during multiple sample measurements.

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