Quartz glass impurity measuring device and method

Abstract

The invention belongs to the related field of quartz glass detection technology, and discloses a quartz glass impurity measuring device, which comprises a displacement table, an excitation light path unit and a detection light path unit, and is characterized in that the displacement table is used for bearing a quartz glass sample to be detected; the excitation light path unit comprises a laser light source and a focusing lens, and the laser light source is used for emitting a narrow-linewidth laser beam with the linewidth of 0.5 nm or below and irradiating the narrow-linewidth laser beam to a sample after passing through the focusing lens so as to excite a Raman spectrum; the detection light path unit comprises an acquisition objective lens, an optical filter, a coupling lens and a spectrograph, and a Raman spectrum excited by the detection light path unit is acquired by the acquisition objective lens, sequentially passes through the optical filter and the coupling lens and returns to the spectrograph for analysis. The invention further discloses a corresponding measuring method. According to the invention, the detection of hydroxyl, hydrogen isotope, fluorine content, and hydrogen molecule content and distribution in quartz glass can be carried out with higher precision and higher efficiency, and the method is well suitable for measurement samples with diameters greater than 100mm and different thicknesses.

Description

Technical Field

[0001] The present invention belongs to the field related to the detection technology of fused silica, and more specifically, relates to a device and method for measuring impurities in fused silica, which is particularly suitable for accurately measuring the hydroxyl OH, hydrogen isotope OD, fluorine content, hydrogen molecule content and distribution of various products such as fused silica ingots, plates and tubes. Background Art

[0002] Fused silica is an important special glass material and is widely used in the fields of optics, electronics, semiconductors, etc. Among them, the hydroxyl OH, hydrogen isotope OD, fluorine content, hydrogen molecule content and distribution are important indicators of fused silica and have a great impact on the performance and quality of the material. Therefore, an accurate determination method for the impurity content in fused silica is of great significance.

[0003] In the prior art, the infrared absorption spectroscopy measurement method is usually adopted to realize the detection of impurities in fused silica. For example, reference can be made to the national standard GB / T 12442-2019. This method includes the following steps: 1) Prepare the fused silica sample by crushing it into fine powder, screening out the powder below 100 mesh, and weighing a certain amount of the sample for use; 2) Uniformly disperse the sample powder on the KBr plate, press it into a transparent thin sheet, and then perform tests on the infrared spectrometer; before the measurement, the baseline scan and the sample scan should be carried out first to obtain the infrared spectrum curve; 3) Use the microscopic infrared spectrometer to process the spectrum curve, compare the integral value of the hydroxyl absorption peak with the integral value of the internal standard peak, so as to calculate the content of hydroxyl.

[0004] However, further research shows that the above prior art still has the following defects or steps: First, this method cannot well adapt to the measurement of hydrogen molecule and fluorine content, mainly because the hydrogen molecule and fluorine content have no absorption peaks and cannot be measured by absorption spectroscopy; second, due to the limitations of the equipment, the existing method often cannot measure samples with a diameter greater than 100 mm; finally, in the existing method, when measuring samples with different contents, samples with different thicknesses need to be prepared, which also causes problems such as complex measurement procedures and low efficiency.

[0005] Correspondingly, there is an urgent need in the art to tackle the technologies for rapid and high-precision detection of hydroxyl OH, hydrogen isotope OD, fluorine content and hydrogen molecules in fused silica, so as to better meet the higher quality control requirements of fused silica products. Summary of the Invention

[0006] In view of one or more of the above-mentioned defects or requirements of the prior art, the present invention provides a device and method for measuring impurities in quartz glass. By closely combining the working conditions and specific requirements of detecting hydroxyl OH, hydrogen isotope OD, fluorine content, hydrogen molecule content and distribution, research and improvement are made on the overall structure composition, working mechanism and some key detection indexes of relevant impurity measuring devices, and a compact measuring device with an excitation optical path separated from the detection optical path can be obtained, which can effectively avoid the adverse effects of fluorescence. It can not only detect the content and distribution of hydroxyl, hydrogen isotope, fluorine content and hydrogen molecule in quartz glass with higher precision and efficiency, but also be well applicable to measuring samples with a diameter greater than 100 mm and different thicknesses.

[0007] To achieve the above object, according to one aspect of the present invention, a device for measuring impurities in quartz glass is provided, characterized in that the measuring device includes a displacement stage, an excitation optical path unit and a detection optical path unit, wherein:

[0008] The displacement stage is used to carry the quartz glass sample to be detected;

[0009] The excitation optical path unit includes a laser light source and a focusing lens. The laser light source is a narrow linewidth laser, which is used to emit a narrow linewidth laser beam with a linewidth of less than 0.5 nm, and after passing through the focusing lens, it irradiates the quartz glass sample to excite Raman spectrum; both the laser light source and the focusing lens can perform free adjustment in the X, Y and Z directions, so that the acquisition objective lens can collect the required scattered signals;

[0010] The detection optical path unit includes an acquisition objective lens, a filter, a coupling lens and a spectrometer. The Raman spectrum excited by the quartz glass sample is collected in real time by the acquisition objective lens, and after passing through the filter and the coupling lens in sequence, it returns to the spectrometer, and then is analyzed by the spectrometer to obtain the detection of the content and distribution of hydroxyl, hydrogen isotope, fluorine content and hydrogen molecule in quartz glass.

[0011] As a further preference of the present invention, the displacement stage is preferably an XYZ displacement stage, which can perform free adjustment of the position and attitude in the X-axis, Y-axis and Z-axis directions.

[0012] As a further preference of the present invention, the laser power of the laser light source is preferably greater than or equal to 1 W.

[0013] As a further preference of the present invention, the focusing lens is preferably made of a material with low fluorescence and low hydroxyl, and more preferably made of low-hydroxyl quartz material.

[0014] As a further preference of the present invention, the working distance of the acquisition objective lens is preferably set to be greater than 5 mm.

[0015] As a further preference of the present invention, it is preferred to connect the coupling lens and the spectrometer with an optical fiber, and the core diameter of the optical fiber is greater than or equal to 50 μm.

[0016] As a further preference of the present invention, the minimum test range of the spectrometer is preferably set to 100 cm -1 ~4300 cm -1 .

[0017] As a further preference of the present invention, the above measurement device further includes a central processing unit, which is used to collect various data of the above optical path excitation and detection processes in real time and obtain the distribution of impurities.

[0018] According to another aspect of the present invention, a corresponding detection method is also provided, which is characterized in that the method includes the following steps:

[0019] Step 1: Use a narrow-linewidth laser to emit a narrow-linewidth laser beam with a linewidth below 0.5 nm to the quartz glass sample to be detected and excite the Raman spectrum;

[0020] Step 2: Use a spectrometer to obtain the excited Raman spectrum, and analyze and calculate the ratio of the impurity Raman peak area to the silicon-oxygen bond Raman peak area therein, thereby obtaining the detection results of the contents of hydroxyl OH, hydrogen isotope OD, fluorine content, and hydrogen molecules in the quartz glass.

[0021] As a further preference of the present invention, the above detection method further includes obtaining the detection results of the distribution of hydroxyl OH, hydrogen isotope OD, fluorine content, and hydrogen molecules in the quartz glass.

[0022] As a further preference of the present invention, the thickness of the quartz glass sample is not limited, and its diameter can be greater than 100 mm.

[0023] Generally speaking, compared with the prior art through the above technical solutions conceived by the present invention, the following technical advantages are mainly possessed:

[0024] (1) By using a narrow-linewidth laser to excite the Raman spectrum of quartz glass and analyzing and calculating the Raman spectrum to obtain the impurity content, this detection method can more accurately obtain the impurity content and distribution, and is especially suitable for detecting the contents and distributions of hydroxyl, hydrogen isotope OD, fluorine content, and hydrogen molecules in quartz glass;

[0025] (2) The present invention further makes targeted optimizations on some key design parameters of the detection device, such as laser linewidth and power, working distance of the collection objective lens, fiber core diameter, etc. During the process of performing the above-mentioned optical path excitation and optical path detection, the signal intensity obtained by the detection device designed above is significantly better than that of other types of devices, and it is more suitable for application scenarios where Raman peaks are very weak;

[0026] (3) The overall structure of the detection device of the present invention is compact and easy to operate. It not only does not require preparing different thicknesses for samples with different contents, but also this detection scheme can be well applied to quartz glass samples with a diameter greater than 100 mm. Therefore, the detection efficiency is significantly improved, the adaptability is expanded, and it is particularly suitable for application occasions for detecting hydroxyl groups, hydrogen isotope OD, fluorine content, hydrogen molecule content and distribution in various products such as quartz glass ingots, plates and tubes. Description of the Drawings

[0027] Figure 1 is a schematic diagram of the main component structure of the quartz glass impurity detection device according to the preferred embodiment of the present application;

[0028] Figure 2 is a schematic diagram of the detection result obtained according to a specific example of the present application;

[0029] Figure 3 is a result comparison diagram used to show the comparison between the test method of the present application and the test method of the prior art;

[0030] In all the drawings, the same reference numerals are used to represent the same elements or structures, where:

[0031] 1 - displacement stage; 2 - focusing lens; 3 - collection objective lens; 4 - filter; 5 - coupling lens; 6 - optical fiber; 7 - spectrometer; 8 - central processing unit; 9 - laser light source. Detailed Embodiments

[0032] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0033] It should be understood that expressions such as "including" and "may include" used in the present application indicate the existence of the disclosed functions, operations or constituent elements, and do not limit one or more additional functions, operations and constituent elements. In the present application, terms such as "including" and / or "having" can be interpreted as indicating a specific characteristic, number, operation, constituent element, component or their combination, but cannot be interpreted as excluding the existence or addition possibility of one or more other characteristics, numbers, operations, constituent elements, components or their combinations.

[0034] It should be understood that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present application.

[0035] In addition, the terms "first" and "second" are only used for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present application, the meaning of "a plurality" is two or more unless otherwise specifically defined.

[0036] In the present application, unless otherwise clearly specified and limited, the terms such as "mounted", "connected", "connected to", "fixed" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0037] Figure 1 is a schematic diagram of the main component structure of the quartz glass impurity detection device of the preferred embodiment of the present application. The following will be combined with Figure 1 to more specifically explain the present invention.

[0038] Refer to Figure 1 , the quartz glass impurity measurement device of the present invention mainly includes a displacement stage 1, an excitation optical path unit and a detection optical path unit. In addition, a central processing unit 8, etc. can be connected in a supporting manner.

[0039] More specifically, the displacement stage 1 is, for example, an XYZ displacement stage, which is used to carry the quartz glass sample to be detected and can perform free adjustment of the position and attitude in the X-axis, Y-axis and Z-axis directions.

[0040] As one of the key improvements of the present invention, the excitation optical path unit and the detection optical path unit are different and separate optical paths from each other. Specifically, the excitation optical path unit may include a laser light source 9 and a focusing lens 2. The laser light source 9 is, for example, a narrow linewidth laser, which is used to emit a narrow linewidth laser beam with a linewidth below 0.5 nm. After passing through the focusing lens 2, it irradiates the quartz glass sample to excite the Raman spectrum. In addition, both the laser light source 9 and the focusing lens 2 can perform free adjustment in the XYZ directions, so that the collecting objective lens 3 can collect the required scattering signal, that is, to maximize the scattering signal.

[0041] More specifically, the laser power of the laser light source 9 is preferably set to be greater than or equal to 1 W. This is because the impurity content in the quartz glass is relatively low and its Raman peak is very weak. The narrow linewidth laser beam with the above power can better complete the excitation process. In addition, the lens of the focusing lens 2 is preferably made of a low-fluorescence and low-hydroxyl material, and more preferably made of a low-hydroxyl quartz material. In this way, it can better avoid the adverse effects of fluorescence generated by the lens on the test.

[0042] As another key improvement of the present invention, the detection optical path unit may include a collecting objective lens 3, a filter 4, a coupling lens 5, a spectrometer 7, etc. The Raman spectrum excited by the quartz glass sample is collected in real time by the collecting objective lens 3, and after passing through the filter 4 and the coupling lens 5 in sequence, it returns to the spectrometer 7, and then is analyzed by the spectrometer 7 to obtain the contents of hydroxyl groups and hydrogen molecules in the quartz glass.

[0043] More specifically, the working distance of the collecting objective lens is preferably set to be greater than 5 mm, and this range can better complete the collection process of the Raman spectrum. The filter 4 is preferably a long-pass filter, or a dichroic mirror can be used as the filter. The coupling lens 5 is, for example, a fiber optic coupling lens, or a spectrometer can be directly used. At this time, a small hole needs to be opened at the focal point of the coupling lens 5 to reduce the influence of stray light. In addition, the coupling lens 5 and the spectrometer 7 are preferably connected by an optical fiber 6, and the core diameter of this optical fiber 6 is greater than or equal to 50 μm. Actual tests show that this can help with the collection and transmission of weak signals. For the spectrometer 7, it can use a cooled CCD or a photomultiplier tube. When using a cooled CCD, it is necessary to ensure that the CCD integration time is greater than or equal to 60 S. In addition, the minimum test range of the spectrometer 7 is preferably set to 100 cm -1 ~4300 cm -1 .

[0044] The following will specifically explain the method for detecting impurities in quartz glass according to the present invention. This method includes the following steps:

[0045] Step 1: Use a narrow linewidth laser to emit a narrow linewidth laser beam with a linewidth below 0.5 nm to the quartz glass sample to be detected, and excite the Raman spectrum;

[0046] Step 2: Use a spectrometer to obtain the excited Raman spectrum, and analyze and calculate the ratio of the area of the impurity Raman peak to the area of the silicon-oxygen bond Raman peak in it, thereby obtaining the detection results of the content of hydroxyl OH, hydrogen isotope OD, fluorine content, and hydrogen molecules in the fused silica glass.

[0047] According to a preferred embodiment of the present invention, a central processing unit can also be used to collect various data of the above optical path excitation and detection processes in real time, and obtain the distribution of impurities.

[0048] It should be noted that in the above measurement process, the thickness of the fused silica glass sample is not limited, and its diameter can be greater than 100 mm.

[0049] See Figure 2 , the peak at 800 cm -1 in the figure is the peak of the silicon-oxygen bond of the fused silica glass. Since the proportion of silicon dioxide in the measured sample is greater than 98%, the area of this peak can be used to calibrate the laser intensity received by the sample. The Raman peak of hydroxyl is at 3663 cm -1 , and the Raman peak of hydrogen molecules is at 4135 cm -1 . Usually, for the measurement near 800 cm -1 , an integration time of less than 5 s is generally used. From 3000 cm -1 to 4300 cm -1 , adjust the integration time according to the impurity content of the sample. Generally, the integration time is greater than 10 s.

[0050] See Figure 3 , by comparing the results between the test method of this application and the test method of the prior art, it can be found that the test data of the two are basically consistent.

[0051] In summary, compared with the prior art, this application can better detect the content and distribution of hydroxyl and hydrogen molecules in fused silica glass. It not only does not need to prepare different thicknesses for samples with different contents, but also this detection scheme can be well applied to fused silica glass samples with a diameter greater than 100 mm. Therefore, the detection efficiency is significantly improved, and the adaptability is expanded. Thus, it is especially suitable for the application occasions of detecting the content and distribution of hydroxyl, hydrogen isotope OD, fluorine content, and hydrogen molecules in various products such as fused silica glass ingots, plates, and tubes, and has good practical value and application prospects.

[0052] It is easy for those skilled in the art to understand that the above are only the preferred embodiments of this application, and are not used to limit this application. Any modifications, equivalent replacements, and improvements made within the spirit and principles of this application shall be included within the protection scope of this application.

Claims

1. A quartz glass impurity measuring device, characterized in that: The measuring device comprises a translation stage, an excitation optical path unit and a detection optical path unit, wherein: The translation stage (1) is used to carry a quartz glass sample to be tested; The excitation optical path unit comprises a laser light source (9) and a focusing lens (2), wherein the laser light source (9) is a narrow line width laser, which is used to emit a narrow line width laser beam with a line width of less than 0.5 nm, and irradiates a quartz glass sample after passing through the focusing lens (2) to excite a Raman spectrum; the laser light source (9) and the focusing lens (2) can both be freely adjusted in the XYZ directions, and enable the collection objective lens (3) to collect the required scattering signal; The detection optical path unit comprises a collection objective lens (3), a filter (4), a coupling lens (5) and a spectrometer (7), wherein the Raman spectrum excited by the quartz glass sample is collected in real time by the collection objective lens (3), and is returned to the spectrometer (7) after passing through the filter (4) and the coupling lens (5) in sequence, and then analyzed by the spectrometer (7) to obtain the content and distribution of hydroxyl groups, hydrogen isotopes, fluorine content, and hydrogen molecules contained in the quartz glass.

2. The quartz glass impurity measuring device according to claim 1, characterized in that: The translation stage (1) is preferably an XYZ translation stage, which can freely adjust the position and posture in the X-axis, Y-axis and Z-axis directions.

3. The quartz glass impurity measuring device according to claim 1 or 2, characterized in that: The laser power of the laser light source (9) is preferably greater than or equal to 1 W.

4. The quartz glass impurity measuring device according to any one of claims 1 to 3, characterized in that: The focusing lens (2) is preferably made of a low-fluorescence, low-hydroxyl material, and is further preferably made of a low-hydroxyl quartz material.

5. The quartz glass impurity measuring device according to any one of claims 1 to 4, characterized in that: The working distance of the collection objective lens (3) is preferably set to be greater than 5 mm.

6. The quartz glass impurity measuring device according to any one of claims 1 to 5, characterized in that: The coupling lens (5) and the spectrometer (7) are preferably connected by an optical fiber (6), and the core diameter of the optical fiber (6) is greater than or equal to 50 μm.

7. The quartz glass impurity measuring device according to any one of claims 1 to 6, characterized in that: The minimum test range of the spectrometer (7) is preferably set to 100 cm -1 ~4300cm -1 .

8. The quartz glass impurity measuring device according to any one of claims 1 to 7, characterized in that: The above-mentioned measuring device preferably also includes a central processing unit (8), which is used to collect various data of the above-mentioned optical path excitation and detection process in real time and obtain the distribution of impurities.

9. A method for measuring impurities in quartz glass, characterized in that: The method comprises the following steps: Step 1: Use a narrow line width laser to emit a narrow line width laser beam with a line width of less than 0.5 nm to the quartz glass sample to be tested, and stimulate Raman spectrum; Step 2: Use a spectrometer to obtain the excited Raman spectrum, and analyze and calculate the ratio of the impurity Raman peak area to the silicon-oxygen bond Raman peak area, thereby obtaining the detection results of the content of hydroxyl OH, hydrogen isotope OD, fluorine content, and hydrogen molecules in the quartz glass.

10. The measuring method according to claim 9, characterized in that: The above detection method also includes obtaining the detection results of the distribution of hydroxyl group OH, hydrogen isotope OD, fluorine content, and hydrogen molecules in the quartz glass.

Images