Light path structure for object spectrum test in vacuum environment

Abstract

The invention discloses a light path structure for an object spectrum test in a vacuum environment. The light path structure comprises a vacuum flange, and an intra-cavity light path and an extra-cavity light path which are communicated through the vacuum flange, the vacuum flange is characterized in that the vacuum flange comprises a flange plate and an optical fiber channel and is connected with the vacuum cavity through the flange plate, and the optical fiber channel is filled with sealing colloid to guarantee vacuum sealing; the intracavity optical path is an intracavity optical fiber group comprising a plurality of optical fibers, one optical fiber is an intracavity transmitting optical fiber connected with a light source, and the other optical fibers are intracavity receiving optical fibers connected with a spectrograph; the extra-cavity light path comprises an extra-cavity transmitting optical fiber and an extra-cavity receiving optical fiber, the extra-cavity transmitting optical fiber guides a light source into the intra-cavity transmitting optical fiber through the vacuum flange, and the extra-cavity receiving optical fiber receives an optical signal of the intra-cavity receiving optical fiber through the vacuum flange and transmits the optical signal to the spectrograph. According to the invention, the optical coupling efficiency can be improved, the excitation and receiving capabilities are enhanced, and the dependence on high-end hardware is reduced, so that the cost is reduced and the generalizability is realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of spectrum testing, and in particular relates to an optical path structure for spectrum testing of an object in a vacuum environment. Background Art

[0002] In the field of spectral analysis and testing, many applications require testing the object under test in a vacuum environment. For example, when using a vacuum coating machine to coat lenses, the film thickness needs to be monitored in real time; when using a vacuum evaporation machine to evaporate the display panel, the thin film deposition needs to be monitored; and some substances need to be stimulated to produce a fluorescent reaction in a vacuum environment to determine their composition or state. In such applications, the following typical problems exist during the testing process: the object under test is usually located inside a vacuum chamber, while the light source, spectrometer and other detection equipment are located in a normal pressure environment. The optical path must pass through the vacuum interface to ensure sealing while maintaining the quality of the optical signal; the light source needs to emit excitation light of sufficient intensity to the object under test, and the spectrometer needs to receive the reflected or fluorescent signal with high sensitivity. The system has high requirements for light transmission efficiency; the entire optical path structure is usually relatively complex, involving multiple optical couplings. If handled improperly, the reflected light or fluorescent signal will be significantly attenuated, especially in low-light-intensity applications such as fluorescence detection.

[0003] In the existing technology, some solutions use a single bidirectional optical fiber to pass through a vacuum cavity to transmit and receive optical signals. This solution has the following defects: the optical fiber inside the cavity is a single bidirectional structure, with low reception efficiency and difficulty in effectively collecting divergent light; the optical fibers need to be docked at the vacuum interface, which increases coupling loss; the optical fiber outside the cavity usually adopts a Y-shaped structure. After docking with the optical fiber inside the cavity, part of the received light will be reflected back into the light source path, resulting in effective signal loss.

[0004] To improve optical coupling efficiency, some high-end solutions utilize high-power laser-excited xenon lamp sources (LDLS) and cooled, high-sensitivity spectrometers to enhance signal excitation and reception capabilities. However, these devices are expensive, with the light source costing approximately 20 times that of a typical light source and the spectrometer approximately five times that of a standard device, making the overall system difficult to commercialize.

[0005] Therefore, there is an urgent need for an optical path structure that can improve the optical coupling efficiency while ensuring vacuum sealing, enhance the excitation and receiving capabilities, reduce dependence on high-end hardware, thereby reducing costs and achieving scalability. Summary of the Invention

[0006] The present invention provides an optical path structure for spectral testing of objects in a vacuum environment, aiming to solve the problems of insufficient enhanced excitation and receiving capabilities and high costs in the existing technology.

[0007] In order to solve the above technical problems, the optical path structure proposed in the present invention includes a vacuum flange, an intra-cavity optical path and an extra-cavity optical path connected by the vacuum flange; The vacuum flange includes a flange plate and an optical fiber channel, which is connected to the vacuum cavity through the flange plate. The optical fiber channel is filled with a sealing colloid to ensure vacuum sealing; The intracavity optical path is an intracavity optical fiber group including multiple optical fibers, one of which is an intracavity transmitting optical fiber connected to a light source, and the other optical fibers are intracavity receiving optical fibers connected to a spectrometer. The intracavity optical fiber group illuminates the object to be measured in the vacuum cavity through a probe connector; The extra-cavity optical path includes an extra-cavity transmitting optical fiber and an extra-cavity receiving optical fiber. The extra-cavity transmitting optical fiber introduces the light source into the intra-cavity transmitting optical fiber through the vacuum flange via the light source end connector. The extra-cavity receiving optical fiber receives the light signal of the intra-cavity receiving optical fiber through the vacuum flange and transmits it to the spectrometer through the spectrometer end connector.

[0008] Preferably, outer layers of the intra-cavity optical fiber group, the extra-cavity transmitting optical fiber and the extra-cavity receiving optical fiber are all provided with protective layers.

[0009] Preferably, the protective layer is a metal hose.

[0010] Preferably, the intracavity optical fiber group is provided with seven optical fibers, one of which is an intracavity transmitting optical fiber, and the remaining six are intracavity receiving optical fibers, which are divided into two groups, each connected to a spectrometer, with three fibers in each group.

[0011] Preferably, the cross-sections of the seven optical fibers are arranged hexagonally, wherein the intra-cavity transmitting optical fiber is arranged at the center, and the intra-cavity receiving optical fiber is arranged at the periphery of the intra-cavity transmitting optical fiber.

[0012] Preferably, the receiving optical fibers in the cavity are divided into two groups according to every other adjacent optical fiber.

[0013] Preferably, the intra-cavity transmitting optical fiber, the intra-cavity receiving optical fiber, the extra-cavity transmitting optical fiber and the extra-cavity receiving optical fiber are all made of polyimide-coated UV quartz optical fiber or radiation-resistant optical fiber.

[0014] Preferably, the probe connector, light source end connector and spectrometer end connector are all SMA905 standard connectors.

[0015] Preferably, the three optical fibers included in the spectrometer end connector are arranged in a straight line.

[0016] Preferably, the vacuum flange is a KF vacuum flange.

[0017] Compared with the prior art, the present invention has the following technical effects: 1. The optical path structure proposed in this invention takes into account the divergence of light. The optical fibers at the probe end are arranged concentrically, using multiple outer fibers to receive light, thereby increasing the intensity of the received light. Two sets of receiving fibers are configured to simultaneously transmit the optical signal to two spectrometers, generating two sets of test data (spectral curves). A differential algorithm converts the absolute values ​​of the test data into relative values, eliminating the influence of system errors and environmental noise, and achieving more accurate test results.

[0018] 2. The optical path structure proposed by the present invention is provided with an optical fiber channel inside the vacuum flange, and the optical fiber passes through and is sealed with glue. The leakage rate can be as good as 10 after helium mass spectrometer testing. -9 .

[0019] 3. The optical path structure proposed in the present invention uses polyimide-coated optical fiber, which has extremely low gas content and meets the vacuum requirements of the cavity.

[0020] 4. The optical path structure proposed by the present invention arranges optical fibers in a straight line on the end connector of the spectrometer, and can align and cover the light-receiving slit of the spectrometer through the positioning key, thereby increasing the intensity of the received light.

[0021] 5. In the optical path structure proposed by the present invention, the transmitting optical fiber inside the cavity and the transmitting optical fiber outside the cavity are a whole optical fiber, which does not require butt coupling; the receiving optical fiber inside the cavity and the receiving optical fiber outside the cavity are also a whole optical fiber, which also does not require butt coupling; thus, coupling loss at the interface is avoided, and the overall optical coupling efficiency of the system is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the optical path structure of the prior art; Figure 2 is an axonometric diagram of the optical path structure of the present invention; Figure 3 is a schematic diagram of the optical path structure according to an embodiment of the present invention; Figure 4 yes Figure 3 Enlarged view of point A in the middle; Figure 5 is a cross-sectional view of an intracavity optical fiber assembly according to an embodiment of the present invention; Figure 6 is a cross-sectional view of an extracavity emission optical fiber according to an embodiment of the present invention; Figure 7 It is a cross-sectional view of the end connector of the extracavity receiving optical fiber and the spectrometer according to an embodiment of the present invention.

[0023] Figure numerals: 1. vacuum flange; 11. flange plate; 12. optical fiber channel; 13. seal; 2. intracavity optical path; 21. intracavity emitting optical fiber; 221. first intracavity receiving optical fiber; 222. second intracavity receiving optical fiber; 23. probe connector; 3. extracavity optical path; 31. extracavity emitting optical fiber; 32. light source end connector; 33. spectrometer end connector; 34. extracavity receiving optical fiber. DETAILED DESCRIPTION

[0024] In order to make the objectives, technical solutions and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in combination with specific embodiments of the present application and with reference to the accompanying drawings.

[0025] The existing method usually configures a xenon lamp light source and a UV-band spectrometer, and transmits light through a single optical fiber. The optical fiber is connected at the vacuum interface and is divided into two parts: the outside of the cavity and the inside of the cavity. Figure 1 As shown, the left side shows the inside of the vacuum cavity, and the right side shows the outside of the vacuum cavity. Outside the vacuum cavity, light emitted by the light source passes through the vacuum interface via the extracavity fiber connected to the light source and enters the intracavity fiber. The received light from the intracavity probe returns through the same intracavity fiber, passing through the vacuum interface and then being transmitted to the light source and spectrometer via two optical fibers, one above and one below. This optical path structure has the following main drawbacks: the intracavity fiber is a single, bidirectional fiber. Due to the divergence angle of the light, its light receiving ability is relatively weak, resulting in most light not being received; the optical fibers are butted at the vacuum interface, increasing primary coupling loss; and the extracavity fiber has a Y-shaped structure. When it is butted against the intracavity fiber, 50% of the received light returns all the way back to the light source.

[0026] To address the low coupling efficiency of optical pathways, high-end hardware is typically deployed. For example, a laser-driven xenon light source (LDLS) can achieve mW output power when connected to a pigtailed fiber. A UV spectrometer with a QE-Pro cooling system can increase sensitivity to weak light signals. However, all of this hardware must be imported, resulting in a light source costing 20 times the cost of conventional equipment and a spectrometer costing 5 times the cost of conventional equipment. This complete optical pathway is very expensive, making it difficult to commercialize.

[0027] Therefore, there is an urgent need for an optical path structure that can improve the optical coupling efficiency while ensuring vacuum sealing, enhance the excitation and receiving capabilities, reduce dependence on high-end hardware, thereby reducing costs and achieving scalability.

[0028] This embodiment is an optical path structure for spectrum testing of objects in a vacuum environment. Figure 2 、 3 As shown, it includes a vacuum flange 1, an intra-cavity optical path 2 and an extra-cavity optical path 3 connected through the vacuum flange 1.

[0029] like Figure 4 As shown, the vacuum flange 1 includes a flange 11 and a fiber channel 12. The flange 11 is connected to the vacuum chamber. The flange 11 and the vacuum chamber are sealed by an external sealing structure. The fiber channel 12 is filled with a sealing colloid to ensure a vacuum seal. A seal 13 is also included for securing the fiber assembly within the chamber.

[0030] The intracavity optical path 2 is an intracavity optical fiber group including multiple optical fibers, one of which is an intracavity transmitting optical fiber 21 connected to the light source, and the other optical fibers are intracavity receiving optical fibers connected to the spectrometer. The intracavity optical fiber group illuminates the object to be measured in the vacuum cavity through the probe connector 23.

[0031] In one embodiment of the present invention, the intracavity optical fiber group is provided with seven optical fibers, one of which is an intracavity transmitting optical fiber 21, and the remaining six are intracavity receiving optical fibers, which are divided into two groups, each connected to a spectrometer, namely the first intracavity receiving optical fiber 221 and the second intracavity receiving optical fiber 222. The first intracavity receiving optical fiber 221 and the second intracavity receiving optical fiber 222 each contain three optical fibers.

[0032] A further structure of an intracavity optical fiber group of the present invention is as follows Figure 5 As shown, the cross sections of the seven optical fibers are arranged hexagonally, wherein the intracavity transmitting optical fiber 21 is arranged in the center, and the intracavity receiving optical fiber is arranged on the periphery of the intracavity transmitting optical fiber 21. Figure 5 The present invention also provides an arrangement of the intracavity receiving optical fibers, wherein the intracavity receiving optical fibers are divided into two groups in a manner that every other adjacent optical fiber is present. Specifically, in the figure, among the six intracavity receiving optical fibers distributed on the periphery, the first intracavity receiving optical fiber 221 and the second intracavity receiving optical fiber 222 are represented by cross-section lines in different directions. The first intracavity receiving optical fiber 221 is arranged around the intracavity transmitting optical fiber 21 in the circumferential direction with one optical fiber spaced apart, and the second intracavity receiving optical fiber 222 is also arranged in the same manner. More specifically, Figure 5 Starting with 221, which is numbered 1, the remaining five intracavity receiving fibers are numbered counterclockwise. The three fibers numbered 1, 3, and 5 form one group, which in the figure is the first intracavity receiving fiber 221. The three fibers numbered 2, 4, and 6 form another group, which in the figure is the second intracavity receiving fiber 222. The first intracavity receiving fiber 221 is connected to one spectrometer, and the second intracavity receiving fiber 222 is connected to another spectrometer.

[0033] In another embodiment of the present invention, the intracavity fiber array can also be configured with nine fibers, including one transmitting fiber and eight receiving fibers. The receiving fibers are divided into two groups of four fibers, each connected to two spectrometers, further enhancing reception strength. This configuration is suitable for detecting weaker signals and improves system stability and accuracy.

[0034] When the film thickness of the lens or panel being tested is at the nm level (>4nm), or when the excitation fluorescence of the object being tested is extremely weak, slight system errors such as physical vibration, voltage fluctuations, and relatively strong ambient light will cause the test data to jump, affecting the accuracy of the test data. Therefore, it is necessary to configure two spectrometers to obtain two sets of detection data (spectral curves). The absolute value of the detection data can be converted into a relative value through a differential algorithm, which can eliminate the influence of system errors and environmental noise and obtain more accurate test results. Based on the above requirements, this embodiment sets two sets of intracavity receiving optical fibers, and the corresponding extracavity receiving optical fibers output two signals to the two spectrometers.

[0035] The extracavity optical path includes an extracavity transmitting optical fiber 31 and an extracavity receiving optical fiber 34. The extracavity transmitting optical fiber 31 guides the light emitted by the light source into the intracavity transmitting optical fiber 21 through the vacuum flange via the light source end connector 32. The extracavity receiving optical fiber 34 receives the light signal of the intracavity receiving optical fiber through the vacuum flange and transmits it to the spectrometer through the spectrometer end connector 33. The cross section of the extracavity transmitting optical fiber 31 is as follows: Figure 6 As shown, it is an optical path structure of a single optical fiber, which is connected to the receiving optical fiber 21 in the cavity and transmits the light emitted by the light source to the probe.

[0036] In one embodiment of the present invention, the three optical fiber cross sections included in the spectrometer end connector 33 are arranged in a straight line. Figure 7 As shown, it is a cross-sectional view of the first intra-cavity receiving optical fiber 221 or the second intra-cavity receiving optical fiber 222 at the spectrometer end connector 33. Inside the spectrometer end connector 33, each group of extra-cavity receiving optical fibers are arranged in a straight line and have positioning keys to facilitate alignment and cover the light-receiving slit of the spectrometer, thereby increasing the intensity of the received light.

[0037] The intracavity transmitting fiber 21, intracavity receiving fiber, extracavity transmitting fiber 31, and extracavity receiving fiber 34 are all made of polyimide-coated UV quartz fiber UV400 / 440-PI or radiation-resistant fiber. The fiber core diameter is 400 μm, the numerical aperture is 0.22, and the operating wavelength range is 190-1100 nm.

[0038] The intracavity transmitting optical fiber 21 and the extracavity transmitting optical fiber 31 described in this embodiment are end-to-end whole optical fibers, without any docking in the middle. They are divided into two parts for the purpose of clearly illustrating the optical path structure of this embodiment. Similarly, the six extracavity receiving optical fibers 34 and the six intracavity receiving optical fibers connecting the two spectrometers are also end-to-end whole optical fibers, a total of six, without any docking in the middle, thus avoiding plug-in loss. That is, in the intracavity optical path and the extracavity optical path, the single optical fibers with the same function are all whole optical fibers, without any docking in the middle. If there is one intracavity transmitting optical fiber, then the corresponding extracavity transmitting optical fiber is also one. The optical fiber with the same transmitting function in both the intracavity part and the extracavity part is a whole optical fiber without breakpoints; if there are six intracavity receiving optical fibers, then there are also six corresponding extracavity receiving optical fibers. The entire optical path structure contains six complete receiving optical fibers.

[0039] The outer layers of the intracavity optical fiber group, the extracavity transmitting optical fiber 31 and the extracavity receiving optical fiber 34 are all provided with a protective layer. The protective layer is a metal hose. Depending on the optical fiber model, the protective layer can be a φ5 metal hose.

[0040] To facilitate the connection of equipment, the probe connector, light source end connector and spectrometer end connector are all SMA905 standard connectors.

[0041] The vacuum flange 1 is a KF vacuum flange, the optical fiber is vacuumed at the vacuum flange 1, and the inside and outside of the flange are sealed.

[0042] By replacing a single receiving fiber with six and introducing two independent spectrometers for reception, the light receiving area is greatly increased and the light intensity loss caused by the Y-shaped structure is avoided. Furthermore, the end-to-end fiber structure avoids coupling loss at the interface, fundamentally improving the overall optical coupling efficiency of the system.

[0043] The optical path structure described in this embodiment can be configured with one halogen tungsten lamp as a light source and two ultraviolet-visible spectrometers to perform spectral testing on objects in a vacuum environment. In combination with the corresponding software system, the absolute values ​​of the detection data of the two spectrometers are converted into relative values ​​through a differential algorithm, eliminating the influence of system errors and environmental noise, and obtaining more accurate test results.

[0044] In summary, the optical path structure described in this embodiment, through the central emission + peripheral hexagonal symmetrical reception + differential dual spectrometer structure design, realizes the efficient collection and accurate detection of weak spectral signals in a vacuum environment. It has the advantages of compact structure, low coupling loss, strong adaptability, and controllable cost. It is suitable for promotion and application in high-precision spectral testing scenarios such as thin film thickness detection and fluorescence excitation.

[0045] The above description is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this field, several variations and improvements can be made without departing from the creative concept of the present invention, which all fall within the scope of protection of the present invention.

Claims

1. An optical path structure for spectral testing of objects in a vacuum environment, comprising a vacuum flange, an intracavity optical path and an extracavity optical path connected by the vacuum flange; It is characterized in that The vacuum flange includes a flange plate and an optical fiber channel, which is connected to the vacuum cavity through the flange plate. The optical fiber channel is filled with a sealing colloid to ensure vacuum sealing; The intracavity optical path is an intracavity optical fiber group including multiple optical fibers, one of which is an intracavity transmitting optical fiber connected to a light source, and the other optical fibers are intracavity receiving optical fibers connected to a spectrometer. The intracavity optical fiber group illuminates the object to be measured in the vacuum cavity through a probe connector; The extra-cavity optical path includes an extra-cavity transmitting optical fiber and an extra-cavity receiving optical fiber. The extra-cavity transmitting optical fiber introduces the light source into the intra-cavity transmitting optical fiber through the vacuum flange via the light source end connector. The extra-cavity receiving optical fiber receives the light signal of the intra-cavity receiving optical fiber through the vacuum flange and transmits it to the spectrometer through the spectrometer end connector.

2. The optical path structure according to claim 1, characterized in that: The outer layers of the intra-cavity optical fiber group, the extra-cavity transmitting optical fiber and the extra-cavity receiving optical fiber are all provided with a protective layer.

3. The optical path structure according to claim 2, characterized in that: The protective layer is a metal hose.

4. The optical path structure according to claim 1, characterized in that: The intracavity optical fiber group is provided with seven optical fibers, one of which is an intracavity transmitting optical fiber, and the remaining six are intracavity receiving optical fibers, which are divided into two groups, each connected to a spectrometer, with three fibers in each group.

5. The optical path structure according to claim 4, characterized in that: The cross sections of the seven optical fibers are arranged hexagonally, wherein the intra-cavity transmitting optical fiber is arranged at the center, and the intra-cavity receiving optical fiber is arranged at the periphery of the intra-cavity transmitting optical fiber.

6. The optical path structure according to claim 5, characterized in that: The receiving optical fibers in the cavity are divided into two groups according to every other adjacent optical fiber.

7. The optical path structure according to claim 1, characterized in that: The intra-cavity transmitting optical fiber, the intra-cavity receiving optical fiber, the extra-cavity transmitting optical fiber and the extra-cavity receiving optical fiber are all made of polyimide-coated ultraviolet quartz optical fiber or radiation-resistant optical fiber.

8. The optical path structure according to claim 1, characterized in that: The probe connector, light source end connector and spectrometer end connector are all SMA905 standard connectors.

9. The optical path structure according to claim 1 or 8, characterized in that: The three optical fiber cross sections included in the spectrometer end connector are arranged in a straight line.

10. The optical path structure according to claim 1, characterized in that: The vacuum flange adopts a KF vacuum flange.

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