System and method for measuring reflectivity of high-reflectivity material with cavity ring-down

Abstract

The invention discloses an optical cavity ring-down high-reflection material reflectivity measurement system, which comprises a reflector, a half-projection half-reflection mirror, a first adjustable measurement device, a second adjustable measurement device and an optical screen, and is characterized in that the reflector is arranged in the vertical direction of the half-projection half-reflection mirror; the reflecting mirror is used for reflecting the coupled laser to form first reflected light and transmitting the first reflected light to the semi-transmission semi-reflecting mirror; after the half-projection half-reflection mirror receives the first reflected light, one half of the first reflected light is transmitted to form transmission light, the other half of the first reflected light is reflected to form second reflected light, and the second reflected light is reflected to a sample A to be detected or / and a sample B to be detected; after receiving the second reflected light, the to-be-detected sample A or / and the to-be-detected sample B is / are reflected again to form third reflected light, and the third reflected light is emitted to the optical screen through the semi-transmission and semi-reflection mirror to form light spots. The adjustable testing device is simple in structure and convenient to adjust, does not need repeated calibration through the upper module and the lower module, and is high in measurement efficiency and good in flexibility.

Description

Technical Field

[0001] The invention relates to the field of high reflectivity measurement, and in particular to a reflectivity measurement system and method for high reflectivity materials of optical cavity ring-down. Background Art

[0002] In modern optical technology, high reflectivity measurement technology is a key technology for a variety of laser systems represented by laser gyroscopes, high-precision passive resonant cavities and high-power lasers. A large number of high-reflectivity (R>99.99%) optical components are used in these laser systems. The reflectivity accuracy of such optical components reflects the performance of the laser system to a certain extent. As we all know, in order to achieve higher precision in the manufacturing field, it is necessary to first improve the measurement accuracy in detection technology.

[0003] The methods commonly used to measure sample reflectivity can be roughly divided into the following three types: spectrophotometry, reflection ratio method, and cavity ring-down method (CRD). For some high-reflectivity films with a reflectivity of more than 99.9%, the light intensity with and without samples is very close in the spectrophotometry method, which requires the detector to have very high sensitivity and the output power of the light source to be stable; the reflection ratio method has a complex structure and requires a high-stability laser source and accurate calibration of reference samples, etc. It has strict requirements on the light source and optical path, especially the detector; the cavity ring-down method is an absolute measurement method with the advantages of simple measurement principle, high measurement accuracy, sensitive response, and insensitivity to fluctuations in light source output power. It is an ideal solution for high reflectivity measurement.

[0004] Cavity ring-down technology is a type of laser absorption spectroscopy technology. When the laser outputs a beam of pulsed laser energy, it oscillates back and forth in the resonant cavity. Due to the existence of various losses including geometric diffraction loss, transmission loss, scattering loss, dielectric absorption loss, etc., the laser loses some optical power each time it goes back and forth in the cavity. The time it takes for the light intensity in the cavity to decay to 1 / e of the initial value is the ring-down time. The reflectivity can be directly calculated through the ring-down time. However, the cavity ring-down method has requirements for optical path alignment. The laser needs to be coupled into the resonant cavity before each measurement. Therefore, in the traditional measurement method, the entire optical path needs to be recalibrated every time the sample is changed, and it is usually necessary to use other measurement equipment to calibrate the optical path. Summary of the invention

[0005] In order to solve the above technical problems, a reflectivity measurement system for high-reflectivity materials with simple structure and high efficiency in measuring cavity ring-down is proposed.

[0006] To achieve the above object, the technical solution adopted by the present invention is as follows: a reflectivity measurement system of a high-reflectivity material of an optical cavity ring-down, comprising a reflector, a semi-transmitting semi-reflecting mirror, a first adjustable measuring device, a second adjustable measuring device and a light screen, The reflector is arranged in a vertical direction of the semi-projecting and semi-reflecting mirror; The first adjustable measuring device, the second adjustable measuring device, the semi-transmissive and semi-reflective mirror and the light screen are arranged in the same horizontal direction; The first adjustable measuring device is installed with a sample A to be tested, and the second adjustable measuring device is installed with a sample B to be tested; The reflecting mirror is used to reflect the coupled laser to form a first reflected light and emit it to the semi-transmitting and semi-reflecting mirror; After receiving the first reflected light, the half-transmitting and half-reflecting mirror transmits half of it to form a transmitted light, and reflects the other half to form a second reflected light, and the second reflected light is reflected onto the sample A to be tested and / or the sample B to be tested; After receiving the second reflected light, the sample A or / and the sample B reflects again to form a third reflected light, and the third reflected light is emitted onto the light screen through a semi-transmitting and semi-reflecting mirror to form a light spot.

[0007] Preferably, the first adjustable measuring device and the second adjustable measuring device each comprise an upper module, a lower module and an adjustable frame, the upper module and the lower module are movably connected in a sleeve connection, and the upper module and the lower module are sleeved and combined to form a cuboid.

[0008] Preferably, an adjustable mirror frame is fixedly mounted on the upper module by screws.

[0009] Preferably, the adjustable mirror frame is provided with a slot for mounting a test sample.

[0010] Preferably, a displacement platform is further provided below the first adjustable measuring device and the second adjustable measuring device, and the displacement platform is installed below the lower module.

[0011] Preferably, the displacement platform comprises an upper panel and a lower panel, and the upper panel and the lower panel are connected via matching tracks.

[0012] Preferably, a nut is provided on the right side of the upper panel, and the upper panel can be driven to slide on the lower panel by rotating it.

[0013] A method for measuring the reflectivity of a high-reflectivity material of an optical cavity ring-down is provided, and the reflectivity measuring system of a high-reflectivity material of an optical cavity ring-down is applied. The steps of the method are as follows: Step S1: calibrating the optical path system of the measuring system so that the parallelism angle α formed between the third reflected light of the test sample X on the first adjustable measuring device and the third reflected light of the test sample Y on the second adjustable measuring device is zero; Step S2: After the system calibration is completed, remove the upper module of the first adjustable test device, install the test sample A into the card slot of the adjustable frame, sleeve the upper module onto the lower module, adjust the reflector and the adjustable frame angle according to the perforation method to ensure that the second reflected light is vertically incident on the sample A, and record the position of the spot on the light screen emitted by the third reflected light; Step S2: remove the upper module of the second adjustable test device, install the test sample B into the card slot of the adjustable frame, sleeve the upper module onto the lower module, adjust the reflector and the adjustable frame angle according to the perforation method to ensure that the second reflected light is vertically incident on the sample B; at this time, record the position of the spot on the light screen emitted by the third reflected light; Step S3: a parallelism angle α is formed between the third reflected light of the test sample A and the third reflected light of the test sample B, and the adjustable mirror frame of the second adjustable test device is fine-tuned so that α is equal to 0, and the debugging is completed; Step S5: repeat steps S1-S3, collect the transmission light intensity signal of the second reflected light projected from the test sample A after debugging is completed, fit the ring-down time, and calculate the reflectivity of the test sample A.

[0014] Preferably, the test system calibration method in step S1 is as follows: Step S-1: The upper module and the lower module of the two adjustable test devices are sleeved and fixed; Step S-2: sequentially installing the test sample 1 and the test sample 2 on the first adjustable test device and the second adjustable test device, respectively adjusting the two adjustable mirror frames to adjust the horizontal and vertical tilt angles of the samples, respectively, to ensure that the second reflected light is vertically incident on the center of the test sample 1 and the test sample 2; Step S-3: Fix the test sample X and measure the spot position of the third reflected light on the light screen; fix the test sample Y and measure the spot position of the third reflected light on the light screen; adjust the sample B so that the angle between the third reflectors of the test sample X and the test sample Y is is 0; Step S1-4: adding a translation stage at the bottom of the first adjustable test device and the second adjustable test device, adjusting the translation stage to change the distance between the test sample X and the test sample Y, observing the transmission spot pattern by scanning the distance between the samples, finding the best position points of the first adjustable test device and the second adjustable test device, completing the calibration of the test system, and not moving the horizontal positions of the first adjustable test device and the second adjustable test device.

[0015] Preferably, the method for calculating the reflectivity of the test sample A in step S5 is as follows: Step S5-1: Collect the transmitted light intensity signal change over time I (t); Step S5-2: Define initial transmitted light intensity Decay to The time required is the ring-down time of the ring-down cavity; Step S5-3: According to the formula = Fit the ring-down time; according to , calculate the sample reflectance R.

[0016] Beneficial technical effects of the present invention: The adjustable test device has a simple structure. The upper module and the lower module can be connected. To replace the sample chamber to be tested, only the upper module needs to be removed. The position of the entire adjustable test device does not need to be changed, and repeated calibration is no longer required, which greatly improves the test efficiency. High measurement efficiency: Each sample can be pre-adjusted independently, reducing the difficulty of overall adjustment and improving measurement efficiency; Good flexibility: The cavity length of the measurement system can be changed by cooperating with the bottom linear translation stage. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The present invention is a principle block diagram of a reflectivity measurement system for high-reflectivity materials with optical cavity ring-down.

[0018] Figure 2 The present invention is a structural block diagram of an adjustable measuring device in a reflectivity measuring system of a high-reflectivity material in an optical cavity ring-down. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments, but the scope of protection claimed in the present invention is not limited to the following specific embodiments.

[0020] A specific embodiment of the present invention is as follows: like Figure 1-Figure 2 As shown, a reflectivity measurement system for high-reflectivity materials of optical cavity ring-down includes a reflector 1, a semi-transmitting semi-reflecting mirror 3, a first adjustable measuring device 4, a second adjustable measuring device 5 and a light screen 8. The reflector 2 is arranged in a vertical direction of the semi-projection semi-reflection mirror 3, and the reflector 2 is arranged on the semi-projection semi-reflection mirror 3 to form a resonant cavity of the measurement system; The first adjustable measuring device 4, the second adjustable measuring device 5, the semi-transmissive semi-reflective mirror 3 and the light screen 8 are arranged in the same horizontal direction; The first adjustable measuring device 4 is installed with a sample A to be tested, and the second adjustable measuring device 5 is installed with a sample B to be tested; The optical path of the laser in the system is as follows: The reflector is used to reflect the coupling laser 1 (incident light) to form a first reflected light 11 and emit it to the semi-transmitting and semi-reflecting mirror 3; after receiving the first reflected light 11, the semi-transmitting and semi-reflecting mirror 3 transmits half of it to form a transmitted light, and reflects the other half to form a second reflected light 12, and the second reflected light 12 is reflected to the sample A to be tested and / or the sample B to be tested; After receiving the second reflected light 12, the sample A or / and the sample B reflects again to form a third reflected light, and the third reflected light is emitted onto the light screen through a semi-transmitting and semi-reflecting mirror to form a light spot.

[0021] In this embodiment, the third reflected light 6 is formed by the reflection of the sample A to be tested, the third reflected light 7 is formed by the reflection of the sample B to be tested, and the angle α9 is formed between the third reflected light 6 and the third reflected light 7.

[0022] Specifically, the two adjustable test devices have the same structure, and both include an upper module 42, a lower module 43, and an adjustable mirror frame 41. The upper module 42 and the lower module 43 are movably connected, and the upper module 42 and the lower module 43 are connected and combined to form a rectangular parallelepiped. After the entire system is calibrated, the positions of the two adjustable test devices are adjusted to the optimal position. At this time, when the test sample is replaced to measure the reflectivity of the new test sample, there is no need to recalibrate the system. It is only necessary to remove the upper module 42, install the new test sample on the adjustable mirror frame 41, and then put the upper module 42 on the lower module 43 to measure the reflectivity of the new test sample.

[0023] The upper module 42 and the lower module 43 are connected by a mechanical mortise and tenon structure. In the embodiment, the lower module has a conical protrusion 45, and the upper module is provided with a conical groove 46 matching the conical protrusion 45. The upper and lower modules are connected by the conical protrusion 45 and the conical groove 46.

[0024] The upper module 42 is fixed with an adjustable mirror frame 41 by screws. The adjustable mirror frame 41 is provided with a slot 44 for mounting a test sample. Specifically, the adjustable mirror frame 41 adopts an existing standard reflector frame, and the tilt angle can be adjusted by rotating a differential screw.

[0025] In addition, a displacement platform 51 is further provided below the first adjustable measuring device and the second adjustable measuring device, and the displacement platform 51 is installed below the lower module 43. The displacement platform 51 includes an upper panel 52 and a lower panel 53, and the upper panel 52 and the lower panel 53 are connected by matching rails 54. A nut 55 is provided on the right side of the upper panel, and the upper panel 52 can be driven to slide on the lower panel 53 by rotating the nut 55. The first adjustable measuring device and the second adjustable measuring device can be adjusted to move horizontally through the displacement platform 51.

[0026] Another solution of this embodiment is: a method for measuring the reflectivity of a high-reflectivity material of an optical cavity ring-down, which uses the above-mentioned system for measuring the reflectivity of a high-reflectivity material of an optical cavity ring-down, and the steps of the method are as follows: Step S1: calibrating the optical path system of the measuring system so that the parallelism angle α formed between the third reflected light of the test sample X on the first adjustable measuring device and the third reflected light of the test sample Y on the second adjustable measuring device is zero; Specifically, the detailed method of the calibration step is as follows: Step S-1: The upper module and the lower module of the two adjustable test devices are sleeved and fixed; Step S-2: sequentially installing the test sample 1 and the test sample 2 on the first adjustable test device and the second adjustable test device, respectively adjusting the two adjustable mirror frames to adjust the horizontal and vertical tilt angles of the samples, respectively, to ensure that the second reflected light is vertically incident on the center of the test sample 1 and the test sample 2; Step S-3: Fix the test sample X and measure the spot position of the third reflected light on the light screen; fix the test sample Y and measure the spot position of the third reflected light on the light screen; adjust the sample B so that the angle between the third reflectors of the test sample X and the test sample Y is is 0; Step S1-4: Add a translation stage at the bottom of the first adjustable test device and the second adjustable test device, adjust the translation stage to change the distance between the test sample X and the test sample Y, and observe the transmission spot pattern by scanning the distance between the samples to find the best position point of the first adjustable test device and the second adjustable test device (the best position is when the spot is the largest and most round after repeated adjustments), complete the calibration of the test system, and do not move the horizontal position of the first adjustable test device and the second adjustable test device.

[0027] Step S2: After the system calibration is completed, remove the upper module of the first adjustable test device, install the test sample A into the card slot of the adjustable frame, sleeve the upper module onto the lower module, adjust the reflector and the adjustable frame angle according to the perforation method to ensure that the second reflected light is vertically incident on the sample A, and record the position of the spot on the light screen emitted by the third reflected light; Step S2: remove the upper module of the second adjustable test device, install the test sample B into the card slot of the adjustable frame, sleeve the upper module onto the lower module, adjust the reflector and the adjustable frame angle according to the perforation method to ensure that the second reflected light is vertically incident on the sample B; at this time, record the position of the spot on the light screen emitted by the third reflected light; Step S3: a parallelism angle α is formed between the third reflected light of the test sample A and the third reflected light of the test sample B, and the adjustable mirror frame of the second adjustable test device is fine-tuned so that α is equal to 0, and the debugging is completed; Step S5: repeat steps S1-S3, collect 10 strong signals of the transmitted light projected from the test sample A by the second reflected light after debugging, fit the ring-down time, and calculate the reflectivity of the test sample A.

[0028] Specifically, the method for calculating the reflectivity of the test sample A in step S5 is as follows: Step S5-1: Collect the transmitted light intensity signal change over time I (t); Step S5-2: define initial transmitted light intensity Decay to The time required is the ring-down time of the ring-down cavity; Step S5-3: According to the formula = Fit the ring-down time; according to , calculate the sample reflectance R.

[0029] The reflectivity R here is the reflectivity of the test sample A and the test sample B together. In theory, the reflectivity of A and B is the same.

[0030] The adjustable test device has a simple structure. The upper module and the lower module can be connected. To replace the sample chamber to be tested, only the upper module needs to be removed. The position of the entire adjustable test device does not need to be changed, and repeated calibration is no longer required, which greatly improves the test efficiency. High measurement efficiency: Each sample can be pre-adjusted independently, reducing the difficulty of overall adjustment and improving measurement efficiency; Good flexibility: The cavity length of the resonant cavity of the measurement system can be changed by cooperating with the bottom linear translation stage.

[0031] According to the disclosure and teaching of the above description, those skilled in the art to which the present invention belongs may also make changes and modifications to the above embodiments. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and some modifications and changes to the invention should also fall within the scope of protection of the claims of the present invention. In addition, although some specific terms are used in this specification, these terms are only for the convenience of description and do not constitute any limitation to the invention.

Claims

1. A reflectivity measurement system for high-reflectivity materials of optical cavity ring-down, characterized in that: The device comprises a reflector, a semi-projection and semi-reflection mirror, a first adjustable measuring device, a second adjustable measuring device and a light screen, The reflector is arranged in a vertical direction of the semi-projecting and semi-reflecting mirror; The first adjustable measuring device, the second adjustable measuring device, the semi-transmissive and semi-reflective mirror and the light screen are arranged in the same horizontal direction; The first adjustable measuring device is installed with a sample A to be tested, and the second adjustable measuring device is installed with a sample B to be tested; The reflecting mirror is used to reflect the coupled laser to form a first reflected light and emit it to the semi-transmitting and semi-reflecting mirror; After receiving the first reflected light, the half-transmitting and half-reflecting mirror transmits half of it to form a transmitted light, and reflects the other half to form a second reflected light, and the second reflected light is reflected onto the sample A to be tested and / or the sample B to be tested; After receiving the second reflected light, the sample A or / and the sample B reflects again to form a third reflected light, and the third reflected light is emitted onto the light screen through a semi-transmitting and semi-reflecting mirror to form a light spot.

2. A reflectivity measurement system for high-reflectivity materials of optical cavity ring-down as claimed in claim 1, characterized in that: The first adjustable measuring device and the second adjustable measuring device both include an upper module, a lower module and an adjustable frame. The upper module and the lower module are movably connected in a sleeve connection. The upper module and the lower module are sleeved and combined to form a cuboid.

3. The reflectivity measurement system of a high-reflectivity material of an optical cavity ring-down as claimed in claim 2, characterized in that: An adjustable mirror frame is fixedly mounted on the upper module by screws.

4. The reflectivity measurement system of a high-reflectivity material of an optical cavity ring-down as claimed in claim 3, characterized in that: The adjustable mirror frame is provided with a slot for mounting a test sample.

5. The reflectivity measurement system of a high-reflectivity material of an optical cavity ring-down as claimed in claim 4, characterized in that: A displacement platform is further provided below the first adjustable measuring device and the second adjustable measuring device, and the displacement platform is installed below the lower module.

6. The reflectivity measurement system of a high-reflectivity material of an optical cavity ring-down as claimed in claim 5, characterized in that: The displacement platform comprises an upper panel and a lower panel, and the upper panel and the lower panel are connected by matching tracks.

7. The reflectivity measurement system of a high-reflectivity material of an optical cavity ring-down as claimed in claim 6, characterized in that: A nut is arranged on the right side of the upper panel, and the upper panel can be driven to slide on the lower panel by rotating.

8. A method for measuring the reflectivity of a high-reflectivity material in an optical cavity ring-down, using a measurement system for rapidly measuring high reflectivity as described in any one of claims 1 to 7, characterized in that: The steps of this method are as follows: Step S1: calibrating the optical path system of the measuring system so that the parallelism angle α formed between the third reflected light of the test sample X on the first adjustable measuring device and the third reflected light of the test sample Y on the second adjustable measuring device is zero; Step S2: After the system calibration is completed, remove the upper module of the first adjustable test device, install the test sample A into the card slot of the adjustable frame, sleeve the upper module onto the lower module, adjust the reflector and the adjustable frame angle according to the perforation method to ensure that the second reflected light is vertically incident on the sample A, and record the position of the spot on the light screen emitted by the third reflected light; Step S2: remove the upper module of the second adjustable test device, install the test sample B into the card slot of the adjustable frame, sleeve the upper module onto the lower module, adjust the reflector and the adjustable frame angle according to the perforation method to ensure that the second reflected light is vertically incident on the sample B; at this time, record the position of the spot on the light screen emitted by the third reflected light; Step S3: a parallelism angle α is formed between the third reflected light of the test sample A and the third reflected light of the test sample B, and the adjustable mirror frame of the second adjustable test device is fine-tuned so that α is equal to 0, and the debugging is completed; Step S5: repeat steps S1-S3, collect the transmission light intensity signal of the second reflected light projected from the test sample A after debugging is completed, fit the ring-down time, and calculate the reflectivity of the test sample A.

9. The method for measuring the reflectivity of a high-reflectivity material of an optical cavity ring-down as claimed in claim 8, characterized in that: The test system calibration method in step S1 is as follows: Step S-1: The upper module and the lower module of the two adjustable test devices are sleeved and fixed; Step S-2: sequentially installing the test sample 1 and the test sample 2 on the first adjustable test device and the second adjustable test device, respectively adjusting the two adjustable mirror frames to adjust the horizontal and vertical tilt angles of the samples, respectively, to ensure that the second reflected light is vertically incident on the center of the test sample 1 and the test sample 2; Step S-3: Fix the test sample X and measure the spot position of the third reflected light on the light screen; fix the test sample Y and measure the spot position of the third reflected light on the light screen; adjust the sample B so that the angle between the third reflectors of the test sample X and the test sample Y is is 0; Step S1-4: adding a translation stage at the bottom of the first adjustable test device and the second adjustable test device, adjusting the translation stage to change the distance between the test sample X and the test sample Y, observing the transmission spot pattern by scanning the distance between the samples, finding the best position points of the first adjustable test device and the second adjustable test device, completing the calibration of the test system, and not moving the horizontal positions of the first adjustable test device and the second adjustable test device.

10. The method for measuring the reflectivity of a high-reflectivity material in an optical cavity ring-down as claimed in claim 8, characterized in that: The method for calculating the reflectivity of the test sample A in step S5 is as follows: Step S5-1: Collect the transmitted light intensity signal change over time I (t); Step S5-2: Define initial transmitted light intensity Decay to The time required is the ring-down time of the ring-down cavity; Step S5-3: According to the formula = Fit the ring-down time; according to , calculate the sample reflectance R. .

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