Method and device for measuring refractive index of transparent material

Abstract

The invention provides a method and a device for measuring the refractive index of a transparent material, and the method is applied to laser measurement equipment, and comprises the steps: transmitting a femtosecond light beam corresponding to a target wavelength to a Michelson interferometer structure device through a laser transmitting module, and controlling the position of a to-be-measured transparent material through a displacement mechanism; the femtosecond light beams are split and returned to be combined to obtain combined light beams corresponding to the positions outside the light paths and the positions in the light paths of one arm; detecting the amplitude of a cross-correlation signal of the combined light beam by using a balance switching detection module, judging whether the amplitude of the cross-correlation signal is equal to a preset value or not by using a servo controller, and adjusting the repetition frequency of a laser emission module to be equal; and recording a first repetition frequency value corresponding to the position outside the light path and a second repetition frequency value corresponding to the position in one light path by using a counter, and calculating to obtain the target refractive index of the transparent material to be measured under the target wavelength. Through the method, the measurement accuracy and the measurement efficiency of the refractive index of the transparent material are improved.

Description

Technical Field

[0001] The present application relates to the field of optical measurement technology, and in particular to a method and device for measuring the refractive index of a transparent material. Background Art

[0002] Refractive index is one of the important physical parameters of transparent materials and an important factor affecting optical properties. The application field of refractive index measurement is very wide. For some instrument systems with higher requirements, there is also an urgent need to accurately measure the refractive index.

[0003] At present, the refractive index measurement methods mainly include interference method and goniometric method. The interference method is limited by the accuracy and stability of the light source wavelength, resulting in a large error in the optical path measurement, which leads to a low measurement accuracy of the refractive index of transparent materials. The goniometric method has high requirements on the accuracy of angle measurement, which makes the measurement of the refractive index of transparent materials more difficult. In addition, the measurement light source of the above method generally uses a single-frequency laser, which can only measure the refractive index value of the transparent material at the wavelength of the light source, and it is difficult to measure the refractive index at multiple wavelengths. Summary of the invention

[0004] In view of this, the purpose of the present application is to provide a method and device for measuring the refractive index of a transparent material, by using a laser emission module in a laser measuring device to emit a femtosecond beam corresponding to a target wavelength to a Michelson interferometer structure device, and for the transparent material to be measured at a position outside the optical path of the Michelson interferometer structure device and a position in one arm of the optical path, respectively, the femtosecond beam is sequentially split and returned and combined, and the combined beam is emitted to a balanced cross-correlation detection module to detect the amplitude of the cross-correlation signal, and the repetition frequency of the laser emission module is adjusted according to the judgment result of whether the amplitude of the cross-correlation signal is equal to a preset value, and based on the repetition frequency values ​​corresponding to the position outside the optical path and the position in one arm of the optical path, respectively, the target refractive index of the transparent material to be measured at the target wavelength is measured, so as to convert the refractive index measurement into the measurement of the femtosecond laser repetition frequency, and then the dependence of the refractive index on the wavelength in a wide spectral range can be determined, thereby improving the measurement accuracy and efficiency of the refractive index of the transparent material.

[0005] The present application provides a method for measuring the refractive index of a transparent material, the method comprising:

[0006] The laser emission module is used to emit a femtosecond light beam corresponding to a target wavelength among a plurality of preset wavelengths to the Michelson interferometer structure device disposed in the vacuum chamber, and the position of the transparent material to be measured is controlled by the displacement mechanism;

[0007] For the transparent material to be tested being located at a position outside the optical path of the Michelson interferometer structure device and a position in one arm of the optical path, the femtosecond light beam is sequentially split and returned and merged using the Michelson interferometer structure device to obtain a merged light beam corresponding to the position outside the optical path and the position in one arm of the optical path, respectively, and the merged light beam is emitted to the balanced mutual correlation detection module;

[0008] Using the balanced cross-correlation detection module to detect the cross-correlation signal amplitude of the combined light beam, and sending the cross-correlation signal amplitude to the servo controller, so as to use the servo controller to determine whether the cross-correlation signal amplitude is equal to a preset value to obtain a determination result;

[0009] According to the judgment result, the repetition frequency of the laser emitting module is adjusted by the servo controller so that the amplitude of the cross-correlation signal is equal to the preset value, and the first repetition frequency value corresponding to the position of the laser emitting module outside the optical path and the second repetition frequency value corresponding to the position in the one-arm optical path are recorded by the counter respectively;

[0010] Based on the first repetition frequency value, the second repetition frequency value and the thickness value of the transparent material to be measured, a target refractive index of the transparent material to be measured at the target wavelength is obtained using a preset refractive index calculation formula.

[0011] Furthermore, the laser emission module includes a femtosecond laser, a grating pair and a slit; the laser emission module is used to emit a femtosecond beam corresponding to a target wavelength among a plurality of preset wavelengths to the Michelson interferometer structure device disposed in the vacuum chamber, comprising:

[0012] Based on a preset spectral range, the femtosecond laser is used to output a wide-spectrum laser, and the grating pair is used to diffract the wide-spectrum laser into a plurality of femtosecond beams of preset wavelengths;

[0013] Based on the target wavelength, the displacement mechanism is used to move the slit so as to emit a femtosecond light beam corresponding to the target wavelength to the Michelson interferometer structure device disposed in the vacuum chamber.

[0014] Furthermore, for the transparent material to be measured being located at a position outside the optical path of the Michelson interferometer structure device and a position in one arm of the optical path, the femtosecond light beam is sequentially split and returned and merged using the Michelson interferometer structure device to obtain a merged light beam corresponding to the position outside the optical path and the position in one arm of the optical path, respectively, including:

[0015] When the displacement mechanism is used to control the transparent material to be measured to be located outside the optical path of the Michelson interferometer structure device, the Michelson interferometer structure device is used to sequentially split and return the femtosecond light beam to obtain a combined light beam corresponding to the position outside the optical path;

[0016] When the displacement mechanism is used to control the transparent material to be measured to be located in a position in an optical path of one arm of the Michelson interferometer structure device, the Michelson interferometer structure device is used to sequentially split and return the femtosecond light beam to obtain a combined light beam corresponding to the position in the optical path of one arm.

[0017] Furthermore, the Michelson interferometer structure device includes a beam splitter, a first reflector and a second reflector; the Michelson interferometer structure device is used to sequentially split and return the femtosecond beam to obtain a combined beam corresponding to a position outside the optical path and a position in the one-arm optical path, respectively, including:

[0018] Using the beam splitter to split the femtosecond beam into a reflected beam directed toward the first reflector and a transmitted beam directed toward the second reflector;

[0019] Using the first reflector to reflect the reflected light beam and return it to the beam splitter along the original path, and using the second reflector to reflect the transmitted light beam and return it to the beam splitter along the original path;

[0020] The reflected light beam and the transmitted light beam are combined using the beam splitter to form the combined light beam.

[0021] Furthermore, the balanced mutual correlation detection module includes a first dichroic mirror and lens, a frequency doubling crystal, a second dichroic mirror and lens, a balanced detector and a third reflector; and using the balanced mutual correlation detection module to detect the amplitude of the mutual correlation signal of the combined light beam includes:

[0022] Focusing the combined light beam on the frequency doubling crystal by using the first dichroic mirror and the lens to generate fundamental frequency light and first frequency doubling light corresponding to the combined light beam;

[0023] Using the second dichroic mirror and lens to collimate the first doubled frequency light and transmit it to the first probe of the balanced detector, so as to detect the first amplitude corresponding to the combined light beam by using the first probe, and using the second dichroic mirror and lens to reflect the fundamental frequency light and return it to the first dichroic mirror and lens along the original path;

[0024] Using the first dichroic mirror and the lens to filter out the second doubled frequency light from the fundamental frequency light, so as to reflect it to the third reflector, and using the third reflector to reflect the second doubled frequency light to the second probe of the balanced detector, so as to use the second probe to detect the second amplitude corresponding to the combined light beam;

[0025] Based on the first amplitude and the second amplitude, a cross-correlation signal amplitude of the combined light beam is determined using the balanced detector.

[0026] Further, the determining the cross-correlation signal amplitude of the combined light beam by using the balanced detector based on the first amplitude and the second amplitude includes:

[0027] When the first amplitude is equal to the second amplitude, determining, by the balanced detector, that the amplitude of the cross-correlation signal of the combined light beam is a preset value;

[0028] When the first amplitude is not equal to the second amplitude, judging whether the combined light beam is an interference light beam based on the first amplitude and the second amplitude;

[0029] If the combined light beam is an interference light beam, using the balanced detector to determine that the amplitude of the cross-correlation signal of the combined light beam is a natural value other than a preset value;

[0030] If the combined light beam is not an interference light beam, the cross-correlation signal amplitude of the combined light beam is determined to be null using the balanced detector.

[0031] Further, according to the judgment result, the servo controller is used to adjust the repetition frequency of the laser emission module so that the amplitude of the cross-correlation signal is equal to the preset value, and the counter is used to respectively record the first repetition frequency value corresponding to the position of the laser emission module outside the optical path and the second repetition frequency value corresponding to the position in the one-arm optical path, including:

[0032] When the judgment result is that the amplitude of the cross-correlation signal is equal to the preset value, using the counter to record the first repetition frequency value or the second repetition frequency value;

[0033] When the judgment result is that the amplitude of the cross-correlation signal is not equal to the preset value, the servo controller is used to adjust the repetition frequency of the laser emission module, and it is repeatedly judged whether the amplitude of the cross-correlation signal obtained after adjustment is equal to the preset value, until the amplitude of the cross-correlation signal is equal to the preset value, so as to use the counter to record the first repetition frequency value or the second repetition frequency value.

[0034] The present application also provides a device for measuring the refractive index of a transparent material, the device comprising:

[0035] A beam emission module is used to emit a femtosecond beam corresponding to a target wavelength among a plurality of preset wavelengths to a Michelson interferometer structure device disposed in a vacuum chamber by using a laser emission module, and control the position of a transparent material to be measured by a displacement mechanism;

[0036] A splitting and merging module is used for sequentially splitting and returning and merging the femtosecond light beam by using the Michelson interferometer structure device for the transparent material to be tested at a position outside the light path and a position in one arm of the light path, so as to obtain a merged light beam corresponding to the position outside the light path and the position in one arm of the light path, respectively, and emitting the merged light beam to a balanced mutual correlation detection module;

[0037] A detection control module, used for detecting the cross-correlation signal amplitude of the combined light beam by using the balanced cross-correlation detection module, and sending the cross-correlation signal amplitude to a servo controller, so as to use the servo controller to determine whether the cross-correlation signal amplitude is equal to a preset value to obtain a determination result;

[0038] a numerical recording module, configured to adjust the repetition frequency of the laser emitting module using the servo controller according to the judgment result, so that the amplitude of the cross-correlation signal is equal to the preset value, and to respectively record the first repetition frequency value corresponding to the position of the laser emitting module outside the optical path and the second repetition frequency value corresponding to the position in the one-arm optical path using a counter;

[0039] The refractive index calculation module is used to obtain the target refractive index of the transparent material to be measured at the target wavelength using a preset refractive index calculation formula based on the first repetition frequency value, the second repetition frequency value and the thickness value of the transparent material to be measured.

[0040] Furthermore, the laser emission module includes a femtosecond laser, a grating pair and a slit; when the light beam emission module uses the laser emission module to emit a femtosecond light beam corresponding to a target wavelength among a plurality of preset wavelengths to a Michelson interferometer structure device disposed in a vacuum chamber, the light beam emission module is used to:

[0041] Based on a preset spectral range, the femtosecond laser is used to output a wide-spectrum laser, and the grating pair is used to diffract the wide-spectrum laser into a plurality of femtosecond beams of preset wavelengths;

[0042] Based on the target wavelength, the displacement mechanism is used to move the slit so as to emit a femtosecond light beam corresponding to the target wavelength to the Michelson interferometer structure device disposed in the vacuum chamber.

[0043] Further, the splitting and merging module is used for the transparent material to be tested to be located at a position outside the optical path of the Michelson interferometer structure device and a position in one arm of the optical path, and to use the Michelson interferometer structure device to sequentially split and return and merge the femtosecond light beam to obtain a merged light beam corresponding to the position outside the optical path and the position in one arm of the optical path, respectively. The splitting and merging module is used to:

[0044] When the displacement mechanism is used to control the transparent material to be measured to be located outside the optical path of the Michelson interferometer structure device, the Michelson interferometer structure device is used to sequentially split and return the femtosecond light beam to obtain a combined light beam corresponding to the position outside the optical path;

[0045] When the displacement mechanism is used to control the transparent material to be measured to be located in a position in an optical path of one arm of the Michelson interferometer structure device, the Michelson interferometer structure device is used to sequentially split and return the femtosecond light beam to obtain a combined light beam corresponding to the position in the optical path of one arm.

[0046] Furthermore, the Michelson interferometer structure device includes a beam splitter, a first reflector and a second reflector; when the splitting and merging module is used to sequentially split and return and merge the femtosecond beam using the Michelson interferometer structure device to obtain a merged beam corresponding to a position outside the optical path and a position in the one-arm optical path, the splitting and merging module is used to:

[0047] Using the beam splitter to split the femtosecond beam into a reflected beam directed toward the first reflector and a transmitted beam directed toward the second reflector;

[0048] Using the first reflector to reflect the reflected light beam and return it to the beam splitter along the original path, and using the second reflector to reflect the transmitted light beam and return it to the beam splitter along the original path;

[0049] The reflected light beam and the transmitted light beam are combined using the beam splitter to form the combined light beam.

[0050] Further, the balanced mutual correlation detection module includes a first dichroic mirror and lens, a frequency doubling crystal, a second dichroic mirror and lens, a balanced detector and a third reflector; when the detection control module is used to detect the amplitude of the mutual correlation signal of the combined light beam using the balanced mutual correlation detection module, the detection control module is used to:

[0051] Focusing the combined light beam on the frequency doubling crystal by using the first dichroic mirror and the lens to generate fundamental frequency light and first frequency doubling light corresponding to the combined light beam;

[0052] Using the second dichroic mirror and lens to collimate the first doubled frequency light and transmit it to the first probe of the balanced detector, so as to detect the first amplitude corresponding to the combined light beam by using the first probe, and using the second dichroic mirror and lens to reflect the fundamental frequency light and return it to the first dichroic mirror and lens along the original path;

[0053] Using the first dichroic mirror and the lens to filter out the second doubled frequency light from the fundamental frequency light, so as to reflect it to the third reflector, and using the third reflector to reflect the second doubled frequency light to the second probe of the balanced detector, so as to use the second probe to detect the second amplitude corresponding to the combined light beam;

[0054] Based on the first amplitude and the second amplitude, a cross-correlation signal amplitude of the combined light beam is determined using the balanced detector.

[0055] Further, when the detection control module is used to determine the cross-correlation signal amplitude of the combined light beam based on the first amplitude and the second amplitude using the balanced detector, the detection control module is used to:

[0056] When the first amplitude is equal to the second amplitude, determining, by the balanced detector, that the amplitude of the cross-correlation signal of the combined light beam is a preset value;

[0057] When the first amplitude is not equal to the second amplitude, judging whether the combined light beam is an interference light beam based on the first amplitude and the second amplitude;

[0058] If the combined light beam is an interference light beam, using the balanced detector to determine that the amplitude of the cross-correlation signal of the combined light beam is a natural value other than a preset value;

[0059] If the combined light beam is not an interference light beam, the cross-correlation signal amplitude of the combined light beam is determined to be null using the balanced detector.

[0060] Further, when the numerical recording module is used to adjust the repetition frequency of the laser emitting module using the servo controller according to the judgment result so that the amplitude of the cross-correlation signal is equal to the preset value, and to use a counter to respectively record the first repetition frequency value corresponding to the position of the laser emitting module outside the optical path and the second repetition frequency value corresponding to the position in the one-arm optical path, the numerical recording module is used to:

[0061] When the judgment result is that the amplitude of the cross-correlation signal is equal to the preset value, using the counter to record the first repetition frequency value or the second repetition frequency value;

[0062] When the judgment result is that the amplitude of the cross-correlation signal is not equal to the preset value, the servo controller is used to adjust the repetition frequency of the laser emission module, and it is repeatedly judged whether the amplitude of the cross-correlation signal obtained after adjustment is equal to the preset value, until the amplitude of the cross-correlation signal is equal to the preset value, so as to use the counter to record the first repetition frequency value or the second repetition frequency value.

[0063] An embodiment of the present application also provides an electronic device, including: a processor, a memory and a bus, wherein the memory stores machine-readable instructions executable by the processor, and when the electronic device is running, the processor and the memory communicate through the bus, and when the machine-readable instructions are executed by the processor, the steps of the method for measuring the refractive index of transparent materials as described above are performed.

[0064] An embodiment of the present application further provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of the method for measuring the refractive index of a transparent material as described above are executed.

[0065] The embodiment of the present application provides a method and device for measuring the refractive index of a transparent material, wherein the method is applied to a laser measuring device; wherein the laser measuring device comprises: a laser emitting module, a Michelson interferometer structure device, a vacuum chamber, a displacement mechanism, a balanced mutual correlation detection module, a servo controller and a counter, and the method comprises: using the laser emitting module to emit a femtosecond light beam corresponding to a target wavelength among a plurality of preset wavelengths to the Michelson interferometer structure device disposed in the vacuum chamber, and controlling the position of the transparent material to be measured by the displacement mechanism; for the transparent material to be measured being located at a position outside the optical path of the Michelson interferometer structure device and a position in one arm of the optical path, using the Michelson interferometer structure device to sequentially split and return and merge the femtosecond light beam to obtain the combined light beams corresponding to the position outside the optical path and the position in one arm of the optical path respectively. Combined light beams are combined and emitted to the balanced mutual correlation detection module; the cross-correlation signal amplitude of the combined light beam is detected by the balanced mutual correlation detection module, and the cross-correlation signal amplitude is sent to the servo controller, so that the servo controller is used to determine whether the cross-correlation signal amplitude is equal to a preset value to obtain a determination result; according to the determination result, the servo controller is used to adjust the repetition frequency of the laser emission module so that the cross-correlation signal amplitude is equal to the preset value, and the counter is used to respectively record the first repetition frequency value corresponding to the position of the laser emission module outside the optical path and the second repetition frequency value corresponding to the position in the one-arm optical path; based on the first repetition frequency value, the second repetition frequency value and the thickness value of the transparent material to be measured, the preset refractive index calculation formula is used to obtain the target refractive index of the transparent material to be measured at the target wavelength.

[0066] Compared with the interference method and the angle measurement method in the prior art, a laser emission module is used in a laser measuring device to emit a femtosecond beam corresponding to a target wavelength to a Michelson interferometer structure device, and the femtosecond beam is sequentially split and returned and combined for the transparent material to be measured at a position outside the optical path of the Michelson interferometer structure device and a position in one arm of the optical path, and the combined beam is emitted to a balanced cross-correlation detection module to detect the amplitude of the cross-correlation signal. According to the judgment result of whether the amplitude of the cross-correlation signal is equal to a preset value, the repetition frequency of the laser emission module is adjusted, and based on the repetition frequency values ​​corresponding to the position outside the optical path and the position in one arm of the optical path, the target refractive index of the transparent material to be measured at the target wavelength is measured, so as to convert the refractive index measurement into the measurement of the femtosecond laser repetition frequency, and further determine the dependence of the refractive index on the wavelength in a wide spectral range, thereby improving the measurement accuracy and efficiency of the refractive index of the transparent material.

[0067] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, preferred embodiments are specifically cited below and described in detail with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0069] Figure 1 One of the structural schematic diagrams of a laser measurement device provided in an embodiment of the present application;

[0070] Figure 2 A flow chart of a method for measuring the refractive index of a transparent material provided in an embodiment of the present application;

[0071] Figure 3 A second structural schematic diagram of a laser measurement device provided in an embodiment of the present application;

[0072] Figure 4 A structural diagram of a balanced mutual correlation detection module provided in an embodiment of the present application;

[0073] Figure 5 A schematic diagram of the structure of a device for measuring the refractive index of a transparent material provided in an embodiment of the present application;

[0074] Figure 6 A schematic diagram of the structure of an electronic device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0075] To make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. The components of the embodiments of the present application usually described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the application claimed for protection, but merely represents the selected embodiments of the present application. Based on the embodiments of the present application, each other embodiment obtained by those skilled in the art without making creative work belongs to the scope of protection of the present application.

[0076] Research has found that currently, the refractive index measurement methods mainly include interference method and angle measurement method.

[0077] Among them, the interference method measures the refractive index by measuring the optical path length of light in the medium to be measured and the thickness of the medium. Due to the limitations of the accuracy and stability of the wavelength of the light source, the error in the optical path length measurement is large, resulting in low measurement accuracy of the refractive index of transparent materials.

[0078] The goniometric method calculates the refractive index by measuring the angle. For example, the minimum deviation angle method is to make the object to be measured into a prism shape, measure the top angle of the prism, and let a beam of light be incident on one side of the prism. After the light passes through the prism, it will be emitted at the other side. By measuring the minimum angle between the incident light and the emitted light, the refractive index is calculated according to the Fresnel law. Another commonly used method in the goniometric method is the critical angle method. Based on the principle of total reflection, the refractive index is calculated by measuring the critical angle of refraction. The above method has high requirements on the accuracy of angle measurement, which makes it difficult to measure the refractive index of transparent materials. In addition, the measurement light source generally uses a single-frequency laser, which can only measure the refractive index value of the transparent material at the wavelength of the light source, and it is difficult to measure the refractive index at multiple wavelengths.

[0079] Based on this, an embodiment of the present application provides a method for measuring the refractive index of a transparent material, by using a laser emission module in a laser measuring device to emit a femtosecond beam corresponding to a target wavelength to a Michelson interferometer structure device, and for the transparent material to be measured being respectively located outside the optical path of the Michelson interferometer structure device and in one arm of the optical path, the femtosecond beam is sequentially split and returned and combined, and the combined beam is emitted to a balanced cross-correlation detection module to detect the amplitude of the cross-correlation signal, and the repetition frequency of the laser emission module is adjusted according to the judgment result of whether the amplitude of the cross-correlation signal is equal to a preset value, and based on the repetition frequency values ​​corresponding to the position outside the optical path and the position in one arm of the optical path, the target refractive index of the transparent material to be measured at the target wavelength is measured, so as to convert the refractive index measurement into the measurement of the femtosecond laser repetition frequency, and then the dependence of the refractive index on the wavelength in a wide spectral range can be determined, thereby improving the measurement accuracy and efficiency of the refractive index of the transparent material.

[0080] It should be noted that the method for measuring the refractive index of a transparent material provided in the embodiment of the present application is generally applied to a laser measuring device.

[0081] For details, please refer to Figure 1 , Figure 1 This is one of the structural schematic diagrams of a laser measurement device provided in an embodiment of the present application. Figure 1 As shown in , the laser measuring device 10 includes: a laser emitting module 110, a Michelson interferometer structure device 120, a vacuum chamber 130, a displacement mechanism 140, a balanced mutual correlation detection module 150, a servo controller 160 and a counter 170.

[0082] Among them, the first end of the laser emitting module 110 is connected to the first end of the counter 170; the second end of the laser emitting module 110 is connected to the first end of the displacement mechanism 140; the third end of the laser emitting module 110 is connected to the first end of the Michelson interferometer structure device 120; the fourth end of the laser emitting module 110 is connected to the first end of the servo controller 160; the Michelson interferometer structure device 120 is arranged in the vacuum chamber 130; the second end of the Michelson interferometer structure device 120 is connected to the first end of the balanced mutual correlation detection module 150; the second end of the balanced mutual correlation detection module 150 is connected to the second end of the servo controller 160.

[0083] Here, the laser emission module 110 is used to diverge a wide-spectrum laser of a preset spectral range into a strip arranged and distributed according to the wavelength size, so as to select femtosecond beams of different wavelengths for emission; the Michelson interferometer structure device 120 is used to split and transmit the femtosecond beam, so as to emit a combined beam reflected and combined along the original path; the vacuum chamber 130 is used to provide a measurement experimental environment for the transparent material to be measured and the Michelson interferometer structure device 120; the displacement mechanism is used to control the laser emission module 110 to select the target wavelength and control the movement of the transparent material to be measured; the balanced mutual correlation detection module 150 is used to detect the amplitude of the mutual correlation signal of the combined beam; the servo controller 160 is used to control the repetition frequency of the laser emission module 110 according to the detection result of the balanced mutual correlation detection module 150; the counter 170 is used to record the repetition frequency value of the laser emission module 110 when the repetition frequency of the laser emission module 110 is locked.

[0084] See also Figure 2 , Figure 2 This is a flow chart of a method for measuring the refractive index of a transparent material provided in an embodiment of the present application. Figure 2 As shown in the embodiment of the present application, the method for measuring the refractive index of a transparent material is applied to Figure 1 In the laser measuring device 10 shown in , the measuring method comprises:

[0085] S101, using the laser emission module to emit a femtosecond light beam corresponding to a target wavelength among a plurality of preset wavelengths to the Michelson interferometer structure device disposed in the vacuum chamber, and controlling the position of the transparent material to be measured by the displacement mechanism.

[0086] In an embodiment of the present application, the laser emission module includes a femtosecond laser, a grating pair and a slit.

[0087] For details, please refer to Figure 3 , Figure 3 This is a second schematic diagram of the structure of a laser measurement device provided in an embodiment of the present application. Figure 3 As shown in , the laser emission module 110 includes a femtosecond laser 111, a grating pair 112 and a slit 113; wherein, the first end of the femtosecond laser 111 is connected to the first end of the counter 170; the second end of the femtosecond laser 111 corresponds to the optical path of the first end of the grating pair 112; the second end of the grating pair 112 corresponds to the optical path of the first end of the slit 113; the second end of the slit 113 corresponds to the optical path of the first end of the Michelson interferometer structure device 120; the third end of the femtosecond laser 111 is connected to the first end of the servo controller 160.

[0088] Among them, the femtosecond laser 111 is used to output a wide-spectrum laser corresponding to a preset spectral range; the grating pair 112 is used to diffract the wide-spectrum laser to separate and expand lasers of different wavelengths to form a strip distributed in order according to the wavelength size; the slit 113 is used to select light beams of different wavelengths to pass through through the movement control of the displacement mechanism 140, so as to emit the femtosecond light beam corresponding to the target wavelength as a measurement light source to the Michelson interferometer structure device 120.

[0089] In one embodiment of the present application, in a specific implementation, the step of using the laser emission module in step S101 to emit a femtosecond beam corresponding to a target wavelength among a plurality of preset wavelengths to the Michelson interferometer structure device disposed in the vacuum chamber may include:

[0090] S1011. Based on a preset spectral range, use the femtosecond laser to output a wide-spectrum laser, and use the grating pair to diffract the wide-spectrum laser into a plurality of femtosecond beams of preset wavelengths.

[0091] S1012. Based on the target wavelength, use the displacement mechanism to move the slit to emit a femtosecond light beam corresponding to the target wavelength to the Michelson interferometer structure device disposed in the vacuum chamber.

[0092] In this way, by moving the slit through the moving mechanism, a femtosecond beam corresponding to a target wavelength can be selected from a plurality of femtosecond beams of preset wavelengths after the wide-spectrum laser emitted by the femtosecond laser is diffracted by the grating pair, so that the femtosecond beam can be emitted as a measuring light source to the Michelson interferometer structure device.

[0093] S102. For the transparent material to be tested that is located outside the optical path of the Michelson interferometer structure device and in one arm of the optical path, the femtosecond light beam is sequentially split and returned and merged using the Michelson interferometer structure device to obtain a merged light beam corresponding to the position outside the optical path and the position in one arm of the optical path, and the merged light beam is emitted to the balanced mutual correlation detection module.

[0094] In this step, during the specific implementation, first, the moving mechanism is used to control the transparent material to be tested to be located outside the optical path of the Michelson interferometer structure device; then, the Michelson interferometer structure device is used to sequentially split and return the femtosecond light beam to obtain a combined light beam corresponding to the position outside the optical path; finally, the combined light beam is emitted to the balanced mutual correlation detection module.

[0095] Furthermore, when the counter locks the repetition frequency of the femtosecond laser and records the first repetition frequency value at this time, first, the moving mechanism is used to control the transparent material to be measured to be in a position in one arm of the optical path of the Michelson interferometer structure device; then, the Michelson interferometer structure device is used to sequentially split and return the femtosecond light beam to obtain a combined light beam corresponding to the position in the one arm of the optical path; finally, the combined light beam is emitted to the balanced mutual correlation detection module.

[0096] In one implementation of the present application, during specific implementation, step S102 may include:

[0097] S1021. When the displacement mechanism is used to control the transparent material to be measured to be located outside the optical path of the Michelson interferometer structure device, the Michelson interferometer structure device is used to sequentially split and return the femtosecond light beam to obtain a combined light beam corresponding to the position outside the optical path.

[0098] S1022. When the displacement mechanism is used to control the transparent material to be measured to be located in a position in an optical path of one arm of the Michelson interferometer structure device, the Michelson interferometer structure device is used to sequentially split and return the femtosecond light beam to obtain a combined light beam corresponding to the position in the optical path of one arm.

[0099] In an embodiment of the present application, the position outside the optical path refers to the position of the transparent material to be measured being outside the optical path formed by the Michelson interferometer structure device and being located in the vacuum chamber; the position in one-arm optical path refers to the position of the transparent material to be measured being in one-arm optical path formed by the Michelson interferometer structure device.

[0100] Here, the optical path formed by the Michelson interferometer structure device may include a reflected optical path and a transmitted optical path, and the position in the one-arm optical path generally refers to the position in the transmitted optical path.

[0101] Further, such as Figure 3 As shown in , the Michelson interferometer structure device 120 includes a beam splitter 121, a first reflector 122 and a second reflector 123; wherein the beam splitter 121 is used to split the femtosecond beam to reflect the femtosecond beam to the first reflector 122, and transmit the femtosecond beam to the second reflector 123; the first reflector 122 and the second reflector 123 are respectively used to reflect the reflected beam and the transmitted beam to return the reflected beam and the transmitted beam to the beam splitter 121 along the original path.

[0102] In one embodiment of the present application, in a specific implementation, the step of using the Michelson interferometer structure device to sequentially split and return the femtosecond light beam in step S102 to obtain a combined light beam corresponding to a position outside the light path and a position in the one-arm light path, respectively, may include:

[0103] S10201. Use the beam splitter to split the femtosecond beam into a reflected beam directed toward the first reflector and a transmitted beam directed toward the second reflector.

[0104] S10202. Use the first reflector to reflect the reflected light beam and return it to the beam splitter along the original path, and use the second reflector to reflect the transmitted light beam and return it to the beam splitter along the original path.

[0105] S10203. Use the beam splitter to merge the reflected light beam and the transmitted light beam into the merged light beam.

[0106] In the embodiment of the present application, the working principle of the Michelson interferometer structure device is to use the interference phenomenon of light to measure very small changes, such as changes in length or refractive index. When two beams of light are recombined, if their phases are properly matched, alternating light and dark interference fringes will be generated. By observing and analyzing these fringes, information about the optical path difference can be obtained.

[0107] S103, using the balanced cross-correlation detection module to detect the cross-correlation signal amplitude of the combined light beam, and sending the cross-correlation signal amplitude to the servo controller, so as to use the servo controller to determine whether the cross-correlation signal amplitude is equal to a preset value to obtain a determination result.

[0108] See also Figure 4 , Figure 4 A structural schematic diagram of a balanced mutual correlation detection module provided in an embodiment of the present application.

[0109] In the embodiments of the present application, Figure 4 As shown in , the balanced cross-correlation detection module 150 includes a first dichroic mirror and lens 151, a frequency doubling crystal 152, a second dichroic mirror and lens 153, a balanced detector 154 and a third reflector 155; wherein the balanced detector 154 includes a first probe and a second probe.

[0110] Here, the first dichroic mirror and lens 151 includes a 45° dichroic mirror and a first lens; the second dichroic mirror and lens 153 includes a 90° dichroic mirror and a second lens.

[0111] Specifically, Figure 4As shown in , the combined light beam passes through the 45° dichroic mirror, is focused on the frequency doubling crystal 152 by the first lens, generates a first frequency doubling light, is then collimated by the second lens, and is transmitted by the 90° dichroic mirror, and is received by the first probe of the balanced detector. The fundamental frequency light corresponding to the combined light beam is reflected by the 90° dichroic mirror, returns to the original path, passes through the frequency doubling crystal again, is filtered out by the 45° dichroic mirror, and is received by the second probe of the balanced detector after being reflected by the third reflector 155.

[0112] In one embodiment of the present application, in a specific implementation, the step of using the balanced cross-correlation detection module to detect the cross-correlation signal amplitude of the combined light beam in step S103 may include:

[0113] S1031. Use the first dichroic mirror and the lens to focus the combined light beam on the frequency doubling crystal to generate fundamental frequency light and first frequency doubling light corresponding to the combined light beam.

[0114] S1032, using the second dichroic mirror and lens to collimate the first doubled frequency light and transmit it to the first probe of the balanced detector, so as to use the first probe to detect the first amplitude corresponding to the combined light beam, and using the second dichroic mirror and lens to reflect the fundamental frequency light and return it to the first dichroic mirror and lens along the original path.

[0115] S1033, using the first dichroic mirror and lens to filter out the second doubled frequency light from the fundamental frequency light, so as to reflect it to the third reflector, and using the third reflector to reflect the second doubled frequency light to the second probe of the balanced detector, so as to use the second probe to detect the second amplitude corresponding to the combined light beam.

[0116] S1034. Based on the first amplitude and the second amplitude, determine the cross-correlation signal amplitude of the combined light beam using the balanced detector.

[0117] In one implementation of the present application, during specific implementation, step S1034 may include:

[0118] S10341. When the first amplitude is equal to the second amplitude, use the balanced detector to determine that the cross-correlation signal amplitude of the combined light beam is a preset value.

[0119] In this step, when the first amplitude is equal to the second amplitude, it indicates that the optical path difference between the reflected light beam and the transmitted light beam is an integer multiple of the spatial interval of the femtosecond laser pulse, and there is no time delay. Then, destructive interference is observed in the balanced cross-correlation detection module, and the cross-correlation signal amplitude of the combined light beam is a preset value.

[0120] In the embodiment of the present application, the preset value is set to 0.

[0121] It can be seen that when the cross-correlation signal amplitude of the combined light beam is 0, it indicates that the optical path difference between the reflected light beam and the transmitted light beam in the Michelson interferometer structure device is an integer multiple of the pulse spatial interval of the femtosecond laser.

[0122] S10342. When the first amplitude is not equal to the second amplitude, determine whether the combined light beam is an interference light beam based on the first amplitude and the second amplitude.

[0123] S10343. If the combined light beam is an interference light beam, use the balanced detector to determine that the amplitude of the cross-correlation signal of the combined light beam is a natural value other than a preset value.

[0124] S10344. If the combined light beam is not an interference light beam, use the balanced detector to determine that the amplitude of the cross-correlation signal of the combined light beam is null.

[0125] In the embodiment of the present application, since the balanced cross-correlation detection module detects the interference signal of the reflected light beam and the transmitted light beam in the Michelson interferometer structure device, that is, when the first amplitude is not equal to the second amplitude, it is necessary to determine whether the cross-correlation signal amplitude of the combined light beam has a value based on whether the combined light beam is an interference light beam.

[0126] S104. According to the judgment result, the servo controller is used to adjust the repetition frequency of the laser emission module so that the amplitude of the cross-correlation signal is equal to the preset value, and the counter is used to respectively record the first repetition frequency value corresponding to the position of the laser emission module outside the optical path and the second repetition frequency value corresponding to the position in the one-arm optical path.

[0127] In this step, when the transparent material to be measured is outside the optical path of the Michelson interferometer structure device, the repetition frequency of the laser emission module is adjusted according to the judgment result of whether the amplitude of the cross-correlation signal is equal to the preset value, so that the amplitude of the cross-correlation signal is equal to the preset value. At this time, the repetition frequency of the femtosecond laser in the laser emission module is locked, and a counter is used to record the first repetition frequency value corresponding to the position of the transparent material to be measured outside the optical path.

[0128] Furthermore, after obtaining the first repetition frequency value, the transparent material to be tested is placed in a position in an optical path of one arm of the Michelson interferometer structure device using a displacement mechanism, and according to a judgment result of whether the amplitude of the cross-correlation signal is equal to a preset value, the repetition frequency of the laser emission module is adjusted so that the amplitude of the cross-correlation signal is equal to the preset value. At this time, the repetition frequency of the femtosecond laser in the laser emission module is locked, and a counter is used to record a second repetition frequency value corresponding to the position of the transparent material to be tested in the optical path of one arm.

[0129] In one implementation of the present application, during specific implementation, step S104 may include:

[0130] S1041. When the judgment result is that the amplitude of the cross-correlation signal is equal to the preset value, use the counter to record the first repetition frequency value or the second repetition frequency value.

[0131] S1042. When the judgment result is that the amplitude of the cross-correlation signal is not equal to the preset value, the servo controller is used to adjust the repetition frequency of the laser emission module, and the judgment is repeated as to whether the amplitude of the cross-correlation signal obtained after adjustment is equal to the preset value, until the amplitude of the cross-correlation signal is equal to the preset value, so as to use the counter to record the first repetition frequency value or the second repetition frequency value.

[0132] In this way, the first repetition frequency value and the second repetition frequency value corresponding to the position of the transparent material to be tested outside the optical path of the Michelson interferometer structure device and the position in one arm of the optical path are obtained, so as to calculate the target refractive index of the transparent material to be tested at the target wavelength using the first repetition frequency value and the second repetition frequency value.

[0133] S105 . Based on the first repetition frequency value, the second repetition frequency value, and the thickness value of the transparent material to be measured, a preset refractive index calculation formula is used to obtain a target refractive index of the transparent material to be measured at the target wavelength.

[0134] In an embodiment of the present application, the expression of the preset refractive index calculation formula is as follows.

[0135]

[0136] Here, the refractive index calculation formula is derived according to the calculation expression described below.

[0137]

[0138] Where n(λ) represents the target refractive index of the transparent material to be tested at the target wavelength; c is the speed of light in vacuum; f r1 and f r2 are the first repetition frequency value and the second repetition frequency value respectively; L is the thickness value of the transparent material to be measured.

[0139] The embodiment of the present application provides a method for measuring the refractive index of a transparent material. A laser emission module is used in a laser measuring device to emit a femtosecond beam corresponding to a target wavelength to a Michelson interferometer structure device. The femtosecond beam is sequentially split and returned and combined for the transparent material to be measured at a position outside the optical path of the Michelson interferometer structure device and a position in one arm of the optical path, respectively. The combined beam is emitted to a balanced cross-correlation detection module to detect the amplitude of a cross-correlation signal. According to a judgment result of whether the amplitude of the cross-correlation signal is equal to a preset value, the repetition frequency of the laser emission module is adjusted. Based on the repetition frequency values ​​corresponding to the position outside the optical path and the position in one arm of the optical path, respectively, the target refractive index of the transparent material to be measured at the target wavelength is measured, so that the refractive index measurement is converted into the measurement of the femtosecond laser repetition frequency, and then the dependence of the refractive index on the wavelength in a wide spectral range can be determined, thereby improving the measurement accuracy and efficiency of the refractive index of the transparent material.

[0140] See also Figure 5 , Figure 5 This is a schematic diagram of a device for measuring the refractive index of a transparent material provided in an embodiment of the present application. Figure 5 As shown in , the measuring device 500 comprises:

[0141] The light beam emission module 510 is used to emit a femtosecond light beam corresponding to a target wavelength among a plurality of preset wavelengths to a Michelson interferometer structure device disposed in a vacuum chamber by using a laser emission module, and control the position of the transparent material to be measured by a displacement mechanism;

[0142] The splitting and merging module 520 is used for sequentially splitting and returning and merging the femtosecond light beam by using the Michelson interferometer structure device for the transparent material to be tested at a position outside the light path and a position in one arm of the light path, so as to obtain a merged light beam corresponding to the position outside the light path and the position in one arm of the light path, and emitting the merged light beam to the balanced mutual correlation detection module;

[0143] A detection control module 530, configured to detect the cross-correlation signal amplitude of the combined light beam by using the balanced cross-correlation detection module, and send the cross-correlation signal amplitude to a servo controller, so as to use the servo controller to determine whether the cross-correlation signal amplitude is equal to a preset value to obtain a determination result;

[0144] A value recording module 540 is used to adjust the repetition frequency of the laser emitting module using the servo controller according to the judgment result, so that the amplitude of the cross-correlation signal is equal to the preset value, and use a counter to respectively record a first repetition frequency value corresponding to a position of the laser emitting module outside the optical path and a second repetition frequency value corresponding to a position in the one-arm optical path;

[0145] The refractive index calculation module 550 is used to obtain the target refractive index of the transparent material to be measured at the target wavelength using a preset refractive index calculation formula based on the first repetition frequency value, the second repetition frequency value and the thickness value of the transparent material to be measured.

[0146] Further, the laser emission module includes a femtosecond laser, a grating pair and a slit; when the light beam emission module 510 uses the laser emission module to emit a femtosecond light beam corresponding to a target wavelength among a plurality of preset wavelengths to a Michelson interferometer structure device disposed in a vacuum chamber, the light beam emission module 510 is used to:

[0147] Based on a preset spectral range, the femtosecond laser is used to output a wide-spectrum laser, and the grating pair is used to diffract the wide-spectrum laser into a plurality of femtosecond beams of preset wavelengths;

[0148] Based on the target wavelength, the displacement mechanism is used to move the slit so as to emit a femtosecond light beam corresponding to the target wavelength to the Michelson interferometer structure device disposed in the vacuum chamber.

[0149] Further, when the splitting and merging module 520 is used to sequentially split and return-merge the femtosecond light beam using the Michelson interferometer structure device for the transparent material to be tested at a position outside the light path of the Michelson interferometer structure device and a position in one arm of the light path, to obtain a merged light beam corresponding to the position outside the light path and the position in one arm of the light path, the splitting and merging module 520 is used to:

[0150] When the displacement mechanism is used to control the transparent material to be measured to be located outside the optical path of the Michelson interferometer structure device, the Michelson interferometer structure device is used to sequentially split and return the femtosecond light beam to obtain a combined light beam corresponding to the position outside the optical path;

[0151] When the displacement mechanism is used to control the transparent material to be measured to be located in a position in an optical path of one arm of the Michelson interferometer structure device, the Michelson interferometer structure device is used to sequentially split and return the femtosecond light beam to obtain a combined light beam corresponding to the position in the optical path of one arm.

[0152] Further, the Michelson interferometer structure device includes a beam splitter, a first reflector and a second reflector; when the splitting and merging module 520 is used to sequentially split and return-merge the femtosecond beam using the Michelson interferometer structure device to obtain a merged beam corresponding to a position outside the optical path and a position in the one-arm optical path, the splitting and merging module 520 is used to:

[0153] Using the beam splitter to split the femtosecond beam into a reflected beam directed toward the first reflector and a transmitted beam directed toward the second reflector;

[0154] Using the first reflector to reflect the reflected light beam and return it to the beam splitter along the original path, and using the second reflector to reflect the transmitted light beam and return it to the beam splitter along the original path;

[0155] The reflected light beam and the transmitted light beam are combined using the beam splitter to form the combined light beam.

[0156] Further, the balanced mutual correlation detection module includes a first dichroic mirror and lens, a frequency doubling crystal, a second dichroic mirror and lens, a balanced detector and a third reflector; when the detection control module 530 is used to detect the amplitude of the mutual correlation signal of the combined light beam using the balanced mutual correlation detection module, the detection control module 530 is used to:

[0157] Focusing the combined light beam on the frequency doubling crystal by using the first dichroic mirror and the lens to generate fundamental frequency light and first frequency doubling light corresponding to the combined light beam;

[0158] Using the second dichroic mirror and lens to collimate the first doubled frequency light and transmit it to the first probe of the balanced detector, so as to detect the first amplitude corresponding to the combined light beam by using the first probe, and using the second dichroic mirror and lens to reflect the fundamental frequency light and return it to the first dichroic mirror and lens along the original path;

[0159] Using the first dichroic mirror and the lens to filter out the second doubled frequency light from the fundamental frequency light, so as to reflect it to the third reflector, and using the third reflector to reflect the second doubled frequency light to the second probe of the balanced detector, so as to use the second probe to detect the second amplitude corresponding to the combined light beam;

[0160] Based on the first amplitude and the second amplitude, a cross-correlation signal amplitude of the combined light beam is determined using the balanced detector.

[0161] Further, when the detection control module 530 is used to determine the cross-correlation signal amplitude of the combined light beam based on the first amplitude and the second amplitude using the balanced detector, the detection control module 530 is used to:

[0162] When the first amplitude is equal to the second amplitude, determining, by the balanced detector, that the amplitude of the cross-correlation signal of the combined light beam is a preset value;

[0163] When the first amplitude is not equal to the second amplitude, judging whether the combined light beam is an interference light beam based on the first amplitude and the second amplitude;

[0164] If the combined light beam is an interference light beam, using the balanced detector to determine that the amplitude of the cross-correlation signal of the combined light beam is a natural value other than a preset value;

[0165] If the combined light beam is not an interference light beam, the cross-correlation signal amplitude of the combined light beam is determined to be null using the balanced detector.

[0166] Further, when the numerical recording module 540 is used to adjust the repetition frequency of the laser emitting module using the servo controller according to the judgment result so that the amplitude of the cross-correlation signal is equal to the preset value, and to use a counter to respectively record the first repetition frequency value corresponding to the position of the laser emitting module outside the optical path and the second repetition frequency value corresponding to the position in the one-arm optical path, the numerical recording module 540 is used to:

[0167] When the judgment result is that the amplitude of the cross-correlation signal is equal to the preset value, using the counter to record the first repetition frequency value or the second repetition frequency value;

[0168] When the judgment result is that the amplitude of the cross-correlation signal is not equal to the preset value, the servo controller is used to adjust the repetition frequency of the laser emission module, and it is repeatedly judged whether the amplitude of the cross-correlation signal obtained after adjustment is equal to the preset value, until the amplitude of the cross-correlation signal is equal to the preset value, so as to use the counter to record the first repetition frequency value or the second repetition frequency value.

[0169] The device for measuring the refractive index of a transparent material provided in an embodiment of the present application uses a laser emission module in a laser measuring device to emit a femtosecond beam corresponding to a target wavelength to a Michelson interferometer structure device, and for transparent materials to be measured that are respectively located outside the optical path of the Michelson interferometer structure device and in one arm of the optical path, the femtosecond beam is sequentially split and returned and combined, and the combined beam is emitted to a balanced cross-correlation detection module to detect the amplitude of a cross-correlation signal. According to a judgment result of whether the amplitude of the cross-correlation signal is equal to a preset value, the repetition frequency of the laser emission module is adjusted, and based on the repetition frequency values ​​corresponding to the position outside the optical path and the position in one arm of the optical path, the target refractive index of the transparent material to be measured at the target wavelength is measured, so that the refractive index measurement is converted into the measurement of the femtosecond laser repetition frequency, and then the dependence of the refractive index on the wavelength in a wide spectral range can be determined, thereby improving the measurement accuracy and efficiency of the refractive index of the transparent material.

[0170] See also Figure 6 , Figure 6 This is a schematic diagram of the structure of an electronic device provided in an embodiment of the present application. Figure 6 As shown in , the electronic device 600 includes a processor 610 , a memory 620 and a bus 630 .

[0171] The memory 620 stores machine-readable instructions executable by the processor 610. When the electronic device 600 is running, the processor 610 communicates with the memory 620 via the bus 630. When the machine-readable instructions are executed by the processor 610, the above-mentioned Figure 2 The steps of the method for measuring the refractive index of a transparent material in the method embodiment shown, and the specific implementation manner can be referred to the method embodiment, which will not be described in detail here.

[0172] The present application also provides a computer-readable storage medium on which a computer program is stored. When the computer program is executed by a processor, the computer program can execute the above-mentioned Figure 2 The steps of the method for measuring the refractive index of a transparent material in the method embodiment shown, and the specific implementation manner can be referred to the method embodiment, which will not be described in detail here.

[0173] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0174] In the several embodiments provided in the present application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. The device embodiments described above are merely schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some communication interfaces, and the indirect coupling or communication connection of devices or units can be electrical, mechanical or other forms.

[0175] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0176] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0177] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a non-volatile computer-readable storage medium that is executable by a processor. Based on this understanding, the technical solution of the present application can essentially be embodied in the form of a software product, or in other words, the part that contributes to the prior art or the part of the technical solution. The computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk.

[0178] Finally, it should be noted that the above-described embodiments are only specific implementation methods of the present application, which are used to illustrate the technical solutions of the present application, rather than to limit them. The protection scope of the present application is not limited thereto. Although the present application is described in detail with reference to the above-mentioned embodiments, ordinary technicians in the field should understand that any technician familiar with the technical field can still modify the technical solutions recorded in the above-mentioned embodiments within the technical scope disclosed in the present application, or can easily think of changes, or make equivalent replacements for some of the technical features therein; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A method for measuring the refractive index of a transparent material, characterized in that: The measuring method is applied to a laser measuring device; wherein the laser measuring device comprises: a laser emission module, a Michelson interferometer structure device, a vacuum chamber, a displacement mechanism, a balance mutual correlation detection module, a servo controller and a counter, and the measuring method comprises: The laser emission module is used to emit a femtosecond light beam corresponding to a target wavelength among a plurality of preset wavelengths to the Michelson interferometer structure device disposed in the vacuum chamber, and the position of the transparent material to be measured is controlled by the displacement mechanism; For the transparent material to be tested being located at a position outside the optical path of the Michelson interferometer structure device and a position in one arm of the optical path, the femtosecond light beam is sequentially split and returned and merged using the Michelson interferometer structure device to obtain a merged light beam corresponding to the position outside the optical path and the position in one arm of the optical path, respectively, and the merged light beam is emitted to the balanced mutual correlation detection module; Using the balanced cross-correlation detection module to detect the cross-correlation signal amplitude of the combined light beam, and sending the cross-correlation signal amplitude to the servo controller, so as to use the servo controller to determine whether the cross-correlation signal amplitude is equal to a preset value to obtain a determination result; According to the judgment result, the repetition frequency of the laser emitting module is adjusted by the servo controller so that the amplitude of the cross-correlation signal is equal to the preset value, and the first repetition frequency value corresponding to the position of the laser emitting module outside the optical path and the second repetition frequency value corresponding to the position in the one-arm optical path are recorded by the counter respectively; Based on the first repetition frequency value, the second repetition frequency value and the thickness value of the transparent material to be measured, a target refractive index of the transparent material to be measured at the target wavelength is obtained using a preset refractive index calculation formula.

2. The method according to claim 1, characterized in that The laser emission module includes a femtosecond laser, a grating pair and a slit; the laser emission module is used to emit a femtosecond beam corresponding to a target wavelength among a plurality of preset wavelengths to the Michelson interferometer structure device arranged in the vacuum chamber, comprising: Based on a preset spectral range, the femtosecond laser is used to output a wide-spectrum laser, and the grating pair is used to diffract the wide-spectrum laser into a plurality of femtosecond beams of preset wavelengths; Based on the target wavelength, the displacement mechanism is used to move the slit so as to emit a femtosecond light beam corresponding to the target wavelength to the Michelson interferometer structure device disposed in the vacuum chamber.

3. The method according to claim 1, characterized in that The method comprises: for the transparent material to be tested to be located at a position outside the optical path of the Michelson interferometer structure device and a position in one arm of the optical path, using the Michelson interferometer structure device to sequentially split and return and merge the femtosecond light beam to obtain a merged light beam corresponding to the position outside the optical path and the position in one arm of the optical path, respectively, including: When the displacement mechanism is used to control the transparent material to be measured to be located outside the optical path of the Michelson interferometer structure device, the Michelson interferometer structure device is used to sequentially split and return the femtosecond light beam to obtain a combined light beam corresponding to the position outside the optical path; When the displacement mechanism is used to control the transparent material to be measured to be located in a position in an optical path of one arm of the Michelson interferometer structure device, the Michelson interferometer structure device is used to sequentially split and return the femtosecond light beam to obtain a combined light beam corresponding to the position in the optical path of one arm.

4. The method according to claim 1, characterized in that The Michelson interferometer structure device comprises a beam splitter, a first reflector and a second reflector; the Michelson interferometer structure device is used to sequentially split and return the femtosecond light beam to obtain a combined light beam corresponding to a position outside the light path and a position in the one-arm light path, respectively, comprising: Using the beam splitter to split the femtosecond beam into a reflected beam directed toward the first reflector and a transmitted beam directed toward the second reflector; Using the first reflector to reflect the reflected light beam and return it to the beam splitter along the original path, and using the second reflector to reflect the transmitted light beam and return it to the beam splitter along the original path; The reflected light beam and the transmitted light beam are combined using the beam splitter to form the combined light beam.

5. The method according to claim 1, characterized in that The balanced mutual correlation detection module includes a first dichroic mirror and a lens, a frequency doubling crystal, a second dichroic mirror and a lens, a balanced detector and a third reflector; the use of the balanced mutual correlation detection module to detect the amplitude of the mutual correlation signal of the combined light beam includes: Focusing the combined light beam on the frequency doubling crystal by using the first dichroic mirror and the lens to generate fundamental frequency light and first frequency doubling light corresponding to the combined light beam; Using the second dichroic mirror and lens to collimate the first doubled frequency light and transmit it to the first probe of the balanced detector, so as to detect the first amplitude corresponding to the combined light beam by using the first probe, and using the second dichroic mirror and lens to reflect the fundamental frequency light and return it to the first dichroic mirror and lens along the original path; Using the first dichroic mirror and the lens to filter out the second doubled frequency light from the fundamental frequency light, so as to reflect it to the third reflector, and using the third reflector to reflect the second doubled frequency light to the second probe of the balanced detector, so as to use the second probe to detect the second amplitude corresponding to the combined light beam; Based on the first amplitude and the second amplitude, a cross-correlation signal amplitude of the combined light beam is determined using the balanced detector.

6. The method according to claim 5, characterized in that The method of determining the cross-correlation signal amplitude of the combined light beam by using the balanced detector based on the first amplitude and the second amplitude comprises: When the first amplitude is equal to the second amplitude, determining, by the balanced detector, that the amplitude of the cross-correlation signal of the combined light beam is a preset value; When the first amplitude is not equal to the second amplitude, judging whether the combined light beam is an interference light beam based on the first amplitude and the second amplitude; If the combined light beam is an interference light beam, using the balanced detector to determine that the amplitude of the cross-correlation signal of the combined light beam is a natural value other than a preset value; If the combined light beam is not an interference light beam, the cross-correlation signal amplitude of the combined light beam is determined to be null using the balanced detector.

7. The method according to claim 1, characterized in that The method comprises: adjusting the repetition frequency of the laser emitting module by using the servo controller according to the judgment result so that the amplitude of the cross-correlation signal is equal to the preset value, and using the counter to respectively record the first repetition frequency value corresponding to the position of the laser emitting module outside the optical path and the second repetition frequency value corresponding to the position in the one-arm optical path. When the judgment result is that the amplitude of the cross-correlation signal is equal to the preset value, using the counter to record the first repetition frequency value or the second repetition frequency value; When the judgment result is that the amplitude of the cross-correlation signal is not equal to the preset value, the servo controller is used to adjust the repetition frequency of the laser emission module, and it is repeatedly judged whether the amplitude of the cross-correlation signal obtained after adjustment is equal to the preset value, until the amplitude of the cross-correlation signal is equal to the preset value, so as to use the counter to record the first repetition frequency value or the second repetition frequency value.

8. A device for measuring the refractive index of a transparent material, characterized in that: The measuring device comprises: A beam emission module is used to emit a femtosecond beam corresponding to a target wavelength among a plurality of preset wavelengths to a Michelson interferometer structure device disposed in a vacuum chamber by using a laser emission module, and control the position of a transparent material to be measured by a displacement mechanism; A splitting and merging module is used for sequentially splitting and returning and merging the femtosecond light beam by using the Michelson interferometer structure device for the transparent material to be tested at a position outside the light path and a position in one arm of the light path, so as to obtain a merged light beam corresponding to the position outside the light path and the position in one arm of the light path, respectively, and emitting the merged light beam to a balanced mutual correlation detection module; A detection control module, used for detecting the cross-correlation signal amplitude of the combined light beam by using the balanced cross-correlation detection module, and sending the cross-correlation signal amplitude to a servo controller, so as to use the servo controller to determine whether the cross-correlation signal amplitude is equal to a preset value to obtain a determination result; a numerical recording module, configured to adjust the repetition frequency of the laser emitting module using the servo controller according to the judgment result, so that the amplitude of the cross-correlation signal is equal to the preset value, and to respectively record the first repetition frequency value corresponding to the position of the laser emitting module outside the optical path and the second repetition frequency value corresponding to the position in the one-arm optical path using a counter; The refractive index calculation module is used to obtain the target refractive index of the transparent material to be measured at the target wavelength using a preset refractive index calculation formula based on the first repetition frequency value, the second repetition frequency value and the thickness value of the transparent material to be measured.

9. An electronic device, characterized in that: include: A processor, a memory and a bus, wherein the memory stores machine-readable instructions executable by the processor, and when the electronic device is running, the processor and the memory communicate through the bus, and the machine-readable instructions are executed by the processor to execute the steps of the method for measuring the refractive index of a transparent material as described in any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the method for measuring the refractive index of a transparent material according to any one of claims 1 to 7 are executed.

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