Device and method for rapidly testing reflectivity of film layer of laser thin film element

Abstract

The invention provides a device and method for rapidly testing the reflectivity of a film layer of a laser thin film element, and the device comprises a laser device, the laser thin film element, a three-dimensional platform, a cut-off device, a detector, and upper computer equipment, and the laser device outputs test laser to irradiate the surface of the to-be-tested film layer of the laser thin film element. Part of the light signals are reflected back and forth between the front film layer and the rear film layer, corresponding transmission light signals are generated on the surfaces of the film layers at the same time, and the multi-light-field superposition phenomenon that the center coordinate moves in the axial direction and the light intensity is continuously attenuated is formed; based on the refractive index of the laser thin film element and the distance between the two film layers, the distance between adjacent transmission light intensity center coordinates after each time of back-and-forth reflection is determined; based on the test laser incident light intensity distribution and the distance between the adjacent transmission light intensity center coordinates, the light intensity signal of the axial position of the backlight surface transmission light center and the known reference film reflectivity are obtained by combining the detector, the reflectivity of the to-be-tested film layer of the laser film element can be rapidly determined, and the test device is simple in light path and high in adaptability.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of optical measurement technology, and in particular to a device and method for rapidly testing the reflectivity of a film layer of a laser film element. BACKGROUND

[0002] A laser film element is a key optical element in a laser system. By coating a special reflective film layer on a substrate, it can achieve high-efficiency reflection of specific wavelength light while greatly reducing transmission and absorption loss, and is widely used in high-energy laser systems, optical communication, precision optical instruments, and other scenarios. For example, using double-sided coating in an interferometer mirror can reduce optical path errors and improve precision measurement. In these high-precision applications, the reflectivity of the film layer of the laser film element is one of its key performance indicators, directly affecting the overall performance and stability of the system. High reflectivity of the film layer means that the laser film element can effectively reflect incident light, thereby reducing light loss and improving system energy utilization and imaging quality.

[0003] Traditional reflectivity testing methods, such as spectrophotometry, mainly rely on measuring the intensity ratio of incident light and reflected light to calculate reflectivity. However, for high-reflectivity film layers, the reflected light is much stronger than the incident light, and the difference is very small, so direct measurement of the intensity of the two and comparison often face the problem of insufficient precision. Traditional optical cavity ring-down method mainly uses the oscillation and decay signal formed by the back-and-forth reflection of laser pulses between cavity mirrors to measure the reflectivity of the optical film layer. Since the decay signal is directly related to the loss of the optical film layer, it can reflect the reflectivity performance of the film layer. However, the optical cavity ring-down method is not suitable for fast, low-cost, and wide-band reflectivity testing scenarios due to its complex testing equipment, high precision requirements for optical path calibration, and slow multi-band testing efficiency. SUMMARY

[0004] Based on the above, the purpose of the present application is to provide a device and method for rapidly testing the reflectivity of a film layer of a laser film element for different wavelength bands.

[0005] To achieve the above purpose, the present application adopts the following technical solutions:

[0006] A device for rapidly testing the reflectivity of a film layer of a laser film element, comprising a laser, a laser film element, a three-dimensional platform, a cutoff device, a detector, and an upper computer, wherein the laser film element is divided into front and back surfaces, and both surfaces are coated with a reflective film layer, with the surface of the laser film element facing the laser defined as the front surface and the other surface defined as the back surface;

[0007] The laser film element and the detector are arranged on the three-dimensional platform, with the detection head of the detector pointing towards the back surface of the laser film element, and the upper computer being in communication with the laser, the three-dimensional platform, and the detector;

[0008] The laser outputs the test laser irradiating the reflective film layer of the laser film element, and cuts off the reflected test laser at a stopper. Part of the light signal is reflected back and forth between the reflective film layers on the front and back surfaces of the laser film element, and corresponding transmitted light signals are generated on the surface of the reflective film layer, forming a multi-light field superposition phenomenon with the central coordinates moving along the axial direction and the light intensity continuously decaying. The detector receives the transmitted light signal behind the laser film element.

[0009] As a preferred solution of the device for rapidly testing the reflectivity of the film layer of the laser film element, one of the front and back surfaces of the laser film element is coated with the reflective film layer, and the other is the reference film layer with known reflectivity.

[0010] As a preferred solution of the device for rapidly testing the reflectivity of the film layer of the laser film element, the laser is a collimated laser with adjustable wavelength and power, which outputs the test laser. The wavelength and power of the collimated laser are adjusted by the host computer.

[0011] As a preferred solution of the device for rapidly testing the reflectivity of the film layer of the laser film element, the three-dimensional platform is a rotatable and liftable platform, and the position of the laser film element is changed by rotating and lifting the three-dimensional platform controlled by the host computer, so as to adjust the incident angle of the test laser.

[0012] As a preferred solution of the device for rapidly testing the reflectivity of the film layer of the laser film element, the detector is a photodetector, and the host computer processes and analyzes the transmitted light signal received by the photodetector, and calculates the reflectivity of the reflective film layer.

[0013] A method for rapidly testing the reflectivity of the film layer of the laser film element, applied to the device for rapidly testing the reflectivity of the film layer of the laser film element, comprising the following steps:

[0014] The laser outputs the test laser with a specific wavelength and power, which is reflected after passing through the measured film layer of the laser film element, and the reflected light is incident on the stopper. Part of the light signal is reflected back and forth between the measured film layer and the reference film layer, and corresponding transmitted light signals are generated on the surface of the reference film layer;

[0015] The detector acquires the light intensity distribution signal of the transmitted light signal of the reference film layer of the laser film element in real time, and transmits it to the host computer.

[0016] The host computer processes and analyzes the central axial light intensity distribution signal of the received transmitted light signal, and calculates the reflectivity of the measured film layer of the laser film element.

[0017] As a preferred solution of the method for testing the reflectivity of the film layer of the laser film element, the specific principle of calculating the reflectivity of the film layer of the laser film element is as follows:

[0018] The laser outputs the test laser to be incident on the surface of the film layer of the laser film element at an angle of θ0. According to the law of refraction in geometric optics, we have:

[0019] n0*sinθ0=n e *sinθ e

[0020] n0 is the refractive index of air, n e is the refractive index of the laser film element;

[0021] When the distance between the film layer to be tested and the reference film layer of the laser film element is h, the distance between the central coordinates of the light intensity of the transmitted light signal of the reference film layer formed by back and forth reflection is Δx, we have:

[0022]

[0023] When the incident light intensity distribution is The light intensity distribution on the surface of the reference film layer of the laser film element can be derived as:

[0024]

[0025] wherein:

[0026]

[0027] η1 is the reflectivity of the film layer to be tested, and η2 is the reflectivity of the reference film layer;

[0028] Based on the incident light intensity distribution The light intensity central coordinate distance Δx, combined with the reflectivity of the reference film layer, the normalized distribution of the transmitted light signal of the reference film layer and the theoretical central axial light intensity normalized distribution curve cluster when the film layer to be tested has different reflectivities are calculated under the theoretical condition;

[0029] The actual central axial light intensity distribution of the transmitted light signal of the reference film layer obtained by the detector is normalized and curve fitting is carried out to obtain the actual central axial light intensity normalized distribution curve.

[0030] By comparing and analyzing the theoretical central axial light intensity normalized distribution curve cluster and the actual central axial light intensity normalized distribution curve, the reflectivity corresponding to the theoretical curve closest to the actual curve is the actual reflectivity of the film layer to be tested.

[0031] As a preferred solution of the method for testing the reflectivity of the film layer of the laser film element, the wavelength of the laser output is changed by the host computer, so that the reflectivity of the film layer to be tested of the laser film element to different wavelengths of laser can be obtained.

[0032] The present application has the following advantages:

[0033] 1. The reflectivity of the film layer is tested by the variation of the central axis light intensity of the transmission light signal formed by the back and forth reflection of the light between the film layers in front of and behind the laser film element, so that the environmental interference can be greatly reduced, and the testing precision is high.

[0034] 2. The light signal intensity of the irradiation surface of the film layer is avoided, the transmission light intensity signal of the back surface of the laser film element is collected for normalization processing, the contrast of the light signal is enhanced, the transmission light intensity signal characteristics are extracted and analyzed, and the testing precision is improved.

[0035] 3. The testing light path is simple and convenient for calibration, the output wavelength of the laser and the position of the laser film element are adjusted by the host computer, so that the reflectivity of the film layer to be tested of the laser film element to different wavelength laser signals can be quickly tested.

[0036] 4. The device is simple in design and uses few elements, the equipment parameters are adjusted by the host computer, only the transmission light intensity axial light intensity signal of the laser film element is extracted for data analysis, and the device has the characteristics of simple operation, small calculation amount, low cost and strong practicability, and is suitable for fast and low-cost testing scenes. BRIEF DESCRIPTION OF DRAWINGS

[0037] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the description of the embodiments of the present application will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of the contents of the embodiments of the present application and the drawings.

[0038] Figure 1 is a structural schematic diagram of the laser film element film layer reflectivity measuring device of the present application;

[0039] Figure 2 is a schematic diagram of the light path transmission of the laser film element irradiated by laser of the present application;

[0040] Figure 3 is a schematic diagram of the testing process of the present application;

[0041] Figure 4 is a schematic diagram of the transmission light intensity normalization distribution of the reference film layer of the laser film element in embodiment 1 of the present application;

[0042] Figure 5is a schematic diagram of a normalized distribution curve of light intensity on the central axis of transmitted light of a reference film layer of a laser film element in Embodiment 1 of the present application;

[0043] Figure 6 is a schematic diagram of a normalized curve of light intensity in a partial region on the central axis of transmitted light formed by different reflectivities in Embodiment 1 of the present application;

[0044] Figure 7 is a schematic diagram of a normalized distribution of transmitted light intensity of a reference film layer of a laser film element in Embodiment 2 of the present application;

[0045] Figure 8 is a schematic diagram of a normalized distribution curve of light intensity on the central axis of transmitted light of a reference film layer of a laser film element in Embodiment 2 of the present application;

[0046] Figure 9 is a schematic diagram of a normalized curve of light intensity in a partial region on the central axis of transmitted light formed by different reflectivities in Embodiment 2 of the present application;

[0047] Figure 10 is a schematic diagram of a normalized distribution of transmitted light intensity of a reference film layer of a laser film element in Embodiment 3 of the present application;

[0048] Figure 11 is a schematic diagram of a normalized distribution curve of light intensity on the central axis of transmitted light of a reference film layer of a laser film element in Embodiment 3 of the present application.

[0049] Explanation of reference signs:

[0050] 1 - laser; 2 - laser film element; 3 - three-dimensional platform; 4 - stopper; 5 - detector; 6 - host computer. DETAILED DESCRIPTION

[0051] The present application will be further described below in conjunction with the accompanying drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the present application, but not to limit the present application. In addition, it should be noted that, for the convenience of description, only the parts related to the present application are shown in the drawings, but not all the structures.

[0052] In the description of the present application, unless otherwise explicitly specified and limited, the terms "connected", "connected", "fixed" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0053] In the present application, unless otherwise explicitly specified and limited, the first feature is "on" or "under" the second feature can include that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, the first feature "on", "above" and "over" the second feature includes that the first feature is directly above and obliquely above the second feature, or only indicates that the first feature is higher in horizontal height than the second feature. The first feature "under", "below" and "under" the second feature includes that the first feature is directly below and obliquely below the second feature, or only indicates that the first feature is lower in horizontal height than the second feature.

[0054] In the description of the present embodiment, the terms "on", "under", "left", "right" and other orientation or position relationships shown in the drawings are based on the orientation or position relationships shown in the drawings, only for the convenience of description and simplification of operation, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In the description of the present application, unless otherwise specified, the meaning of "a plurality of" is two or more. In addition, the terms "first", "second" are only used to distinguish in description, and have no special meaning.

[0055] The present application provides a device for quickly testing the reflectivity of the film layer of a laser film element, as shown in Figure 1 The device includes a laser 1, a laser film element 2, a three-dimensional platform 3, a stopper 4, a detector 5 and a host computer 6. The laser film element 2 is divided into front and back two sides, and both sides are coated with reflective film layers. The side of the laser film element 2 facing the laser 1 is defined as the front side, and the other side is the back side.

[0056] The laser film element 2 and the detector 5 are arranged on the three-dimensional platform 3, the detection head of the detector 5 points to the back side of the laser film element 2, and the host computer 6 is communicatively connected with the laser 1, the three-dimensional platform 3 and the detector 5.

[0057] The laser 1 outputs test laser irradiation to the reflective film layer of the laser film element 2 and cuts off the reflected test laser at the stopper 4, as shown in Figure 2 Part of the light signal is reflected back and forth between the reflective film layers of the front and back sides of the laser film element 2, and at the same time generates corresponding transmitted light signals on the surface of the reflective film layer, forming a multi-light field superposition phenomenon with the central coordinates moving along the axial direction and the light intensity continuously decaying, and the detector 5 receives the transmitted light signal from the back side of the laser film element 2.

[0058] Further, the laser film element 2 is coated with reflective film layers on the front and back sides, one of which is a to-be-measured film layer, and the other is a reference film layer. The reflectivity of the reference film layer is known, and the reflectivity of the to-be-measured film layer is the test target.

[0059] Preferably, the laser 1 is a collimated laser 1 with adjustable wavelength and power, outputting test laser, and the wavelength and power of the collimated laser 1 are adjusted by the host computer 6.

[0060] Preferably, the three-dimensional platform 3 is a rotatable and liftable platform, and the rotation and lifting of the three-dimensional platform 3 are controlled by the host computer 6 to change the position of the laser film element 2, so as to adjust the incident angle of the test laser.

[0061] Preferably, the stopper 4 is used to cut off the reflected laser, and generally uses a device with laser cutting function such as a power meter.

[0062] Preferably, the detector 5 is a photodetector, and the host computer 6 processes and analyzes the transmitted light signal received by the photodetector, and calculates the reflectivity of the reflective film layer.

[0063] Preferably, the host computer 6 is generally a computer, which is used to control the opening and closing of the laser 1 and the adjustment of the wavelength and power, the lifting and rotation of the three-dimensional platform 3, and process and analyze the light intensity signal received by the detector 5 to obtain the reflectivity of the to-be-tested film layer of the laser film element 2.

[0064] The application also provides a method for quickly testing the reflectivity of a film layer of a laser film element, which is applied to the device for quickly testing the reflectivity of a film layer of a laser film element and comprises the following steps: Figure 3 as shown in the figure, which comprises the following steps:

[0065] S1, the laser 1 outputs test laser with a specific wavelength and power, and the reflected light is incident on the stopper 4 after being reflected by the to-be-tested film layer of the laser film element 2, and part of the light signal is reflected back and forth between the to-be-tested film layer and the reference film layer, and corresponding transmitted light signal is generated on the surface of the reference film layer;

[0066] S2, the detector 5 acquires the light intensity distribution signal of the transmitted light signal of the reference film layer of the laser film element 2 in real time and transmits it to the host computer 6;

[0067] S3, the host computer 6 processes and analyzes the center axis light intensity distribution signal of the received transmitted light signal, and calculates the reflectivity of the to-be-tested film layer of the laser film element 2;

[0068] S4, the wavelength of the laser 1 outputted by the host computer 6 is changed, and the reflectivity of the to-be-tested film layer of the laser film element 2 to different wavelengths of laser is obtained.

[0069] Specifically, the specific principle of calculating the reflectivity of the to-be-tested film layer of the laser film element 2 is as follows:

[0070] The laser 1 outputs test laser to be incident on the surface of the to-be-tested film layer of the laser film element 2 at an angle of θ0, and according to the knowledge of geometric optics, the law of refraction is:

[0071] n0*sinθ0=n e *sinθ e

[0072] n0 is the refractive index of air, n e Let be the refractive index of laser thin-film element 2;

[0073] When the distance between the test film and the reference film of laser thin film element 2 is h, the distance Δx between the center coordinates of the transmitted light signal of the reference film formed by back and forth reflection is:

[0074]

[0075] When the incident light intensity distribution is The light intensity distribution on the reference film surface of laser thin film element 2 can be derived:

[0076]

[0077] in:

[0078]

[0079] η1 is the reflectance of the film to be tested, and η2 is the reflectance of the reference film.

[0080] Based on incident light intensity distribution The light intensity center coordinate spacing Δx, combined with the reflectivity of the reference film, is used to calculate the normalized distribution of the transmitted light signal of the reference film and the cluster of normalized distribution curves of the light intensity along the theoretical center axis when the film to be tested takes different reflectivities.

[0081] By normalizing the central axis light intensity distribution of the transmitted light signal of the actual reference film obtained by detector 5 and performing curve fitting, the normalized distribution curve of the actual central axis light intensity is obtained.

[0082] By comparing and analyzing the theoretical central axis light intensity normalized distribution curves and the actual central axis light intensity normalized distribution curves, the reflectance corresponding to the theoretical curve that is closest to the actual curve is the actual reflectance of the film under test. In practical applications, if the actual curve is exactly in the middle of the two theoretical curves, the decision is made based on the measurement accuracy requirements. If high measurement accuracy is required, the calculation accuracy is further increased until the calculated reflectance value meets the measurement accuracy requirements. If the measurement accuracy requirements are already met, but the actual curve is still in the middle of the two theoretical curves, the reflectance is determined by rounding down.

[0083] To make the objectives, technical solutions, and advantages of this invention clearer, the following description is provided in conjunction with the appendix. Figure 4—11 and three specific embodiments, the application is further described in detail. It should be understood that the specific embodiments described herein are merely intended to explain the application and are not intended to limit the application. In addition, the technical features involved in the various embodiments of the application described below can be combined with each other as long as they do not conflict with each other.

[0084] Embodiment 1

[0085] For the application scenario of testing the reflectivity of the film layer of the laser film element, the reflectivity of the front film layer to be tested is unknown, and the reflectivity of the rear reference film layer is known, the reference Figures 4 to 6 The embodiment of the application provides a device and a method for quickly testing the reflectivity of the film layer of a laser film element. The device is composed of a wavelength and power adjustable laser 1, a laser film element 2, a three-dimensional platform 3, a cutoff device 4, a detector 5 and an upper computer 6.

[0086] Specifically, the power and wavelength adjustable laser 1 is a laser with a spot radius of 10 mm, a wavelength adjustable in the range of 1000-1100 nm, and a power adjustable in the range of 0-1000 W, which is used to output laser beams with different wavelengths and powers.

[0087] Specifically, the laser film element 2 is a high-reflectivity mirror with different reflective film layers plated on both sides, the refractive index of the mirror is 1.45, the size is 200*200*10 mm, the front side is the film layer to be tested, and the rear side is a reference film layer with a reflectivity of 99.95%.

[0088] Specifically, the three-dimensional platform 3 is used to adjust the position and attitude of the laser film element 2, and change the incident angle and irradiation position of the detection light beam.

[0089] Specifically, the cutoff device 4 is a power meter, which is used to cut off the reflected light of the laser film element 2.

[0090] Specifically, the detector 5 is a photodetector, which is used to acquire the reference film layer surface light intensity distribution signal of the laser film element 2 in real time.

[0091] Specifically, the upper computer 6 is a computer, which is used to process and analyze the received light intensity signal, and calculate the reflectivity of the film layer to be tested of the laser film element 2.

[0092] The embodiment of the application also provides a method for quickly testing the reflectivity of the film layer of a laser film element, and the specific steps are as follows:

[0093] S101, the wavelength and power adjustable laser 1 outputs a detection laser beam with a power of 1000 W, a spot radius of 10 mm and a wavelength of 1064 nm, and the main reflected light is incident on the cutoff device 4 after being reflected by the laser film element 2;

[0094] S102, the detector 5 acquires the light intensity distribution signal of the reference film layer of the laser film element 2 in real time and transmits it to the host computer 6;

[0095] S103, the host computer 6 processes and analyzes the central axial light intensity distribution signal of the received light signal, and in combination with the reflectivity of the reference film layer, the reflectivity of the to-be-measured film layer of the laser film element can be calculated.

[0096] Specifically, the light intensity distribution signal processing and analysis in S103 and the calculation principle and method of the reflectivity of the to-be-measured film layer of the laser film element 2 are as follows:

[0097] The laser output by the laser 1 is incident on the surface of the laser film element 2 at an angle of θ0. According to the knowledge of geometric optics, by the law of refraction:

[0098] n0*sinθ0=n e *sinθ e

[0099] n0 is the refractive index of air, n e is the refractive index of the lens, and the incident angle θ0 is 3° in this embodiment.

[0100] The distance between the to-be-measured film layer and the reference film layer is h, that is, the thickness of the laser film element 2 is 10 mm, and the distance between the light intensity center coordinates after the back and forth reflection is Δx:

[0101]

[0102] When the incident light intensity distribution is The light intensity distribution on the surface of the reference film layer of the laser film element can be derived as:

[0103]

[0104] Wherein:

[0105]

[0106] η1 is the reflectivity of the to-be-measured film layer, and η2 is the reflectivity of the reference film layer.

[0107] Therefore, based on the determined refractive index 1.45 of the laser film element 2, the distance between the two film layers 10 mm, and the incident angle 3°, the light intensity center coordinate distance after the back and forth reflection of the film layers before and after the laser film element 2 can be determined as 0.7223 mm;

[0108] Based on the incident light intensity distribution, the light intensity center coordinate distance of the reference film layer of the laser film element 2, and the reflectivity of the reference film layer 99.95%, the central axial light intensity distribution of the reference film layer under different reflectivity conditions is calculated, and then divided by the highest light intensity value. The normalized distribution curve cluster of the central axial light intensity of the reference film layer under different reflectivity calculated by theory is as follows:Figure 6 As shown in the figure, a plurality of curves in the figure correspond to theoretical central axial light intensity normalized distribution curves of different reflectivities (99.9%, 99.91%, 99.92%, 99.93%, etc.), and the light intensity gradually decreases with the increase of the distance;

[0109] In combination with the actual acquired laser film element reference film layer transmitted light signal light intensity distribution of the photodetector 5, normalization processing is performed to obtain a normalized light intensity distribution as shown in the figure, Figure 4 The central axial light intensity signal is extracted, and a change curve as shown in the figure is fitted, the curve in which the light intensity gradually decreases with the increase of the distance is the target for contrastive analysis; Figure 5

[0110] By contrastively analyzing the theoretical calculation curve and the actual test curve, the reflectivity corresponding to the theoretical curve closest to the actual curve is the actual reflectivity of the to-be-tested film layer, and thus it is determined that the reflectivity of the to-be-tested film layer of the laser film element 2 is 99.91%.

[0111] Further, by changing the wavelength size of the output of the laser 1, the reflectivity of the to-be-tested film layer of the laser film element 2 to different wavelengths of laser light can be obtained.

[0112] Embodiment 2

[0113] The exemplary embodiments will be described in more detail below with reference to the accompanying drawings.

[0114] For the laser film element film layer reflectivity test application scenario in which the front and rear reflection film layers of the laser film element 2 are both the same to-be-tested film layer, referring to Figures 7 to 9 The embodiment of the present application provides a device and a method for quickly testing film layer reflectivity. The device is composed of a wavelength and power adjustable laser 1, a laser film element 2, a three-dimensional platform 3, a cutoff device 4, a detector 5, and an upper computer 6.

[0115] Specifically, the power and wavelength adjustable laser 1 is a collimated laser with a spot radius of 10 mm, a wavelength band of 1000-1100 nm, and a power adjustable range of 0-1000 W, which is used to output collimated laser beams with different wavelength bands and powers.

[0116] Specifically, the laser film element 2 is a high reflector with the same film layer on both sides, the refractive index of the mirror is 1.45, the size is 200 mm*200 mm*10 mm, the specified test laser irradiation surface is the to-be-tested film layer, and the other surface is the reference film layer. The two film layers are completely consistent and have the same reflectivity.

[0117] Specifically, the three-dimensional platform 3 is used to adjust the position and attitude of the laser film element, and change the incident angle and irradiation position of the detection light beam.

[0118] ​Specifically, the stopper 4 is a power meter for cutting off the reflected light of the laser film element.

[0119] Specifically, the detector 5 is a photodetector for acquiring the light intensity distribution signal of the reference film layer transmitted light of the laser film element in real time.

[0120] Specifically, the host computer 6 is a computer for processing and analyzing the received light intensity signal, and calculating the reflectivity of the film layer of the laser film element 2.

[0121] The embodiment of the present application also provides a method for quickly testing the reflectivity of the film layer of the laser film element, and the specific steps are as follows:

[0122] S201, the wavelength and power adjustable laser 1 outputs a power of 1000W, and a spot radius of 10mm, and a detection laser beam with a wavelength of 1064nm is reflected by the film layer to be measured of the laser film element 2, and the main reflected light is incident on the stopper 4;

[0123] S202, the detector 5 acquires the light intensity distribution signal of the reference film layer transmitted light of the laser film element in real time, and transmits the light intensity distribution signal to the host computer 6;

[0124] S203, the host computer 6 processes and analyzes the received light intensity distribution signal, and calculates the reflectivity of the film layer of the laser film element.

[0125] Specifically, the light intensity distribution signal processing and analysis in S203 and the calculation principle and method of the reflectivity of the film layer of the laser film element 2 are as follows:

[0126] The laser output by the laser 1 is incident on the surface of the film layer to be measured of the laser film element 2 at an angle of θ0, and according to the knowledge of geometric optics, according to the refraction law:

[0127] n0*sinθ0=n e *sinθ e

[0128] n0 is the refractive index of air, n e is the refractive index of the lens, and the incident angle θ0 is 3° in the embodiment.

[0129] When the distance between the two film layers is h, that is, the thickness of the laser film element 2 is 10mm, the light intensity center coordinate distance Δx after the back and forth reflection is:

[0130]

[0131] When the incident light intensity distribution is When the front and back two film layers are consistent, the reference film layer transmitted light intensity distribution of the back surface of the laser film element 2 can be derived as:

[0132]

[0133] wherein:

[0134]

[0135] η is the reflectivity of the film layer to be measured of the laser film element 2 and the reference film layer.

[0136] Therefore, based on the determined refractive index 1.45 of the laser film element 2, the distance between the two film layers 10 mm, and the incident angle 3°, the distance between the central coordinates of the transmitted light intensity formed after the back and forth reflection of the two film layers is determined to be 0.7223 mm;

[0137] By calculating the axial light intensity distribution of the transmitted light center of the reference film layer when the film layer to be measured has different reflectivities, and then dividing by the highest light intensity value, a theoretically calculated normalized axial light intensity distribution curve cluster of the transmitted light center of the reference film layer under different reflectivities is obtained as shown in Figure 9 The multiple curves in the figure correspond to the theoretical normalized axial light intensity distribution curves of different reflectivities (99.88%, 99.89%, 99.9%, 99.91%, etc.), and the light intensity gradually decreases with the increase of the distance;

[0138] Combined with the actual light intensity distribution of the transmitted light of the reference film layer of the laser film element obtained by the photodetector 5, the normalized light intensity distribution is obtained as shown in Figure 7 The central axial light intensity signal is extracted, and the change curve is fitted as shown in Figure 8 The curve in which the light intensity gradually decreases with the increase of the distance is the target for comparative analysis;

[0139] By comparing the theoretical calculation curve cluster with the actual test curve, the reflectivity corresponding to the theoretical curve closest to the actual curve is the actual reflectivity of the film layer to be measured, and the reflectivity of the film layer to be measured of the laser film element 2 is obtained to be 99.89%.

[0140] Further, by changing the wavelength of the output of the laser 1, the reflectivity of the film layer to be measured of the laser film element 2 to different wavelengths of laser light can be obtained.

[0141] Example 3

[0142] The exemplary embodiments will be described in more detail below with reference to the accompanying drawings.

[0143] As shown in Figure 10 For the test case of small light spot and large film layer distance, when Δx≥4ω (ω is the radius of the light spot), the adjacent two transmitted light spots are completely separated without superposition, and form individual discrete transmitted light spots. The present application provides a device and method for quickly testing the reflectivity of the film layer. The device is composed of a wavelength and power adjustable laser 1, a laser film element 2, a three-dimensional platform 3, a cutoff device 4, a detector 5, and an upper computer 6.

[0144] Specifically, the power and wavelength adjustable laser 1 is a collimated laser with a spot radius of 1 mm, a wavelength adjustable range of 1000-1100 nm, and a power adjustable range of 0-1000 W, and is used for outputting collimated laser beams with different wavelengths and powers.

[0145] Specifically, the laser film element 2 is a double-sided coated high-reflectivity mirror with a refractive index of 1.45, a size of 200 mm*200 mm*60 mm, and a specified test laser irradiation surface as a to-be-tested film layer and the other surface as a reference film layer (with a known reflectivity) or the same as the to-be-tested film layer.

[0146] Specifically, the three-dimensional platform 3 is used for adjusting the position and attitude of the laser film element, and changing the incident angle and irradiation position of the probe light beam.

[0147] Specifically, the stopper 4 is a power meter used for cutting off the reflected light of the laser film element.

[0148] Specifically, the detector 5 is a photodetector used for acquiring the light intensity distribution signal of the reference film layer transmission light of the laser film element in real time.

[0149] Specifically, the host computer 6 is a computer used for processing and analyzing the received light intensity signal and calculating the reflectivity of the film layer of the laser film element 2.

[0150] The embodiment of the present application also provides a method for quickly testing the reflectivity of the film layer of a laser film element.

[0151] S301, the wavelength and power adjustable laser 1 outputs a probe laser beam with a power of 1000 W, a spot radius of 1 mm, and a wavelength of 1064 nm, and the main reflected light is incident on the stopper 4 after being reflected by the to-be-tested film layer of the laser film element 2;

[0152] S302, the detector 5 acquires the light intensity distribution signal of the reference film layer transmission light of the laser film element in real time and transmits the signal to the host computer 6;

[0153] S303, the host computer 6 processes and analyzes the received light intensity distribution signal, extracts the highest peak light intensity of each transmission light field center, and calculates and analyzes to obtain the reflectivity of the film layer of the laser film element.

[0154] Specifically, the processing and analysis of the light intensity distribution signal and the calculation principle and method of the reflectivity of the film layer of the laser film element 2 in S303 are as follows:

[0155] The laser output by the laser 1 is incident on the surface of the to-be-tested film layer of the laser film element 2 at an angle of θ0, and according to the knowledge of geometric optics, the refraction law is:

[0156] n0*sinθ0=n e *sinθe

[0157] n0 is the air refractive index, n is the lens refractive index, and θ0 is the incident angle in this embodiment. e

[0158] When the distance between the two film layers is h, the distance between the center coordinates of the light intensity after back and forth reflection is Δx:

[0159]

[0160] When the incident light intensity distribution is When the reflectivity of the front and back two film layers is η1 and η2, respectively, the center light intensity of each transmitted light spot on the back surface of the laser film element 2 can be derived:

[0161] I1 = I0(1-η1)*(1-η2)

[0162] I2 = I0(1-η1)*(1-η2)*η1*η2

[0163]

[0164] Obviously, the center light intensity of the transmitted light spot is attenuated by η1η2 times. By normalizing the highest peak light intensity of each transmitted light field center extracted, and fitting analysis according to the exponential decay function, the value of η1η2 is obtained. Combined with the known reflectivity of one reference film layer (or the reflectivity of the two film layers is consistent), the reflectivity of the measured film layer can be calculated.

[0165] In this embodiment, based on the determined refractive index of the laser film element 2 of 1.45, the distance between the two film layers of 60 mm, and the incident angle of 3°, the center coordinate distance of the transmitted light intensity after back and forth reflection between the two film layers is 4.3341 mm;

[0166] Based on the incident light intensity distribution, the center coordinate distance of the transmitted light intensity of the reference film layer of the laser film element is 4.3341 mm, and the reflectivity is 99.9%. Combined with the center axial light intensity distribution of the transmitted light signal of the reference film layer of the laser film element obtained by the detector 5, the normalized light intensity distribution is obtained as shown in Figure 11 The highest peak light intensity of each transmitted light field center after normalization is extracted, and the reflectivity of the measured film layer of the laser film element 2 is calculated to be 99.81% according to the exponential decay fitting analysis.

[0167] ​Other embodiments of the disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the features disclosed herein. It is intended that the specification and examples be considered as exemplary only, with the true scope and spirit of the disclosure being indicated by the following claims.

[0168] It should be understood that the present disclosure is not limited to the precise structures as herein described and illustrated in the drawings, and that various modifications and changes can be made without departing from its scope. The scope of the present disclosure is limited only by the claims that follow.

Claims

1. A device for rapidly testing the reflectivity of a laser thin-film element, characterized in that, The system includes a laser (1), a laser thin film element (2), a three-dimensional platform (3), a cutoff (4), a detector (5), and a host computer (6). The laser thin film element (2) is divided into front and back sides, and both sides are coated with a reflective film layer. The side of the laser thin film element (2) facing the laser (1) is defined as the front side, and the other side is defined as the back side. The laser thin film element (2) and the detector (5) are mounted on the three-dimensional platform (3). The probe head of the detector (5) points to the back of the laser thin film element (2). The host computer (6) is communicatively connected to the laser (1), the three-dimensional platform (3) and the detector (5). The laser (1) outputs a test laser to irradiate the reflective film layer of the laser thin film element (2) and cuts off the reflected test laser at the cutoff (4). Part of the light signal is reflected back and forth between the reflective film layers on the front and back sides of the laser thin film element (2), and at the same time, a corresponding transmitted light signal is generated on the surface of the reflective film layer, forming a multi-field superposition phenomenon in which the center coordinate moves along the axial direction and the light intensity continuously decreases. The detector (5) receives the transmitted light signal behind the laser thin film element (2).

2. The apparatus for rapidly testing the reflectivity of a laser thin-film element according to claim 1, characterized in that, The laser thin film element (2) has a reflective film layer deposited on both the front and back sides, one side being the film layer to be tested and the other side being a reference film layer, the reflectivity of which is known.

3. The apparatus for rapidly testing the reflectivity of a laser thin-film element according to claim 1, characterized in that, The laser (1) is a collimated laser with adjustable wavelength and power, which outputs the test laser. The wavelength and power of the collimated laser are adjusted by the host computer (6).

4. The apparatus for rapidly testing the reflectivity of a laser thin-film element according to claim 1, characterized in that, The three-dimensional platform (3) is a rotatable and liftable platform. The host computer (6) controls the rotation and lifting of the three-dimensional platform (3) to change the position of the laser thin film element (2), thereby adjusting the incident angle of the test laser.

5. The apparatus for rapidly testing the reflectivity of a laser thin-film element according to claim 1, characterized in that, The detector (5) is a photodetector, and the host computer (6) processes and analyzes the transmitted light signal received by the photodetector and uses it to calculate the reflectivity of the reflective film.

6. A method for rapidly testing the reflectivity of a laser thin-film element, characterized in that, An apparatus for rapidly testing the reflectivity of a laser thin-film element as described in any one of claims 1-5, comprising the following steps: The laser (1) outputs a test laser with a specific wavelength power. After being reflected by the test film layer of the laser thin film element (2), the reflected light is incident on the cutoff (4). Part of the light signal is reflected back and forth between the test film layer and the reference film layer, and at the same time, the corresponding transmitted light signal is generated on the surface of the reference film layer. The detector (5) acquires the light intensity distribution signal of the transmitted light signal of the reference film layer of the laser thin film element (2) in real time and transmits it to the host computer (6); The host computer (6) processes and analyzes the central axis light intensity distribution signal of the received transmitted light signal, and calculates the reflectivity of the test film layer of the laser thin film element (2).

7. The method for rapidly testing the reflectivity of a laser thin-film element according to claim 6, characterized in that, The specific principle for calculating the reflectivity of the test film layer of the laser thin film element (2) is as follows: The laser (1) outputs the test laser, which is incident on the surface of the film layer to be tested of the laser thin film element (2) at an angle of θ0. According to the knowledge of geometric optics, by the law of refraction: n0*sinθ0=n e *sinθ e n0 is the refractive index of air, n e The refractive index of the laser thin film element (2) is given by the refractive index. When the distance between the test film layer and the reference film layer of the laser thin film element (2) is h, the light intensity center coordinate distance Δx of the transmitted light signal of the reference film layer formed by back and forth reflection is: When the incident light intensity distribution is The light intensity distribution on the surface of the reference film of the laser thin film element (2) can be derived: in: η1 is the reflectance of the film to be tested, and η2 is the reflectance of the reference film. Based on the incident light intensity distribution The light intensity center coordinate spacing Δx, combined with the reflectivity of the reference film, is used to calculate the normalized distribution of the transmitted light signal of the reference film and the cluster of normalized distribution curves of the light intensity along the theoretical center axis when the film to be tested takes different reflectivities. By normalizing the central axial light intensity distribution of the actual transmitted light signal of the reference film obtained by the detector (5) and performing curve fitting, the normalized distribution curve of the actual central axial light intensity is obtained. By comparing and analyzing the theoretical central axis light intensity normalized distribution curves and the actual central axis light intensity normalized distribution curves, the reflectance corresponding to the theoretical curve that is closest to the actual curve is the actual reflectance of the film layer under test.

8. The method for rapidly testing the reflectivity of a laser thin-film element according to claim 6, characterized in that, By changing the wavelength of the laser (1) output by the host computer (6), the reflectivity of the test film layer of the laser thin film element (2) to different wavelength lasers can be obtained.

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