A flexible high-energy laser perception film sensor and a preparation method thereof

Abstract

The application provides a flexible high-energy laser sensing film sensor, which comprises a sensing film and a laser high-reflection film layer on the surface of the sensing film. The sensing film is composed of a flexible substrate, an upper surface transition layer, a lower surface transition layer, an upper surface thermistor layer, a lower surface thermistor layer, an upper surface lead layer, a lower surface lead layer, an upper surface protective layer and a lower surface protective layer. The application utilizes a thin film type double-sided resistance array to monitor the transient thermal effect of laser irradiation in real time, combines the laser high-reflection film layer to improve the laser detection threshold, and can realize the rapid and accurate measurement of laser irradiation parameters such as laser power density, spot size and irradiation position, solves the problem that the photosensitive diameter of current laser power meters, laser spot analyzers and other devices is limited and it is difficult to be applied to the measurement of large spot size laser parameters and laser sensing and warning, and has the advantages of flexibility, large area, simple structure, low cost and the like.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of thin film sensor technology, and particularly relates to a flexible high-energy laser sensing thin film sensor and a preparation method thereof. BACKGROUND

[0002] With the vigorous development of laser technology, high-energy lasers are widely used in the fields of aerospace, weapon equipment, intelligent manufacturing, etc. The accurate measurement of laser power density, spot shape, size and other parameters is a necessary prerequisite for the development and utilization of high-energy laser beams. The existing laser power measurement device is mainly realized by a laser power meter based on a thermocouple. The detection range of the laser power is affected by the heat dissipation mode of the power meter, and the effective light sensing diameter is limited, which makes it difficult to meet the measurement of high-power density, large spot size and high-energy laser beam power.

[0003] At present, there is still a lack of a high-energy laser measurement device that can be applied to large spot sizes of several centimeters or more and laser powers of hundreds of watts or more. On the other hand, the development of high-power laser weapons poses a serious threat to satellites, weapon equipment, etc. To protect against high-energy laser weapons, not only is it necessary to develop laser protection materials based on linear and nonlinear optical principles to improve the laser damage resistance strength, but also it is necessary to quickly respond to laser threats by detecting laser power, spot size, attack position and other signals to assess the threat level of laser attacks and issue an alarm signal for taking appropriate active defense measures. Therefore, the development of a flexible high-energy laser sensing thin film sensor with flexibility, large area and the ability to detect large spot sizes of centimeters or more not only can be used for accurate measurement of laser parameters in scientific research, but also can be used to realize rapid sensing and warning of laser attack threats on the surface of key structures and components to improve the ability to resist laser attacks. SUMMARY

[0004] To solve the above problems, the present application provides a flexible high-energy laser sensing thin film sensor and a preparation method thereof, which can be used for accurate measurement of high-energy laser power density and spot size. The flexible substrate surface row-column linear resistor array arrangement can realize rapid and accurate sensing of laser power, spot size and irradiation position, and has the advantages of being suitable for accurate measurement of high-energy laser parameters such as high-energy laser power density and large spot size, and being flexible, large-area arrangement, and integrated protection and sensing.

[0005] A flexible high-energy laser sensing thin film sensor includes a sensing thin film 1 and a laser high-reflective film layer 2 on the upper surface of the sensing thin film 1.

[0006] The sensing film 1 is composed of a flexible substrate 101, an upper surface transition layer 102, a lower surface transition layer 106, an upper surface thermistor layer 103, a lower surface thermistor layer 107, an upper surface lead layer 104, a lower surface lead layer 108, an upper surface protective layer 105, and a lower surface protective layer 109; wherein the upper surface transition layer 102, the upper surface thermistor layer 103, the upper surface lead layer 104, and the upper surface protective layer 105 are sequentially covered on the upper surface of the flexible substrate 101, and the lower surface transition layer 106, the lower surface thermistor layer 107, the lower surface lead layer 108, and the lower surface protective layer 109 are sequentially covered on the lower surface of the flexible substrate 101;

[0007] The laser high-reflection film layer 2 is used to reduce the absorption of incident laser by the flexible high-energy laser sensing thin film sensor, and to increase the laser power density range that the thin film sensor can perceive. The laser high-reflection film layer 2 is one of the laser high-reflection films based on all-dielectric multilayer optical film or metal high-reflection film.

[0008] Furthermore, the flexible substrate 101 is a flexible film or foil with a thickness of 10 μm to 500 μm;

[0009] When the flexible substrate 101 is an insulating film or foil, the material of the upper surface transition layer 102 and the lower surface transition layer 106 is one of Ti, Cr, and Ta; when the flexible substrate 101 is a conductive film or foil, the upper surface transition layer 102 and the lower surface transition layer 106 are a combination of multilayer films, wherein the structure of the multilayer film includes an alloy film, an Al2O3 insulating layer, and an adhesion layer prepared on the surface of the Al2O3 insulating layer.

[0010] Furthermore, the upper and lower surface thermistor layers are high-density linear resistor arrays composed of multiple parallel thin film thermistors. A single thermistor in the linear resistor array is a long strip structure with a width of 20μm to 2mm. The resistor array spacing is 20μm to 2mm, and its length covers the entire sensing area of ​​the sensing film 1.

[0011] Furthermore, the orientation of the linear resistor array arranged on the upper surface thermistor layer 103 and the orientation of the linear resistor array arranged on the lower surface thermistor layer 107 are orthogonal to each other.

[0012] Furthermore, the thickness of the thermistor layer is between 100 nm and 20 μm, and the material is one of the thermistor films such as Pt, Ni, NiCr, etc., which have good resistance temperature coefficient and linearity in a wide temperature range.

[0013] Further, the upper surface lead layer 104 and the lower surface lead layer 108 each comprise a plurality of leads separated from each other, and the upper surface lead layer 104 and the lower surface lead layer 108 are used to form electrical contact with the upper surface thermistor layer 103 and the lower surface thermistor layer 107 respectively and provide an electrical interface for sensor measurement, one end of each thermistor strip in the linear resistance array is connected to a single lead to form electrical contact, and the other end of the thermistor strip is shared by a plurality of thermistor strips with one or more leads.

[0014] Further, the upper surface protective layer 105 and the lower surface protective layer 109 are polyimide film or oxide / nitride ceramic film.

[0015] Further, when the laser high reflection film layer 2 is a full dielectric multilayer optical film, the preferred film layer system is one of HfO2 / SiO2 or Ta2O5 / SiO2 multilayer film, and high and low refractive index thin film materials and thicknesses are designed and optimized to obtain high reflection in the measured laser wavelength band.

[0016] Further, when the laser high reflection film layer 2 is a metal high reflection film, the metal high reflection film comprises a high reflectivity thin film and a transparent radiation heat dissipation thin film on the surface of the high reflectivity thin film.

[0017] The high reflectivity thin film is preferably one of aluminum, silver, and gold thin film, which is used to improve the wide-band laser reflectivity of the flexible high-energy laser sensing thin film sensor.

[0018] The radiation heat dissipation layer thin film is one of silicon oxide, aluminum oxide, and transparent infrared high-radiation thin film, which is used to increase the heat dissipation capacity of the flexible high-energy laser sensing thin film sensor.

[0019] A preparation method of a flexible high-energy laser sensing thin film sensor, comprising the following steps:

[0020] S1: preparing a flexible substrate 101;

[0021] S2: preparing lead layers on the upper and lower surfaces and patterning;

[0022] S3: depositing and patterning a transition layer and a thermistor layer;

[0023] S4: surface pasting a protective layer;

[0024] S5: electrical interface enhancement treatment;

[0025] S6: preparing a laser high reflection film layer 2.

[0026] Advantages:

[0027] 1. The application provides a flexible high-energy laser sensing thin film sensor, comprising a sensing thin film and a laser high-reflection film layer on the surface of the sensing thin film, the sensing thin film is composed of a flexible substrate and a transition layer, a thermistor layer, a lead layer and a protective layer prepared on the upper and lower surfaces of the flexible substrate, wherein the transition layer and the thermistor layer are arranged in linear resistance arrays, and the upper and lower surface resistance array arrangement directions are 90 degrees to each other; the laser high-reflection film layer is located on the surface of the sensing thin film, and is used for improving the laser reflectivity of the thin film sensor and improving the laser sensing damage threshold; therefore, by arranging the row / column resistance linear arrays on the upper and lower surfaces of the flexible substrate, the flexible high-energy laser sensing thin film sensor can realize the rapid and accurate measurement of laser irradiation parameters such as laser power density, spot size and irradiation position, and solves the problems that the current laser power meter and laser spot analyzer have limited photosensitive diameters and are difficult to be applied to the measurement of large spot size laser parameters and laser sensing warning, and has the advantages of simple structure, low cost and the like.

[0028] 2. The application provides a flexible high-energy laser sensing method, by integrating a laser high-reflection layer on the surface of a sensing thin film, the laser damage threshold of the sensing thin film can be greatly improved, so that the sensing thin film is applicable to the sensing and warning of high-power density energy laser, and by the integrated design of protection and sensing, the flexible high-energy laser sensing method has important application prospects in the fields of satellite safety and the like. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 It is a whole schematic view of the flexible high-energy laser sensing thin film sensor.

[0030] Figure 2 It is a cross-sectional schematic view of the first implementation mode of the flexible high-energy laser sensing thin film sensor.

[0031] Figure 3 It is a cross-sectional schematic view of the second implementation mode of the flexible high-energy laser sensing thin film sensor.

[0032] Figure 4 It is a schematic view of the upper and lower surface resistance array arrangement of the flexible high-energy laser sensing thin film sensor.

[0033] Figure 5 It is a curve of the normalized resistance value of the upper surface resistance array obtained in the first embodiment of the flexible high-energy laser sensing thin film sensor changing with time.

[0034] Figure 6 It is a Gaussian fitting curve of the normalized resistance value of the upper surface resistance array obtained in the first embodiment of the flexible high-energy laser sensing thin film sensor.

[0035] Figure 7 It is a relationship between the Gaussian fitting half-width of the normalized resistance value and the spot radius in the first embodiment of the flexible high-energy laser sensing thin film sensor.

[0036] 1-sensing film; 101-flexible substrate; 102-upper surface transition layer; 103-upper surface thermistor layer; 104-upper surface lead layer; 105-upper surface protective layer; 106-lower surface transition layer; 107-lower surface thermistor layer; 108-lower surface lead layer; 109-lower surface protective layer; 2-laser high reflection film layer; 201-Ta2O5 film; 202-SiO2 film; 203-metal high reflection film; 204-radiation heat dissipation layer. DETAILED DESCRIPTION

[0037] In order to make the personnel in the technical field better understand the scheme of the present application, the technical scheme in the embodiments of the present application will be clearly and completely described below in combination with the drawings in the embodiments of the present application.

[0038] The purpose of the present application is to provide a flexible high-energy laser sensing film sensor, which realizes laser sensing by preparing a high-density linear resistance array on a flexible film substrate, and improves the anti-laser damage threshold by integrating a laser high reflection film layer on the surface of the sensing film, so as to realize accurate measurement of high-energy laser power density and spot size and other parameters.

[0039] Reference Figure 1 、 Figure 2 The flexible high-energy laser sensing film sensor provided by the present application comprises a sensing film 1 and a laser high reflection film layer 2 located on the surface of the sensing film.

[0040] The sensing film is used for real-time sensing of laser power, spot size, irradiation position and other parameters, and is composed of a flexible substrate and transition layers, thermistor layers, lead layers and protective layers located on the upper and lower surfaces of the flexible substrate. Specifically, the sensing film 1 is composed of a flexible substrate 101, an upper surface transition layer 102, a lower surface transition layer 106, an upper surface thermistor layer 103, a lower surface thermistor layer 107, an upper surface lead layer 104, a lower surface lead layer 108, an upper surface protective layer 105 and a lower surface protective layer 109; wherein the upper surface transition layer 102, the upper surface thermistor layer 103, the upper surface lead layer 104 and the upper surface protective layer 105 are sequentially covered on the upper surface of the flexible substrate 101, and the lower surface transition layer 106, the lower surface thermistor layer 107, the lower surface lead layer 108 and the lower surface protective layer 109 are sequentially covered on the lower surface of the flexible substrate 101.

[0041] The laser high reflection film layer 2 is used for reducing the absorption of incident laser by the flexible high-energy laser sensing film sensor and improving the range of laser power density that can be sensed by the film sensor, and the laser high reflection film layer 2 is preferably one of a laser high reflection film based on a full-dielectric multilayer optical film or a metal high reflection film.

[0042] When the laser high-reflection film layer 2 is a full dielectric multilayer optical film, the film layer system is preferably one of HfO2 / SiO2 or Ta2O5 / SiO2 multilayer film, and high and low refractive index thin film materials and thicknesses are designed and optimized to obtain high reflection in the laser wavelength band to be measured.

[0043] When the laser high-reflection film layer 2 is a metal high-reflection film, the metal high-reflection film includes a high-reflection thin film and a transparent radiation heat dissipation thin film on the surface of the high-reflection thin film; the high-reflection thin film is preferably one of a metal aluminum, silver, and gold thin film, which is used to improve the wide-band laser reflectivity of the flexible high-energy laser sensing thin film sensor; and the radiation heat dissipation layer thin film is preferably one of a silicon oxide, aluminum oxide, and hafnium oxide transparent infrared high-emissivity thin film, which is used to increase the heat dissipation capacity of the high-energy laser sensing thin film sensor.

[0044] The upper surface transition layer 102 and the lower surface transition layer 106 are deposited on the upper and lower surfaces of the flexible substrate 101 through thin film preparation processes such as evaporation and sputtering, and have a thickness of 10 nm to 5 μm, and can be a single layer or a combination of multiple layers of thin films, and are mainly used to enhance the adhesion of the two thermistor layers prepared on the upper and lower surfaces of the flexible substrate 101, and provide an insulating layer when the flexible substrate 101 is a conductive metal foil material.

[0045] To improve the stability and environmental suitability of the thin film sensor, the flexible substrate 101 is a flexible thin film or foil material such as a polyimide thin film with a thickness of 10 μm to 500 μm, a stainless steel foil, a pure nickel and nickel-based alloy foil, and mica; when the flexible substrate 101 is an insulating substrate such as polyimide and mica, the transition layer is used to enhance the adhesion between the thermistor thin film and the flexible substrate, and the upper and lower surface transition layers are preferably one of Ti, Cr, Ta, and the like; when the flexible substrate 101 is a conductive foil material such as a stainless steel foil, a pure nickel and nickel-based alloy foil, and the like, the upper and lower surface transition layers are a combination of multiple layers of thin films, which are used for insulation and adhesion enhancement between the metal substrate 101 and the thermistors 103 and 107, and the preferred material is an alloy thin film such as NiCoCrAlY and FeCrAlY, and an Al2O3 insulating layer is formed by high-temperature aluminum oxidation, and a Ti, Cr, Ta, and the like adhesion layer is prepared on the surface of the insulating layer to form a multilayer structure.

[0046] Reference Figure 4The upper surface thermistor layer 103 and the lower surface thermistor layer 107 of the flexible high-energy laser sensing thin film sensor are prepared above the upper surface transition layer 102 and the lower surface transition layer 106. After the upper surface thermistor layer 103 is patterned, a high-density linear resistance array is arranged on the upper surface of the flexible substrate 101, and each single thermistor in the resistance array is a long strip structure with a width of 20 μm to 2 mm, and the length covers the entire sensing thin film sensing area, and the number of thermistors in the resistance array is preferably 10 to 256. After the lower surface thermistor layer 107 is patterned, a high-density linear resistance array with the same array size as the upper surface thermistor layer 103 is arranged on the upper surface of the flexible substrate 101, and the linear resistance array arranged on the upper surface of the upper surface thermistor layer 103 is orthogonal to the linear resistance array arranged on the lower surface of the lower surface thermistor layer 107.

[0047] Further, the thickness of the upper surface thermistor layer 103 and the lower surface thermistor layer 107 is between 100 nm and 20 μm, and the preferred material is a thermistor film of Pt, Ni, NiCr, etc. with good resistance temperature coefficient and linearity in a wide temperature range.

[0048] The upper surface lead layer 104 and the lower surface lead layer 108 are used to form reliable electrical contact with the upper surface thermistor layer 103 and the lower surface thermistor layer 107 respectively and provide an electrical interface for sensor measurement. The upper surface lead layer 104 and the lower surface lead layer 108 are patterned into multiple separated leads, and one end of each thermistor strip in the linear resistance array is connected to a single lead to form electrical contact, and the other end of the thermistor strip is shared by multiple thermistor strips. For a linear array of n thermistor strips, the total number of leads is between n+1 and 2n.

[0049] The upper surface protective layer 105 and the lower surface protective layer 109 can be one of an insulating film such as a polyimide film, an oxide / nitride ceramic film, etc. The upper surface protective layer 105 and the lower surface protective layer 109 are respectively located on the upper surface of the upper surface thermistor layer 103 and the lower surface thermistor layer 107 to form passivation protection for the two thermistor layers.

[0050] The laser high-reflection film layer 2 is located on the upper surface of the sensing thin film 1, and is one of a laser high-reflection film based on a full-dielectric multilayer optical film or a metal high-reflection film, which is used to greatly reduce the absorption of incident laser and improve the laser damage threshold of the flexible high-energy laser sensing thin film sensor.

[0051] Reference Figure 2Wherein, the laser high reflection film layer 2 in the flexible high-energy laser sensing film sensor provided by the application is a full dielectric multilayer optical film, the film layer system is a Ta2O5 / SiO2 multilayer film, the high reflection capability of more than 95% at the 1.064 μm laser wavelength band is obtained by using the refractive index difference between the Ta2O5 film 201 and the SiO2 film 202, and the design and optimization of the multilayer film system combination and thickness.

[0052] Further, the preparation method of the flexible high-energy laser sensing film sensor provided by the application comprises the following steps:

[0053] Step 1: Flexible substrate 101 preparation: a 50 μm thick polyimide substrate is adopted, and the flexible substrate 101 is checked and cleaned to remove surface contaminants;

[0054] Step 2: Preparing and patterning the lead layer on the upper and lower surfaces: a sputtering + electroplating two-step process is adopted to deposit a Cu lead film with a thickness of 8 μm on the upper surface and the lower surface of the flexible substrate 101; the pattern on the negative is transferred to the flexible substrate 101 by using an exposure and development method, and etching and film removal processes are completed to form a lead pattern;

[0055] Step 3: Depositing and patterning the transition layer and the thermistor layer: the upper surface transition layer 102, the upper surface thermistor layer 103, the lower surface transition layer 106 and the lower surface thermistor layer 107 are prepared on the upper surface and the lower surface of the flexible substrate 101 by using a magnetron sputtering method, and are patterned; wherein the upper surface transition layer 102 and the lower surface transition layer 106 are Ti films, and the upper surface thermistor layer 103 and the lower surface thermistor layer 107 are Pt films; after the double-sided deposition of 30 nm Ti + 200 nm Pt films is completed by the magnetron sputtering method, the laser etching technology is adopted to remove the excess Ti + Pt films on the surface of the flexible substrate 101 to form a linear resistance array on the upper and lower surfaces;

[0056] In another embodiment, the upper surface thermistor layer 103 and the lower surface thermistor layer 107 are prepared by using a screen printing process to directly obtain a linear resistance array, and the subsequent patterning process of the upper surface thermistor layer 103 and the lower surface thermistor layer 107 can be omitted.

[0057] That is, the thermistor layer can be prepared by using various preparation processes such as evaporation, sputtering and screen printing; when the thermistor film is obtained by using the evaporation and sputtering processes, the laser etching method is preferably adopted to remove the excess thermistor film material to realize the preparation of a large-area sensing film on the flexible substrate; when the thermistor thick film is obtained by using the screen printing process, the screen printing process can realize the patterning process at the same time.

[0058] Step 4: Surface coating protective layer: after the lead layer and thermistor layer processes are completed, the upper surface protective layer 105 and the lower surface protective layer 109 are respectively coated on the upper and lower surfaces of the flexible substrate 101, and the electrical interface area is exposed; both protective layers are polyimide films, and after being attached, they are subjected to pressing treatment;

[0059] Step 5: Electrical interface enhancement treatment: a structure enhancement layer is added to the electrical interface part, and gold plating is performed at the exposed lead position to improve the structure and electrical reliability of the electrical interface;

[0060] Step 6: Preparation of laser high-reflection film layer 2: using ion beam sputtering, a Ta2O5 / SiO2 multilayer film is alternately plated on the upper surface of the sensing film 1 according to the multilayer film design film layer system to improve the laser reflectivity of the sensing film at a specific wavelength of 1.064 μm.

[0061] It should be noted that in another specific implementation, the deposition in step 3, the two transition layers, and the two thermistor layers in the preparation method can be completed before the two lead layers are prepared on the upper and lower surfaces in step 2 and are patterned, which can achieve the process goal of forming reliable electrical connections between the lead layers and the thermistor layers.

[0062] Reference Figure 3 The flexible high-energy laser sensing thin film sensor provided in Embodiment Two of the present application can use a metal high-reflection film coated with a transparent oxide radiation heat dissipation layer as the laser high-reflection film layer, which can achieve the same laser sensing goal as Embodiment One. The preparation method is replaced by: using magnetron sputtering to plate an Ag film as a metal high-reflection film 203 on the upper surface of the sensing film 1, and further plating a 1 μm-10 μm thick transparent aluminum oxide / silicon oxide radiation heat dissipation layer 204 on the surface of the Ag film, which can obtain wide-band laser high-reflection capability, improve the infrared emissivity of the thin film sensor, and further enhance the laser loss threshold of the thin film sensor.

[0063] Reference Figure 5 , Figure 6 , Figure 7 The laser parameter measurement method of the flexible high-energy laser sensing thin film sensor provided in the present application is as follows: when laser irradiation is performed on the thin film sensor coated with the laser high-reflection film layer on one side, the laser thermal effect causes the temperature of the irradiated area of the thin film sensor to rapidly rise, which in turn causes the resistance of the linear resistor array in the thin film sensor to change. In one specific embodiment, the normalized resistance change trend of the upper surface multiple resistor arrays under laser irradiation is shown in Figure 5 By measuring the normalized change amount of the upper and lower surface array resistances, the laser parameter information such as the laser irradiation power, spot size, and irradiation center position can be obtained through a laser parameter inversion algorithm. The specific inversion process includes:

[0064] S1: The multi-channel data acquisition circuit continuously and rapidly acquires the resistance values ​​of the thermistors on the upper and lower surfaces of the linear resistor array and obtains the resistance benchmark when the laser is not irradiated;

[0065] S2: When it is detected that the change in the resistance value of one or more resistors in the linear resistor array is greater than 0.1%, it is determined that the laser irradiation has started and the inversion algorithm starts running;

[0066] S3: Select a time after the laser starts irradiating, such as 1 second after the acquisition of the row resistance array and the normalized change of the column resistance, and perform Gaussian fitting, such as Figure 6 As shown in , the Gaussian center position obtained by fitting is the laser irradiation center position, and the half-height width of the Gaussian distribution obtained is proportional to the laser spot size, as shown in Figure 7 As shown, the laser spot size can be obtained: laser spot diameter D = A × w, where A is the proportional coefficient and w is the half-height width of the Gaussian distribution;

[0067] S4: Perform differential processing on the resistance values ​​of thermistor array collected over a period of time to obtain resistance change rate data. Select the maximum resistance change rate of a single resistor in the row and column array during laser irradiation. Combined with the relationship between the maximum resistance change, laser spot size, and laser power density, the laser power density can be obtained: laser power density in, is the maximum value of resistance change rate;

[0068] S5: When it is detected that the resistance change rate of a single resistor or multiple resistor arrays is less than 0, it is detected as laser off and the sensor is in standby mode.

[0069] It can be seen that the flexible high-energy laser sensing thin film sensor provided by the present invention uses a flexible film as a substrate. By preparing thermistor layers on the upper and lower surfaces and patterning them into a linear resistor array distributed in rows and columns, it can achieve accurate perception of parameters such as laser power density, spot size, and irradiation position. Furthermore, in order to improve the laser damage threshold of the thin film sensor, a laser high-reflection film layer is integrated on the surface of the thin film sensor, which can increase the detectable laser power density of the thin film sensor to 200W / cm 2 above, making it suitable for high power density 0.1W / cm 2 ~200W / cm 2 , high-energy laser sensing applications with large spot sizes of 3mm to 100mm, and integrated laser protection and perception functions, have excellent prospects in applications such as high-energy laser beam detection and characterization, laser weapon attack protection and perception.

[0070] Of course, the present application can have other various embodiments, and those skilled in the art can certainly make various corresponding changes and modifications according to the present application without departing from the spirit and essence of the present application, but these corresponding changes and modifications shall all belong to the protection scope of the claims attached to the present application.

Claims

1. A flexible high-energy laser sensing thin film sensor, characterized in that: It comprises a sensing film (1) and a laser high-reflection film layer (2) located on the upper surface of the sensing film (1); The sensing film (1) is composed of a flexible substrate (101), an upper surface transition layer (102), a lower surface transition layer (106), an upper surface thermistor layer (103), a lower surface thermistor layer (107), an upper surface lead layer (104), a lower surface lead layer (108), an upper surface protective layer (105), and a lower surface protective layer (109); wherein the upper surface transition layer (102), the upper surface thermistor layer (103), the upper surface lead layer (104), and the upper surface protective layer (105) are sequentially covered on the flexible substrate. The upper surface of the flexible substrate (101), the lower surface transition layer (106), the lower surface thermistor layer (107), the lower surface lead layer (108), and the lower surface protective layer (109) are sequentially covered on the lower surface of the flexible substrate (101); the upper surface thermistor layer and the lower surface thermistor layer are linear resistor arrays composed of multiple parallel thin film thermistors; the linear resistor array arranged on the upper surface thermistor layer (103) and the linear resistor array arranged on the lower surface thermistor layer (107) are orthogonal to each other; The laser high-reflection film layer (2) is used to reduce the absorption of incident laser light by a flexible high-energy laser sensing thin film sensor, thereby increasing the laser power density range that can be sensed by the thin film sensor. The laser high-reflection film layer (2) is a type of laser high-reflection film based on an all-dielectric multilayer optical film or a metal high-reflection film.

2. The flexible high-energy laser sensing thin film sensor according to claim 1, characterized in that: The flexible substrate (101) is a flexible film or foil with a thickness of 10 μm to 500 μm; When the flexible substrate (101) is an insulating film or foil, the material of the upper surface transition layer (102) and the lower surface transition layer (106) is one of Ti, Cr, and Ta; when the flexible substrate (101) is a conductive film or foil, the upper surface transition layer (102) and the lower surface transition layer (106) are a combination of multilayer films, wherein the structure of the multilayer film includes an alloy film, an Al2O3 insulating layer, and an adhesion layer prepared on the surface of the Al2O3 insulating layer.

3. The flexible high-energy laser sensing thin film sensor according to claim 1, characterized in that: A single thermistor in the linear resistor array is a long strip structure with a width of 20 μm to 2 mm, the resistor array spacing is 20 μm to 2 mm, and its length covers the entire sensing area of ​​the sensing film (1).

4. A flexible high-energy laser sensing thin film sensor according to claim 1 or 3, characterized in that: The thickness of the thermistor layer is between 100 nm and 20 μm, and the material is one of the thermistor films such as Pt, Ni, NiCr, etc., which have good resistance temperature coefficient and linearity in a wide temperature range.

5. The flexible high-energy laser sensing thin film sensor according to claim 1, characterized in that: The upper surface lead layer (104) and the lower surface lead layer (108) each include a plurality of leads separated from each other. The upper surface lead layer (104) and the lower surface lead layer (108) are respectively used to form electrical contact with the upper surface thermistor layer (103) and the lower surface thermistor layer (107) and provide an electrical interface for sensor measurement. One end of each thermistor strip in the linear resistor array is respectively connected to a single lead to form electrical contact, and the other end of the thermistor strip is a lead shared by multiple thermistor strips.

6. The flexible high-energy laser sensing thin film sensor according to claim 1, characterized in that: The upper surface protection layer (105) and the lower surface protection layer (109) are polyimide films or oxide / nitride ceramic films.

7. The flexible high-energy laser sensing thin film sensor according to claim 1, characterized in that: When the laser high-reflection film layer (2) is an all-dielectric multilayer optical film, the preferred film layer system is one of HfO2 / SiO2 or Ta2O5 / SiO2 multilayer films, and high reflection in the laser band to be measured is obtained by optimizing the design of high and low refractive index film materials and thickness.

8. The flexible high-energy laser sensing thin film sensor according to claim 1, characterized in that: When the laser high-reflection film layer (2) is a metal high-reflection film, the metal high-reflection film comprises a high-reflectivity film and a transparent radiation heat dissipation film on the surface of the high-reflectivity film; The high reflectivity film is preferably one of metal aluminum, silver, and gold films, and is used to improve the wide-band laser reflectivity of the flexible high-energy laser sensing film sensor; The radiation heat dissipation layer film is one of silicon oxide, aluminum oxide, and hafnium oxide transparent infrared high-emissivity films, and is used to increase the heat dissipation capacity of the high-energy laser sensing film sensor.

9. A method for preparing a flexible high-energy laser sensing thin film sensor according to claim 1, characterized in that: The following steps are involved: S1: Preparation of flexible substrate (101); S2: Prepare the lead layer on the upper and lower surfaces and pattern them; S3: Deposition and patterning of transition layer and thermistor layer; S4: surface coating protective layer; S5: electrical interface enhancement processing; S6: Preparation of laser high reflective film layer (2).

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