Flexible infrared laser detection card for visualizing quantifying laser power and method of manufacturing the same

Abstract

The application provides a flexible infrared laser detection card for visualizing and quantifying laser power and a preparation method thereof. The flexible infrared laser detection card comprises a red porous luminescent layer on the top, a green porous luminescent layer in the middle and a smooth shielding layer on the bottom; the luminescent layer is uniformly distributed with red or green up-conversion luminescent powder in PDMS, both of which jointly form a luminescent / color-changing layer and contain a porous structure with an average pore diameter of 150-300 microns. The application first proposes a flexible infrared laser detection card for visualizing and quantifying laser power by means of double up-conversion luminescent powder and a porous structure, which can change color in response to laser emission power. The novel infrared laser detection card exhibits a very low laser power detection limit, has high sensitivity, and can directly display the distribution of the applied laser signal. This is the first demonstration of a color-adjustable infrared laser detection card, which has great potential applications in future self-powered visualizing sensing systems.

Description

Technical Field

[0001] This invention relates to the field of optical sensor technology, specifically to a flexible infrared laser detection card for visualizing and quantifying laser power and its fabrication method. Background Technology

[0002] The advent of the 5G information age and the Fourth Industrial Revolution has led to the emergence of numerous smart terminals in advanced industries and multidisciplinary fields. Laser detection devices, as a key component of laser experimental systems, possess excellent detection performance and low power consumption, making them a hot research area. In particular, a self-powered, visual, flexible infrared laser detection card capable of wirelessly displaying quantitative laser power information and simultaneously converting it into human-readable visual optical signals has attracted renewed interest due to its superior optimization of current traditional infrared laser detection cards.

[0003] Infrared laser detection cards, also known as laser observation cards or infrared laser display cards, can convert invisible laser beams of various wavelengths into visible light over a wide spectral range. They can be used for detecting and tracking various semiconductor laser beams, detecting optical communication signals, and in other fields. Infrared laser detection cards are commonly used for locating space lasers to prevent human injury from laser irradiation. Users can also observe the laser's optical path and adjust it for experiments. The luminous intensity of an infrared laser detection card typically increases proportionally to the laser's emission power.

[0004] To date, reported infrared laser detection cards are mainly hard plastic / ceramic card structures based on a single upconversion luminescent material. However, several significant drawbacks hinder their practical application: (i) the inherent emission color of a single upconversion luminescent material can only be used for observing the laser signal, not for visual quantitative analysis; (ii) traditional infrared laser detection cards have complex manufacturing processes, poor recyclability, and high production costs, preventing their widespread use in fields such as lidar; and (iii) the hard plastic / ceramic card structure has poor environmental adaptability and cannot be applied to complex experimental systems. Therefore, developing an infrared laser detection card based on a novel mechanism to address these challenging issues is of great significance. Summary of the Invention

[0005] The purpose of this invention is to provide a flexible infrared laser detection card for visualizing and quantifying laser power and its preparation method, so as to solve the problems of traditional infrared laser detection cards that cannot perform visual quantitative analysis, have high manufacturing costs, and poor environmental adaptability.

[0006] This invention is implemented as follows:

[0007] A flexible infrared laser detector card for visualizing and quantifying laser power comprises a top red porous luminescent layer, a middle green porous luminescent layer, and a bottom smooth shielding layer. The red porous luminescent layer is composed of red upconversion luminescent powder uniformly distributed in a polydimethylsiloxane matrix, and the green porous luminescent layer is composed of green upconversion luminescent powder uniformly distributed in a polydimethylsiloxane matrix. The red and green porous luminescent layers together constitute a luminescent / color-changing layer and contain a porous structure with an average pore size of 150–300 μm. The smooth shielding layer is composed of TiO2 powder uniformly distributed in a polydimethylsiloxane matrix, with the TiO2 powder having a diameter of approximately 200 μm.

[0008] Preferably, the thickness of the red porous light-emitting layer, the green porous light-emitting layer, and the smooth substrate shielding layer are all 500 μm.

[0009] Preferably, the red porous light-emitting layer and the green porous light-emitting layer are prepared by the sacrificial template method, and the template used is NaCl particles, sugar particles, NaHCO3 powder, NH4CO3 powder or polystyrene microspheres.

[0010] When a laser signal is incident on the detector card, it is first absorbed by the red porous emitting layer, causing the device to emit red light. The intensity of the red light gradually increases with increasing laser power. As the laser power continues to increase, the laser signal not absorbed by the red porous emitting layer enters the green porous emitting layer, resulting in green light emission. The intensity of this green light also gradually increases with increasing laser power. The emitted color is a mixture of green and red. The color change of the infrared laser detector card is caused by the change in the ratio of R-PL to G-PL; that is, the visible light color displayed by the infrared laser detector card changes with the incident light power. By correlating the color displayed by the flexible infrared laser detector card with the incident laser power, the incident laser power can be determined by directly observing the emitted color.

[0011] The specific fabrication process of the aforementioned device is as follows: A certain amount of red upconversion luminescent powder and NaCl particles are dispersed in PDMS and coated onto an acrylic substrate using a blade coating method to form a red luminescent layer. This layer is then cured in a constant-temperature oven at 80°C for 1 hour. Next, a certain amount of green upconversion luminescent powder and NaCl particles are dispersed in PDMS and coated onto the red luminescent layer using a blade coating method to form a green luminescent layer. This layer is then cured in a constant-temperature drying oven at 80°C for 1 hour. Finally, a certain amount of TiO2 powder is dispersed in PDMS and coated onto the green luminescent layer using a blade coating method. This layer is then cured in a constant-temperature drying oven at 80°C for 1 hour. The cured device is then peeled off from the acrylic substrate and immersed in deionized water. It undergoes cyclic ultrasonic and high-temperature curing treatments to completely dissolve and remove the NaCl particles. Finally, it is dried in a constant-temperature oven, completing the final fabrication.

[0012] The present invention has the following beneficial effects:

[0013] 1. The flexible infrared laser detector card for visualizing and quantifying laser power provided by this invention integrates two colors of upconversion luminescent materials, which can realize the color change of visible light generated by the laser detector card as the incident light power changes. By corresponding the color displayed by the flexible infrared laser detector card with the incident laser power, the incident laser power can be obtained by directly observing the luminescent color displayed by the device, providing a more diverse and flexible option for the quantitative analysis of laser power.

[0014] 2. The flexible infrared laser detection card with visualized quantitative laser power provided by the present invention can flexibly change the size of the infrared laser detection card by curing a mixed film of upconversion phosphor and PDMS and a mixed film of TiO2 powder and PDMS. At the same time, it solves the problems of complex manufacturing process, poor recyclability and high production cost of traditional infrared laser detection cards, and is suitable for wide application in the fields of lidar.

[0015] 3. The flexible infrared laser detector card for visualizing and quantifying laser power provided by this invention has a flexible structure, can adapt to complex experimental environments, and is easy to integrate with other testing systems. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of a flexible infrared laser detection card for visualizing and quantifying laser power, provided in an embodiment of the present invention.

[0017] Figure 2 This is a schematic diagram of the porous structure on the luminescent layer of a flexible infrared laser detector card for visualizing and quantifying laser power, provided in an embodiment of the present invention.

[0018] Figure 3The emission spectrum and CIE coordinate diagram of the flexible infrared laser detector card for visualizing quantitative laser power as the absorbed laser power increases, as provided in the embodiments of the present invention.

[0019] Figure 4 The emission color comparison chart of the flexible infrared laser detector card for visualizing quantitative laser power provided in the embodiments of the present invention at four characteristic powers (1mW, 5mW, 9mW, 13mW).

[0020] Figure 5 The present invention provides a method for fabricating a flexible infrared laser detection card for visualizing and quantifying laser power.

[0021] The structure consists of: 1. a red porous light-emitting layer; 2. a green porous light-emitting layer; and 3. a smooth substrate shielding layer. Detailed Implementation

[0022] like Figure 1 As shown, the flexible infrared laser detector card for visualizing and quantifying laser power provided by this invention consists of three layers of composite material: a top red porous luminescent layer 1, a middle green porous luminescent layer 2, and a bottom smooth substrate shielding layer 3. In this invention, the red porous luminescent layer 1 has red upconversion luminescent powder uniformly distributed in a polydimethylsiloxane (PDMS) matrix, and the green porous luminescent layer 2 has green upconversion luminescent powder uniformly distributed in a PDMS matrix. The red porous luminescent layer 1 and the green porous luminescent layer 2 together constitute the luminescent / color-changing layer, and its luminescence mechanism is photoluminescence. The smooth substrate shielding layer 3 has TiO2 powder uniformly distributed in a PDMS matrix, which reflects laser signals not absorbed by the luminescent / color-changing layer.

[0023] The thicknesses of the red porous light-emitting layer 1, the green porous light-emitting layer 2, and the smooth substrate shielding layer 3 are all 500 μm. For example... Figure 2 As shown, the red porous light-emitting layer 1 and the green porous light-emitting layer 2 contain densely distributed pores with an average pore size of 150–300 μm. The smooth substrate shielding layer 3 is a dense layer, and the TiO2 powder used has a diameter of approximately 200 μm.

[0024] The top red porous light-emitting layer 1 acts as a red light source; when laser light shines on it, red photoluminescence (R-PL) is produced. The green porous light-emitting layer 2 is a green light source; when laser light shines on it, green photoluminescence (G-PL) is produced. The red and green porous light-emitting layers together constitute the light-emitting / color-changing layer. When a laser signal shines on the red porous light-emitting layer 1, a visible light emission signal converted by a collection device above it is generated; this signal is a combination of the R-PL and G-PL of the light-emitting layer. When a laser signal is incident on the device, it is first absorbed by the red porous light-emitting layer 1, and the device emits red light. As the laser power increases, the intensity of the red light gradually increases. When the laser power continues to increase, the laser signal that is not absorbed by the red porous light-emitting layer 1 is incident on the green porous light-emitting layer 2, and the device emits green light. As the laser power increases, the intensity of the green light also gradually increases. The light emitted by the device is a mixture of green and red. As the intensity ratio of R-PL and G-PL changes, the color of the infrared laser detector card changes.

[0025] The porous structure on the emitting layer reduces diffuse reflection and focuses the laser signal, lowering the detection limit of the laser power. Simultaneously, the porous structure focuses visible light signals, making color changes in visible light more pronounced and improving the device's detection sensitivity. Furthermore, the diffuse reflection from the porous structure prevents laser light from being reflected, reducing the risk of laser damage to the human eye. A smooth shielding layer is introduced at the bottom of the green porous emitting layer, allowing laser signals not absorbed by the red and green porous emitting layers to be reflected back to the device, while also reducing visible light signal dispersion and improving device performance.

[0026] The laser power output from the optical fiber is controlled by a tunable laser and incident on the top red porous emitting layer 1 and the middle green porous emitting layer 2. During factory calibration or detailed comparison, a spectrometer can be used to observe the emission spectrum in detail using color coordinates. Specifically, an optical fiber probe can be placed on the red porous emitting layer 1 to collect the visible light signal generated on the device surface and guide it to a spectrometer to monitor the emission spectrum produced by the device. Without instrument monitoring, an approximate laser power can be determined by visual observation.

[0027] Figure 3The diagram shows the changes in the coordinates of the corresponding emission spectra and chromaticity coordinates of the flexible infrared laser detector card of the present invention under different incident laser power intensities (1mW, 3mW, 5mW, 7mW, 9mW, 11mW, 13mW). In the diagram, spectral changes are observed between the pure R-PL peak at 650nm and the pure G-PL peak at 510nm. As the incident laser power gradually increases, the intensities of both red and green light increase, and the ratio of the two colors changes. In the chromaticity coordinate diagram, the red coordinates of the pure red PL luminescent powder are (0.71, 0.32), and the green coordinates of the pure green PL luminescent powder are (0.21, 0.51). The chromaticity coordinates produced by the device change significantly as the incident laser power increases. This indicates that with the increase of the incident laser power intensity, the flexible infrared laser detector card undergoes a significant color transition between pure R-PL and pure G-PL, and the colors displayed by the flexible infrared laser detector card have a one-to-one correspondence with the incident laser power, further demonstrating the excellent color conversion capability of the flexible infrared laser detector card.

[0028] Figure 4 The diagram shows the different emission colors of the flexible infrared laser detector card in this embodiment under laser irradiation with four different powers: 1mW, 5mW, 9mW, and 13mW. The four different laser powers of 1mW, 5mW, 9mW, and 13mW correspond to the emission colors of the detector card as red, orange, yellow, and green, respectively. Thus, the laser power can be roughly inferred from the emission color of the detector card.

[0029] By correlating the color displayed by the flexible infrared laser detector with the incident laser power, the incident laser power can be determined by directly observing the emitted color of the detector with the human eye.

[0030] like Figure 5 As shown, the method for preparing the flexible infrared laser detector card for visualizing quantitative laser power in this invention includes the following steps:

[0031] Step S1: Using laser cutting technology, an acrylic substrate and three identical PET frames are prepared. The acrylic substrate measures 5×5×0.5cm, and the PET frames are squares with sides of 5cm and a thickness of 500μm, with a 4cm square section cut out in the center. The PET frames are then attached to the acrylic substrate to form the overall confinement framework for film preparation.

[0032] In step S2, a certain amount of red upconversion luminescent powder and NaCl particles are dispersed in PDMS. The ratio of PDMS matrix to curing agent (the curing agent is a reagent that transforms the PDMS matrix from a liquid state to a flexible rubber state) is 10:1. After stirring evenly, the mixture is applied to an acrylic substrate with a PET frame by a scraping method. After scraping, a red luminescent layer is formed. The PET frame restricts the red luminescent layer to 500μm. The entire layer is placed in a constant temperature oven and cured at 80℃ for 1 hour.

[0033] Step S3: After the red luminescent layer has cured, remove it from the oven and attach another identical PET frame to the existing PET frame. Then, disperse a certain amount of green upconversion luminescent powder and NaCl particles in PDMS. The ratio of PDMS matrix to curing agent is 10:1. After stirring evenly, apply it to the red luminescent layer using a scraping method to form a green luminescent layer. At this time, the thickness of the green luminescent layer is 500μm, and the overall thickness is 1000μm. Place the whole thing in a constant temperature drying oven and cure at 80℃ for 1 hour.

[0034] Step S4: After the green light-emitting layer is cured, remove it from the oven and attach another layer of the same PET frame to the existing PET frame. Then, disperse a certain amount of TiO2 powder in PDMS. The ratio of PDMS matrix to curing agent is 10:1. After stirring evenly, apply it to the green light-emitting layer using a scraping method. At this time, the overall thickness of the device is 1500μm. Place the whole device in a constant temperature drying oven and cure it at 80℃ for 1 hour.

[0035] Step S5 involves peeling the cured device off the acrylic substrate and immersing it in deionized water. The device undergoes repeated ultrasonic and high-temperature curing processes to completely dissolve and remove the NaCl particles from the red and green light-emitting layers. It is then dried in a constant-temperature oven, completing the final preparation. After the NaCl particles are removed, a porous structure is formed in the red and green light-emitting layers, resulting in a red porous light-emitting layer and a green porous light-emitting layer.

[0036] This invention presents for the first time a flexible infrared laser detector card that utilizes dual upconversion luminescent powder and a porous structure to visualize and quantify laser power. The card's emitted color changes in response to the laser emission power. This novel infrared laser detector card exhibits a remarkably low laser power detection limit (human eye resolution is approximately 1mW, machine resolution is approximately 0.1mW, and it can be detected in the presence of light) and high sensitivity (human eye resolution is 1mW, machine resolution is approximately 0.1mW). It can also visually display the distribution of the applied laser signal. This is the first demonstration of a color-tunable (i.e., the device changes color with the laser power) infrared laser detector card, which has significant potential applications in future self-powered visual sensing systems.

Claims

1. A flexible infrared laser detection card for visualizing and quantifying laser power, characterized in that, It includes a top red porous light-emitting layer, a middle green porous light-emitting layer, and a bottom smooth base shielding layer; the red porous light-emitting layer is composed of red upconversion luminescent powder uniformly distributed in polydimethylsiloxane matrix, the green porous light-emitting layer is composed of green upconversion luminescent powder uniformly distributed in polydimethylsiloxane matrix, and the smooth base shielding layer is composed of TiO2 powder uniformly distributed in polydimethylsiloxane matrix.

2. The flexible infrared laser detection card for visualizing and quantitatively measuring laser power according to claim 1, characterized in that, The red porous light-emitting layer and the green porous light-emitting layer each contain a porous structure with an average pore size of 150 to 300 μm.

3. The flexible infrared laser detection card for visualizing and quantitatively measuring laser power according to claim 2, characterized in that, The red porous light-emitting layer and the green porous light-emitting layer are prepared by the sacrificial template method, and the template used is NaCl particles, sugar particles, NaHCO3 powder, NH4CO3 powder or polystyrene microspheres.

4. The flexible infrared laser detection card for visualizing and quantitatively measuring laser power according to claim 1, characterized in that, The diameter of the TiO2 powder used in the smooth shielding layer of the substrate is 200 μm.

5. The flexible infrared laser detection card for visualizing and quantitatively measuring laser power according to claim 1, characterized in that, The thickness of the red porous light-emitting layer, the green porous light-emitting layer, and the smooth shielding layer on the substrate are all 500 μm.

6. A method for fabricating a flexible infrared laser detector card for visualizing and quantifying laser power, characterized in that, Includes the following steps: S1. Prepare an acrylic substrate and three identical PET frames, which are hollow frame structures; attach one of the PET frames to the acrylic substrate. S2. Disperse red upconversion luminescent powder and NaCl particles in polydimethylsiloxane matrix, stir evenly, and then apply it to an acrylic substrate with a PET frame by scraping method to form a red luminescent layer. Then place it in a constant temperature oven for curing. S3. After the red luminescent layer has cured, remove it and attach another PET frame to the PET frame. Disperse the green upconversion luminescent powder and NaCl particles in polydimethylsiloxane matrix, stir evenly, and then use a scraping method to scrape it onto the red luminescent layer to form a green luminescent layer. Then place it in a constant temperature oven for curing. S4. After the green light-emitting layer has cured, remove it and attach another PET frame to the second PET frame. Disperse TiO2 powder in polydimethylsiloxane matrix, stir evenly, and then apply it to the green light-emitting layer by scraping. Then place it in a constant temperature oven for curing. S5. Peel the cured device from the acrylic substrate and immerse it in deionized water. Repeat the ultrasonic and high-temperature curing process to completely dissolve and remove the NaCl particles in the red and green light-emitting layers. Then dry it in a constant temperature oven to complete the final preparation.

7. The method for preparing a flexible infrared laser detector card for visualizing and quantitatively measuring laser power according to claim 6, characterized in that, In steps S2, S3, and S4, the curing parameters in the constant temperature oven are: temperature 80℃, time 1h.

8. The method for preparing a flexible infrared laser detector card for visualizing and quantitatively measuring laser power according to claim 6, characterized in that, The ratio of polydimethylsiloxane to curing agent in the porous light-emitting layer is 10:1.

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