Flexible lens and flexible lens spectral analysis system for gas concentration detection

Abstract

The invention provides a flexible lens and a flexible lens spectrum analysis system used for gas concentration detection, the flexible lens is formed by combining a lens body and elastic driving parts fixed at two ends of the lens body, the lens body is made of polydimethylsiloxane, and the elastic driving parts are made of flexible materials. The elastic driving part is formed by combining a plurality of liquid crystal elastic fibers side by side, one end of the elastic driving part is fixedly connected with the lens body, and the other end of the elastic driving part is connected with the clamp. According to the invention, the flexible lens is prepared by using the characteristic of large reversible deformation generated by the liquid crystal elastomer under illumination driving and the dispersion property of the flexible lens, so that the curvature of the front and rear surfaces of the flexible lens is adjustable, the purpose of tuning the focal lengths of light with different wavelengths is achieved, and accurate detection of multiple absorption peak gases is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of optical detection, and particularly to the detection of gas concentration by using spectral analysis. Background Art

[0002] The analysis of gas concentration has been widely applied in many fields. Therefore, various methods for detecting it have emerged in an endless stream, but each has its own deficiencies. Currently, common methods for detecting gas concentration include chemical sensing method, gas chromatography, and spectral absorption method, etc. The chemical sensing method is based on the chemical reaction between the gas and the surface of the chemical sensor, and detects the gas concentration by changing the electrical properties. This kind of method has relatively low cost and is easy to miniaturize, but its response time is long, and it is greatly affected by environmental factors such as temperature and humidity, with poor stability and repeatability.

[0003] Gas chromatography is a highly sensitive gas analysis technology. By separating the gas sample in the chromatographic column from the mobile phase (usually an inert gas), it relies on the difference in the residence time of different gas components in the chromatographic column to achieve detection. This method can provide very precise chemical composition analysis, but the equipment is usually relatively complex and expensive, and is more suitable for laboratory analysis rather than real-time on-site monitoring.

[0004] In gas concentration monitoring, the spectral absorption type gas detection technology measures by using the interaction characteristics between light and gas molecules, and has the advantages of high detection accuracy, wide measurement range, and continuous real-time monitoring, etc., and has become the main technology for monitoring gas concentration. In addition, the single-wavelength spectral absorption method is one of the most common methods. It can only detect the spectral information at a single wavelength and cannot obtain the spectral information at multiple absorption peaks. For gases with multiple absorption peaks, it will reduce the detection accuracy. To solve the deficiencies of the single-wavelength spectral absorption method, based on the characteristics of the tunable grating, it can be used to realize the scanning and analysis of multi-wavelength spectra. However, when it uses spectra above the first order for analysis, its light intensity will gradually decrease, which brings the disadvantage that it is not conducive to signal reception and detection due to the small light intensity. Summary of the Invention

[0005] The object of the present invention is to propose a flexible lens with adjustable front and rear surface curvatures, and further to realize a spectral analysis system capable of accurately detecting gases with multiple absorption peaks.

[0006] To achieve the above object, the present invention proposes a flexible lens, which includes a lens body and an elastic driving component; the material of the lens body is polydimethylsiloxane, having characteristics of dispersion and high light transmittance; both ends of the lens body are each connected with a set of elastic driving components; the elastic driving component is composed of a plurality of liquid crystal elastic fibers arranged side by side, one end of the elastic driving component is fixedly connected with the lens body, and the other end is connected with a fixture; based on the large-scale reversible deformation characteristic of the liquid crystal elastomer under light irradiation, by irradiating near-infrared light, the front and rear surface curvatures of the flexible lens 7 are adjusted, so as to achieve the purpose of tuning the focal lengths of lights with different wavelengths.

[0007] Further, the elastic driving component is composed of 10 liquid crystal elastic fibers with a diameter of 600 microns arranged side by side, and both ends of the 10 liquid crystal elastic fibers are adhesively fixed by an adhesive.

[0008] The present invention also proposes a flexible lens spectral analysis system for gas concentration detection, which uses a broadband light source as a detection light source, and in the conduction direction of the detection light source, there are successively arranged an input coupling optical fiber, a gas absorption cell, an output coupling optical fiber, a collimating and beam expanding device, a slit, a flexible lens and a photoelectric receiving and detecting device; it also includes two groups of driving lights, and the two groups of driving lights are respectively arranged towards the elastic driving components at both ends of the flexible lens.

[0009] Further, the power of the driving light is 1W and the wavelength is 808nm; the driving light irradiates the elastic driving component to generate deformation, and then adjusts the front and rear surface curvatures of the flexible lens to tune the focal lengths of lights with different wavelengths.

[0010] Compared with the prior art, the advantages of the present invention are as follows:

[0011] 1. The present invention makes full use of the large-scale reversible deformation characteristic of the liquid crystal elastomer under light driving and the dispersion property of the flexible lens to prepare the flexible lens, and then realizes the adjustable front and rear surface curvatures of the flexible lens, achieving the purpose of tuning the focal lengths of lights with different wavelengths, and realizing the precise detection of gases with multiple absorption peaks.

[0012] 2. Compared with the problem of weak optical signals and other deficiencies when using a tunable grating to scan the first-order or higher-order spectra, the present invention makes full use of the light converging ability of the flexible lens, so that the utilization rate of light energy is improved. At the same time, the zoom range of the flexible lens is designed to be larger, adapting to the focal length adjustment of more lights with different wavelengths.

[0013] 3. The liquid crystal elastomer of the flexible lens of the present invention responds quickly to changes in light, enabling the present invention to exhibit extremely high efficiency in real-time gas concentration detection. In addition, the light-driven method reduces energy consumption, making the present invention have low energy consumption in continuous monitoring environments. The analysis system of the present invention can adaptively select a broadband light source according to the range where the absorption spectrum of the gas to be measured is located. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a system schematic diagram of the flexible lens spectral analysis system in the initial state in the embodiment of the present invention;

[0015] Figure 2 It is a system schematic diagram of the flexible lens spectral analysis system in the light-driven working state in the embodiment of the present invention;

[0016] Figure 3 It is a schematic diagram of the mold for preparing the flexible lens in the embodiment of the present invention;

[0017] Figure 4 It is a schematic diagram of the flexible driving component in the embodiment of the present invention;

[0018] Figure 5 It is a schematic diagram of the overall structure of the flexible lens in the embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0019] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions of the present invention will be further described below.

[0020] The present invention provides a flexible lens spectral analysis system for gas concentration detection to solve the deficiencies of existing grating technologies in multispectral analysis and to meet the applications in industrial and environmental protection scenarios that require low energy consumption, fast, and continuous monitoring.

[0021] The specific structure is as Figure 1 shown. Using a broadband light source 1 as the detection light source, an input coupling optical fiber 2, a gas absorption cell 4, an output coupling optical fiber 3, a collimating and beam expanding device 5, a slit 6, a flexible lens, and a photoelectric receiving and detecting device 13 are sequentially arranged along the conduction direction of the detection light source. There is also a driving light directed towards the flexible lens. By irradiating the driving light, the surface curvature of the flexible lens is changed to achieve the purpose of tuning the focal length of light of different wavelengths, enabling light of each wavelength to be scanned by the photoelectric receiving and detecting device 13, and realizing the precise detection of multi-absorption peak gases.

[0022] Among them, the structure and working principle of the flexible lens are as follows:

[0023] As Figure 1As shown in the figure, the flexible lens is composed of a lens body 7, a first elastic driving component 9, and a second elastic driving component 12. The lens body 7 is made of polydimethylsiloxane, with characteristics of dispersion and high light transmittance. To ensure that the focal length tuning for multiple wavelengths can be accepted by the optoelectronic detection device, its initial structure is designed to have a large zoom range to meet the focusing requirements for different wavelengths. At the same time, by utilizing the light converging ability of the flexible lens, the utilization rate of light energy is improved. Different from traditional tunable gratings, when scanning the first-order or higher-order spectra, there are problems such as weak optical signals.

[0024] As Figure 4 shown in the figure, in this embodiment, to ensure the utilization efficiency of the driving light intensity and the stretching effect, the first elastic driving component 9 and the second elastic driving component 12 have the same structure, and are both composed of 10 liquid crystal elastic fibers 3-2 with a diameter of 600 microns arranged side by side. The length of each is intercepted as 8 cm, and the two ends of the 10 liquid crystal elastic fibers 3-2 are adhesively fixed through an adhesive 3-1; it has a higher tensile strength (up to the MPa level) compared to GNPs / PDMS; as Figure 5 shown in the figure, one end of the first elastic driving component 9 and the second elastic driving component 12 are respectively connected to both ends of the flexible lens, and the other ends of the first elastic driving component 9 and the second elastic driving component 12 are each connected to a fixture 8.

[0025] The working principle of the flexible lens is as follows: The first elastic driving component 9 and the second elastic driving component 12 made of liquid crystal elastic fibers 3-2 can achieve large-scale reversible deformation under the drive of an infrared laser, thereby pulling the front and rear surface curvatures of the lens body 7 to change, achieving focal length tuning for light of different wavelengths, so that the optoelectronic detection device at the fixed position behind the flexible lens can obtain all the spectral information of the broadband light source 1.

[0026] To further ensure the quality of the flexible lens of the present invention, according to the flexible lens structure that can achieve a large zoom range, a corresponding mold is made to perform injection molding and heating on PDMS. The mold structure is as Figure 3 shown in the figure, the middle part is a mirror groove 2-2, and on both sides of the mirror groove 2-2 are connecting grooves 2-1. The outer edge of the connecting groove 2-1 is provided with an inclined edge 2-3. To ensure the light passing effect and high-quality focusing effect of the flexible lens, the machining accuracy of the mold is less than 10 microns, and the surface roughness Ra is 0.05 microns. In addition, to ensure the connection between the flexible lens and the driving component, it is also necessary to reserve a certain connection space on both sides of the flexible lens. Therefore, the grooves on both sides of the mirror in the center of the mold are also designed in the shape of rectangular grooves. In addition, to facilitate processing, slopes with corresponding heights are designed on both sides of the rectangular grooves.

[0027] The specific preparation method of the flexible lens is as follows:

[0028] S1: After determining the specific dimensions of the flexible lens, select die steel as the material for mold processing. To ensure that the surface finish of the PDMS reaches the mirror standard after injection molding and heating, the machining accuracy of the mold should be less than 1 micron during the machining process, and the surface roughness Ra is 0.05 micron.

[0029] S2: To ensure that the flexible lens can be connected to the driving component, connection grooves 2-1 with a certain thickness need to be added on both sides of the flexible lens mold, so as to form a part for connecting the two.

[0030] S3: To ensure the machinability of the connection grooves 2-1, a ramp also needs to be added beside the connection grooves 2-1 on both sides to facilitate the machining of the tool.

[0031] S4: The flexible driving component is composed of 10 liquid crystal elastic fibers 3-2 with a diameter of 600 microns. Through the adhesive 3-1, the two ends of the 10 liquid crystal elastic fibers 3-2 placed side by side are bonded.

[0032] S5: Connect one side of each of the two driving components to both sides of the flexible lens respectively to form a light-driven flexible lens.

[0033] Based on the above structure of the flexible lens, in this flexible lens spectral analysis system, the first driving light 10 is set to irradiate the first elastic driving component 9 directly, and the second driving light 11 is set to irradiate the second elastic driving component 12 directly. The power of the first driving light 10 and the second driving light 11 is 1W, the wavelength is 808nm, the spot shape is a square spot, and the irradiation area can just cover the near-infrared laser driving on the surface of the driving component. Through irradiation, the liquid crystal elastomer can be deformed reversibly in a large range, so as to tune the focal length of the flexible lens.

[0034] In this embodiment, the specific working steps of the flexible lens spectral analysis system are as follows:

[0035] S1: According to the gas to be measured, select a broadband light source 1 with its characteristic absorption spectrum as the detection light source.

[0036] S2: Couple the broadband light source 1 into the gas absorption cell 4 through the input coupling optical fiber 2.

[0037] S3: Couple the light with the gas absorption spectrum into the collimating and beam expanding device 5 through the output coupling optical fiber 3.

[0038] S4: Select the light transmissible amount matching the light transmissible aperture of the flexible lens through the slit 6.

[0039] S5: In the initial state of the flexible lens, such as Figure 1As shown, the wavelength 1 is focused at the receiving position of the photoelectric detection device, and the wavelength 2 is not received.

[0040] S6: During the driving process, as Figure 2 shown, by turning on the first driving light 10 and the second driving light 11, the focal length of light of different wavelengths is tuned so that the focusing position of the wavelength 2 is tuned to the focusing position of the photoelectric detection device, and the spectral scanning of each wavelength in the broadband is completed in sequence.

[0041] The light passes through a group of known-concentration gases (0%-40%) with a concentration gradient to collect spectra, record the spectral absorption characteristics at each concentration, and establish a spectral library. Subsequently, the gas sample with an unknown concentration is introduced into the detection chamber. Using the established spectral library, the concentration of the unknown gas is predicted and calculated through spectral comparison and machine learning algorithms.

[0042] The above are only the preferred embodiments of the present invention and do not impose any limitation on the present invention. Any person skilled in the art, within the scope of the technical solution of the present invention, makes any form of equivalent replacement or modification and other changes to the technical solution and technical content disclosed by the present invention, which are all within the content of the technical solution of the present invention and still fall within the protection scope of the present invention.

Claims

1. A flexible lens, characterized in that, It includes a lens body and an elastic drive component; The material of the lens body is polydimethylsiloxane, and one set of the elastic drive components is connected to each end of the lens body; The elastic drive component is composed of multiple liquid crystal elastic fibers arranged side by side. One end of the elastic drive component is fixedly connected to the lens body, and the other end is connected to a fixture.

2. The flexible lens according to claim 1, wherein The elastic drive component is composed of 10 liquid crystal elastic fibers with a diameter of 600 microns arranged side by side, and the two ends of the 10 liquid crystal elastic fibers are adhesively fixed by an adhesive.

3. A flexible lens spectroscopic analysis system for gas concentration detection, using the flexible lens as described in any one of claims 1-3, characterized in that, Using a broadband light source as the detection light source, an input coupling optical fiber, a gas absorption cell, an output coupling optical fiber, a collimating and beam expanding device, a slit, a flexible lens, and a photoelectric receiving and detecting device are sequentially arranged in the conduction direction of the detection light source; there are also two sets of drive lights, and the two sets of drive lights are respectively arranged towards the elastic drive components at both ends of the flexible lens.

4. The flexible lens spectroscopic analysis system for gas concentration detection according to claim 4, characterized in that, The power of the drive light is 1W, and the wavelength is 808nm; the drive light irradiates the elastic drive component to generate deformation, thereby adjusting the curvature of the front and rear surfaces of the flexible lens and tuning the focal length of light with different wavelengths.

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