CN115657185A - Ultraviolet filter lens and preparation method and application thereof - Google Patents

Abstract

The invention discloses an ultraviolet filter lens and a preparation method and application thereof, wherein the ultraviolet filter lens comprises a substrate, a first film layer and a second film layer; the substrate is provided with a first surface and a second surface which are oppositely arranged; the first film layer is formed by alternately arranging a plurality of first high-refractive-index material layers and a plurality of first low-refractive-index material layers, and the first high-refractive-index material layers are arranged on one side of the first film layer close to the first surface and one side of the first film layer far away from the first surface; the second film layer is arranged on the second surface and is formed by alternately arranging a plurality of second high-refractive-index material layers and a plurality of second low-refractive-index material layers. According to the ultraviolet filter, the high-refractive-index material layers and the low-refractive-index material layers which are alternately arranged are arranged on the two opposite sides of the substrate, so that the reflection band is divided into two parts, the whole film layers are distributed more reasonably, the surface stress of the two opposite sides of the substrate is relatively uniform, and the film cracking phenomenon caused by overlarge single-side stress is avoided.

Description

A kind of ultraviolet filter mirror and its preparation method and application

technical field

The invention belongs to the technical field of optical elements and gas detection, and in particular relates to an ultraviolet filter, a preparation method and application thereof.

Background technique

At present, the detection system of SO ₂ gas concentration generally uses a zinc lamp as the detection light source. After the zinc lamp light source, a collimating lens is added to collimate the beam, and then it is filtered with a transmission interference filter to obtain a beam in the effective excitation light band. , the light beam enters the measurement cavity to detect the concentration of SO ₂ gas.

In the detection of _SO2 gas concentration by ultraviolet fluorescence spectroscopy, ultraviolet light (near 213nm-214nm) is needed as excitation light to make the measured _SO2 gas emit fluorescence (300nm-420nm). Expensive, usually use the filter method to filter out other wavelength components from the zinc lamp containing the 213nm light source, and only keep the required effective wavelength. The size is small and easy to integrate, but this kind of filter is expensive, and the light transmission efficiency is extremely low. Usually, the effective wavelength has only 10-20% transmittance, and other invalid wavelengths will also have a transmittance close to 5%, resulting in SO _2. When the gas is detected optically, the background signal is too large, submerging the characteristic signal of SO ₂ gas, so that the analysis cannot be carried out, and the transmission interference filter has a short life and low spectral purity (mainly due to the inconsistency of the film layer uniformity) pinhole light leakage), and is currently one of the most important consumables in this type of instrument.

Contents of the invention

In view of this, an object of the present invention is to propose a kind of ultraviolet light filter mirror, by arranging different high-refractive-index material layers and low-refractive-index material layers alternately arranged on the opposite sides of the substrate, the reflection band is divided into two parts: Second, the distribution of the overall film layer is more reasonable, and the surface stress on the opposite sides of the substrate is relatively uniform, and at the same time, the phenomenon of film cracking caused by excessive stress on one side is avoided.

Another object of the present invention is to provide a method for preparing an ultraviolet filter.

Another object of the present invention is to provide a filter device.

Another object of the present invention is to provide a filtering method.

Another object of the present invention is to propose an application of a filtering method in the detection of sulfur dioxide gas concentration.

In order to achieve the above purpose, the embodiment of the first aspect of the present invention proposes an ultraviolet filter, including

a substrate having oppositely disposed first and second surfaces;

The first film layer, the first film layer is arranged on the first surface, the first film layer is formed by alternately setting several first high refractive index material layers and several first low refractive index material layers, the The side of the first film layer close to the first surface and the side away from the first surface are both first high refractive index material layers;

The second film layer, the second film layer is arranged on the second surface, and the second film layer is formed by alternately setting several second high-refractive index material layers and several second low-refractive index material layers. The side of the second film layer close to the second surface is a second low refractive index material layer, and the side of the second film layer away from the second surface is a second high refractive index material layer.

In the ultraviolet filter of the embodiment of the present invention, different high-refractive-index material layers and low-refractive-index material layers are arranged alternately on opposite sides of the substrate, so that the reflection band is divided into two, and the overall film layer distribution is more precise. Reasonable, and the surface stress on the opposite sides of the substrate is relatively uniform, and at the same time, the film cracking phenomenon caused by excessive stress on one side is avoided.

In some embodiments of the present invention, the unit thickness of the first high refractive index material layer is 27-33 nm, and the thickness of the first high refractive index material layer is between 20-43.9 nm; the first low refractive index material The unit thickness of the layer is 35-41nm, the thickness of the first low refractive index material layer is between 32.66-53.78nm; the unit thickness of the second high refractive index material layer is 27-33nm, and the second high refractive index material layer The thickness of the second low refractive index material layer is between 22.91-43.09 nm; the unit thickness of the second low refractive index material layer is 35-41 nm, and the thickness of the second low refractive index material layer is between 30.63-84.54 nm.

In some embodiments of the present invention, the total number of the first high refractive index material layer and the first low refractive index material layer in the first film layer is 19-39 layers; the second high refractive index material layer in the second film layer The total number of the high-index material layer and the second low-refractive-index material layer is 18-38 layers.

In some embodiments of the present invention, the material of the substrate is ultraviolet fused silica or calcium fluoride; the materials of the first high refractive index material layer and the second high refractive index material layer are both hafnium dioxide or aluminum oxide ; The materials of the first low-refractive index material layer and the second low-refractive index material layer are aluminum fluoride or magnesium fluoride.

In order to achieve the above purpose, the embodiment of the second aspect of the present invention proposes a method for preparing an ultraviolet filter, which includes pretreating the substrate;

sequentially premelting and sintering the first high refractive index material layer material, the first low refractive index material layer material, the second high refractive index material layer material and the second low refractive index material layer material;

The first film layer and the second film layer are respectively formed on the first surface and the second surface of the pretreated substrate by vacuum evaporation.

The preparation method of the ultraviolet filter mirror of the embodiment of the present invention pretreats the substrate, pre-melts and sinters the film layer material and vacuum evaporates it, the process is simple, the formed film layer and the substrate have strong bonding force, and the film The layer is stronger, and the film layer does not contain impurities.

In some embodiments of the present invention, the pretreatment method is as follows: the substrate is ultrasonically cleaned, then purged and dried with an inert gas, and then treated with high-energy ions from an ion source.

In some embodiments of the present invention, the method of pre-melting the material of the first high refractive index material layer and the material of the second high refractive index material layer is: using an electron gun to perform pre-melting under the condition of a current of 0.1-180mA Melting, and the current increases from 0.1mA to the surface of the first high refractive index material layer material or the surface of the second high refractive index material layer material repeatedly by 30mA until the first high refractive index material layer material or The material particles of the second high refractive index material layer are all melted, and the surface of the first high refractive index material layer material or the material surface of the second high refractive index material layer is completely melted and flat.

In some embodiments of the present invention, the method of pre-melting the material of the first low refractive index material layer and the material of the second low refractive index material layer is: using an electron gun at a current of 0.1-15mA and a scanning radius of 10- Repeated premelting under the condition of 20mm.

In some embodiments of the present invention, the process conditions for vacuum evaporation of the first high refractive index material layer material and the second high refractive index material layer material are: vacuum degree (0.5×10 ^-3 )-(2 ×10 ^-3 ) Pa, evaporation rate 1-3nm/s, baking temperature 270-310°C, baking time 30-60min.

In some embodiments of the present invention, the process conditions for vacuum evaporation of the first low refractive index material layer material and the second low refractive index material layer material are: vacuum degree (0.5×10 ^-3 )-(2 ×10 ^-3 ) Pa, evaporation rate 0.3-1.3nm/s, baking temperature 270-310°C, baking time 30-60min.

In order to achieve the above purpose, the embodiment of the third aspect of the present invention proposes a filter device, including a light source, a collimator lens and at least two ultraviolet filters described in the embodiment of the present invention arranged in sequence, the light emitted by the light source The light beam is incident on each UV filter sequentially at the same angle.

In addition to the beneficial effects of the ultraviolet filter of the embodiment of the present invention, the filter device of the embodiment of the present invention also has the following beneficial effects: after the light source is collimated by the collimating lens, it is filtered by a plurality of ultraviolet filters in sequence, The comprehensive reflectance of the reflected light emitted after each filter decreases exponentially according to the power of the filter times, and the spectral intensity and full width at half maximum are reduced and converged.

In some embodiments of the present invention, the first film layer of the ultraviolet filter is the incident surface of the light beam.

In some embodiments of the present invention, the incident angle of the light beam is 22.5-45°; the number of the ultraviolet filters is four.

In some embodiments of the present invention, a photodetector is provided behind each ultraviolet filter, and the photodetector is arranged perpendicular to the transmission direction of the light beam.

In order to achieve the above purpose, the embodiment of the fourth aspect of the present invention proposes a light filtering method, which is applied to the light filtering device described in the embodiment of the present invention, including

The light beam emitted by the light source is collimated through the collimation transparency to obtain collimated light;

The collimated light is sequentially reflected and filtered by each piece of the ultraviolet filter at the same incident angle to obtain a light source beam with a converged spectral range.

The beneficial effects of the light filtering method in the embodiment of the present invention are basically the same as those of the light filtering device in the embodiment of the present invention, and will not be repeated here.

In some embodiments of the present invention, the filtering method further includes: each of the photodetectors synchronously detects the transmitted light intensity of the corresponding ultraviolet filter, and The reference light intensity is corrected.

In order to achieve the above purpose, the embodiment of the fifth aspect of the present invention proposes the application of the filtering method in the detection of sulfur dioxide gas concentration as described in the embodiment of the present invention, including

Said light source zinc lamp or flashing xenon lamp;

The incident angle of the light beam is 22.5-45°;

The number of the ultraviolet filter is 4;

The spectral range of the light source converges to 200-230nm after being filtered by all ultraviolet filters.

The application of the filter method described in the embodiments of the present invention in the detection of sulfur dioxide gas concentration uses ultraviolet light at a specific angle (22.5-45°) to irradiate on the ultraviolet filter mirror with high reflectivity characteristics, combined with multiple filters to make The spectral range of ultraviolet light covers the 200-230nm band absorption cross section of _SO2 molecules as a whole, and at the same time suppresses the noise band after 230nm, and uses the transmitted light intensity after each filter to detect the luminous efficiency of the light source in real time, and timely correct the fluctuation of the light source boost , Reduce background signal interference, lower the detection limit of SO ₂ , after a long time of testing and calculation of Allen variance, the lower detection limit of SO ₂ gas can be reduced to 85ppt.

Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.

Description of drawings

The above and/or additional aspects and advantages of the present invention will become apparent and easy to understand from the following description of the embodiments in conjunction with the accompanying drawings, wherein:

FIG. 1 is a schematic diagram of a simple structure of an ultraviolet filter according to an embodiment of the present invention.

FIG. 2 is a schematic diagram of reflection characteristics of an ultraviolet filter according to an embodiment of the present invention.

Fig. 3 is a schematic diagram of reflection characteristics of an ultraviolet filter according to an embodiment of the present invention in the range of incident angle 22.5-45°.

Fig. 4 is a reflectance curve of an ultraviolet filter according to an embodiment of the present invention at 200-700nm.

FIG. 5 is a flow chart of a method for designing and manufacturing a film layer of an ultraviolet filter according to an embodiment of the present invention.

FIG. 6 is a schematic diagram of a simple structure of a filter device according to an embodiment of the present invention.

Fig. 7 is a schematic structural diagram of a filter device according to another embodiment of the present invention.

Figure 8 is a cross-sectional view of the absorption of sulfur dioxide gas in the ultraviolet band.

FIG. 9 is a comparison diagram between the traditional transmission filter and the reflective filter in Embodiment 3 of the present invention.

Fig. 10 is a graph of the intensity of the ultraviolet light source after multiple reflections.

Fig. 11 is a result diagram of the lower detection limit of sulfur dioxide gas concentration calculated by Allen variance in Example 3 of the present invention.

Reference signs:

1-substrate; 101-first surface; 102-second surface; 2-first film layer; 201-first high refractive index material layer; 202-first low refractive index material layer; 3-second film layer ; 301-the second high refractive index material layer; 302-the second low refractive index material layer; 4-light source; 5-collimating lens; 6-ultraviolet filter mirror; 7-photodetector; - Cast beams.

Detailed ways

Embodiments of the invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below by referring to the figures are exemplary and are intended to explain the present invention and should not be construed as limiting the present invention.

The inventors found that in the current _SO2 gas concentration detection system, the output voltage is unstable when the ultraviolet light source is boosted and flickered. The area is incomplete and the relative intensity of the transmitted part of the invalid ultraviolet light is relatively high, which introduces a large amount of background noise, which leads to an increase in the background signal of the measurement system, zero point drift, and an obliteration of the characteristic signal of SO ₂ gas, resulting in the measurement system being unable to measure the trace concentration. The problem of accurate measurement of SO ₂ gas. Based on the above, the present invention develops and designs an ultraviolet filter, and provides a preparation method of the ultraviolet filter, a filter device, a filter method and its application in the detection of sulfur dioxide gas concentration.

The ultraviolet filter, the preparation method of the ultraviolet filter, the filter device and the filter method of the embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a schematic diagram of a simple structure of an ultraviolet filter according to an embodiment of the present invention.

As shown in Figure 1, the ultraviolet filter of the embodiment of the present invention comprises a substrate 1, a first film layer 2 and a second film layer 3; the substrate 1 has a first surface 101 and a second surface 102 oppositely arranged; The first film layer 2 is arranged on the first surface 101. The first film layer 2 is formed by alternately setting several first high refractive index material layers 201 and several first low refractive index material layers 202. The first film layer 2 is close to the first The side of the surface 101 and the side away from the first surface 101 are the first high refractive index material layer 201; the second film layer 3 is arranged on the second surface 102, and the second film layer 3 is composed of several second high refractive index material layers 301 and several second low refractive index material layers 302 are arranged alternately, the side of the second film layer 3 close to the second surface 102 is the second low refractive index material layer 302, and the side of the second film layer 3 away from the second surface 102 is The second high refractive index material layer 301 .

In the ultraviolet filter of the embodiment of the present invention, different high-refractive-index material layers and low-refractive-index material layers are arranged alternately on opposite sides of the substrate, so that the reflection band is divided into two, and the overall film layer distribution is more precise. Reasonable, and the surface stress on the opposite sides of the substrate is relatively uniform, and at the same time, the film cracking phenomenon caused by excessive stress on one side is avoided. Wherein, the side of the first film layer close to the first surface and the side away from the first surface are the first high refractive index material layer, the side of the second film layer close to the second surface is the second low refractive index material layer, and the second film layer is the second low refractive index material layer. The side of the film layer away from the second surface is the second high refractive index material layer. This design can effectively suppress and reduce the background stray light reflected back from the surface on the side opposite to the incident surface of the light beam.

In the ultraviolet filter of the embodiment of the present invention, the first surface and the second surface may be the front surface and the rear surface of the substrate, or the upper surface and the lower surface, or the left surface and the right surface, etc. of the substrate.

Optionally, the substrate 1 is made of quartz or calcium fluoride; the materials of the first high refractive index material layer 201 and the second high refractive index material layer 301 are both hafnium dioxide or aluminum oxide; the first low refractive index material layer The materials of the material layer 202 and the second low refractive index material layer 302 are both aluminum fluoride or magnesium fluoride.

The design thought of the ultraviolet light filter mirror of the embodiment of the present invention is:

在紫外光谱区185nm-320nm有两个吸收区域，270nm-320nm有一个吸收强度低于1e-18的光谱区，在290nm左右吸收最强，在此区域的振动转动结构比较复杂，195nm-230nm是吸收最强的波段，呈现连续的吸收峰特征，吸收强度在1e-18-1.4e-17之间，从200nm-230nm随着波长变短吸收逐渐增强，吸收200nm-212nm的吸收强度超过1e-17量级，如图8所示。By analyzing the ultraviolet spectrum absorption cross section of _SO2 gas, the ground state of _SO2 is

There are two absorption regions in the ultraviolet spectral region 185nm-320nm, there is a spectral region with an absorption intensity lower than 1e-18 in 270nm-320nm, and the strongest absorption is around 290nm. The vibration and rotation structure in this region is more complicated. 195nm-230nm is The band with the strongest absorption shows continuous absorption peak characteristics. The absorption intensity is between 1e-18-1.4e-17. From 200nm-230nm, the absorption gradually increases as the wavelength becomes shorter. The absorption intensity of 200nm-212nm exceeds 1e- 17 magnitude, as shown in Figure 8.

振动转动结构相对简单，跃迁归属

从而辐射出荧光信号。本发明实施例的紫外滤光镜在基底相对的两侧分别交替设置第一高折射率材料层、第一低折射率材料层、第二高折射率材料层和第二低折射率材料层，通过对膜料光学常数拟合模拟计算，将反射带一分为二，第一膜层实现200-230nm高反射、230-700nm高透射，第二膜层实现220-290nm反射、290nm-700nm高透射，235nm-290nm为透—反射的过渡带，把反射带一分为二整体膜层分布更加合理，第一膜层和第二膜层应力相对均匀、同时避免了单面应力过大出现的裂膜现象，对膜系初始单元设计如下：其中以210nm-214nm为参考波长H代表高折射率材料，L代表低折射率材料，S代表周期数，Air代表空气。Among the electronic transitions involved in the 200nm-230nm band, there is only one excited state 5.279eV higher than the ground state

The vibration and rotation structure is relatively simple, and the transition belongs to

A fluorescent signal is thereby emitted. In the ultraviolet filter of the embodiment of the present invention, the first high refractive index material layer, the first low refractive index material layer, the second high refractive index material layer and the second low refractive index material layer are alternately arranged on opposite sides of the substrate, Through the simulation calculation of the optical constants of the film material, the reflection band is divided into two parts. The first film layer achieves 200-230nm high reflection and 230-700nm high transmission, and the second film layer realizes 220-290nm reflection and 290nm-700nm high Transmission, 235nm-290nm is the transmission-reflection transition zone, it is more reasonable to divide the reflection zone into two parts, the overall film distribution is more reasonable, the stress of the first film layer and the second film layer is relatively uniform, and at the same time, it avoids the occurrence of excessive stress on one side Film cracking phenomenon, the initial unit design of the film system is as follows: where 210nm-214nm is used as the reference wavelength H represents high refractive index materials, L represents low refractive index materials, S represents the period number, and Air represents air.

Sub|(0.5HL 0.5H) ^s |Air;

The film structure of the first film layer: the unit thickness of the first high refractive index material layer is 27-33nm, such as 30nm; the unit thickness of the first low refractive index material layer is 35-41nm, such as 38nm;

Sub|(0.5HL 0.5H) ⁷ 1.15(0.5HL 0.5H) ⁷ |Air;

The second film layer structure: the unit thickness of the second high refractive index material layer is 27-33nm, such as 30nm; the unit thickness of the second low refractive index material layer is 35-41nm, such as 38nm;

Sub|0.85(0.5HL 0.5H) ⁷ (0.5HL 0.5H) ⁷ |Air.

Optimize the film structure of the first film layer and the second film layer respectively. After optimization:

In some embodiments, the total number of the first high refractive index material layer 201 and the first low refractive index material layer 202 in the first film layer 2 is 19-39 layers, and the thickness of the first high refractive index material layer 201 is between 20-39 layers. between 43.9 nm and the thickness of the first low refractive index material layer 202 is between 32.66-53.78 nm.

In some embodiments, the total number of the second high refractive index material layer 301 and the second low refractive index material layer 302 in the second film layer 3 is 18-38 layers, and the thickness of the second high refractive index material layer 301 is between 22.91- between 43.09 nm and the thickness of the second low refractive index material layer 302 is between 30.63-84.54 nm.

It should be noted that in the ultraviolet filter of the embodiment of the present invention, the number of layers of the first high refractive index material layer and the first low refractive index material layer in the first film layer, the second high refractive index material layer in the second film layer The selection of the number of layers of the material layer and the second low refractive index material layer is related to the period number S, the greater the period number S, the higher the reflectivity, and the more layers there are. The period number S here refers to the number of times that the first high refractive index material layer and the first low refractive index material layer are alternately arranged for the first film layer, and refers to the second high refractive index material layer and the second low refractive index material layer for the second film layer Rate material layer alternates the number of times it is set.

The ultraviolet filter of the embodiment of the present invention takes the first film layer as the incident light side, and the principle diagram of its reflection characteristics is shown in FIG. 2 . When a light source with a wavelength between 200-700nm is incident on the first film layer, the light beam with a wavelength between 200-230nm is reflected by the first film layer, and the light beam with a wavelength between 220-290nm is reflected by the second film layer. Beams between 290-700nm are transmitted. When the incident angle of the light source on the first film layer is within the range of 22.5°-45°, the schematic diagram of the reflection characteristics of the ultraviolet filter according to the embodiment of the present invention is shown in FIG. 3 . In the angle range of 22.5-45°, the reflectivity of 200nm-230nm exceeds 60%, and the reflectivity near the wavelength of 214nm exceeds 80%, while the reflectivity of 230nm-290nm is below 30%, and the reflectivity of 290nm-700nm does not exceed 10%. It can be seen that there is a huge difference in reflectance before and after the wavelength of 230 nm in the ultraviolet filter of the embodiment of the present invention.

After the optimization of the overall film structure design is completed, the ultraviolet filter of this embodiment is prepared. The preparation method of the ultraviolet filter mirror of this embodiment includes but not limited to chemical vapor deposition (CVD) process, atomic layer deposition (ALD) process, physical vapor deposition (PVD) process or other suitable processes, such as physical vapor deposition process can be Vacuum evaporation or sputtering.

As a possible example, as shown in Figure 5, the method for preparing the ultraviolet filter of the embodiment of the present invention adopts a double-sided split vacuum evaporation method, including

Pretreat the substrate;

Premelting and sintering the first high refractive index material layer material, the first low refractive index material layer material, the second high refractive index material layer material and the second low refractive index material layer material in sequence;

A first film layer and a second film layer are respectively formed on the first surface and the second surface of the pretreated substrate by means of vacuum evaporation.

In the preparation method of the ultraviolet filter in the embodiment of the present invention, the purpose of pretreatment is to remove the impurities adsorbed on the surface of the substrate, fill the depressions on the surface of the substrate, activate the surface particles at the same time, and improve the binding force between the substrate and the film material molecules. Make the film layer more firm. Pretreatment methods include, but are not limited to, ultrasonic cleaning, ion source treatment, and the like. As a possible example, the pretreatment method is as follows: the substrate is ultrasonically cleaned, then purged and dried with an inert gas, and then treated with high-energy ions from an ion source. Optionally, the ultrasonic cleaning is carried out twice, the first time is to put the substrate into a mixed solution of alcohol, ether and other volumes, and the second time is to put the substrate after the first cleaning into deionized water. , the first cleaning time and the second cleaning time are 5-15min. Optionally, one or more of nitrogen, argon, and helium may be selected as the inert gas. Optionally, the high-energy ions of the ion source are high-energy ions of the anode ion source, high-energy ions of the Hall ion source, and the like.

In the preparation method of the ultraviolet filter mirror of the embodiment of the present invention, for the first high refractive index material layer material, the second high refractive index material layer material, the first low refractive index material layer material and the second low refractive index material layer The purpose of sintering and pre-melting the material is to remove the gas and impurities adsorbed in the film material gap and surface.

In some embodiments, the method of pre-melting the material of the first high refractive index material layer and the material of the second high refractive index material layer is: using an electron gun to pre-melt the current from 0.1-180mA, and the current is from 0.1 The mA starts to be increased by 30mA to repeatedly premelt the surface of the first high refractive index material layer material or the second high refractive index material layer material until all the particles of the first high refractive index material layer material or the second high refractive index material layer material are melted , until the surface of the material of the first high refractive index material layer or the material of the second high refractive index material layer is completely melted.

In some embodiments, the method of pre-melting the material of the first low-refractive index material layer and the material of the second low-refractive index material layer is: using an electron gun to perform repeated pre-melting under the conditions of a current of 0.1-15mA and a scanning radius of 10-20mm. melt.

It should be noted that pre-melting the first high refractive index material layer material and the second high refractive index material layer material and pre-melting the first low refractive index material layer material and the second low refractive index material layer material are both It is performed by connecting the stun gun to 220V voltage.

In some embodiments, the process conditions for vacuum evaporation of the first high refractive index material layer material and the second high refractive index material layer material are: vacuum degree (0.5×10 ^-3 )-(2×10 ^-3 ) Pa, The evaporation rate is 1-3nm/s, the baking temperature is 270-310℃, and the baking time is 30-60min.

In some embodiments, the process conditions for vacuum evaporation of the first low-refractive index material layer material and the second low-refractive index material layer material are: vacuum degree (0.5×10 ^-3 )-(2×10 ^-3 ) Pa, The evaporation rate is 0.3-1.3nm/s, the baking temperature is 270-310℃, and the baking time is 30-60min.

In some embodiments, the sintering temperature of the first high refractive index material layer is 1650-1950°C, and the holding time is 200-300min; the sintering temperature of the second high refractive index material layer is 1650-1950°C, and the holding time is 200-300min; the sintering temperature of the first low refractive index material layer is 1250-1350°C, and the holding time is 250-350min; the sintering temperature of the second low refractive index material layer is 1250-1350°C, and the holding time is 250- 350min.

Based on the filtering characteristics of the ultraviolet filter of the embodiment of the present invention, multiple sets of ultraviolet filter of the embodiment of the present invention can be set for light filtering.

The inventive idea of the light filtering device and the light filtering method of the embodiment of the present invention is:

There is a huge difference in the reflectivity of the ultraviolet filter mirror in the embodiment of the present invention before and after the wavelength of 230nm, and the transmission mode of light beam multiple reflection filtering is adopted to make the low reflectivity wavelength in the light beam form an exponential attenuation of light intensity, thereby making the light beam The high-reflectivity spectral region gradually converges and compresses, and the comprehensive reflectance R _total of the overall spectrum of the light beam has an exponentially decreasing relationship with the number of reflections (N=1, 2, 3, 4...) (R _total = R _single ^N ), making many After the second filter, the spectral intensity I and the full width at half maximum (FWHM) are reduced and converged as a whole, and the transmission of the band after 230nm is gradually suppressed, and finally the high-intensity ultraviolet light in the effective band of 200nm-230nm is retained, and the ultraviolet light in the band of 200nm-230nm covers the SO ₂ The strong absorption area and weak absorption area of the gas absorption cross section can excite the SO ₂ gas radiation fluorescence signal to the greatest extent.

Based on the above ideas, as shown in Figure 6 and Figure 7, the filter device of the embodiment of the present invention includes a light source 4, a collimator lens 5 and at least two ultraviolet filters 6 of the embodiment of the present invention arranged in sequence, the light source 4 The emitted light beams are sequentially incident on each ultraviolet filter 6 at the same angle.

Optionally, the light source 4 is a zinc lamp or a flashing xenon lamp. The light source 4, the collimator lens 5 and a plurality of ultraviolet filter mirrors all have space between adjacent two. It should be noted that as long as it can be ensured that the light beams emitted by the light source are sequentially incident on each ultraviolet filter at the same angle, the position of each ultraviolet filter is not limited. At the same time, based on the filtering characteristics of the ultraviolet filter in the embodiment of the present invention, the number of ultraviolet filters can be set according to the requirements of light filtering. The specific principle is: if the light source needs to pass through the filter device, the emitted reflected light The lower the comprehensive reflectance, the more times of filtering are required, and the more corresponding UV filters are required. As a possible example, a zinc lamp is selected as the light source, the incident angle of the light beam emitted by the light source is 22.5-45°, and the number of ultraviolet filter mirrors 6 is four.

Optionally, the first film layer 2 of the ultraviolet filter is the incident surface of the light beam.

Optionally, as a possible implementation of the present invention, when the light source is a zinc lamp, due to the pulsed trigger characteristics of the ultraviolet light source, the output light intensity is unstable when the light source boosts and flickers, and the continuous boost and flicker for a long time will affect the light source. There is loss, which leads to a decrease in luminous efficiency at the same voltage. It is necessary to monitor the intensity of the light source in real time, so as to adjust the boosting range of the light source. When the luminous efficiency of the light source decreases, adjust the boost in time to maintain the luminous efficiency of the light source. The zero point drift of the system, while using the ultraviolet filter for multiple filtering, a photodetector 7 is added vertically behind each ultraviolet filter along the beam transmission direction, and the transmission spectrum of each ultraviolet filter is detected synchronously Intensity I _T continuously corrects the pulse boost range of the ultraviolet light source through the intensity of the light signal detected by each photodetector, so that the luminous efficiency of the light source is stable and the intensity range converges. The photodetector behind each ultraviolet filter detects the light intensity change in the band with the highest transmittance of the corresponding filter, and compares it with the reference light intensity after filtering at each stage for real-time correction. Taking the number of UV filters as 4 as an example, define the 4 UV filters according to the order of incident light sources as the first UV filter, the second UV filter, and the third UV filter and the fourth ultraviolet filter mirror, then their corresponding photodetectors are respectively the first photodetector, the second photodetector, the third photodetector and the fourth photodetector, then the first A photodetector measures the spectral intensity of the 400-700nm section after one filter as I _T1 , the second photodetector measures the spectral intensity of the 230-290nm section after twice filtering as I _T2 , and the third photodetector measures the three-time filtered The spectral intensity of the 230-290nm section after the light is I _T3 , and the fourth photodetector measures the spectral intensity of the 200-230nm section after four times of filtering is I _T4 , and the relative intensity I _T1 -I _T4 is compared with the standard light intensity in real time , to obtain the deviation ratio P of the overall relative intensity, and use the deviation ratio P to adjust the output voltage value of the light source, thereby controlling the output of the relative light intensity.

Taking the case where the light source is a zinc lamp and four ultraviolet filters are set as an example (as shown in Figures 6 and 7), the working principle of the filter device in the embodiment of the present invention is:

After the ultraviolet light is collimated by the collimating lens 5, it is incident on the first film layer of the first ultraviolet filter mirror 6 (R _total =R _single ) with a specific angle, and the light beam filtered for the first time is again with the same The angle is incident on the second ultraviolet filter mirror 6, and now the outgoing light is filtered twice, and the comprehensive reflectance of the outgoing reflected light decreases by the square (R _total =R _single ² ), so that the light after twice filtering The spectral intensity I and the full width at half maximum (FWHM) both decreased and converged. The outgoing reflected light is incident on the third ultraviolet filter 6 at the same angle, and after the third filter, the comprehensive reflectance of the outgoing reflected light decreases by the third power (R _total =R _single ³ ), so that three times Both the filtered spectral intensity I and the full width at half maximum (FWHM) are reduced and converged again. The outgoing reflected light is incident on the fourth ultraviolet filter 6, and after the fourth filter, the comprehensive reflectance of the outgoing reflected light decreases by the fourth power (R _total =R _single ⁴ ), so that the spectral line intensity and half The peak full widths are again reduced and converged. During the whole filtering process, the photodetector behind each ultraviolet filter detects the light intensity change in the band with the highest transmittance of the corresponding filter, and compares it with the reference light intensity after filtering at each stage for real-time correction.

The light filtering method of the embodiment of the present invention is applied to the light filtering device of the embodiment of the present invention, and the method includes

The light beam emitted by the light source is collimated and transparently collimated to obtain collimated light;

The collimated light passes through the reflection and filtering of each ultraviolet filter sequentially at the same incident angle to obtain a light source beam with a convergent spectral range.

In some embodiments, the light filtering method of the embodiment of the present invention also includes: each photodetector 7 synchronously detects the transmitted light intensity of its corresponding ultraviolet filter, and the reference light intensity of the ultraviolet filter Make corrections.

The specific process of the light filtering method in the embodiment of the present invention is similar to the working principle of the light filtering device in the embodiment of the present invention, and will not be repeated here.

The filtering method of the embodiment of the present invention can be used for the detection of sulfur dioxide gas concentration, and is used to reduce the detection limit of ultraviolet fluorescence trace SO2 gas concentration. In the filtering process of reducing the detection limit of ultraviolet fluorescence trace _SO2 gas concentration, _the light source adopts zinc Lamp or flashing xenon lamp, the incident angle of the beam is 22.5-45°, and the number of ultraviolet filters is 4 pieces; the spectral range of the light source converges to 200-230nm after being filtered by all ultraviolet filters.

The ultraviolet filter of the present invention and its preparation method will be described below in combination with preferred embodiments of the present invention.

Embodiment 1 ultraviolet filter mirror

The ultraviolet light filter of the embodiment of the present invention comprises a substrate 1, a first film layer 2 and a second film layer 3; the substrate 1 has a first surface 101 and a second surface 102 oppositely arranged; the first film layer 2 is provided On the first surface 101, the first film layer 2 is alternately arranged by several first high-refractive-index material layers 201 and several first low-refractive-index material layers 202. The first film layer 2 is close to the first surface 101 and away from One side of the first surface 101 is the first high refractive index material layer 201; the second film layer 3 is arranged on the second surface 102, and the second film layer 3 is composed of several second high refractive index material layers 301 and several second low refractive index material layers. Material layers 302 are arranged alternately, the side of the second film layer 3 close to the second surface 102 is the second low refractive index material layer 302, and the side of the second film layer 3 away from the second surface 102 is the second high refractive index material Layer 301.

Wherein, the first surface 101 is the upper surface of the substrate, and the second surface 102 is the lower surface of the substrate. The substrate 1 is made of ultraviolet fused silica (F_silica); the materials of the first high refractive index material layer 201 and the second high refractive index material layer 301 are hafnium dioxide; the first low refractive index material layer 202 and the second low refractive index material layer The material of the high-density material layer 302 is aluminum fluoride. The first film layer is a 29-layer film with a total thickness of 1.14 μm; the second film layer is a 28-layer film with a total thickness of 1 μm. The specific structural composition of the first film layer and the second film layer is shown in Table 1, wherein the film layer 1 is the outermost film on the side away from the substrate surface.

The first film layer and the second film layer structure of table 1 embodiment 1 ultraviolet light filter

The preparation method of ultraviolet filter mirror in embodiment 2 embodiment 1

Put the quartz substrate into a mixed solution of alcohol and ether in an equal volume ratio and ultrasonically clean it for 10 minutes, and then use deionized water to ultrasonically clean the quartz substrate for 10 minutes. Subsequently, the cleaned quartz substrate is blown and dried with Ar gas, and then the cleaned quartz substrate is subjected to secondary treatment with Hall ion source high-energy ions. Afterwards, pre-melt HfO ₂ and AlF ₃ (the melting point of HfO ₂ is at 2750°C, and the melting point of AlF ₃ is _at 1300°C). The surface _of the HfO ₂ film material is repeatedly pre-melted until the particles of the HfO ₂ film material are completely melted and the surface of the HfO ₂ film material is completely melted; The scanning radius of the electron gun is up to 15mm, so that the light spot can cover the whole and repeatedly pre-melt the surface of the AlF ₃ film. Then put the pre-melted HfO ₂ into the muffle furnace and sinter at 1900°C for 240min, then put the pre-melted AlF ₃ into the muffle furnace and sinter at 1250°C for 300min to remove the gas adsorbed on the gap between the two membrane materials and the surface and impurities. Finally, set the parameters of the vacuum evaporation, in which the vacuum degree is set to 1×10-3Pa, the evaporation rate is set to HfO ₂ —2nm/s, AlF ₃ —0.8nm/s, and the baking temperature of the quartz substrate is set to 290 ℃, and the baking time is set to 30 minutes. Finally, the vapor deposition of the first film layer and the second film layer is completed, and the ultraviolet filter of Example 1 is obtained.

The filter effect of the ultraviolet filter prepared in this example 1 was tested, and the test results are shown in FIG. 4 . It can be seen from Figure 4 that the 200-230nm band is a high reflection range, the 235nm-290nm band is a transmission-reflection transition range, and the 290nm-700nm band is a high transmission range.

Embodiment 3 contains the filter device of the ultraviolet filter mirror of embodiment 1 and reduces the filter method of ultraviolet fluorescence trace sulfur dioxide gas concentration detection limit

As shown in Figure 7, comprise the ultraviolet filter mirror 6 of light source 4, collimating lens 5 and 4 sheets of embodiment 1 arranged in sequence, light source 4, collimating lens 5 and 4 ultraviolet filter mirror 6, adjacent two There is a space between them. A photodetector 7 is provided behind each ultraviolet filter 6, and the photodetector 7 is arranged perpendicular to the transmission direction of the light beam.

Among them, the central axis of the light source 4 coincides with the central axis of the collimator lens 5, and the four ultraviolet filters are defined according to the order of the incident light source as the first ultraviolet filter, the second ultraviolet filter, and the third ultraviolet filter. filter and the fourth ultraviolet filter, then their corresponding photodetectors are respectively the first photodetector, the second photodetector, the third photodetector and the fourth photodetector. The central axis of the first UV filter and the collimating lens 5 is arranged at 45°; the second UV filter is positioned directly below the first UV filter, and both are parallel to each other; the third UV filter The light mirror is positioned at the bottom right of the first UV filter, and the third UV filter is set at -45° to the central axis of the collimating lens 5; the fourth UV filter is located at the first UV filter The right side of the mirror, and the fourth UV filter is set parallel to the third UV filter.

Among them, the light source 4 adopts a zinc lamp; the light beam emitted by the light source 4 is sequentially incident on the first ultraviolet filter, the second ultraviolet filter, and the third ultraviolet filter at a relative angle of 45° relative to the ultraviolet filter. Mirror and the fourth ultraviolet filter mirror, the first film layer 2 of each ultraviolet filter mirror is the incident surface of the light beam.

The filter method for reducing the detection limit of ultraviolet fluorescence trace sulfur dioxide gas concentration by using the filter device of the present embodiment is:

After the ultraviolet light is collimated by the collimating lens 5, it is incident on the first film layer (R _total =R _single ) of the first ultraviolet filter mirror 6 with respect to the relative angle of the ultraviolet filter 45 °, through the first The light beam of the second filter is incident on the second ultraviolet filter mirror 6 with the same angle of 45 °, and now the outgoing light is filtered twice, and the integrated reflectance of the reflected light of the outgoing light decreases by the square (R _total =R _single ² ), so that the spectral intensity I and the full width at half maximum (FWHM) after twice filtering are reduced and converged. The reflected light that emerges is incident on the third ultraviolet filter mirror 6 with the same angle of 45 °. After the third time filtering, the comprehensive reflectance of the reflected light that emerges decreases by the cube (R _total =R _single ³ ), The spectral intensity I and the full width at half maximum (FWHM) after three times of filtering are reduced and converged again. The reflected light that emerges is incident on the fourth ultraviolet filter mirror 6 with the same angle of 45 °. After the fourth filter, the integrated reflectance of the reflected light that emerges decreases by the fourth power (R _total =R _single ⁴ ), The intensity of the spectral line and the full width at half maximum are reduced and converged again. After 4 times of filtering, the spectral range of ultraviolet light converges to 200nm-230nm, and the light intensity after 230nm is less than 1%, finally forming a high intensity covering the strong absorption cross section of the whole _SO2 molecule suitable for _SO2 gas detection , narrow-band ultraviolet light, while suppressing the noise band after 230nm, as shown in Figure 10. During the whole filtering process, the photodetector behind each ultraviolet filter detects the light intensity change in the band with the highest transmittance of the corresponding filter, and compares it with the reference light intensity after filtering at each stage for real-time correction. Reduce background signal interference, lower SO ₂ detection limit. Specifically, the first photodetector measures the spectral intensity in the 400nm-700nm segment after one filter is I _T1 , the second photodetector measures the spectral intensity in the 230nm-290nm segment after twice filtering is I _T2 , and the third The photodetector measures the spectral intensity of the 230nm-290nm section after three times of filtering as I _T3 , and the fourth photodetector measures the spectral intensity of the 200nm-230nm section after four times of filtering as I _T4 , through the relative intensity I _T1 -I _T4 Comparing with the standard light intensity in real time, the deviation ratio P of the overall relative intensity is obtained, and the deviation ratio P is used to adjust the output voltage value of the light source, thereby controlling the output of the relative light intensity.

After 800 s of testing and calculation of Allen variance, the detection limit of SO ₂ gas can be reduced to 85ppt by using the filter device and filter method of this embodiment, as shown in FIG. 11 .

Comparing the filtering effect of the multi-reflective filtering device and the filtering method of this embodiment with the traditional transmission interference filtering effect, the results are shown in FIG. 9 . As can be seen from Fig. 9, after the ultraviolet light passes through the filter device and filter method of the present embodiment for 4 reflective filters, the spectral intensity of the central wavelength in the 200nm-230nm band exceeds 50%, and the spectral intensity is lower after the 230nm band. The spectral intensity of the central wavelength of ultraviolet light after the transmission filter does not exceed 20%, and the spectral intensity part exceeds 5% after the 230nm band, as shown in Figure 9. It can be seen that the multiple reflection filtering effect of the optical filtering device and filtering method of the present invention is obviously better than that of the traditional transmission interference filtering.

Embodiment 4 Contains the filter device of the ultraviolet filter lens of embodiment 1 and the filter method that reduces the detection limit of ultraviolet fluorescence trace sulfur dioxide gas concentration

This embodiment is basically the same as Embodiment 3, the difference is:

As shown in Figure 6, in the filter device:

The central axis of the first UV filter and the collimating lens 5 is set at 67.5°; the second UV filter is positioned at the lower left side of the first UV filter, and both are arranged in parallel; the third UV filter Light mirror and collimating lens 5 central axis become-67.5 ° set; Between the light mirror and the third UV filter.

The light beam emitted by the light source 4 is sequentially incident on the first ultraviolet filter, the second ultraviolet filter, the third ultraviolet filter and the fourth ultraviolet filter at a relative angle equivalent to 22.5° of the optical filter .

In the filtering method of reducing the detection limit of ultraviolet fluorescence trace sulfur dioxide gas concentration by using the filtering device of the present embodiment:

After the ultraviolet light is collimated by the collimating lens 5, it is successively incident on the first ultraviolet filter mirror, the second ultraviolet filter mirror, the third ultraviolet filter mirror and Fourth UV filter.

The light filtering effect of the light filtering device and the light filtering method of this embodiment is basically the same as that of the light filtering effect in the third embodiment, and will not be repeated here.

In summary, the present invention adopts double-sided splitting vacuum evaporation method to divide the reflective band into two, and prepares an ultraviolet filter mirror with a first film layer and a second film layer, and utilizes a specific angle of ultraviolet light (22.5°- 45°) is irradiated on the first film layer and the second film layer of the ultraviolet filter with high reflectivity characteristics, combined with multiple filtering to make the spectral range of the ultraviolet light cover the absorption cross section of the 200-230nm band of the _SO2 molecule as a whole, and at the same time Suppress the noise band after 230nm, use the transmitted light intensity after each filter to detect the luminous efficiency of the light source in real time, correct the fluctuation of the light source boost voltage in time, reduce the background signal interference, and reduce the detection limit of SO _2. After a long time of testing And the calculation of Allen variance can reduce the detection limit of SO ₂ gas to 85ppt.

In describing the present invention, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", " Back", "Left", "Right", "Vertical", "Horizontal", "Top", "Bottom", "Inner", "Outer", "Clockwise", "Counterclockwise", "Axial", The orientation or positional relationship indicated by "radial", "circumferential", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying the referred device or element Must be in a particular orientation, be constructed in a particular orientation, and operate in a particular orientation, and therefore should not be construed as limiting the invention.

In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be interpreted as indicating or implying relative importance or implicitly specifying the quantity of indicated technical features. Thus, the features defined as "first" and "second" may explicitly or implicitly include at least one of these features. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

In the present invention, unless otherwise clearly specified and limited, terms such as "installation", "connection", "connection" and "fixation" should be understood in a broad sense, for example, it can be a fixed connection or a detachable connection , or integrated; can be mechanically connected, can also be electrically connected or can communicate with each other; can be directly connected, can also be indirectly connected through an intermediary, can be the internal communication of two components or the interaction relationship between two components, unless expressly defined otherwise. Those of ordinary skill in the art can understand the specific meanings of the above terms in the present invention according to specific situations.

In the present invention, unless otherwise clearly specified and limited, the first feature may be in direct contact with the first feature or the first and second feature may be in direct contact with the second feature through an intermediary. touch. Moreover, "above", "above" and "above" the first feature on the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. "Below", "beneath" and "beneath" the first feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is less horizontally than the second feature.

As used herein, the terms "one embodiment," "some embodiments," "example," "specific examples," or "some examples" mean specific features, structures, materials, or features described in connection with the embodiment or example. A feature is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the described specific features, structures, materials or characteristics may be combined in any suitable manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine different embodiments or examples and features of different embodiments or examples described in this specification without conflicting with each other.

Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention, those skilled in the art can make the above-mentioned The embodiments are subject to changes, modifications, substitutions and variations.

Claims (17)

1. An ultraviolet filter is characterized by comprising

A substrate having a first surface and a second surface disposed opposite;

the first film layer is arranged on the first surface and is formed by alternately arranging a plurality of first high-refractive-index material layers and a plurality of first low-refractive-index material layers, and the first high-refractive-index material layers are arranged on one side of the first film layer close to the first surface and on one side of the first film layer far away from the first surface;

the second rete, the second rete is established the second surface, the second rete is formed by setting up in turn a plurality of second high refractive index material layers and a plurality of second low refractive index material layers, the second rete is close to second surface one side is the low refractive index material layer of second, the second rete is kept away from second surface one side is the second high refractive index material layer.

2. The ultraviolet filter according to claim 1,

the unit thickness of the first high-refractive-index material layer is 27-33nm, and the thickness of the first high-refractive-index material layer is 20-43.9 nm;

the unit thickness of the first low-refractive-index material layer is 35-41nm, and the thickness of the first low-refractive-index material layer is 32.66-53.78 nm;

the unit thickness of the second high refractive index material layer is 27-33nm, and the thickness of the second high refractive index material layer is 22.91-43.09 nm;

the unit thickness of the second low-refractive index material layer is 35-41nm, and the thickness of the second low-refractive index material layer is 30.63-84.54 nm.

3. The ultraviolet filter of claim 1, wherein the first layer of high index material and the first layer of low index material total 19-39 layers; the total number of the second high refractive index material layer and the second low refractive index material layer in the second film layer is 18-38 layers.

4. The ultraviolet filter of claim 1, wherein the substrate is made of ultraviolet fused silica or calcium fluoride; the first high-refractive-index material layer and the second high-refractive-index material layer are both made of hafnium oxide or aluminum oxide; the first low-refractive-index material layer and the second low-refractive-index material layer are both made of aluminum fluoride or magnesium fluoride.

5. A process for producing an ultraviolet filter as claimed in any of claims 1 to 4, which comprises

Pretreating the substrate;

pre-melting and sintering the first high refractive index material layer material, the first low refractive index material layer material, the second high refractive index material layer material and the second low refractive index material layer material in sequence;

and respectively forming the first film layer and the second film layer on the first surface and the second surface of the pretreated substrate by adopting a vacuum evaporation method.

6. The method for producing an ultraviolet filter according to claim 5, wherein the pretreatment is a method of: and carrying out ultrasonic cleaning on the substrate, then blowing and drying by using inert gas, and then carrying out high-energy ion treatment by using an ion source.

7. The method for manufacturing the ultraviolet filter according to claim 5, wherein the method for pre-melting the first high refractive index material layer material and the second high refractive index material layer material comprises: and (2) performing pre-melting by using an electron gun under the condition of current of 0.1-180mA, and repeatedly pre-melting the surface of the material of the first high-refractive-index material layer or the material of the second high-refractive-index material layer every 30mA from 0.1mA until the material of the first high-refractive-index material layer or the material of the second high-refractive-index material layer is completely melted down and the surface of the material of the first high-refractive-index material layer or the material of the second high-refractive-index material layer is completely melted down.

8. The method for manufacturing the ultraviolet filter according to claim 5, wherein the method for pre-melting the material of the first low-refractive-index material layer and the material of the second low-refractive-index material layer comprises the following steps: an electron gun is adopted to carry out repeated premelting under the conditions that the current is 0.1-15mA and the scanning radius is 10-20 mm.

9. The method for manufacturing the ultraviolet filter lens according to claim 5, wherein the process conditions of vacuum evaporation of the first high refractive index material layer material and the second high refractive index material layer material are as follows: degree of vacuum (0.5X 10) ^-3 )-(2×10 ^-3 ) Pa, evaporation rate of 1-3nm/s, baking temperature of 270-310 ℃ and baking time of 30-60min.

10. The method for manufacturing the ultraviolet filter lens according to claim 5, wherein the process conditions for vacuum evaporation of the material of the first low-refractive-index material layer and the material of the second low-refractive-index material layer are as follows: degree of vacuum (0.5X 10) ^-3 )-(2×10 ^-3 ) Pa, evaporation rate of 0.3-1.3nm/s, baking temperature of 270-310 ℃, and baking time of 30-60min.

11. A light filtering device, comprising a light source, a collimating lens and at least two UV filters according to any of claims 1 to 4 arranged in sequence, wherein the light beam emitted from the light source is incident on each UV filter in sequence at the same angle.

12. A light-filtering device according to claim 11, wherein said first layer of said uv filter is the entrance face for said light beam.

13. The filter device according to claim 11, wherein the incident angle of the light beam is 22.5-45 °; the number of the ultraviolet filter lenses is 4.

14. A filter device according to any one of claims 11 to 13, wherein each of said uv filters is followed by a photodetector, and wherein said photodetectors are arranged perpendicular to the direction of transmission of said light beams.

15. A method of filtering light for use in a filtering device according to any one of claims 11 to 14, comprising

The light beam emitted by the light source is collimated by the collimation transparent device to obtain collimated light;

and the collimated light sequentially passes through the ultraviolet filter lenses at the same incident angle to be reflected and filtered, so that light source beams with a converged spectral range are obtained.

16. A method of filtering light according to claim 15, further comprising: and each photoelectric detector synchronously detects the transmission light intensity of the corresponding ultraviolet filter and corrects the reference light intensity of the ultraviolet filter.

17. Use of a filtering method according to claim 15 or 16 for sulphur dioxide gas concentration detection, comprising

The light source is a zinc lamp or a flashing xenon lamp;

the incident angle of the light beam is 22.5-45 degrees;

the number of the ultraviolet filter lenses is 4;

the light source is converged to 200-230nm in the spectral range after being filtered by all the ultraviolet filters.

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