High stability ultraviolet energy sensor based on polarization passivation

Abstract

The application relates to a high-stability ultraviolet energy sensor based on polarization passivation, and belongs to the field of photoelectric sensors. The ultraviolet energy sensor comprises a first substrate, a fluorescence conversion crystal arranged above the first substrate and used for converting ultraviolet light into visible light or near-infrared light, a second substrate arranged above the fluorescence conversion crystal, a light-absorbing plate arranged above the second substrate and used for absorbing excess light, a filter arranged above the second substrate and distributed on both sides of the light-absorbing plate and used for filtering stray light, and a photoelectric converter arranged above the second substrate and distributed on both sides of the light-absorbing plate and used for converting the light signal filtered by the filter into an electric signal. The surfaces of the first substrate, the fluorescence conversion crystal and the second substrate are all provided with polarization passivation structures for passivating the polarization sensitivity of the surface interface. The application can solve the problem that the light energy response fluctuation of a traditional ultraviolet energy sensor is large due to slight changes, and improve the energy detection accuracy and working stability of the sensor.

Description

Technical Field

[0001] This invention belongs to the field of photoelectric sensors and relates to the optimization of polarization response characteristics of fluorescence conversion type ultraviolet energy sensors, specifically to a high-stability ultraviolet energy sensor based on polarization passivation. Background Technology

[0002] Non-coaxial indirect detection ultraviolet energy sensors based on fluorescence conversion crystal wavelength conversion have the outstanding advantage of strong resistance to laser damage and have been widely used in lithography machines, high-energy laser detection, and other fields. However, due to the significant differences in reflectivity and transmittance of the fluorescence conversion crystal surface for incident ultraviolet light and the converted fluorescence (at different angles) of s-rays and p-rays, conventional ultraviolet energy sensors exhibit significant polarization response sensitivity. In practical applications, subtle changes in incident light angle, illumination position, optical system numerical aperture, and spot size often cause large fluctuations in the sensor's light energy response, affecting the sensor's energy detection accuracy, operational stability, and application range.

[0003] On the other hand, traditional passivation of polarization selectivity is usually achieved by growing polarization passivation films on the surface of optical media. However, fluorescence conversion ultraviolet energy sensors need to passivate the polarization selectivity of excitation light (ultraviolet light) and fluorescence (converted visible and near-infrared light) at the same time. The optical properties of the thin film materials required for the two are very different, and the design and growth of the film structure are extremely difficult (visible and near-infrared polarization passivation films absorb ultraviolet light, which greatly affects the sensor's responsivity; the growth precision of ultraviolet films requires nanometer level, otherwise it will affect the film transmittance and polarization passivation effect), making it difficult to achieve both at the same time. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a highly stable ultraviolet energy sensor based on polarization passivation, which passivates the polarization sensitivity of the light response of a fluorescence conversion type ultraviolet energy sensor, improves the accuracy and stability of energy detection, and expands the application range.

[0005] This invention proposes to create a "sandwich" structure by texturing the upper and lower interfaces of a fluorescence conversion crystal and introducing texturized quartz sheets onto the upper and lower surfaces of the crystal. This texturized interface helps to eliminate the influence of changes in polarization state (the proportion of s-rays and p-rays) caused by different incident and reflection angles of the optical surface under different operating conditions (minor changes in incident light angle, irradiation position, numerical aperture of the optical system, spot size, etc.), thereby improving the stability and repeatability of the energy detection of the optical sensor.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A high-stability ultraviolet energy sensor based on polarization passivation, comprising: First base; A fluorescent conversion crystal disposed above the first substrate is used to convert ultraviolet light into visible light or near-infrared light. A second substrate positioned above the fluorescence conversion crystal; A light-absorbing plate is placed above the second substrate to absorb excess light; The filters, positioned above the second substrate and distributed on both sides of the light-absorbing plate, are used to filter out stray light. The photoelectric converters, located above the second substrate and distributed on both sides of the light-absorbing plate, are used to convert the light signals filtered by the filter into electrical signals. The surfaces of the first substrate, the fluorescence conversion crystal, and the second substrate are all provided with polarization passivation structures to passivate the polarization sensitivity of the interface. The passivation structures can be fabricated as periodic (100 nm~3000 nm) superstructures using etching processes according to the passivation band, or as random (non-periodic) textured surfaces (0.5 μm~3 μm deep) using mechanical polishing or wet etching processes.

[0007] Furthermore, both the first and second substrates are made of quartz material.

[0008] Furthermore, the fluorescence conversion crystal is made of materials such as Ce:YAG, sapphire, or titanium sapphire.

[0009] Furthermore, the light-absorbing plate is made of stainless steel or aluminum alloy with micro-nano structures or coatings, and achieves high absorption of ultraviolet light by utilizing the high k value of the material itself.

[0010] Furthermore, the filter is molded using organic materials and dyes.

[0011] Furthermore, the polarization passivation structures on the surfaces of both the first and second substrates are made of quartz material.

[0012] Furthermore, the polarization passivation structure on the surface of the fluorescence conversion crystal is formed by a thinning pad containing diamond abrasive through a mechanical grinding process.

[0013] Furthermore, the photoelectric converter is a photodiode.

[0014] Furthermore, the sensor also includes a signal processing module connected to the photoelectric converter for processing the electrical signals output by the photoelectric converter.

[0015] The beneficial effects of this invention are as follows: This invention adopts a "sandwich" structure composed of a texturized fluorescence conversion crystal and a texturized quartz sheet. By utilizing the surface micro-nano structure, the incident angle of the incident light is randomized or averaged, reducing the transmission / reflection difference between s-light and p-light, and passivating the polarization response characteristics of the sensor. This avoids the problems of difficult optical thin film compatibility design and difficult thin film growth engineering in traditional methods that rely on optical thin films to passivate polarization characteristics. It also solves the problem of large fluctuations in light energy response caused by subtle changes in incident angle, irradiation position, numerical aperture of the optical system, and spot size in traditional ultraviolet energy sensors during actual use, thus improving the energy detection accuracy and working stability of the sensor.

[0016] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0017] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein: Figure 1 This is a schematic diagram of the high-stability ultraviolet energy sensor structure based on polarization passivation proposed in this invention; Figure 2 This is a schematic diagram showing the relationship between the relative responsivity of the S-ray and p-ray of an ultraviolet energy sensor and the incident angle of the light.

[0018] Reference numerals: 1-First substrate, 2-First polarization passivation structure, 3-Fluorescence conversion crystal, 4-Second polarization passivation structure, 5-Second substrate, 6-Third polarization passivation structure, 7-Light absorbing plate, 8-Filter, 9-Photodiode, 10-Signal processing circuit board. Detailed Implementation

[0019] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0020] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual pictures. They should not be construed as limiting the invention. To better illustrate the embodiments of the invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0021] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "front," and "rear" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present invention. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0022] like Figure 1 As shown, a high-stability ultraviolet energy sensor based on polarization passivation is provided in an embodiment of the present invention, which mainly consists of the following structure: 1. The first substrate 1 serves as the polarization passivation structure substrate. It is made of high-purity quartz material (e.g., quartz material with a purity of 99.99% or higher), with a thickness of 2 mm and a diameter of 50 mm.

[0023] 2. A first polarization passivation structure 2 (50 mm in diameter) is fabricated on the surface of the first substrate 1 to average the incident and reflection angles of ultraviolet light (193 nm, 248 nm, etc.) and near-infrared light, eliminating the influence of fixed optical irradiation angles introduced by incident light angle, irradiation position, and optical system numerical aperture and spot size, thus passivating the polarization sensitivity of the surface interface. The first polarization passivation structure 2 is formed by mechanical grinding using a thinning pad containing diamond abrasive (microstructure depth 0.5 μm~3 μm, lateral dimension 0.5 μm~5 μm).

[0024] like Figure 2 The results shown are the theoretical calculation results of polarization passivation of pure micro-nano structures. Before passivation, the responsivity of s-light and p-light varies greatly with the incident angle and is prone to significant deviation with test time and test conditions. After passivation, the responsivity of s-light and p-light does not change with the incident angle, and the response stability is enhanced.

[0025] 3. A fluorescent conversion crystal 3 is disposed above the first substrate 1 to convert 193 nm ultraviolet light into visible light or near-infrared light.

[0026] The fluorescence conversion crystal 3 is 2 mm thick and 50 mm in diameter, and is made of sapphire.

[0027] 4. A second polarization passivation structure 4 is fabricated on the fluorescent conversion crystal 3 to average the incident angle and reflection angle of ultraviolet light (193nm, 248nm, etc.) and near-infrared light, eliminate the influence of fixed optical irradiation angle introduced by incident angle, irradiation position, numerical aperture of optical system, spot size, etc., and passivate the polarization sensitivity of the surface.

[0028] The parameters of the second polarization passivation structure 4 are the same as those of the first polarization passivation structure 2. It also uses a thinning pad containing diamond grit and is formed by mechanical grinding.

[0029] 5. A second substrate 5 is disposed above the fluorescent conversion crystal 3 as the substrate for the third polarization passivation structure 6.

[0030] The second substrate 5 is made of high-purity quartz material.

[0031] 6. A third polarization passivation structure 6 is fabricated on the surface of the second substrate 5 to average the incident and reflection angles of ultraviolet light (193nm, 248nm, etc.) and near-infrared light, eliminating the influence of fixed optical irradiation angles introduced by incident light angle, irradiation position, and optical system numerical aperture and spot size, thus passivating the polarization sensitivity of the surface interface. The third polarization passivation structure 6 is formed by mechanically grinding a thinning pad containing diamond abrasive; its structural parameters are the same as those of the first polarization passivation structure 2.

[0032] 7. An absorber plate 7 is provided above the second substrate 5 to absorb excess ultraviolet light, visible light or near-infrared light.

[0033] The light-absorbing plate 7 is 10 mm thick and 30 mm in diameter, and is made of stainless steel.

[0034] 8. Filters 8 are disposed above the second substrate 5 and on both sides of the light-absorbing plate 7 to filter out stray light from the light source and after crystal conversion, ensuring the light purity of the downstream photodiode. The filters are annular in shape, with an inner diameter of 30.2 mm, an outer diameter of 50 mm, and a thickness of 2 mm.

[0035] 9. A photodiode 9 is placed above the filter 8 to convert the light signal filtered by the filter 8 into a current signal.

[0036] Photodiode 9 is implemented using a silicon-based near-infrared response enhancement photodiode.

[0037] 10. A signal processing circuit board 10 is disposed above the photodiode 9 for low-noise amplification of photodiode current, digital processing, driver control, sensor signal and status storage, and differential output.

[0038] For an ultraviolet energy sensor, its output signal voltage can be expressed as: (1) in, S is the light responsivity. P is the light responsivity. For S-light intensity, Let P be the intensity of the light, and θ be the angle of incidence of the light.

[0039] If the total light intensity is The proportion of P light is According to equation (1), the output voltage V can be expressed as: (2) By employing the passivation polarization technology provided in this embodiment, the incident angle of the incident light is randomized or averaged through the micro-nano structure on the surface of the passivation polarization structure, thereby reducing the transmission / reflection difference between s-rays and p-rays. , , , , The value will be constant (equivalent to taking the average value), and will not change with the angle of light incidence (the angle of light incidence will change slightly when the sensor is used at different times and under different working conditions), thereby improving the energy detection stability of the sensor.

[0040] Example 2 Compared with Example 1, the sensor provided in this example uses Ce:YAG to fabricate a fluorescent conversion crystal 3 to convert 365 nm ultraviolet light into visible or near-infrared light. Meanwhile, the light-absorbing plate is made of aluminum alloy surface micro-nano structure.

[0041] The other parameters and structure of the sensor remain consistent with those of Example 1.

[0042] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A highly stable ultraviolet energy sensor based on polarization passivation, characterized in that, It includes: First base; A fluorescent conversion crystal disposed above the first substrate is used to convert ultraviolet light into visible light or near-infrared light. A second substrate positioned above the fluorescence conversion crystal; A light-absorbing plate is placed above the second substrate to absorb excess light; The filters, positioned above the second substrate and distributed on both sides of the light-absorbing plate, are used to filter out stray light. The photoelectric converters, located above the second substrate and distributed on both sides of the light-absorbing plate, are used to convert the light signals filtered by the filter into electrical signals. The surfaces of the first substrate, the fluorescent conversion crystal, and the second substrate are all provided with polarization passivation structures to passivate the polarization sensitivity of the interface.

2. The ultraviolet energy sensor according to claim 1, characterized in that, Both the first and second substrates are made of quartz material.

3. The ultraviolet energy sensor according to claim 1, characterized in that, Fluorescent conversion crystals are made of Ce:YAG, sapphire, or titanium sapphire.

4. The ultraviolet energy sensor according to claim 1, characterized in that, The light-absorbing plate is made of stainless steel or aluminum alloy with micro-nano structures or coatings.

5. The ultraviolet energy sensor according to claim 1, characterized in that, The filter is made of organic materials and dyes through molding.

6. The ultraviolet energy sensor according to claim 1, characterized in that, The polarization passivation structures on the surfaces of both the first and second substrates are made of quartz material.

7. The ultraviolet energy sensor according to claim 1, characterized in that, The polarization passivation structure on the surface of the fluorescence conversion crystal is formed by a thinning pad containing diamond abrasive and a mechanical grinding process.

8. The ultraviolet energy sensor according to claim 1, characterized in that, The photoelectric converter is a photodiode.

9. The ultraviolet energy sensor according to any one of claims 1 to 8, characterized in that, It also includes a signal processing module connected to the photoelectric converter, used to process the electrical signals output by the photoelectric converter.

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