阅读说明：本技术 基于下转换发光的日盲紫外探测器、制备方法和探测相机 (Solar blind ultraviolet detector based on down-conversion luminescence, preparation method and detection camera ) 是由 粘伟 唐义 丁明烨 苏云 郑国宪 单瑞* 董联庆 杨立欣 于 2020-12-16 设计创作，主要内容包括：本发明涉及基于下转换发光的日盲紫外探测器、制备方法和探测相机。所述日盲紫外探测器通过采用热蒸发法镀膜技术,将粉末状下转换纳米材料在可见光CCD芯片感光面形成一层均匀纳米薄膜,实现直接耦合,通过纳米薄膜吸收日盲段紫外光发射可见光的特性,从而实现高效的紫外光探测,有效解决天基紫外预警探测器面阵小、量子效率低的问题。(The invention relates to a solar blind ultraviolet detector based on down-conversion luminescence, a preparation method and a detection camera. The solar blind ultraviolet detector adopts a thermal evaporation method coating technology to form a layer of uniform nano film on a photosensitive surface of a visible light CCD chip by using a powdery down-conversion nano material, so that direct coupling is realized, and the characteristic that the nano film absorbs ultraviolet light at a solar blind section to emit visible light is utilized, so that efficient ultraviolet detection is realized, and the problems of small area array and low quantum efficiency of the space-based ultraviolet early warning detector are effectively solved.)

1. A solar blind ultraviolet detector based on down-conversion luminescence is characterized by comprising a visible light CCD and a down-conversion nano material film, wherein the down-conversion nano material film is deposited on a visible light CCD photosensitive surface;

the down-conversion nano material is used for realizing the conversion from a solar blind ultraviolet spectrum section to a visible spectrum section;

the visible light CCD is a detection device with a response spectrum section being a visible light spectrum section and is used for responding to visible light and outputting a current signal corresponding to the intensity of the visible light.

2. The solar-blind ultraviolet detector based on the down-conversion luminescence of claim 1, wherein the down-conversion nano material is a rare earth doped fluoride nano material.

3. The solar-blind ultraviolet detector based on down-conversion luminescence according to claim 2, wherein the down-conversion material is Ce³⁺As sensitizer, Tb³⁺As a luminescent ion, beta-NaYF₄As matrix, the three are prepared by a solvothermal method according to the ion concentration ratio of 1:2:4And (4) performing nano synthesis.

4. The solar-blind ultraviolet detector based on down-conversion luminescence of claim 1, wherein the down-conversion material film has broadband excitation and narrow-band emission characteristics, the excitation wavelength range is 215nm to 275nm, and the peak value is 248 nm; the emission wavelength has four peaks of 485nm, 542nm, 581nm and 621 nm.

5. The solar-blind ultraviolet detector based on down-conversion luminescence according to claim 1, wherein the thickness of the down-conversion material film ranges from 30nm to 800 nm.

6. The solar-blind ultraviolet detector based on down-conversion luminescence of claim 1, wherein the down-conversion material film is deposited on the visible light CCD photosensitive surface by means of thermal evaporation.

7. The method for preparing a solar blind ultraviolet detector based on down-conversion luminescence as claimed in claim 1, characterized by comprising the following steps:

s1, removing a light-sensitive surface window of the visible CCD, and exposing the light-sensitive surface of the visible CCD device to the outside;

s2, placing the visible light CCD with the photosensitive surface window removed and a lower conversion material in a vacuum chamber, placing the lower conversion material on an evaporation boat, placing the visible light CCD above the evaporation boat, and placing the photosensitive surface downwards;

s3, adopting resistance type evaporation principle, heating the down-conversion material on the evaporation boat by current to melt and evaporate the down-conversion material, thereby depositing the down-conversion material film on the surface of the detector chip and realizing the direct coupling of the material and the detector.

8. The method for preparing a solar-blind ultraviolet detector based on down-conversion luminescence of claim 7, wherein the current is controlled to be 100A ± 0.5A in step S3, and the evaporation rate is maintained to be between 1A/S and 1.5A/S.

9. A solar-blind ultraviolet detection camera, characterized by comprising the solar-blind ultraviolet detector of claim 1, an ultraviolet lens and an ultraviolet filter; ultraviolet light entering the ultraviolet lens passes through the ultraviolet filter, visible light and near ultraviolet light are filtered by the ultraviolet filter, and ultraviolet light reaching the film surface of the solar blind ultraviolet detector is concentrated in a solar blind spectral band.

Technical Field

The invention belongs to the field of space-based ultraviolet early warning, and relates to a solar blind ultraviolet detector based on down-conversion luminescence, a preparation method and a detection camera.

Background

The ultraviolet early warning is an important development direction of space-based early warning, and has the advantages of low false alarm rate and false alarm rate, no need of refrigeration, simple system, capability of effectively resisting blindness caused by laser weapons and the like compared with infrared early warning. The ultraviolet detector is used as an indispensable device in an ultraviolet early warning system, and the development of the ultraviolet detector mainly goes through three stages: the first stage is represented by an ultraviolet photomultiplier, the second stage is a Si-based ultraviolet detector, and the third stage is a wide-bandgap semiconductor material. The method is limited by technical maturity and use conditions, no effective ultraviolet detection device exists in the current space-based ultraviolet early warning, all detectors are in a photomultiplier tube form, and the working conditions are vacuum and high pressure. A typical structure commonly used is shown in figure 1 and mainly comprises 6 parts of an incidence window, a photoelectric cathode, a micro-channel plate MCP, a fluorescent screen, a coupling optical fiber and a visible light CMOS. The basic working principle is as follows: photons incident from an incidence window irradiate on a photocathode, are converted into photoelectrons according to a certain quantum conversion efficiency, enter an MCP for multiplication under the action of an accelerating electric field, are focused on a fluorescent screen to excite visible light, couple an image to a visible light CMOS through a fiber optic cone, and finally read by an electronic circuit to finish the conversion from the incident light to the electronic image.

The detector assembly has the advantages of good stability, high response speed, low dark current and high current gain. However, the detector assembly has large volume, large power consumption and high price, optical window materials and optical filters are required to be used, and the quantum efficiency is only 10% -20%.

Disclosure of Invention

The technical problem solved by the invention is as follows: the solar blind ultraviolet detector, the preparation method and the detection camera based on down-conversion luminescence are provided, and the problems that no effective detector for space-based ultraviolet early warning is small in area array and low in quantum efficiency are solved.

The technical scheme of the invention is as follows: a solar blind ultraviolet detector based on down-conversion luminescence comprises a visible light CCD and a down-conversion nano material film, wherein the down-conversion nano material film is deposited on a photosensitive surface of the visible light CCD;

the down-conversion nano material is used for realizing the conversion from a solar blind ultraviolet spectrum section to a visible spectrum section;

the visible light CCD is a detection device with a response spectrum section being a visible light spectrum section and is used for responding to visible light and outputting a current signal corresponding to the intensity of the visible light.

The down-conversion nano material is a rare earth doped fluoride nano material.

The down-conversion material is Ce³⁺As sensitizer, Tb³⁺As a luminescent ion, beta-NaYF₄The three are taken as matrixes, and the three are subjected to nano synthesis by a solvothermal method according to the ion concentration ratio of 1:2: 4.

The down-conversion material film has broadband excitation and narrow-band emission characteristics, the excitation wavelength range is 215nm-275nm, and the peak value is 248 nm; the emission wavelength has four peaks of 485nm, 542nm, 581nm and 621 nm.

The thickness of the down-conversion material film ranges from 30nm to 800 nm.

The down-conversion material film is deposited on the visible light CCD photosensitive surface by a thermal evaporation method.

The invention provides another technical scheme that: the preparation method of the solar blind ultraviolet detector based on down-conversion luminescence comprises the following steps:

s1, removing a light-sensitive surface window of the visible CCD, and exposing the light-sensitive surface of the visible CCD device to the outside;

s2, placing the visible light CCD with the photosensitive surface window removed and a lower conversion material in a vacuum chamber, placing the lower conversion material on an evaporation boat, placing the visible light CCD above the evaporation boat, and placing the photosensitive surface downwards;

s3, adopting resistance type evaporation principle, heating the down-conversion material on the evaporation boat by current to melt and evaporate the down-conversion material, thereby depositing the down-conversion material film on the surface of the detector chip and realizing the direct coupling of the material and the detector.

The current is controlled to be 100A + -0.5A in the step S3, and the evaporation rate is kept between 1A/S and 1.5A/S.

The invention provides another technical scheme that: a solar-blind ultraviolet detection camera comprising the solar-blind ultraviolet detector of claim 1, an ultraviolet lens, and an ultraviolet filter; ultraviolet light entering the ultraviolet lens passes through the ultraviolet filter, visible light and near ultraviolet light are filtered by the ultraviolet filter, and ultraviolet light reaching the film surface of the solar blind ultraviolet detector is concentrated in a solar blind spectral band.

Compared with the prior art, the invention has the beneficial effects that:

(1) the invention adopts the down-conversion nano material to realize the conversion from the solar blind ultraviolet spectrum section to the visible spectrum section, and then the material is directly coupled with the visible light CCD, thereby enlarging the induction area of the existing ultraviolet detector and improving the quantum efficiency.

(2) The nano material is a rare earth doped fluoride nano material, belongs to an inorganic substance, and has the characteristics of narrow-band absorption, narrow-band emission, extremely high light conversion efficiency, excellent physical and chemical stability and light stability, low biological toxicity and the like.

(3) The invention down-converts the nanomaterial with Ce³⁺Ions as sensitizer, Tb³⁺As a luminescent ion, beta-NaYF₄Nano-synthesis by solvothermal method using Ce as matrix³⁺Absorb ultraviolet photons and then transfer the energy to Tb³⁺Ion, Tb³⁺The ions undergo radiative transitions, thereby achieving an efficient down-conversion (transfer) luminescence phenomenon.

(4) The preparation method of the solar blind ultraviolet detector based on down-conversion luminescence can conveniently control the evaporation rate of the coating material by adjusting the magnitude of the applied current, and ensure that the surface of the film layer is uniform and smooth;

(5) the solar-blind ultraviolet spectral band camera provided by the invention is additionally provided with the high-performance ultraviolet filter, and ultraviolet light reaching the surface of the detector film is concentrated in the solar-blind spectral band, so that the influence of light of other spectral bands on imaging is reduced.

Drawings

FIG. 1 is a schematic diagram of a microchannel electron multiplier detector according to an embodiment of the present invention;

FIG. 2 is a schematic view of the luminescent principle of the rare earth doped fluoride nano-material according to the embodiment of the present invention;

FIG. 3 is a graphical representation of the conversion of the absorption and emission spectra of nanomaterials in accordance with embodiments of the present invention;

FIG. 4 is a schematic view of thermal evaporation coating according to an embodiment of the present invention;

FIG. 5 is a schematic view of a reflective measurement optical path of a coated CCD camera according to an embodiment of the present invention.

Detailed Description

The invention is further illustrated by the following examples.

The invention provides a solar blind ultraviolet detector based on down-conversion luminescence, which comprises a visible light CCD and a down-conversion nano material film, wherein the down-conversion nano material film is deposited on the photosensitive surface of the visible light CCD. Each part is characterized in that:

the down-conversion nano material is used for realizing the conversion from a solar blind ultraviolet spectrum section to a visible spectrum section;

the visible light CCD is a detection device with a response spectrum section being a visible spectrum section and is used for responding to visible light and outputting a current signal corresponding to the intensity of the visible light, so that the solar blind ultraviolet spectrum section can be effectively detected.

The down-conversion nano material is a rare earth doped fluoride nano material. The material belongs to inorganic substances, and has the characteristics of narrow-band absorption, narrow-band emission, extremely high light conversion efficiency, excellent physical and chemical stability and light stability, low biological toxicity and the like.

Down-converting the nanomaterial with Ce³⁺As sensitizer, Tb³⁺As a luminescent ion, beta-NaYF 4 is used as a matrix, and the three are subjected to nano synthesis by a solvothermal method according to an ion concentration ratio of 1:2: 4. Ce³⁺Absorb ultraviolet photons and then transfer the energy to Tb³⁺Ion, Tb³⁺The ions undergo radiative transitions, thereby achieving an efficient down-conversion (transfer) luminescence phenomenon, the luminescent color being green light. As shown in fig. 2.

The down-conversion nano material film has the characteristics of broadband excitation and narrow-band emission, the excitation wavelength range is 215nm-275nm, and the peak value is 248 nm; the emission wavelength had four peaks of 485nm, 542nm, 581nm and 621nm, respectively, as shown in FIG. 3.

The visible light CCD refers to a detection device with a response spectrum section being a visible light spectrum section, and a basic component unit of the detection device is an MOS capacitor. When a light photon is incident, an electron is excited in the semiconductor material of the MOS capacitor, and the electron accumulates in the MOS capacitor to await transfer readout. The readout voltage is obtained by performing a predetermined sequence of operations on the gate voltage of the semiconductor material, so that the charges can be sequentially transferred and finally outputted at the output stage.

The thickness of the down-conversion nano material film ranges from 30nm to 800 nm.

The down-conversion nano material film is deposited on the visible light CCD photosensitive surface by a thermal evaporation method, namely, under high vacuum, the down-conversion nano material film is heated and evaporated on an evaporation boat by using large current by adopting a resistance type evaporation principle, so that the down-conversion nano material film is melted and evaporated at high temperature, and the down-conversion nano material film is deposited on the surface of a detector chip, and the direct coupling of the material and the detector is realized.

The detector adopts a down-conversion nano material to form a layer of uniform nano film on the photosensitive surface of the visible light CCD chip by a thermal evaporation coating technology, so that direct coupling is realized, and efficient ultraviolet light detection is realized by the characteristic that the nano film absorbs ultraviolet light in the solar blind section to emit visible light.

The invention also provides a solar blind ultraviolet detection camera, which comprises the solar blind ultraviolet detector, an ultraviolet lens and an ultraviolet filter; ultraviolet light entering the ultraviolet lens passes through the ultraviolet filter, visible light and near ultraviolet light are filtered by the ultraviolet filter, and ultraviolet light reaching the film surface of the solar blind ultraviolet detector is concentrated in a solar blind spectral band. And finally, the detection of ultraviolet spectrum bands of 215nm-275nm can be realized, a high-performance ultraviolet filter is required to be added in an optical system, and the ultraviolet light reaching the surface of a detector film is concentrated in a solar blind spectrum band so as to reduce the influence of light of other spectrum bands on imaging.

The preparation method of the solar blind ultraviolet detector based on down-conversion luminescence comprises the following steps:

s1, removing a light-sensitive surface window of the visible CCD, and exposing the light-sensitive surface of the visible CCD device to the outside;

s2, placing the visible light CCD with the photosensitive surface window removed and the down-conversion nano material in a vacuum chamber with the vacuum degree of 1 multiplied by 10^-5Pa. The down-conversion nano material is placed on an evaporation boat, a visible light CCD is placed above the evaporation boat, and the photosensitive surface is downward;

s3, adopting resistance type evaporation principle, using current to heat the evaporation boat to convert the nanometer material, melting and evaporating, depositing the down-conversion nanometer material film on the surface of the detector chip, realizing the direct coupling of the material and the detector.

The evaporation rate of the coating material can be conveniently controlled by adjusting the magnitude of the applied current. In the invention, in order to ensure that the surface of the film layer is uniform and smooth, the current in the step S3 is controlled to be 100A +/-0.5A, and the evaporation rate is kept between 1A/S and 1.5A/S.

Example 1:

in a specific embodiment of the present invention, a highly efficient down-conversion nanomaterial is coupled with a visible light CCD by thermal evaporation, as shown in fig. 4, wherein the down-conversion nanomaterial has broadband excitation and narrow-band emission characteristics, the excitation wavelength range is 215nm to 275nm, and the peak value is 248 nm; the emission wavelength has four peaks of 485nm, 542nm, 581nm and 621 nm. And removing the light-sensitive surface window of the visible light CCD, and exposing the light-sensitive surface of the visible light CCD device to enable the nano material film to be in direct contact with the CCD light-sensitive surface. During thermal evaporation, the vacuum degree is maintained at 1X 10^-5Pa, controlling the current to be always at 100A +/-0.5A, further keeping the evaporation rate between 1 angstrom/second and 1.5 angstrom/second, and carrying out thermal evaporation coating for 100 minutes under the condition to complete the thickness of the 600nm film layer.

The coated CCD device is arranged on a visible light camera, an ultraviolet lens is replaced, a high-performance ultraviolet filter is added in an optical system, most of visible light and near ultraviolet light are filtered, ultraviolet light reaching the surface of a detector film is concentrated in a solar blind spectrum band, the influence of light of other spectrum bands on imaging is reduced, and the detection of the ultraviolet spectrum band of 215nm-275nm is realized. As shown in fig. 5, the performance of the novel ultraviolet detector based on down-conversion luminescence can be qualitatively verified by using an ultraviolet LED array lamp with a central wavelength of 250nm and a power of 35mW to irradiate a target and shooting the target through a novel ultraviolet CCD camera to reflect ultraviolet light for imaging.

Although the present invention has been described with reference to the preferred embodiments, it is not intended to limit the present invention, and those skilled in the art can make variations and modifications of the present invention without departing from the spirit and scope of the present invention by using the methods and technical contents disclosed above.