A matte fluorescent screen for low-light-level image intensifier and its preparation method

Abstract

The present invention discloses a matte fluorescent screen for a low-light-level image intensifier and a method for preparing the same. The fluorescent screen comprises a fiber optic panel substrate, a substrate adhesive layer, a phosphor layer, and an aluminum film layer. The aluminum film layer has an uneven surface structure and a matte property. The preparation method comprises separately preparing an ultrathin adhesive solution, a potassium silicate solution, and an organic film solution; and sequentially applying the ultrathin adhesive, phosphor, organic film solution, and aluminum film to the fiber optic panel substrate. The fluorescent screen of the present invention has matte properties and can significantly reduce light emissivity, thereby reducing optical feedback from the fluorescent screen, improving the imaging contrast of the image intensifier, and making the image clearer, more eye-catching, and the colors more vivid and bright. The method of the present invention has the advantages of low production cost and high efficiency.

Description

Technical Field

[0001] The present invention relates to the field of low-light-level image intensifiers, and in particular to a matte fluorescent screen for image intensifiers and a preparation method thereof. Background Art

[0002] The phosphor screen is a crucial component of a low-light-level image intensifier (LILI) that converts electronic images into visible light. Its performance directly impacts the image quality and visual quality of the image intensifier's output. The imaging performance of the phosphor screen is closely related to the phosphor material and the screen manufacturing process. Factors such as phosphor particle size and shape, agglomeration, powder layer thickness, aluminum film thickness, backing glue thickness, organic film thickness, and the film formation method all influence the screen's imaging performance. During the phosphor screen manufacturing process, its structure comprises a backing glue layer, a phosphor layer, an organic film layer, and an aluminum film layer. After fabrication, the backing glue layer and organic film layer are removed at high temperatures, leaving only the phosphor layer and aluminum film layer on the glass or optical fiber panel substrate. The aluminum film, as the surface of the phosphor screen, has a certain light reflectivity and can reflect a portion of the light input from the photocathode and the light generated by the phosphor screen back to the photocathode, generating optical feedback. This optical feedback phenomenon can severely reduce the contrast performance of the image intensifier, resulting in unclear and blurred images. Traditionally, increasing the thickness of the aluminum film layer has been used to eliminate optical feedback, but this approach increases production costs and reduces efficiency. Here, we propose a new method. By optimizing the process, during the production of the fluorescent screen, the aluminum film layer is made into an uneven structure, giving it a matte property, thereby reducing the light reflectivity of the aluminum film layer, eliminating light feedback, and improving the imaging contrast of the image intensifier. Summary of the Invention

[0003] The main purpose of the present invention is to provide a matte fluorescent screen for an image intensifier and a preparation method thereof, and to reduce the light reflectivity of the fluorescent screen by improving the preparation process of the fluorescent screen, thereby eliminating the light feedback phenomenon of the image intensifier and improving the imaging contrast of the image intensifier.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is: a matte fluorescent screen for an image intensifier, comprising a fiber optic panel substrate, a fluorescent powder layer and an aluminum film layer.

[0005] Preferably, a substrate adhesive layer is prepared on the optical fiber panel substrate, and the adhesive used is ultra-thin adhesive.

[0006] Preferably, a phosphor layer is brush-coated on the glue layer.

[0007] Preferably, the organic film is dry-sprayed on the phosphor layer, and the diluted organic film solution is sprayed on the phosphor layer to adhere to the edges of the phosphor particles, forming an uneven structure.

[0008] Preferably, the aluminum layer is evaporated on the organic film layer twice.

[0009] The present invention also provides a method for preparing the above-mentioned fluorescent screen, the specific steps of which are as follows:

[0010] Step 1: prepare ultrathin glue, potassium silicate and organic film solution respectively;

[0011] Step 2: Applying the ultra-thin adhesive solution on the optical fiber panel substrate by centrifugation to prepare an ultra-thin adhesive layer on the substrate;

[0012] Step 3: Apply the phosphor to the ultra-thin adhesive layer of the substrate by brush coating;

[0013] Step 4: Remove the substrate glue layer under high temperature conditions in an oven;

[0014] Step 5: Immerse the optical fiber panel substrate coated with phosphor powder in potassium silicate solution, remove it, and centrifuge to dry it to strengthen the phosphor powder layer;

[0015] Step 6: spraying the organic film solution onto the phosphor layer by dry spraying to form an organic film layer;

[0016] Step 7: Use vacuum evaporation equipment to evaporate aluminum film onto the organic film layer with a thickness of

[0017] Step 8: Remove the organic film under high temperature conditions in an oven;

[0018] Step 9: Use vacuum evaporation equipment to evaporate aluminum film again. The thickness of the evaporated aluminum film is

[0019] Step 10: Check the screen for pinholes, cracks, etc. under a microscope using transmitted light and oblique light;

[0020] Step 11: Use an electron gun detector under a microscope to check the fluorescent screen dots, dark marks, etc.

[0021] Step 12: Clean the polishing flange with polishing felt, polishing paste, and cotton swabs;

[0022] Step 13: Apply silver dots on the coating to obtain the matte fluorescent screen.

[0023] Preferably, when preparing the ultra-thin adhesive solution, raw materials such as butyl acetate, 2046 resin, dibutyl phthalate and isobutyl alcohol are selected for preparation.

[0024] Preferably, when preparing the organic membrane solution, polyvinyl alcohol, isopropyl alcohol, polyethylene oxide, acrylic resin and deionized water are selected as raw materials.

[0025] Preferably, when the organic film solution is sprayed onto the phosphor layer by dry spraying, the organic film solution needs to be diluted first so as to form an irregular structure with a concave and convex shape along the edge of the phosphor particles on the phosphor layer.

[0026] Preferably, the phosphor is ZnS:Cu-Al phosphor.

[0027] Mechanism of the present invention:

[0028] If the organic film solution concentration is too high, the resulting organic film layer will inevitably have a flat surface. Therefore, the organic film solution must be diluted before it can be applied to the phosphor layer to form the organic film layer with a concave-convex structure along the edges of the phosphor particles. Subsequently, aluminum is evaporated to form the aluminum film layer with a concave-convex surface structure on the organic film layer.

[0029] First, vapor deposition The thickness of the aluminum film is placed in an oven to remove the organic film layer at high temperature. Thick aluminum layer. Evaporation is carried out twice in order to facilitate the removal of the organic film. The thickness of the aluminum film is too great to completely remove the organic film. Furthermore, the enormous energy impact of aluminum vapor deposition can penetrate the organic film, further damaging the phosphor layer. A thinner aluminum film is required during the first aluminum deposition phase. This is to prevent high energy impact on the organic film, which could damage the phosphor layer. Furthermore, the organic film has an uneven surface structure, and aluminum vapor deposition cannot form a uniform aluminum film on the surface of the organic film. The actual deposition result is a thicker aluminum film on the raised areas of the organic film and a thinner one on the sunken areas. Therefore, a thinner aluminum film should be applied during the first aluminum deposition phase to ensure that the uneven surface structure of the aluminum film is formed.

[0030] Due to the uneven structure of the aluminum film layer, when the light emitted by the fluorescent screen is emitted in the direction of the photocathode, the light is refracted along the normal direction of the concave and convex surface of the aluminum film layer. Ultimately, only a very small portion of the light, or even no light, reaches the photocathode. In addition, the electronic signal input to the photocathode is also mixed with a small amount of light signal. Due to the uneven structure of the aluminum film layer, when this part of the light signal reaches the aluminum film layer, it is refracted along the normal direction of the concave and convex surface of the aluminum film layer, making it impossible for this part of the light to return directly to the photocathode. In summary, the uneven structure of the aluminum film layer can reduce the visible light emitted by the fluorescent screen that returns to the photocathode, while also reducing the small amount of light signal input to the photocathode that returns to the photocathode, thereby reducing optical feedback.

[0031] Beneficial effects of the present invention:

[0032] (1) The aluminum film layer of the fluorescent screen of the present invention has a non-flat, uneven structure with a matte property, which can greatly reduce the light transmittance, thereby reducing the light feedback of the fluorescent screen, improving the imaging contrast of the image intensifier, making the imaging clearer and more eye-catching, and the colors more vivid and bright.

[0033] (2) The present invention also provides a method for preparing the above-mentioned fluorescent screen, which has a simple preparation process, low production cost, and can effectively improve production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 Schematic diagram of the working principle of the low-light-level image intensifier.

[0035] Figure 2 Schematic diagram of the working principle of the fluorescent screen of the present invention.

[0036] In the figure: 1-fiber optic panel substrate, 2-phosphor layer, 3-aluminum film layer. DETAILED DESCRIPTION

[0037] The following description is intended to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments described below are merely examples, and those skilled in the art may conceive of other obvious variations.

[0038] like Figure 2 As shown in FIG. 1 , a fluorescent screen for a low-light-level image intensifier according to the present invention is a multi-layer structure including an optical fiber panel substrate 1 , a fluorescent powder layer 2 and an aluminum film layer 3 .

[0039] The fiber optic panel substrate 1 utilizes a small-diameter fiber optic panel to support the phosphor layer 2 and aluminum film layer 3. The phosphor layer 2 converts the electronic image input from the photocathode into an optical image. The aluminum film layer 3 not only transmits the light generated by the phosphor toward the anode, increasing the brightness, but also serves as a protective layer, preventing the phosphor layer from being contaminated and poisoned by cesium vapor.

[0040] The working principle of low-light image intensifier is as follows Figure 1 As shown. The objective lens forms a weak optical image on the optical fiber panel, and the image is transmitted to the photocathode of the image intensifier through the input window of the optical fiber panel. The photocathode generates a corresponding electronic image. The electron image beam is amplified by the microchannel plate, and then converted into a brightness-enhanced optical image by the anode high-voltage accelerated excitation fluorescent screen, and finally output through the output window of the optical fiber panel. The entire image intensifier completes the conversion of "input weak optical image → corresponding electronic image → high-energy and high-beam current electronic image → output optical image". Among them, the working principle of the image intensifier using the fluorescent screen is as follows Figure 2 As shown, electrons penetrate the aluminum film layer 3 and excite the phosphor layer 2. After the phosphor absorbs the electrons, it emits visible light and outputs a visible light image through the output window of the optical fiber panel substrate 1. Figure 2 As shown, the aluminum film layer has an uneven structure, which can reduce the visible light emitted by the fluorescent screen returning to the photocathode, and at the same time reduce the small amount of light signal input by the photocathode returning to the photocathode, thereby reducing light feedback.

[0041] Example: The above fluorescent screen can be prepared by the following methods:

[0042] The present invention provides a method for preparing a matte fluorescent screen for a low-light-level image intensifier. First, a small-diameter optical fiber panel substrate is selected and cleaned; a glue solution is evenly applied to the optical fiber panel substrate by a centrifugal method to form a substrate glue layer; phosphor powder (ZnS:Cu-Al micron phosphor powder) is evenly applied to the substrate glue by a brush coating method to form a phosphor powder layer; the glue layer is removed in an oven at 400°C; the powder layer is reinforced by immersing in a 5% potassium silicate solution; a diluted organic film solution is sprayed onto the phosphor powder layer to form an organic film layer; and an aluminum film layer is evaporated in a vacuum coating machine to a thickness of 1000 nm. Add and remove the organic film in the oven; evaporate the aluminum film layer in the vacuum coating machine with a thickness of After the aluminum plating process is complete, the screen is inspected for pinholes, cracks, and other defects under a microscope using both transmitted and oblique light. Dark spots and dark marks are also inspected under a microscope using an electron gun. The flange is further polished with polishing felt and polishing paste to achieve a bright surface. Once the surface passes inspection, silver dots are applied to the coating. This completes the matte fluorescent screen described in the present invention.

[0043] The above description describes the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and description only describe the principles of the present invention. Various changes and improvements may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and improvements fall within the scope of the present invention as claimed.

Claims

1. A method for preparing a matte fluorescent screen for a low-light-level image intensifier, wherein the matte fluorescent screen comprises an optical fiber panel, characterized in that: The optical fiber panel further comprises a phosphor layer (2) located on the substrate (1) of the optical fiber panel and an aluminum film layer (3) supported on the phosphor layer (2), wherein the surface of the aluminum film layer (3) is uneven and has a matte property; an organic film layer is coated on the phosphor layer (2) between the phosphor layer (2) and the aluminum film layer (3), and the phosphor layer (2) is reinforced with a potassium silicate solution before the organic film layer is coated; and before the organic film solution is sprayed onto the phosphor layer (2), the organic film solution is diluted so that an irregular structure with a concave and convex shape along the edge of the phosphor particles is formed on the phosphor layer (2); The preparation method specifically comprises the following steps: Step 1: prepare ultrathin glue, potassium silicate and organic film solution respectively; Step 2: coating the ultra-thin adhesive solution on the substrate (1) by centrifugation to prepare an ultra-thin adhesive layer on the substrate; Step 3: Apply the phosphor to the ultra-thin adhesive layer of the substrate by brush coating; Step 4: Remove the substrate glue layer under high temperature conditions in an oven; Step 5: Immerse the substrate coated with phosphor powder in potassium silicate solution, remove it, and centrifuge to dry it to strengthen the phosphor powder layer (2); Step 6: spraying an organic film solution onto the phosphor layer (2) by a dry spraying method to form an organic film layer; the organic film solution is prepared by selecting polyvinyl alcohol, isopropyl alcohol, polyethylene oxide, acrylic resin and deionized water as raw materials; Step 7: using a vacuum evaporation device to deposit an aluminum film onto the organic film layer, wherein the thickness of the aluminum film is 300 Å; Step 8: Remove the organic film under high temperature conditions in an oven; Step 9: Vacuum evaporation equipment is used to evaporate an aluminum film layer (3) again, wherein the thickness of the aluminum film is 600Å; Step 10: Check under a microscope using transmitted light and oblique light to confirm that there are no pinholes or cracks on the phosphor screen; Step 11: Check the fluorescent screen under a microscope using an electron gun detector to confirm that there are no dark spots or dark marks; Step 12: Clean the polishing flange with polishing felt, polishing paste, and cotton swabs; Step 13: Apply silver dots on the coating to obtain the matte fluorescent screen.

2. The preparation method according to claim 1, wherein: In step 1, when preparing the ultra-thin adhesive solution, butyl acetate, 2046 resin, diacetone alcohol and isobutanol are selected as raw materials for preparation.

3. The preparation method according to claim 1, characterized in that The substrate (1) is a small-diameter optical fiber panel.

4. The preparation method according to claim 1, characterized in that The phosphor is ZnS:Cu-Al phosphor.

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