Encoding disk for single-pixel imaging and method for manufacturing thereof

Abstract

The present application relates to an encoding disc for single-pixel imaging and a preparation method thereof. A preparation method of an encoding disc for single-pixel imaging can include: forming a photoresist layer on a transparent substrate; performing exposure and development on the photoresist layer to form a photoresist pattern layer, the photoresist pattern layer having an opening pattern to expose a part of the substrate; sequentially orienting and depositing a contact layer and a reflective metal layer on the photoresist pattern layer and the exposed part of the substrate; peeling off the photoresist pattern layer and the contact layer and the reflective metal layer located on the photoresist pattern layer, leaving the contact layer and the reflective metal layer located on the substrate, wherein the area of peeling off the photoresist pattern layer forms a transmission area pattern in the encoding area of the encoding disc, and the area of leaving the contact layer and the reflective metal layer located on the substrate forms a reflection area pattern in the encoding area of the encoding disc, wherein the contact layer comprises a Ti layer, and the reflective metal layer comprises an Ag layer.

Description

Technical Field

[0001] This invention relates to an encoding disk for single-pixel imaging and a method for preparing the same. Background Technology

[0002] In single-pixel imaging systems, the single-pixel detector and spatial light modulator play crucial roles, their performance directly impacting the overall imaging quality and efficiency. The primary function of the single-pixel detector is to detect and record the light signal passing through the spatial light modulator. The excellent spectral response and operating bandwidth of a single-pixel detector mean it can cover a wider spectral range, thus capturing a greater variety of light signals. This is critical for imaging systems because different objects and materials may emit or reflect light of different wavelengths. Therefore, a single-pixel detector with superior spectral response and operating bandwidth can provide richer and more accurate image information. However, the performance of a spatial light modulator is often difficult to match that of a single-pixel detector.

[0003] Spatial light modulators typically consist of an opaque material layer, also known as a mask layer, formed on a transparent substrate. The optical properties of the mask material significantly impact image quality. Appropriate materials must be selected to achieve low transmittance and high reflectance across the imaging spectral bands of a single-pixel detector, while also possessing good optical stability and durability, as well as strong adhesion to the substrate material to ensure long-term use. For example, reflective layers typically made of metal have different coefficients of thermal expansion than substrates typically made of glass; therefore, the metal layer may detach from the glass substrate due to thermal expansion and contraction. Furthermore, mask design must ensure good isolation between different spectral bands to avoid mutual interference and cross-influence. This usually requires the use of multilayer films or special optical structures. Finally, due to the need for multi-band spectral imaging, the design of the mask's coding pattern is crucial. Optimization is needed in aspects such as the mask's filtering method, the arrangement of the coding pattern, and the size of the coding pattern to achieve optimal multi-band spatial mask coding design, ultimately resulting in high-efficiency single-pixel imaging. Single-pixel mask modulation imaging systems are superior to other modulation methods in terms of system complexity, and therefore have been widely used in non-optical fields such as X-rays and terahertz waves.

[0004] For the reasons mentioned above, a scheme to achieve single-pixel imaging using rotational encoding has been proposed. Currently, most single-pixel encoding disks are made by plating chromium onto a glass substrate. Since the reflectivity of chromium is in the range of approximately 60-70%, the imaging modulation depth still needs improvement.

[0005] It should be noted that the background information presented here is only for illustrating relevant information about the present invention to aid in understanding the technical solution of the present invention, and does not imply that the relevant information is necessarily prior art. The relevant information was submitted and disclosed together with the present invention, and should not be considered prior art unless there is evidence that the relevant information was disclosed before the filing date of the present invention. Summary of the Invention

[0006] To address the above problems, this invention is proposed.

[0007] One aspect of the present invention provides a method for fabricating an encoding disk for single-pixel imaging, comprising: forming a photoresist layer on a transparent substrate; performing exposure and development on the photoresist layer to form a photoresist pattern layer, the photoresist pattern layer having an opening pattern to expose a portion of the substrate; sequentially and directionally depositing a contact layer and a reflective metal layer on the exposed portion of the photoresist pattern layer and the substrate; stripping the photoresist pattern layer and the contact layer and reflective metal layer located on the photoresist pattern layer, leaving the contact layer and reflective metal layer located on the substrate, wherein the area where the photoresist pattern layer is stripped forms a transmissive area pattern in an encoding region of the encoding disk, and the area where the contact layer and reflective metal layer are left on the substrate forms a reflective area pattern in an encoding region of the encoding disk, wherein the contact layer comprises a Ti layer and the reflective metal layer comprises an Ag layer.

[0008] The method further includes: forming an adhesion promoter layer on the substrate before forming a photoresist layer; and after performing exposure and development on the photoresist layer to form a photoresist pattern layer, etching away the portion of the adhesion promoter layer exposed through the photoresist pattern layer to expose the substrate, wherein, when stripping the photoresist pattern layer, the remaining portion of the adhesion promoter layer located below the photoresist pattern layer is also stripped.

[0009] Specifically, during the sequential directional deposition of the contact layer and the reflective metal layer, a transparent protective layer is also directionally deposited on the reflective metal layer. During the stripping of the photoresist pattern layer, the contact layer, the reflective metal layer, and the transparent protective layer on the photoresist pattern layer are simultaneously stripped.

[0010] In some embodiments, the method further includes: after stripping the photoresist pattern layer, blanket-depositing a transparent protective layer on the reflective metal layer and on the exposed surface of the substrate.

[0011] In some embodiments, the thickness of the contact layer is in the range of 10 nm to 100 nm, and the thickness of the reflective metal layer is in the range of 20 nm to 220 nm.

[0012] In some embodiments, the thickness of the contact layer is in the range of 20 nm to 80 nm, and the thickness of the reflective metal layer is in the range of 30 nm to 200 nm.

[0013] In some embodiments, the contact layer and the reflective metal layer are formed by electron beam evaporation or magnetron sputtering.

[0014] In some embodiments, forming a photoresist layer includes: coating a photoresist material onto the substrate using a spin coating method; and baking the coated photoresist material to cure it.

[0015] In some embodiments, the method further includes baking the photoresist layer after exposure and before development.

[0016] Another aspect of the present invention provides an encoding disk for single-pixel imaging, which is prepared by the above method.

[0017] The above and other features and advantages of the present invention will become apparent from the following detailed description of exemplary embodiments in conjunction with the accompanying drawings. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of an encoding disk for single-pixel imaging according to an embodiment of the present invention.

[0019] Figure 2 This is a schematic diagram of the encoding area and encoding pattern of an encoding disk according to an embodiment of the present invention.

[0020] Figure 3A-3G This is a schematic diagram of a method for manufacturing an encoded disk according to an embodiment of the present invention.

[0021] Figure 4 yes Figure 3C The photograph shows the exposure process.

[0022] Figure 5 yes Figure 3F The photo shows the coating process.

[0023] Figure 6 These are the reflectance spectral curves of multiple encoder disk samples prepared according to embodiments of the present invention. Detailed Implementation

[0024] Exemplary embodiments of the present invention will now be described with reference to the accompanying drawings.

[0025] Figure 1 A schematic diagram of an encoder disk 100 for single-pixel imaging according to an embodiment of the present invention is shown. Figure 1As shown, the encoder disk 100 may include a disk body 101, which may be opaque, for example, including an opaque material layer covering a transparent body. The transparent body may include plastic, glass, quartz, sapphire substrate, etc., and the opaque material may include, for example, but not limited to, a metal layer. The disk body 101 may have a disk shape, and one or more positioning holes 102 may be formed at the center for fixing the disk body 101 to a drive mechanism to rapidly rotate the disk body 101. The positioning holes 102 are not limited to... Figure 1 It can be any other shape, not just a circle as shown.

[0026] exist Figure 1 In the illustrated embodiment, a coding area 110 may be provided on the disk body 101, and the coding area 110 may be located in a code track on the disk body 101. The code track is a plurality of circular rings divided in the radial direction, and the coding area 110 may extend a portion of the code track, or it may extend the entire code track. Although Figure 1 Only one encoding region 110 is shown; however, it should be understood that the encoding disk 100 may include multiple encoding regions disposed in the same code track, and the encoding regions may be separated by an opaque disk body portion. This separating region can be used to distinguish the imaging signals formed by each code track. Furthermore, the encoding disk 100 may also include multiple encoding regions disposed in different code tracks, without imposing any special limitations on this invention.

[0027] Figure 2 A schematic diagram of the encoding area 110 and its encoding pattern of an encoding disk 100 according to an embodiment of the present invention is shown. For convenience, the encoding area 110 is shown as a rectangular strip shape, but in reality it is as follows: Figure 1 The diagram shows a circular shape. As shown, the coding pattern in coding area 110 includes a transmissive area (i.e., a transparent area, shown in white) and a reflective area (shown in black). The transmissive area may be an area where the reflective metal layer on the disk body 101 has been removed, while the reflective area may be an area where a reflective metal layer is formed on the transparent body of the disk body 101. The transparent body of the disk body 101 may include, for example, glass, quartz, plastic, sapphire substrate, etc. The reflective metal layer in the reflective area of ​​coding area 110 may include multiple layers of metal material, which will be described in further detail below. It should be understood that the non-transparent material of the disk body portion outside coding area 110 of the coding disk 100 may be different from the reflective metal layer of the reflective area; for example, it may be formed of an opaque material that does not have strong reflective properties.

[0028] The encoding area 110 of the encoding disk 100 can employ various encoding schemes, such as, but not limited to, Fourier sampling basis encoding, Hadamard matrix encoding, and cyclic S-matrix encoding. In use, the encoding disk 100 is driven to rotate rapidly, and the imaging optical system focuses the light beam reflected or emitted by the imaging object onto the encoding pattern in the code track, such as... Figure 2As shown in the speckle pattern, as the encoder disk 100 rotates, the speckle scans the entire encoding area 110. The light beams in the speckle are either reflected by the reflection area or transmitted through the transmission area. The reflected or transmitted signal light is detected by the single-pixel detector and converted into an electrical signal. Using this electrical signal, an image of the imaging object can be reconstructed based on a reconstruction algorithm. The imaging principle of a single-pixel imaging system is known and will not be described in detail here.

[0029] As mentioned earlier, the reflective area of ​​the encoding region 110 should have sufficiently high reflectivity, while the transmissive area should have sufficiently high transmittance to improve the modulation depth of the image. Furthermore, the reflective area should also possess good optical stability and durability, as well as good adhesion to the host material, to ensure long-term use. To address these issues, this application proposes a method for fabricating the encoding disk 100, which will be described below with reference to... Figure 3A-3G Let me explain in detail.

[0030] First refer to Figure 3A A transparent substrate 201 is provided, which serves as the main body of the encoding disk 100. The transparent substrate 201 can be disc-shaped or other shapes, such as rectangles, and can be cut into a disc shape in subsequent processes, such as after the encoding area 110 has been formed. The surface of the transparent substrate 201 can be pretreated to thoroughly remove various contaminants such as particles, organic matter, and process residues, ensuring a clean and flawless surface. Simultaneously, the potential impact of water vapor on the surface must be effectively eliminated to provide ideal conditions for subsequent processing. Effective surface treatment and pre-baking ensure the adhesion and stability of subsequent layers formed on the substrate 201.

[0031] like Figure 3A As shown, an adhesion promoter layer 202 can be formed on a transparent substrate 201. The adhesion promoter layer 202 ensures the strong adhesion of the subsequently formed photoresist layer to the transparent substrate 201. The adhesion promoter can be selected according to the photoresist material used. In one embodiment, a commercially available adhesion promoter, such as AR300-80, can be used. The adhesion promoter layer 202 can be formed by spin coating, for example, by using a dropper to drop the adhesion promoter onto the surface of the transparent substrate 201, and then using a coating machine to spin the transparent substrate 201 at a speed of 1500 to 6000 RPM for a predetermined time, such as 10 seconds to 1 minute. It is understood that the higher the speed and the longer the spin time, the thinner the adhesion promoter layer 202 will be. In one embodiment, a heating process can also be performed after spin coating of the adhesion promoter to rapidly cure it. For example, for the adhesion promoter AR300-80, it can be baked at a temperature of 180°C for 2 minutes.

[0032] Then, as Figure 3BAs shown, a photoresist layer 203 can be formed on the tackifier layer 202. The photoresist layer 203 can be formed using methods such as spin coating or spray coating. Since different types of photoresists have different properties, such as viscosity, process parameters, such as rotation speed, ramp speed, and rotation time, can be adjusted according to specific circumstances. In some embodiments, positive photoresist AZ6130, negative photoresist AZ5214E, or double-layer photoresist LOR2A can be selected. Positive photoresist is the photoresist whose exposed portions are developed and removed, negative photoresist is the photoresist whose unexposed portions are developed and removed, and double-layer photoresist is a material that can be coated multiple times to form two or more layers. Each coating can be baked and cured before the next coating is applied. When using spin coating, the rotation speed can be in the range of 1500 to 6000 RPM, for example, around 4000 RPM, and the rotation time can be from 10 seconds to 1 minute. In some embodiments, a thicker photoresist layer 203 can be formed by controlling process parameters such as rotation speed, rotation time, and number of photoresist layers. For example, the thickness can range from 1 μm to 100 μm, preferably from 10 μm to 100 μm. After spin-coating the photoresist material, it can also be heated, also known as a pre-baking process, to effectively remove solvents from the photoresist, allowing it to solidify, enhancing its adhesion and mechanical strength, releasing internal stress, and preventing photoresist contamination of the equipment. The pre-baking process varies for different photoresist materials. For example, photoresist LOR2A can be baked at 180°C for about 1 minute, photoresist AZ6130 for about 3 minutes at 180°C, and photoresist AZ5214E ​​for about 1.5 minutes at 90°C.

[0033] After the pre-baking process and natural cooling described above, the photoresist layer 203 can be exposed. For example... Figure 3C As shown, during the exposure process, the substrate 201 is placed on the sample stage with the photoresist layer 203 facing upwards. By moving the sample stage, the substrate 201 is ensured to be perfectly aligned with the mask 204. Then, the exposure parameters are adjusted and the exposure operation is performed. A predetermined light source, such as a 365nm wavelength light source, is typically used in a constant intensity mode, and the exposure amount is adjusted by controlling the exposure time. The mask 204 has a pattern formed by light-transmitting areas and light-blocking areas, which can correspond to a predetermined coded pattern in the coded area 110. By irradiating the corresponding area of ​​the photoresist layer 203 with a predetermined amount of light, the pattern on the mask 204 can be accurately transferred to the photoresist, thereby achieving pattern replication and transfer. Figure 4 The image shows a photoresist layer 203 placed under an exposure mask during the exposure process, where the dark areas are the light-blocking areas in the mask and the light-transmitting areas are the light-transmitting areas in the mask.

[0034] In some embodiments, during execution Figure 3CFollowing the exposure process shown, and before development, the photoresist layer 203 can be post-baked. Post-baking eliminates standing wave effects, improves pattern clarity and accuracy, and thus further optimizes photoresist performance and imaging results. In some embodiments, post-baking can be omitted.

[0035] Continue to refer to Figure 3D After exposure, the photoresist layer 203 can be developed. Development involves placing the photoresist in a specific developer solution for selective etching, clearly revealing the subtle differences between exposed and unexposed areas in the photoresist, thereby achieving precise pattern transfer and obtaining the desired pattern. As mentioned earlier, for positive photoresist, the exposed photoresist portions are etched away, while the unexposed photoresist portions are retained; the opposite is true for negative photoresist, thus achieving precise transfer of the pattern from the photomask used for exposure to the photoresist. Commonly used developers generally include aqueous solutions of organic amines or inorganic salts, but an appropriate developer can be selected depending on the photoresist used. In some embodiments, commercially available developer AZ300MIF can be used, with a development time of, for example, 30 seconds to 3 minutes, such as about 1 minute. After development, baking can be performed to remove the developer from the sample.

[0036] After development, such as Figure 3D As shown, the adhesive layer 202 remains on the substrate 201, located below the photoresist layer 203. Etching processes, such as reactive ion etching, can be performed to remove the adhesive layer 202 located in the openings of the photoresist layer 203, thereby exposing the substrate 201 within the openings, as shown. Figure 3E As shown. Reactive ion etching (RIE) is a dry etching technique that uses ions to bombard a surface and react chemically with chemicals in a reactive gas to achieve precise etching of the material surface. In RIE processes, for example, oxygen plasma can be used to remove the tackifier AR300-80.

[0037] Then, refer to Figure 3FA contact layer 205 and a reflective metal layer 206 can be sequentially deposited on the sample. The contact layer 205 provides a tight contact between the reflective metal layer 206 and the substrate 201, reducing the risk of the reflective metal layer 206 detaching from the substrate 201 due to thermal expansion and contraction. Furthermore, the contact layer 205 provides a good growth interface for the reflective metal layer 206, such as a flat growth interface with appropriate lattice parameters. In addition, the contact layer 205 should cooperate with the reflective metal layer 206 to provide good visible light or electromagnetic wave reflectivity within the imaging wavelength range. Therefore, the material of the contact layer 205 should be carefully selected considering many factors. In one embodiment, the contact layer 205 may include Ti, with a thickness ranging from, for example, 10 nm to 100 nm, preferably from 20 nm to 80 nm. The reflective metal layer 206 may include a metallic material with excellent reflectivity. In some embodiments, the reflective metal layer 206 may include Ag, with a thickness ranging from, for example, 20 nm to 220 nm, preferably from 30 nm to 200 nm. Figure 5 This is a photograph of the sample after the deposition of contact layer 205 and reflective metal layer 206, where the dark areas are the opening areas and the light areas are the areas corresponding to photoresist layer 203. Figure 5 It can be seen that the above process steps can produce the desired pattern with clear boundaries.

[0038] Continue to refer to Figure 3FThe contact layer 205 and the reflective metal layer 206 can be deposited using a directional deposition process, covering the upper surface of the photoresist layer 203 and the exposed surface of the substrate 201. However, they will not conformally cover the sidewalls of the photoresist layer 203, thus preventing the layers deposited on the photoresist layer 203 and the layers deposited on the exposed surface of the substrate 201 from connecting. Such a connection would completely cover the photoresist layer 203, which would be detrimental to subsequent stripping processes. In some embodiments, the contact layer 205 and the reflective metal layer 206 can be formed using an electron beam evaporation process. Electron beam evaporation is a highly efficient vacuum evaporation deposition technique. Its principle is to use an electron beam to directly heat the material in a vacuum environment, vaporize it, and deposit it onto the substrate to form a thin film. In electron beam evaporation, the source material is placed in a crucible, and an electron beam is emitted by an electron gun. After acceleration to form an electric field of 5-10 keV, the electron beam is focused and deflected by a magnetic field coil. The electron beam bombards and heats the source material in the crucible. Once the material evaporates into a gaseous state, a baffle is opened, and the gaseous metal adheres to the sample. These atoms or molecules are deposited onto the substrate surface in a high vacuum environment, forming a thin film. This process allows for control of the deposition rate and film thickness, thus enabling precise control over the film's properties. One advantage of electron beam evaporation is its high deposition rate, allowing for rapid film fabrication. Furthermore, due to the high energy and focusing ability of the electron beam, this technology also offers high material utilization and high deposition accuracy. This technology provides high controllability, allowing for precise adjustment of the film's thickness and properties. In other embodiments, magnetron sputtering, pulsed laser deposition, or other processes can also be used to form the contact layer 205 and the reflective metal layer 206.

[0039] Although Figure 3F Although not shown in the diagram, in some embodiments, a transparent protective layer, such as a silicon dioxide layer, may be deposited on the reflective metal layer 206 to protect it from oxidation or corrosion. For example, Ag materials are easily oxidized by oxygen in the air; silver oxide turns black, thus reducing reflectivity. Therefore, forming a transparent protective layer can prevent Ag oxidation and extend the service life of the encoder disk. The process for forming the transparent protective layer may be the same as or different from the process for forming the contact layer 205 and the reflective metal layer 206. For example, both may be formed by magnetron sputtering, or the contact layer 205 and the reflective metal layer 206 may be formed by electron beam evaporation, while the transparent protective layer may be formed by magnetron sputtering.

[0040] Next, as Figure 3GAs shown, a lift-off process can be performed to remove the photoresist layer 203 and its on-bed contact layer 205 and reflective metal layer 206 (and a transparent protective layer, if present), leaving the contact layer 205 and reflective metal layer 206 (and a transparent protective layer, if present) on the substrate 201, forming the coded pattern in the coded region 110. In the lift-off process, the photoresist layer 203 is peeled off from the substrate 201 using a stripping solution (also called a stripping fluid) or other methods to obtain the target structure. In some embodiments, acetone can be used for the lift-off, which, in addition to removing the photoresist layer 203, also effectively removes the tackifier layer 202, leaving a clean substrate surface, such as... Figure 3G As shown. After peeling, the sample can be washed with deionized water and then dried.

[0041] In some embodiments, it is possible to Figure 3F No transparent protective layer is formed in the steps shown, but after the peeling process is performed, a protective layer is formed. Figure 3G The structure shown has a blanket-like (conformal) deposition of a transparent protective layer, which can completely cover the upper surface and sidewalls of the reflective metal layer 206, thereby better protecting the reflective metal layer 206 from oxidation or moisture erosion.

[0042] In the process described above, by employing a reflective metal layer 206, such as an Ag layer, the reflectivity of the reflective area can be improved compared to the currently used Cr layer. Furthermore, by using a contact layer 205, such as a Ti layer, the tight contact between the Ag layer and the substrate can be enhanced, improving the device's durability. Moreover, by stripping the contact layer 205 and the reflective metal layer 206 during the stripping of the photoresist layer 203, a self-aligned reflective area pattern is formed, avoiding the need to etch the contact layer 205 and the reflective metal layer 206 to form the reflective area pattern. Such etching is often disadvantageous because it requires high power to etch the metal layer and it is difficult to accurately control the etching stop point. Under-etching leaves an unclean surface; over-etching damages the exposed surface of the substrate 201 to some extent, affecting its light transmittance. In other words, by using a stripping process, part of the contact layer 205 and the reflective metal layer 206 can be completely removed without damaging the surface of the substrate 201. Therefore, the above process can prepare an encoding disk 100 with good reflective and transmissive characteristics, thereby improving the depth of imaging modulation, i.e. the contrast between reflectivity and transmissivity.

[0043] The applicant prepared the following samples: Sample 1, with a 200 nm thick Cr layer deposited by vapor deposition; Sample 2, with a 20 nm thick Ti layer and a 180 nm thick Ag layer deposited by vapor deposition; the reflectance spectra of each sample under the same light source were measured, and the results are shown below. Figure 6 In the middle. For example Figure 6As shown, in the wavelength range of approximately 500 nm to 1000 nm, sample 2, employing both a Ti contact layer and an Ag reflective layer, exhibits significantly higher reflected light intensity than sample 1, which uses only a Cr reflective layer, thus demonstrating higher reflectivity. Further experiments revealed that a preferred thickness of the Ti contact layer in the range of 20 nm to 80 nm and a thickness of the Ag reflective layer in the range of 30 nm to 200 nm, more preferably in the range of 50 nm to 150 nm, can form a reflective region of the encoder disk with desired reflective properties and appropriate cost-effectiveness, achieving a high image modulation depth.

[0044] Unless the context explicitly requires otherwise, throughout the specification and claims, the words “comprising,” “including,” “comprise,” “including,” etc., shall be interpreted in an inclusive sense, rather than an exclusive or exhaustive sense. That is, they mean “including but not limited to.” The term “connection” as commonly used herein refers to two or more elements that can be directly connected or connected via one or more intermediate elements. Furthermore, when used in this application, the terms “this,” “above,” “below,” and similar terms shall refer to the entire application and not any particular part thereof. Where the context permits, the term “or” refers to a list of two or more items, encompassing all of the following interpretations: any item in the list, all items in the list, and any combination of items in the list.

[0045] Furthermore, unless otherwise specifically stated or otherwise understood in the context in which they are used, the conditional language used herein, such as “can,” “may,” “possibly,” “can,” “for example,” “likely,” “such as,” etc., is generally intended to express that certain embodiments include certain features, elements, and / or states, while other embodiments do not. Therefore, such conditional language is not generally intended to imply that one or more embodiments require features, elements, and / or states in any way, or that one or more embodiments must include logic for making a decision, with or without author input or prompts, that determines whether such features, elements, and / or states are included in or will be performed in any particular embodiment.

[0046] While certain embodiments have been described, these embodiments are presented by way of example only and are not intended to limit the scope of this disclosure. In fact, the novel facilities, methods, and systems described herein can be embodied in a variety of other forms; furthermore, various omissions, substitutions, and changes can be made to the form of the methods and systems described herein without departing from the spirit of this disclosure. For example, although blocks are presented in a given arrangement, alternative embodiments may perform functions similar to different components and / or circuit topologies, and some blocks may be deleted, moved, added, subdivided, combined, and / or modified. Each of these blocks can be implemented in a variety of different ways. Any suitable combination of elements and actions of the various embodiments described above can be combined to provide further embodiments. The appended claims and their equivalents are intended to cover these forms or modifications that fall within the scope and spirit of this disclosure.

[0047] The above description has been given for purposes of illustration and description. Furthermore, this description is not intended to limit the embodiments of the invention to the forms disclosed herein. Although numerous exemplary aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, alterations, additions, and sub-combinations therein.

Claims

1. A method for fabricating an encoding disk for single-pixel imaging, comprising: A photoresist layer is formed on a transparent substrate; Exposure and development are performed on the photoresist layer to form a photoresist pattern layer having an opening pattern to expose a portion of the substrate; A contact layer and a reflective metal layer are sequentially and directionally deposited on the photoresist pattern layer and the exposed portion of the substrate, wherein the contact layer provides a growth interface for the reflective metal layer and also cooperates with the reflective metal layer to provide visible light or electromagnetic wave reflectivity in the imaging wavelength range; The photoresist pattern layer, the contact layer, and the reflective metal layer located on the photoresist pattern layer are stripped away, leaving the contact layer and reflective metal layer located on the substrate. The area where the photoresist pattern layer is stripped forms the transmissive area pattern in the encoding area of ​​the encoding disk, and the area where the contact layer and reflective metal layer are left on the substrate forms the reflective area pattern in the encoding area of ​​the encoding disk. The contact layer includes a Ti layer, and the reflective metal layer includes an Ag layer. The method further includes: Before forming the photoresist layer, an adhesion promoter layer is formed on the substrate; and After exposing and developing the photoresist layer to form a photoresist pattern layer, the portion of the tackifier layer exposed through the photoresist pattern layer is etched away to expose the substrate. Specifically, when peeling off the photoresist pattern layer, the remaining portion of the adhesion promoter layer located beneath the photoresist pattern layer is also peeled off. Specifically, during the sequential directional deposition of the contact layer and the reflective metal layer, a transparent protective layer is directionally deposited on the reflective metal layer. When stripping the photoresist pattern layer, the contact layer, reflective metal layer, and transparent protective layer on the photoresist pattern layer are also stripped.

2. The method of claim 1, further comprising: After stripping the photoresist pattern layer, a transparent protective layer is blanket-deposited on the reflective metal layer and on the exposed surface of the substrate.

3. The method as described in claim 1, wherein, The thickness of the contact layer is in the range of 10 nm to 100 nm, and the thickness of the reflective metal layer is in the range of 20 nm to 220 nm.

4. The method of claim 3, wherein, The thickness of the contact layer is in the range of 20 nm to 80 nm, and the thickness of the reflective metal layer is in the range of 30 nm to 200 nm.

5. The method of claim 1, wherein, The contact layer and the reflective metal layer are formed by electron beam evaporation or magnetron sputtering.

6. The method of claim 1, wherein, Forming the photoresist layer includes: Photoresist material is coated onto the substrate using a spin coating method; and The coated photoresist material is baked to cure it.

7. The method of claim 6, further comprising: The photoresist layer is baked after exposure and before development.

8. An encoding disk for single-pixel imaging, which is prepared by the method described in any one of claims 1-7.

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