Preparation method for improving imaging quality of lens

Abstract

The invention discloses a preparation method for improving the imaging quality of a lens, and belongs to the technical field of optical element preparation, and the method comprises the steps: providing a substrate, and carrying out the pretreatment; forming a micro-lens array with a cutting path on the surface of the substrate; uniformly spin-coating light absorption / shading ultraviolet glue on the surface of the array; carrying out precise overlay exposure by utilizing a preset mask pattern, and only reserving a patterned photoresist covering layer in the edge area of the micro lens after developing; carrying out high-temperature curing on the covering layer to improve the hardness and adhesive force of the covering layer; and finally, separating into single lens products along the cutting path. The high-precision shading structure is directly integrated in the edge area of the lens through the photoetching technology, wavefront distortion and stray light caused by the edge non-uniform area can be effectively eliminated, the imaging definition, the contrast ratio and the system stability are remarkably improved, and the method has the advantages of being high in technology integration degree, high in production efficiency, low in cost and wide in applicability and has wide application prospects. The method is especially suitable for large-scale preparation of wafer-level micro-lens arrays.

Description

Technical Field

[0001] This invention relates to the field of optical element fabrication technology, and more specifically to a method for improving the imaging quality of a lens. Background Technology

[0002] As a core component of optical systems, lens-type optical components have applications covering multiple key areas such as uniform light imaging, image adjustment, and astigmatism correction. Specifically, these include the core applications of aspherical microlens arrays in uniform light equipment and imaging systems, the image size and height adjustment functions of cylindrical lens arrays in cinema projection systems, fax machines, and printing typesetting and scanning imaging systems, as well as astigmatism correction and high-definition imaging support in the medical field (gastroscopy, laparoscopy) and the automotive field (vehicle video systems).

[0003] In practical applications of optical systems, after lenses or cylindrical mirrors are manufactured, their edge regions are prone to forming non-uniform structural areas. These non-uniform areas have two major negative impacts on the performance of the optical system: first, they cause wavefront distortion, leading to light propagation paths deviating from the ideal trajectory, resulting in problems such as blurred images and reduced resolution; second, they generate stray light interference, with excess light scattering within the optical system, which not only reduces image contrast but may also interfere with light reception in the core imaging area, affecting the detection accuracy and reliability of the optical system.

[0004] Current industry solutions to these problems have significant limitations: traditional physical aperture methods require additional structural design and fabrication, along with assembly processes, resulting in low production efficiency and precision deviations in the structural components typically ranging from tens to hundreds of micrometers, making high-precision edge correction impossible. On the other hand, processes relying on precision machining or manual polishing are limited by the precision of processing equipment and human error, leading to deviations in lens edge curvature. This is especially true for micro / nano-sized lens arrays, which rely heavily on precision machining, and due to material properties, it is difficult to effectively eliminate the influence of non-uniform edge regions. Therefore, developing a high-precision, high-efficiency technical solution that fundamentally addresses optical performance defects caused by non-uniform lens edge regions has become a pressing technical challenge in this field. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a method for improving the imaging quality of lenses. This method directly integrates a high-precision light-shielding structure in the edge region of the lens using photolithography, which can effectively eliminate wavefront distortion and stray light caused by non-uniform edge regions, significantly improving imaging clarity, contrast, and system stability. This method has the advantages of high process integration, high production efficiency, low cost, and wide applicability, and is especially suitable for the large-scale fabrication of wafer-level microlens arrays.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A method for improving the imaging quality of a lens includes the following steps: S1. Provide a substrate and pretreat the surface of the substrate; S2. A microlens array is formed on the substrate surface, the microlens array comprising multiple microlens units, with pre-reserved cutting paths between each unit; S3. On the surface of the formed microlens array, uniformly spin-coat the light-absorbing / light-shielding UV adhesive to ensure that the UV adhesive can completely cover the edge area of ​​the microlens unit. Control the uniformity of the adhesive layer thickness during the spin-coating process to avoid adhesive layer accumulation or omission. S4. Using an exposure machine with a preset mask pattern, precise overlay exposure is performed based on the alignment mark. The mask pattern is precisely matched with the edge contour and invalid area of ​​the microlens unit. After exposure, the UV photoresist in the unexposed area is removed by the development process, leaving only the locally patterned photoresist cover layer in the edge area of ​​the microlens. S5. The microlens array after development is subjected to high-temperature curing. The curing temperature and time are precisely controlled according to the characteristics of the UV adhesive material to improve the hardness, density and adhesion of the photoresist coating to the microlens unit. S6. Along the reserved cutting path, the wafer-level microlens array is cut and separated into individual microlens products, completing the fabrication process.

[0007] Furthermore, the substrate is made of glass or silicon.

[0008] Further, the pretreatment in step S1 includes cleaning, drying and surface activation of the substrate to remove surface impurities and oil stains, and to improve the adhesion between the substrate and the subsequent polymer adhesive material.

[0009] Furthermore, the microlens array in step S2 is formed using a nanoimprint lithography process, including the following steps: S2.1 Apply the polymer adhesive material to the pretreated substrate surface; S2.2. The polymer adhesive material is imprinted using a master plate to replicate the three-dimensional shape of the master plate. S2.3 After curing, the microlens unit array is formed by demolding.

[0010] Further, after demolding, an etching step is included to transfer the morphology to the substrate material.

[0011] Further, in step S6, the cutting is performed using laser cutting or a blade wheel cutting process.

[0012] Compared with the prior art, the beneficial effects of the present invention are: 1. High-precision edge correction to eliminate wavefront distortion: This invention uses a spin-coating process to uniformly fill the edge area of ​​a lens or cylindrical mirror with light-absorbing / shielding UV resist, effectively filling the edge curvature deviation caused by photolithography and precision machining during processing, as well as the uneven edge transition defects caused by manual polishing. Compared with the problem of edge slope error in traditional processing, this solution suppresses wavefront distortion from the source through the shape masking effect of the photoresist cover layer, thereby improving imaging clarity and resolution.

[0013] 2. Significantly improved production efficiency and reduced manufacturing costs: Compared with traditional physical aperture technology, this invention, based on wafer-level integration technology, can simultaneously complete the fabrication of edge-masking structures for thousands to tens of thousands of lenses during the fabrication of an 8-inch wafer. This eliminates the need for additional aperture structure components and subsequent assembly processes, significantly shortening the production cycle and improving production efficiency. Simultaneously, it avoids material waste and labor costs during component processing and assembly, significantly reducing product manufacturing costs.

[0014] 3. Significant stray light suppression and a leap in image quality: Traditional physical apertures can only block the periphery of the lens array, failing to address stray light generated by the edges of individual lenses within the array. This invention, through precise positioning in overlay exposure, enables targeted shielding of the edges and ineffective areas of each lens or cylindrical mirror. The light-absorbing / shielding UV adhesive directly absorbs or blocks stray light generated in these areas, significantly reducing stray light scattering within the optical system, dramatically improving image contrast and image clarity, and achieving a leap in optical imaging quality.

[0015] 4. Enhanced Product Reliability and Adaptability: Through a high-temperature curing process, the hardness, density, and adhesion to the lens surface of the photoresist coating layer in this invention are significantly enhanced, effectively preventing issues such as coating layer peeling and wear during use, and improving the product's lifespan and reliability in complex environments. Simultaneously, the masking range can be flexibly adjusted by modifying the mask pattern, adapting to lenses or cylindrical mirrors of different sizes and curvatures, thus possessing broad application adaptability.

[0016] 5. Compensating for demolding deviation and solving optical path defocusing problems: In the nanoimprint lithography (NIL) process, the uneven demolding force causes PV value deviation at the lens edge and optical path defocusing problems. The locally patterned photoresist coating layer of this invention can compensate for the surface shape deviation generated during demolding through shape correction and light control, so that the actual optical performance of the lens is close to the ideal state. This effectively solves the problem of image quality degradation caused by demolding defects in the traditional NIL process, and further ensures the stability and accuracy of the optical system. Detailed Implementation

[0017] In the description of this invention, it should be noted that the directional terms such as "center", "horizontal (X)", "longitudinal (Y)", "vertical (Z)", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", and "counterclockwise" are used to indicate the orientation and positional relationship based on the indicated orientation or positional relationship. They are only for the convenience of describing this 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. They should not be construed as limiting the specific protection scope of this invention.

[0018] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features. Thus, the use of "first" and "second" to define a feature may explicitly or implicitly include one or more of that feature. In the description of this invention, "several" or "a number" means two or more, unless otherwise explicitly specified.

[0019] A method for improving the imaging quality of a lens includes the following steps: S1. Provide a substrate and pretreat the surface of the substrate; S2. A microlens array is formed on the substrate surface, the microlens array comprising multiple microlens units, with pre-reserved cutting paths between each unit; S3. On the surface of the formed microlens array, uniformly spin-coat the light-absorbing / light-shielding UV adhesive to ensure that the UV adhesive can completely cover the edge area of ​​the microlens unit. Control the uniformity of the adhesive layer thickness during the spin-coating process to avoid adhesive layer accumulation or omission. S4. Using an exposure machine with a preset mask pattern, precise overlay exposure is performed based on the alignment mark. The mask pattern is precisely matched with the edge contour and invalid area of ​​the microlens unit. After exposure, the UV photoresist in the unexposed area is removed by the development process, leaving only the locally patterned photoresist cover layer in the edge area of ​​the microlens. S5. The microlens array after development is subjected to high-temperature curing. The curing temperature and time are precisely controlled according to the characteristics of the UV adhesive material to improve the hardness, density and adhesion of the photoresist coating to the microlens unit. S6. Along the reserved cutting path, the wafer-level microlens array is cut and separated into individual microlens products, completing the fabrication process.

[0020] Preferably, the substrate is made of glass or silicon. Glass substrates are low-cost and easy to process, making them suitable for mass production of optical components. Silicon substrates, on the other hand, are easy to integrate with optoelectronic integrated systems such as CMOS, thereby improving system integration and reliability.

[0021] Preferably, the pretreatment in step S1 includes cleaning, drying and surface activation of the substrate to remove surface impurities and oil. The pretreatment effectively improves the interfacial bonding between the substrate and the subsequent functional layers, reduces defects such as coating peeling and bubbles, and ensures the structural integrity and optical consistency of the microlens array.

[0022] Preferably, the microlens array in step S2 is formed using a nanoimprint lithography process, including the following steps: S2.1 Apply the polymer adhesive material to the pretreated substrate surface; S2.2. The polymer adhesive material is imprinted using a master plate to replicate the three-dimensional shape of the master plate. S2.3 After curing, the microlens unit array is demolded. Preferably, after demolding, an etching step is also included to transfer the morphology to the substrate material. After the polymer adhesive structure is shaped, the structure is further transferred to the substrate material by dry or wet etching process to form a permanent optical structure. The etched structure has higher mechanical strength, thermal stability and environmental resistance, and is suitable for harsh application scenarios such as high temperature, high humidity or strong light irradiation, thereby improving the service life and reliability of the lens.

[0023] Preferably, the cutting in step S6 is performed using laser cutting or a blade cutting process.

[0024] advantage: 1. High-precision edge correction to eliminate wavefront distortion: This invention uses a spin-coating process to uniformly fill the edge area of ​​a lens or cylindrical mirror with light-absorbing / shielding UV resist, effectively filling the edge curvature deviation caused by photolithography and precision machining during processing, as well as the uneven edge transition defects caused by manual polishing. Compared with the problem of edge slope error in traditional processing, this solution suppresses wavefront distortion from the source through the shape masking effect of the photoresist cover layer, thereby improving imaging clarity and resolution.

[0025] 2. Significantly improved production efficiency and reduced manufacturing costs: Compared with traditional physical aperture technology, this invention, based on wafer-level integration technology, can simultaneously complete the fabrication of edge-masking structures for thousands to tens of thousands of lenses during the fabrication of an 8-inch wafer. This eliminates the need for additional aperture structure components and subsequent assembly processes, significantly shortening the production cycle and improving production efficiency. Simultaneously, it avoids material waste and labor costs during component processing and assembly, significantly reducing product manufacturing costs.

[0026] 3. Significant stray light suppression and a leap in image quality: Traditional physical apertures can only block the periphery of the lens array, failing to address stray light generated by the edges of individual lenses within the array. This invention, through precise positioning in overlay exposure, enables targeted shielding of the edges and ineffective areas of each lens or cylindrical mirror. The light-absorbing / shielding UV adhesive directly absorbs or blocks stray light generated in these areas, significantly reducing stray light scattering within the optical system, dramatically improving image contrast and image clarity, and achieving a leap in optical imaging quality.

[0027] 4. Enhanced Product Reliability and Adaptability: Through a high-temperature curing process, the hardness, density, and adhesion to the lens surface of the photoresist coating layer in this invention are significantly enhanced, effectively preventing issues such as coating layer peeling and wear during use, and improving the product's lifespan and reliability in complex environments. Simultaneously, the masking range can be flexibly adjusted by modifying the mask pattern, adapting to lenses or cylindrical mirrors of different sizes and curvatures, thus possessing broad application adaptability.

[0028] 5. Compensating for demolding deviation and solving optical path defocusing problems: In the nanoimprint lithography (NIL) process, the uneven demolding force causes PV value deviation at the lens edge and optical path defocusing problems. The locally patterned photoresist coating layer of this invention can compensate for the surface shape deviation generated during demolding through shape correction and light control, so that the actual optical performance of the lens is close to the ideal state. This effectively solves the problem of image quality degradation caused by demolding defects in the traditional NIL process, and further ensures the stability and accuracy of the optical system.

[0029] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A manufacturing method for improving the imaging quality of a lens, characterized by, The method comprises the following steps: S1, providing a substrate, and pre-treating the surface of the substrate; S2, forming a microlens array on the surface of the substrate, the microlens array comprising a plurality of microlens units, and a cutting path being reserved between each unit; S3, uniformly spin-coating light-absorbing / shading ultraviolet glue on the surface of the formed microlens array, ensuring that the ultraviolet glue can completely cover the edge region of the microlens units, and controlling the uniformity of the glue layer thickness in the spin-coating process to avoid glue accumulation or omission; S4, using an exposure machine with a preset mask pattern, performing accurate overlay exposure based on alignment marks, and accurately matching the mask pattern with the edge profile and invalid region of the microlens units; after exposure, the ultraviolet glue in the unexposed region is removed through a development process, and only the partial patterned photoresist cover layer in the edge region of the microlens is reserved; S5, performing high-temperature curing treatment on the microlens array after development, and accurately controlling the curing temperature and time according to the characteristics of the ultraviolet glue material to improve the hardness, density and adhesion of the photoresist cover layer to the microlens units; S6, cutting and separating the wafer-level microlens array into single microlens products along the reserved cutting path, and completing the preparation process.

2. The preparation method for improving the imaging quality of a lens according to claim 1, characterized in that: The substrate is made of glass or silicon.

3. The method of claim 1, wherein the lens has a surface profile that is substantially parabolic. The pre-treatment in step S1 comprises cleaning, drying and surface activation treatment of the substrate to remove surface impurities and oil stains and improve the bonding force of the substrate and the subsequent polymer glue material.

4. The method of claim 1, wherein the method further comprises: The microlens array in step S2 is formed by a nano-imprint lithography process, comprising the following steps: S2.1, coating the polymer glue material on the surface of the pre-treated substrate; S2.2, imprinting the polymer glue material by a master plate to make the polymer glue material replicate the three-dimensional topography of the master plate; S2.3, forming a microlens unit array after demolding and curing treatment.

5. The method of claim 1 or 4, wherein the method is a method of improving the imaging quality of a lens. After demolding, an etching step is further included to transfer the topography to the substrate material.

6. The method of claim 1, wherein the method further comprises: In step S6, laser cutting or cutter wheel cutting process is used for cutting.