3D-Printed Optical Lens Smoothing with Defocused Projection
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Solution Overview
Problem
Conventional 3D printing methods for optical lenses suffer from stair-stepping defects due to the discrete nature of 3D printing layers, leading to degraded optical quality and limited flexibility in prototyping and customization.
Innovation Solution
A combination of vat photopolymerization with defocused image projection and precision spin coating is employed to smooth both lateral and vertical stair-stepping defects, utilizing a liquid crystal display (LCD) screen to project unfocused images and applying spin coating with controlled resin application to achieve sub-micron precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional 3D printing methods are used to manufacture optical lenses, then fabrication speed and flexibility are improved, but surface smoothness and optical quality deteriorate due to stair-stepping defects
Solution Approach 1:
The patent applies preliminary action by performing spin coating immediately after each layer is deposited during the 3D printing process. This preliminary smoothing action prevents stair-stepping defects from forming, allowing the lens surface to maintain high smoothness throughout the entire fabrication process while preserving the rapid additive manufacturing approach
Solution Approach 2:
The patent introduces spin coating as an intermediary process between layer deposition and the next printing step. This intermediary smoothing action mediates between the discrete layered structure inherent to 3D printing and the continuous smooth surface required for optical quality, effectively eliminating the contradiction between fabrication speed and surface smoothness
2Manufacturing precision
If conventional grinding and polishing processes are used to achieve smooth lens surfaces, then optical quality is improved, but fabrication time and process complexity increase
Solution Approach 1:
The patent replaces the traditional mechanical grinding and polishing system with a spin coating process that uses centrifugal force and fluid dynamics to achieve surface smoothing. This substitution eliminates time-consuming mechanical removal of material while achieving superior surface smoothness through controlled resin deposition and spinning, dramatically reducing fabrication time
Solution Approach 2:
The patent changes the fundamental approach from subtractive (grinding/polishing) to additive (spin coating) manufacturing. By controlling parameters such as spin speed, resin viscosity, and coating thickness, the process achieves the desired surface smoothness directly during fabrication rather than through subsequent removal of material, eliminating the time loss associated with conventional post-processing
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method produces optical lenses with excellent surface smoothness, precision, and reproducibility, achieving minimal distortion and outstanding optical clarity across the visible light spectrum, with fabrication times reduced to minutes for lenses ranging from 3 mm to 70 mm in diameter.
Implementation Method 1
Additive manufacturing, particularly vat photopolymerization (VPP), has emerged as a promising alternative
Implementation Method 2
utilizing a liquid crystal display (LCD) screen to project unfocused images
Implementation Method 3
precision spin coating is employed to smooth both lateral and vertical stair-stepping defects
Implementation Method 4
applying spin coating with controlled resin application to achieve sub-micron precision
Data Source
AI summary
A method is provided for fabricating an optical lens using vat photopolymerization (VPP). The method includes generating a digital lens model and printing the lens in discrete layers along a print direction. During printing, defocused image patterns are projected to mitigate lateral surface pixelation across the layers. Following printing, a photocurable resin is applied to the outer surface of the lens. The lens is then spin coated, distributing the resin uniformly and smoothing layered steps along the print direction. Finally, the coated resin is cured, producing a lens with improved surface quality.