Optical Shaping Apparatus Diffracted Light Suppression
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Solution Overview
Problem
The use of DMD-based stereolithography in manufacturing optical articles results in stereoscopic diffraction due to a non-homogeneous refractive index distribution, leading to suboptimal optical performance, with first-order diffracted light intensity often exceeding acceptable levels for high-performance applications.
Innovation Solution
A method and apparatus that modulate the light-curing process by varying the output light flux, stage movement, and projection optical system settings to reduce the contrast of the periodical refractive index distribution, including diffusion of the light flux and adjusting the stage and projection system parameters to minimize diffracted light generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If DMD-based stereolithography is used to manufacture optical articles, then the manufacturing process can be implemented with existing technology, but the resulting optical article exhibits stereoscopic diffraction with first-order diffracted light intensity exceeding acceptable levels
Solution Approach 1:
The patent applies parameter changes by modifying the stage movement distances in the first direction to be non-uniform across different cured layers. Specifically, the movement distance for each layer is varied within a range of ±5 μm to ±20 μm from the average distance, which randomizes the reticulated refractive index distribution and suppresses stereoscopic diffraction while maintaining the DMD-based manufacturing approach
Solution Approach 2:
The patent introduces asymmetry by making the stage movement distances asymmetric and non-repetitive across layers. This breaks the periodicity of the micromirror projection pattern, transforming the symmetric reticulated structure into an asymmetric distribution that eliminates diffraction grating effects while preserving the manufacturing process
2Productivity
If uniform stage movement is used in layer-by-layer curing, then the manufacturing process is simple and efficient, but a reticulated periodical refractive index distribution is generated causing diffraction
Solution Approach 1:
The patent changes the movement distance parameter in the first direction for each cured layer to suppress diffraction. By varying the stage movement distance within a controlled range (±5 μm to ±20 μm) while maintaining overall layer-by-layer progression, the patent eliminates the periodic refractive index distribution that causes diffraction without significantly impacting manufacturing efficiency
Solution Approach 2:
The patent introduces dynamics by making the stage movement distances variable and adaptive across different layers rather than fixed and uniform. This dynamic adjustment of movement parameters randomizes the refractive index distribution, preventing the formation of diffraction gratings while maintaining efficient layer-by-layer manufacturing
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 approach effectively suppresses diffracted light intensity to levels below 6% of the zero-order light, achieving high optical performance in optical articles like lenses, with potential to reduce it further to 0.01% or less.
Implementation Method 1
a method for shaping an object layer by layer from a plurality of solidified layers by repeating steps by irradiating a light-curable resin (photopolymer) in a container through a bottom portion of a container which stores the light-curable resin with light
Implementation Method 2
a micromirror device, e.g. a DMD (Digital Micromirror Device), is generally used for generating a desired shape light flux for irradiating the light-curable resin. The micromirror device has a plurality of micromirrors arranged on the surface thereof in two-dimensional repetition structure
Data Source
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AI summary
A method of manufacturing an optical article, wherein an output light flux generating process of generating an output light flux by inputting a light from a light source to an output setting element having a repetition structure; a cured layer forming process of forming a cured layer at an irradiation area that is formed in correspondence with the output area by introducing the output light flux through a projection optical system into a container in which light-curable resin is contained and a stage is arranged and condensing the output light flux; and a stage moving process of moving the stage in a desired distance along the direction of the output flux propagating, are sequentially performed in this order and an irradiation variation process of varying the irradiation area in the cured layer generating process are further included, thereby the optical article is formed on a surface of the stage.