Lens Spacer Inner Wall Roughness for Flare Suppression
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Solution Overview
Problem
In lens units with wafer-level lenses and spacers, specular reflection of incident light on the inner wall of the spacer's through hole can cause flare and/or ghost on the imaging plane, particularly in lenses with long focal lengths.
Innovation Solution
The lens unit is designed with a spacer portion that includes a through hole with an inner wall surface having a surface roughness greater than the opposing surface of the spacer, which diffusely reflects or scatters light to prevent specular reflection and flare/ghost generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a spacer with a smooth inner wall surface is used in the lens unit, then the manufacturing precision is improved, but specular reflection of light occurs on the inner wall, causing flare and/or ghost on the imaging plane
Solution Approach 1:
The inner wall surface of the spacer is given a different surface roughness than the outer wall surface. Specifically, the inner wall surface has a surface roughness of 0.03 μm or more and 3.0 μm or less, which is different from the outer wall surface. This local differentiation allows the inner wall to diffuse light and prevent flare while the outer wall maintains its original manufacturing precision and appearance.
2Object-generated harmful factors
If the surface roughness of the inner wall is increased to suppress specular reflection, then flare and ghost are reduced, but the manufacturing complexity increases
Solution Approach 1:
The surface roughness parameter of the inner wall surface is specifically controlled within the range of 0.03 μm to 3.0 μm. This parameter change transforms the smooth inner wall into a light-diffusing surface that prevents specular reflection and reduces flare, while the controlled range ensures the manufacturing process remains manageable.
3Object-generated harmful factors
If the surface roughness of the inner wall is increased to diffuse light, then flare and ghost are suppressed, but the manufacturing precision deteriorates
Solution Approach 1:
The spacer is designed with non-uniform surface quality: the inner wall surface has increased roughness (0.03-3.0 μm) for light diffusion, while the outer wall surface maintains its original smooth finish. This local quality differentiation allows the inner wall to suppress flare without compromising the overall manufacturing precision and appearance of the spacer.
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
This configuration effectively suppresses the generation of flare and/or ghost by diffusely reflecting light on the roughened inner wall surface of the spacer, ensuring improved image quality in lens units with wafer-level lenses.
Implementation Method 1
light irradiated on the inner wall portion of the spacer portion through the lens portion is diffusely reflected or scattered by the roughened surface
Implementation Method 2
light irradiated on the inner wall portion of the spacer portion through the lens portion is diffusely reflected or scattered by the roughened surface
Data Source
AI summary
There is provided a technique that can suppress generation of flare and/or ghost by incident light reflecting off an inner wall of the spacer in a lens unit including a wafer-level lens and a spacer. A lens unit is formed by joining a lens portion including a lens and a spacer portion including a through hole through which light emitted from the lens passes, in which the spacer portion includes, in an end surface in which the lens portion is joined, an opening portion of the through hole and an inner wall portion, which is a wall surface of an outer edge of the opening portion, and the inner wall portion has a surface roughness greater than a surface roughness of an end surface of the spacer portion opposite to the end surface in which the lens portion is joined.