Optical System Filter Ghosting Shielding
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Solution Overview
Problem
Existing optical systems used in imaging apparatuses suffer from ghosting due to stray light reflected by filters, which affects image quality and spectral information accuracy.
Innovation Solution
The optical system is arranged with a specific configuration where the optical surface and filter array are positioned to satisfy a conditional expression, ensuring that stray light is prevented from entering adjacent filters, thereby suppressing ghosting. This involves setting the normal line angle of the optical surface and the distance between filters to specific values to effectively shield stray light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a light-shielding plate is arranged on the image side to shield light incident on areas other than the effective area, then vignetting is reduced, but stray light reflected by filters enters adjacent filters causing ghosting
Solution Approach 1:
A light-shielding plate is introduced as an intermediary element positioned between the filter and the image sensor. This plate selectively blocks stray light reflected by the filter from entering adjacent filters, while allowing effective light to pass through to form the image. The plate acts as a mediator that separates the useful light path from the harmful reflected light path.
Solution Approach 2:
The harmful reflected light is extracted and blocked from the optical system by the light-shielding plate. The plate is designed to specifically intercept stray light that has been reflected by the filter at angles that would cause it to enter adjacent filters, removing this harmful component while preserving the main image-forming light path.
2Volume of moving object
If filters are positioned closer together to reduce system size, then compactness is improved, but stray light from one filter more easily enters adjacent filters
Solution Approach 1:
The light-shielding plate serves as a mediator that enables closer positioning of filters by blocking the stray light path between them. When filters are positioned closer together, the plate intercepts reflected light before it can travel to adjacent filters, allowing compact arrangement without increasing ghosting.
Solution Approach 2:
The light-shielding plate provides localized light blocking in specific regions where stray light would cause problems. Rather than requiring large spacing between all filters, the plate creates local shielding zones that allow compact overall arrangement while maintaining optical performance.
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 solution effectively reduces the occurrence of ghosting in image information, improving image quality and spectral accuracy by ensuring stray light is shielded from entering other filters, thus enhancing the overall performance of the imaging apparatus.
Implementation Method 1
a light beam from the object incident from an opposite side of the optical axis of the second optical portion on a first point in a first filter among the plurality of filters; θ1 [deg] is an angle formed between the optical axis and a normal line to the optical surface at a second point where the light beam reflected at the first point is incident
Data Source
AI summary
An optical system is arranged on an object side relative to a first optical portion, the first optical portion including a plurality of lens portions each configured to form an image of an object, and a plurality of filters corresponding to the plurality of lens portions, and the optical system includes a second optical portion including an optical surface common to the plurality of lens portions, wherein the following conditional expression is satisfied:12×arctan{2×tanω1-Δh1D11-tanω1×(tanω1-Δh1D1)}<θ1.