Catadioptric Optical System Ghosting Suppression via Light-Shielding Portions
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Solution Overview
Problem
Image pickup apparatuses using catadioptric systems suffer from ghosting due to unnecessary light not passing through reflection surfaces, which is not adequately suppressed by existing solutions, particularly in the arrangement of reflection and image pickup surfaces.
Innovation Solution
The apparatus incorporates a catadioptric optical system with specific surface arrangements, including a first refractive surface and two reflection surfaces, where the light receiving surface is positioned closer to the optical axis than point C, and the intervals between these surfaces are optimized to satisfy conditional expressions, ensuring that unnecessary light is shielded by light-shielding portions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a catadioptric system is used for size reduction, then the optical system becomes more compact, but ghosting occurs due to unnecessary light reaching the image pickup surface
Solution Approach 1:
The patent extracts and blocks unnecessary light paths from reaching the image pickup surface by strategically positioning light-shielding portions. The light-shielding portions are placed to intercept stray light that does not pass through the intended reflection surfaces, effectively removing the harmful light paths while preserving the compact catadioptric structure.
Solution Approach 2:
The light-shielding portions act as intermediary elements between the optical components and the image pickup surface. These intermediaries selectively block unnecessary light while allowing useful light to pass through, resolving the contradiction between compact size and ghost suppression by mediating the light paths.
2Object-affected harmful factors
If black finishing is applied between refractive and reflection surfaces to suppress unnecessary light, then some ghosting is reduced, but the ghost cannot be sufficiently suppressed due to improper arrangement of reflection surface and image pickup surface
Solution Approach 1:
The patent moves beyond simple surface coating (two-dimensional approach) to a three-dimensional spatial arrangement solution. By carefully positioning the light-shielding portions and image pickup surface in space, and by optimizing the intervals L1 and L2, the patent creates a volumetric solution that effectively blocks unnecessary light paths from multiple angles, achieving superior ghost suppression compared to mere black finishing.
Solution Approach 2:
The patent changes critical geometric parameters including the interval L1 between reflection surfaces, the interval L2 between the first reflection surface and image pickup surface, and the positional relationship defined by points A, B, and C. By optimizing these parameters, the patent achieves effective ghost suppression that cannot be attained by black finishing alone.
3Object-affected harmful factors
If the light receiving surface is positioned to block unnecessary light, then ghosting is suppressed, but the optical system becomes more complex
Solution Approach 1:
The light-shielding portions serve multiple functions: they block unnecessary light to prevent ghosting, and they can be integrated with existing optical components without adding separate dedicated shielding structures. This multi-functionality reduces overall system complexity while achieving effective ghost suppression.
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 ghosting by preventing unnecessary light from reaching the image pickup surface, while maintaining a compact size and correcting various aberrations, thereby enhancing image forming performance.
Implementation Method 1
a first refractive surface having a convex shape toward an object side... a light flux travelling through the first refractive surface, the second reflection surface, and the first reflection surface
Implementation Method 2
a second reflection surface having a convex shape toward the object side... a light flux travelling through the first refractive surface, the second reflection surface, and the first reflection surface
Implementation Method 3
a first reflection surface having a convex shape toward the object side... a light flux travelling through the first refractive surface, the second reflection surface, and the first reflection surface
Data Source
AI summary
An image pickup apparatus including an optical system and an image pickup element. The optical system includes a first refractive surface disposed closest to an object, a first reflection surface, and a second reflection surface. A light receiving surface of the image pickup element is disposed at only one side with respect to the optical axis and at a position closer to the optical axis than an intersection between a straight line connecting an intersection on the first refractive surface and an intersection on an imaginary extension surface of the second reflection surface and an imaginary extension surface of the light receiving surface. Expression 1.5≤L2/L1≤6.5 is satisfied where L1 is an interval between the first reflection surface and the second reflection surface, and L2 is an interval between the first reflection surface and the light receiving surface.