Adjustable Aperture Gate for Stray Light Reduction in Camera Systems
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Solution Overview
Problem
Conventional camera iris systems fail to effectively reduce stray light, leading to lower image quality due to ghost images and diffraction effects, especially under strong lighting conditions, and internal reflections within optical components.
Innovation Solution
A method involving a camera with a lens assembly and an adjustable aperture unit, where multiple images of a scene are acquired using unique aperture gate settings, and data on stray light content is analyzed to produce an output image with reduced stray light, by selecting images or parts with lower stray light content and merging them to create an improved image.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a conventional iris with metal plates is used to control aperture, then the aperture size can be adjusted, but stray light causes ghost images and reduces image quality
Solution Approach 1:
The aperture gate is divided into multiple independently controllable segments that can be positioned at different locations in the aperture plane. This segmentation allows selective blocking of stray light paths while maintaining the desired aperture size for image formation, thereby reducing ghost images without sacrificing aperture control functionality
Solution Approach 2:
An aperture gate is introduced as an intermediary element between the lens assembly and image sensor. This aperture gate can be dynamically positioned to block stray light rays that would otherwise reach the sensor and create ghost images, while allowing the main image-forming light to pass through unchanged
2Ease of operation
If a conventional iris is used under strong lighting conditions, then aperture control is maintained, but diffraction effects reduce image quality
Solution Approach 1:
The aperture gate is made dynamically adjustable, allowing it to change position and configuration based on lighting conditions. Under strong lighting, the aperture gate can be positioned to reduce diffraction effects from the iris edges while maintaining proper aperture control, thereby improving image quality without sacrificing operational flexibility
3Object-affected harmful factors
If multiple images are acquired with unique aperture gate settings, then stray light content can be reduced, but acquisition time increases
Solution Approach 1:
Multiple images are acquired with periodically varying aperture gate settings, where the aperture gate is adjusted to different positions for successive images. This periodic variation in aperture configuration allows stray light to be blocked from different angles across multiple frames, and through computational processing, a final image with reduced stray light content is produced
Solution Approach 2:
The aperture gate is pre-positioned to specific configurations before acquiring each image in the sequence. By preliminarily setting the aperture gate to block specific stray light paths for each acquisition, the system prepares optimal blocking configurations in advance, reducing the need for complex post-processing and minimizing total acquisition time
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 significantly reduces stray light content in output images, enhancing image quality by selecting and combining images with lower stray light, thereby improving signal-to-noise ratio and reducing unwanted light effects.
Implementation Method 1
light originating from the scene is collected using some form of lens system of the camera in question. The light originating from the scene is then focused by means of the lens system
Implementation Method 2
an aperture unit having an aperture gate in an aperture plane being orthogonal to an optical axis of the lens assembly, the aperture gate being adjustable in the aperture plane
Implementation Method 3
analyzing the plurality of images for generating data pertaining to a difference in stray light content with respect to the plurality of images
Data Source
Figure 1~2a
Figure 2b
Figure 3
AI summary
The present invention relates to a method (300) for reducing stray light in an output image of a scene, said method comprising; providing (301) a camera (100) comprising a lens assembly (102, 202), providing (302) an aperture unit (103, 203) having an aperture gate (204a, 204b) in an aperture plane being orthogonal to an optical axis (OA) of said lens assembly (102, 202), said aperture gate (204a, 204b) being adjustable in said aperture plane, acquiring (303), by means of said camera (100), a plurality of images of said scene, wherein each image of said plurality of images is acquired using an unique aperture gate setting, wherein each of said unique aperture gate settings correspond to a unique combination of a position and a shape of said aperture gate (204a, 204b) in said aperture plane, analyzing (305) said plurality of images for generating data pertaining to a difference in stray light content with respect to said plurality of images, and producing (306) said output image based on said data pertaining to said difference in stray light content. The invention also relates to a lens assembly (102, 202) for reducing stray light and a camera (100), comprising such a lens assembly (102, 202), and a processing unit arranged to perform the method (300). Further, the invention also relates to a system comprising a camera (100) and a processing unit arranged to perform the method (300). The camera (100) of the system comprises a lens assembly (102, 202) for reducing stray light. Furthermore, the invention also relates to a use of the camera and the system.