Catadioptric Lens System for Surround-View Imaging Saturation
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Solution Overview
Problem
Surround-view imaging systems face challenges with saturation and overexposure of image detectors due to varying light intensities from different directions, particularly in wide field-of-view applications, where conventional lenses struggle to control exposure effectively without compromising sensitivity and signal-to-noise ratio.
Innovation Solution
A cylindrically shaped monolithic catadioptric lens system with aspherical surfaces is used, along with a spatially controlled illuminator and illumination controller, to limit the field of view and adjust illumination power dynamically, preventing saturation and overexposure by selectively allowing relevant light to enter the detector and optimizing the optical design for improved aberration correction and mechanical stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If a conventional fisheye lens is used to achieve wide field of view, then the horizontal field of view is enlarged, but the resolution decreases and the f-number becomes low causing vignetting and illumination problems
Solution Approach 1:
The lens system is divided into multiple functional elements: a catadioptric lens for wide field of view, a separate diaphragm for aperture control, and a second lens for image correction. This segmentation allows each element to optimize its specific function without compromising the others.
Solution Approach 2:
A diaphragm element is introduced as an intermediary component between the catadioptric lens and the image detector. This diaphragm acts as a mediator to control the aperture size and adjust the f-number independently, preventing vignetting while maintaining the wide field of view.
2Manufacturing precision
If a catadioptric lens system is used to avoid fisheye lens disadvantages, then the resolution and illumination are improved, but the f-number is fixed and exposure cannot be controlled by an adjustable diaphragm
Solution Approach 1:
The system separates the catadioptric lens (for optical quality) from a separate adjustable diaphragm (for exposure control). This segmentation allows the f-number to be changed by adjusting the diaphragm aperture while keeping the lens design fixed, providing operational flexibility without redesigning the optical path.
3Ease of operation
If neutral density filters are placed on the lens to adjust exposure, then the f-number is effectively changed, but the sensitivity of the system decreases and the signal-to-noise ratio is reduced
Solution Approach 1:
An adjustable diaphragm is introduced as an intermediary element that controls light intensity through mechanical aperture adjustment rather than filtering. This allows exposure control without inserting neutral density filters into the optical path, thereby maintaining high transmission and preserving the signal-to-noise ratio.
4Illumination intensity
If HDR techniques are applied to handle varying light intensities, then the dynamic range is extended, but the implementation becomes difficult with depth-sensitive technologies requiring constant time base
Solution Approach 1:
The system performs preliminary action by pre-adjusting the aperture size through the diaphragm to control the amount of light entering the system before the image is captured. This prevents saturation and overexposure in advance, eliminating the need for complex post-capture HDR processing and maintaining a constant time base for depth-sensitive applications.
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 prevents detector saturation, maintains high sensitivity and signal-to-noise ratio, and enhances image quality by controlling light intensity and field of view, allowing for reliable imaging across a wide dynamic range without the need for complex HDR techniques.
Implementation Method 1
imaging light from a surrounding of the imager enters the corpus by the mantle, is firstly reflected by a circumferential first aspheric lens region arranged around a center of the bottom surface
Implementation Method 2
is secondly reflected by a second aspheric lens region arranged at a center of the top surface, and leaves the corpus towards the image detector by a third aspheric lens region at the center of the bottom surface
Data Source
AI summary
A surround-view imaging system for 3D imaging of a surrounding of the system which avoid saturation and overexposure of an associated image detector, comprising an imager and an illuminator. The illuminator and the imager are arranged one over another and separated from one another by a distance to form an intermediate region which is neither in the field of view of the illuminator nor in the field of view of the imager, and corresponding imager for such surround-view imaging system.