Freeform Lens Rectangular Image Sensor Utilization
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Solution Overview
Problem
Fisheye lenses with circular images result in inefficient use of rectangular image sensors, as only a small region overlaps with the image, leaving large areas unused, and existing solutions like toric lenses form elliptical images, which do not fully utilize the sensor's area.
Innovation Solution
A lens system with a front and rear lens group, including at least one freeform surface lens asymmetric about the optical axis, that forms a substantially rectangular image on a rectangular image sensor, satisfying specific optical path length conditions to efficiently utilize the sensor's area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fisheye lens forms a circular image on a rectangular image sensor, then the lens can capture wide-angle views, but large regions of the image sensor remain unused
Solution Approach 1:
The patent employs a freeform surface lens with asymmetric geometry about the optical axis. This asymmetric design transforms the traditionally circular fisheye image into a rectangular image that conforms to the rectangular sensor geometry, thereby eliminating wasted sensor area while preserving wide-angle capture capability
Solution Approach 2:
The patent modifies the optical path length parameters through the freeform surface lens design. By controlling the optical path lengths from off-axis object points through the asymmetric lens to the sensor plane, the image geometry is transformed from circular to rectangular, optimizing sensor utilization
2Loss of energy
If a toric lens is used to form an elliptical image on a rectangular image sensor, then some sensor area is utilized better than circular images, but the image shape still does not fully match the sensor geometry
Solution Approach 1:
The patent uses a freeform surface lens with asymmetric geometry that goes beyond the symmetric elliptical correction of toric lenses. This asymmetric design enables the image to conform precisely to the rectangular sensor geometry, achieving complete sensor area utilization without shape mismatch
Solution Approach 2:
The freeform surface lens effectively copies the rectangular geometry of the sensor onto the image plane. By designing the lens surface to match the sensor's rectangular boundaries, the image shape is transformed to exactly fit the sensor area, eliminating the elliptical shape mismatch inherent in toric lens systems
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 lens system effectively forms a rectangular image on a rectangular image sensor, maximizing the use of the sensor's area and improving image capture efficiency, especially in wide-angle applications like fisheye lenses.
Implementation Method 1
a lens system which includes a lens group including at least one lens element... at least one of the front lens group and the rear lens group includes a freeform surface lens asymmetric about an optical axis
Data Source
AI summary
A lens system which includes a lens group including at least one lens element and forms an image on an image sensor which is rectangular with a first side and a second side greater than or equal to the first side in length, the lens system including: in order from an object side to an image surface side, a front lens group; a diaphragm; and a rear lens group, wherein at least one of the front lens group and the rear lens group includes a freeform surface lens asymmetric about an optical axis, and the lens system satisfies 1<A/(B−C)<10000 and 1<A/(D−E)<10000.