Folded Camera Optics With Dual Prisms for Compact High Resolution
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Solution Overview
Problem
Conventional small cameras in mobile devices struggle to capture high-resolution, high-quality images due to limitations in compact imaging lens systems, requiring improved optical designs that accommodate smaller form factors while maintaining high brightness and resolution.
Innovation Solution
A folded camera design using two light folding elements (prisms) and an independent lens system with refractive lens elements, including an aperture stop, to redirect light paths and reduce the camera's Z-height, while providing low F-number, 3x optical zoom, and high resolution imaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional small camera lens system is used, then the camera has a compact form factor, but the image resolution and quality are lower
Solution Approach 1:
The patent employs a folded optical path design where light travels through a zigzag path between two prisms, effectively converting a long linear optical path into a compact three-dimensional arrangement. This allows the optical system to achieve a long effective focal length (high resolution) while maintaining a short physical Z-height (compact form factor), directly resolving the contradiction between image resolution and camera size.
Solution Approach 2:
The lens system is designed as a nested structure where multiple lens elements are arranged in a compact sequence between the two prisms. The independent lens system with its aperture stop and multiple refractive elements is positioned within the folded optical path, allowing high-resolution imaging capability to be nested within a compact overall camera structure.
2Measurement precision
If the pixel size in photosensors is reduced to achieve higher resolution, then image resolution improves, but the demand for compact imaging lens systems with improved imaging quality increases
Solution Approach 1:
The patent optimizes multiple parameters of the lens system including the refractive indices, curvatures, thicknesses, and spacing of lens elements to achieve diffraction-limited imaging performance. By carefully adjusting these parameters, the system maintains high imaging quality despite the compact folded configuration and small pixel sizes, resolving the contradiction between resolution and manufacturing precision requirements.
3Length of moving object
If a long back focal length is provided to accommodate the second prism, then the optical system can be folded, but the lens system becomes more complex
Solution Approach 1:
The optical system is segmented into distinct functional modules: the first prism, the independent lens system with aperture stop and multiple elements, and the second prism. This segmentation allows the long back focal length to be achieved through the folded path while keeping each module relatively simple and manageable, reducing overall system complexity.
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 folded camera design enables high-resolution, high-quality image capture in a compact form factor, suitable for small devices like smartphones and tablets, with features like autofocus and optical image stabilization.
Implementation Method 1
A first prism redirects light from an object field from a first axis (AX 1) to the lens system on a second axis (AX 2). The lens element(s) in the lens stack receive the light through the aperture stop and refract the light to a second prism that redirects the light onto a third axis (AX 3)
Implementation Method 2
The lens element(s) in the lens stack receive the light through the aperture stop and refract the light to a second prism
Data Source
Figure 1A
Figure 1B
Figure 2
AI summary
A folded camera that includes two light folding elements such as prisms and an independent lens system, located between the two prisms, which includes an aperture stop and a lens stack. The lens system may be moved on one or more axes independently of the prisms to provide autofocus and/or optical image stabilization for the camera. The shapes, materials, and arrangements of the refractive lens elements in the lens stack may be selected to capture high resolution, high quality images while providing a sufficiently long back focal length to accommodate the second prism.