Folded Lens System with Prism for Compact High-Resolution Imaging
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Solution Overview
Problem
Conventional small form factor cameras in mobile devices face challenges in achieving high-resolution, high-quality images due to limitations in compact imaging lens systems, particularly in scaling up aperture size and controlling aberrations at large lens apertures, leading to low brightness and limited angular resolution.
Innovation Solution
The development of compact folded lens systems with five refractive lens elements and a light folding element, such as a prism, which redirects the optical axis, allowing for a 35 mm equivalent focal length of 50-85 mm and less than 6.5 mm Z-height, enabling high-resolution, high-quality imaging at low F/# operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If conventional small form factor cameras use compact imaging lens systems, then the device size is reduced, but the image resolution and quality deteriorate
Solution Approach 1:
The patent introduces a light folding element (prism) that redirects the optical axis from a first axis to a second axis, effectively adding a dimensional component to the optical path. This allows the lens system to achieve a longer effective focal length (50-85 mm equivalent) within a compact physical footprint (less than 6.5 mm Z-height), resolving the contradiction between small camera size and high image resolution
2Illumination intensity
If the aperture size is increased to improve brightness, then the brightness improves, but aberration control deteriorates
Solution Approach 1:
The patent merges five lens elements with different refractive powers into a single integrated lens system. This combination allows the system to maintain a large aperture (low F/# operation) for high brightness while the collective optical design of all five elements works together to control and correct aberrations, resolving the contradiction between brightness and aberration control
Solution Approach 2:
The patent employs lens elements with varying refractive indices and Abbe numbers (including materials with Vd>40 and Vd<40) to change the optical parameters of the system. This allows the large aperture design to achieve both high brightness and acceptable aberration control through careful selection and arrangement of materials with different optical properties
3Length of stationary object
If a light folding element is added to achieve compact size, then the Z-height is reduced, but the device complexity increases
Solution Approach 1:
The light folding element (prism) serves multiple functions: it redirects the optical axis to achieve compact Z-height, maintains the required optical path length for high resolution, and integrates seamlessly with the five lens elements. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in overall device 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 compact folded lens system achieves high brightness and angular resolution, capable of capturing sharp, high-resolution images in a small package size, suitable for mobile devices while maintaining low F/# operation, thereby overcoming the limitations of conventional lens systems.
Implementation Method 1
a light folding element such as a prism located between a first lens element on the object side of the lens system and a second lens element that redirects the light refracted from the first lens element
Implementation Method 2
Lens systems are described that may include five lens elements with refractive power
Data Source
AI summary
Compact folded lens systems are described that may be used in small form factor cameras. Lens systems are described that may include five lens elements with refractive power, with a light folding element such as a prism, located between a first lens element on the object side of the lens system and a second lens element, that redirects the light refracted from the first lens element from a first axis onto a second axis on which the other lens elements and a photosensor are arranged. The lens systems may include an aperture stop located behind the front vertex of the lens system, for example at the first lens element, and an optional infrared filter, for example located between the last lens element and a photosensor.