Folded Telephoto Camera Module for Large Aperture Miniaturization
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Solution Overview
Problem
Existing telephoto lens assemblies for portable devices face challenges in achieving a large effective focal length without significantly increasing the optical path length, leading to limitations in miniaturization and performance in low-light conditions due to restricted apertures and weight demands on optical image stabilization motors.
Innovation Solution
An optical system with a first lens having positive refractive power, a reflective element, and a second lens with negative refractive power, configured to redirect light through a planar reflector, allowing for a large aperture and reduced overall height while maintaining imaging quality and stabilization performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the effective focal length of the optical system is increased to achieve telephoto characteristics, then the imaging quality of distant objects is improved, but the optical path length and total length of the system increase significantly
Solution Approach 1:
The patent introduces a reflective element (prism or mirror) to fold the optical path, changing the linear optical path into a multi-dimensional path. Light enters the first lens, reflects off the reflective element, and exits through the second lens, creating a folded optical path that achieves long effective focal length within a compact physical envelope. This dimensional change allows the optical system to achieve telephoto characteristics without proportionally increasing the total system length.
Solution Approach 2:
The reflective element is positioned within the optical path between the first and second lenses, nesting the reflection function within the existing lens structure. This nested arrangement allows the optical system to achieve extended optical path length without increasing the external dimensions proportionally, as the light path is folded within the available internal space.
2Illumination intensity
If the aperture of the optical system is increased to improve low-light performance, then the light gathering capability is improved, but the overall size and weight of the system increase
Solution Approach 1:
The folded optical path created by the reflective element allows the system to achieve a large aperture diameter without proportionally increasing the system length. By folding the light path, the system can accommodate a larger first lens aperture while keeping the overall system compact, thereby improving light gathering capability without excessive weight increase.
3Adaptability or versatility
If the optical system is miniaturized for portable devices, then the adaptability to portable devices is improved, but the effective focal length and aperture are reduced
Solution Approach 1:
The patent uses a reflective element to fold the optical path, enabling the system to achieve a long effective focal length within a short physical length. This allows the optical system to maintain telephoto characteristics (long effective focal length) while being miniaturized for portable device integration, resolving the contradiction between compact size and effective focal length.
Solution Approach 2:
The reflective element is nested within the optical path between the first and second lenses, allowing the system to achieve extended optical functionality within a compact form factor. This nested arrangement enables the miniaturized system to maintain the required effective focal length for telephoto imaging.
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 enables a compact telephoto lens assembly with improved low-light performance and reduced motor burden, achieving a larger aperture and minimizing the overall size and weight, while maintaining high imaging quality and effective optical image stabilization.
Implementation Method 1
The reflective element is configured to reflect light exiting from the first lens
Implementation Method 2
a first lens having a positive refractive power
Implementation Method 3
a second lens with negative refractive power, configured to redirect light
Data Source
AI summary
An optical system and a camera module are provided, and the optical system along an optical axis from an object side to an image side sequentially includes: a first element group, a second element group, and a third element group having a positive refractive power. The first element group, from the object side to the image side sequentially includes: a first lens having a positive refractive power and a reflective element. The reflective element is configured to reflect light exiting from the first lens. The optical system satisfies: 0.85<|FG12/FG3|<1.1, where FG12 is a combined focal length of the first element group and the second element group, and FG3 is an effective focal length of the third element group.