Five-Lens Aspherical Optical Lens for Compact ToF Imaging
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Solution Overview
Problem
Existing ToF lenses in smartphones fail to simultaneously achieve high resolution, small size, wide angle, and large aperture, which are essential for precise depth measurement and miniaturization, while maintaining imaging quality.
Innovation Solution
An optical lens design comprising a sequence of five plastic aspherical lenses with specific focal powers and surface profiles, including a negative and positive focal power arrangement, a stop, and a filter, which satisfies the expressions (1) to (14) to control effective focal length, field of view, and aberration correction, enabling a compact and high-quality imaging system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the ToF lens is designed with high resolution and small size, then the imaging quality and miniaturization requirements are met, but the field of view and aperture are reduced
Solution Approach 1:
The optical lens is divided into five separate lens elements with different focal powers (negative, positive, positive, positive, negative), each contributing to different aspects of image formation and aberration correction. This segmentation allows the system to achieve compact size while maintaining wide field of view through optimized light path management
Solution Approach 2:
The patent employs aspherical surfaces on multiple lens elements, transitioning from simple spherical geometry to complex aspherical geometry. This dimensional change in surface shape enables better control of light rays across wide angles while keeping the overall lens size small, effectively resolving the contradiction between compact size and wide field of view
2Measurement precision
If the ToF lens is designed with wide angle and large aperture, then the depth measurement precision is improved, but the lens size and complexity increase
Solution Approach 1:
Different lens elements are assigned specific focal powers (negative, positive, positive, positive, negative) and specific surface characteristics (convex/concave combinations) to address local optical requirements. The aspherical surfaces are applied selectively to specific lens elements where they are most effective for aberration correction, optimizing the balance between performance and complexity
Solution Approach 2:
The patent systematically varies key optical parameters including focal lengths of individual elements, spacing between elements, and aspherical surface coefficients to achieve the desired wide field of view and large aperture while controlling overall size. The ratio constraints on focal lengths and the inflection point positions represent parameter optimization to balance precision and complexity
3Manufacturing precision
If the lens uses multiple inflection points on aspherical surfaces, then the aberration correction and imaging quality are improved, but the manufacturing difficulty increases
Solution Approach 1:
Instead of applying complex aspherical surfaces with multiple inflection points to all lens elements, the patent applies them selectively to specific elements (first, second, third, and fifth lenses) where they provide the most benefit. This partial application achieves adequate aberration correction while reducing overall manufacturing complexity compared to universal application
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 optical lens design achieves a high-quality resolution with a small outer diameter, short total length, high relative illumination, wide angle, and large aperture, effectively addressing the requirements of ToF technology and enabling a compact, high-performance imaging system suitable for smartphones.
Implementation Method 1
an optical lens, which sequentially includes a first lens with a negative focal power, where an object side surface of the first lens is convex, and an image side surface of the first lens is concave
Data Source
AI summary
Disclosed are an optical lens, a camera module and a terminal camera. From an object side to an image side, the optical lens include: a first lens with a negative focal power, which has a convex object side surface and a concave image side surface; a stop; a second lens with a positive focal power, which has a convex object side surface and a concave image side surface; a third lens with a positive focal power, which has a convex object side surface and a concave image side surface; a fourth lens with a positive focal power, which has a convex object side surface and a convex image side surface; a fifth lens with a negative focal power, an object side surface of the fifth lens is convex at a paraxial region and an image side surface of the fifth lens is concave at a paraxial region; and a filter.