Two-Element Aspheric Lens System for Time-of-Flight Sensing
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Solution Overview
Problem
Conventional time of flight sensing modules face limitations in receiving quality, receiving distance, and image recognition, restricting their application scope and failing to meet market demands for multi-functionality.
Innovation Solution
An optical lens system with two lens elements, each having at least one aspheric surface, optimized by specific refractive index, Abbe number, and geometric constraints, to enhance image quality and miniaturization, suitable for time of flight sensing modules.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional receiver of time of flight sensing module is used, then the structure is simple, but the receiving quality and receiving distance are limited
Solution Approach 1:
The optical lens is divided into two separate lens elements (first lens element and second lens element) with specific refractive indices and Abbe numbers. This segmentation allows each lens to be optimized for specific optical functions, improving overall receiving quality and distance measurement capability while maintaining a compact structure.
Solution Approach 2:
The patent specifies precise parameter ranges for the lens elements including refractive indices (N1, N2), Abbe numbers (V1, V2), and geometric parameters (f/EPD ratio, TL, BL). By optimizing these parameters, the system achieves improved receiving quality and distance measurement without excessive complexity.
2Measurement precision
If the optical lens system uses more lens elements to improve image quality, then the receiving quality improves, but the size of the time of flight sensing module increases
Solution Approach 1:
The system uses composite optical design combining two lens elements with different material properties (different refractive indices and Abbe numbers). This composite approach achieves superior image quality and depth of field comparable to more complex multi-element systems, but with a compact total track length suitable for miniaturized modules.
Solution Approach 2:
The patent employs aspheric surfaces on the lens elements, utilizing surface geometry optimization to achieve better optical performance within a constrained axial distance. This dimensional optimization allows high image quality in a compact form factor.
3Area of moving object
If the focal length is increased to improve field of view, then the receiving distance improves, but the image quality and depth of field deteriorate
Solution Approach 1:
The patent optimizes the focal length to entrance pupil diameter ratio (f/EPD) within a specific range (0.50-2.00) and controls the axial distance parameters (TL, BL) to achieve the desired balance between field of view, receiving distance, and image quality. This parameter optimization resolves the contradiction by finding the optimal operating point.
Solution Approach 2:
The combination of two lens elements with different optical properties enables independent optimization of field of view and image quality. The first lens element with lower refractive index and the second lens element with higher refractive index work together to achieve both wide field of view and high image quality simultaneously.
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 system improves image quality and reduces size while maintaining effective sensing capabilities, enabling wider field of view and accurate distance identification, suitable for time of flight sensing modules.
Implementation Method 1
a refractive index of the first lens element is N1... a refractive index of the second lens element is N2
Implementation Method 2
at least one of the object-side surface and the image-side surface of at least one lens element of the optical lens system is aspheric
Data Source
AI summary
An optical lens system includes two lens elements which are, in order from an object side to an image side along an optical path: a first lens element and a second lens element. Each of the two lens elements has an object-side surface facing toward the object side and an image-side surface facing toward the image side. At least one of the object-side surface and the image-side surface of at least one lens element of the optical lens system is aspheric. A total number of the lens elements in the optical lens system is two.