Four-Lens Optical System for Compact 3D Imaging
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional lens systems for mobile devices face a trade-off between high lens speed and large depth of field, making it difficult to achieve both simultaneously in a compact design, especially for 3D imaging systems that require infrared light processing.
Innovation Solution
An optical lens system with four lenses, including two meniscus lenses with specific curvature ratios and refractive powers, along with a beam-limiting aperture diaphragm and a planoparallel plate, optimized for high-index materials like PMMA, to achieve high lens speed and depth of field while maintaining compactness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional lens systems use more than four lenses to achieve high lens speed, then lens speed is improved, but device complexity and compactness are worsened
Solution Approach 1:
The patent divides the optical system into exactly four lens segments (L1, L2, L3, L4) with specific refractive power configurations. This segmentation achieves high lens speed (f/1.5) while maintaining compactness by optimizing each lens's contribution rather than simply adding more lenses.
Solution Approach 2:
The patent changes the refractive power parameters of the four lenses, specifically making L2 and L3 meniscus lenses with positive refractive power and L4 a negative lens. This parameter optimization enables high lens speed with only four lenses, resolving the contradiction between lens speed and device complexity.
2Length of stationary object
If conventional lens systems reduce the number of lenses to achieve compact design, then compactness is improved, but lens speed and depth of field are worsened
Solution Approach 1:
The patent optimizes the refractive power parameters and curvature radii of the four lenses, particularly using meniscus lenses L2 and L3 with specific curvature relationships. This enables achieving f/1.5 lens speed with a compact total length of only 4.84mm, resolving the contradiction between compactness and lens speed.
Solution Approach 2:
The patent employs meniscus lenses with specific curvature radii relationships (e.g., -1.42 < R21/R32 < 2.0) to optimize light path control. This curvature optimization enables compact lens system length while maintaining high lens speed and adequate depth of field.
3Reliability
If conventional lens systems increase depth of field by reducing lens speed, then depth of field is improved, but lens speed is worsened
Solution Approach 1:
The patent optimizes the refractive power and curvature parameters of all four lenses, particularly the meniscus lenses L2 and L3. This parameter optimization achieves both high lens speed (f/1.5) and adequate depth of field for TOF imaging, resolving the contradiction between lens speed and depth of field.
Solution Approach 2:
The patent uses high-refractive-index materials (n > 1.6 in the 800-1000nm wavelength range) for the lens elements. This material selection enables achieving both high lens speed and adequate depth of field by reducing the angles of incidence and minimizing aberrations.
4Illumination intensity
If conventional lens systems use high-index materials, then lens speed is improved, but manufacturing precision requirements are worsened
Solution Approach 1:
The patent optimizes the curvature radii and refractive power parameters of the four lenses to reduce sensitivity to manufacturing tolerances. By carefully balancing the optical parameters, the system achieves high lens speed with acceptable tolerance sensitivity, particularly for the meniscus lenses L2 and L3.
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 lens system achieves high lens speed and large depth of field with reduced sensitivity to production tolerances, suitable for 3D TOF image sensors, enabling acceptable image sharpness over a wide object distance zone with minimized aberrations and compact dimensions.
Implementation Method 1
an optical lens system having exactly four lenses, wherein there are provided in an order from an end at the object side to an end at the image side a first lens L1 having a positive refractive power, a second lens L2 having a positive refractive power, a third lens L3 having a positive refractive power, and a fourth lens L4 having a negative refractive power
Data Source
AI summary
The present invention relates to an optical lens system for a camera comprising in an order from an end at the object side to an end at the image side a first lens having a positive refractive power, a second lens having a positive refractive power, a third lens having a positive refractive power, and a fourth lens having a negative refractive power, wherein the second and third lenses are each designed as meniscus lenses, wherein the surface of the second lens at the object side is convex and the surface of the third lens at the object side is concave. The invention further relates to an imaging system having an image sensor that has a plurality of light-sensitive elements arranged in rows and columns and having such an optical lens system.