Wafer-Level Lens Miniaturization via Aspherical Surfaces
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Solution Overview
Problem
Conventional wafer-level image capture lenses face challenges in miniaturization due to difficulties in controlling lens surface accuracy and handling tiny structures, resulting in inferior modulation transfer function (MTF) and longer total track length compared to conventional 3-D lenses.
Innovation Solution
A wafer-level lens system with only three aspherical optical surfaces, where the total track length from the first surface to the image plane is less than 1.7 times the effective focal length, with specific focal length ratios for each surface, allowing for miniaturization while maintaining good MTF and aberration performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If wafer-level lens uses conventional multi-surface design to improve MTF, then modulation transfer function is improved, but total track length increases
Solution Approach 1:
The patent employs aspherical surfaces for all three lens elements, replacing conventional spherical surfaces. This allows each surface to provide optimal optical power distribution, achieving high MTF with fewer surfaces. The aspherical profiles enable better control of light rays across the aperture, reducing aberrations without requiring additional lens elements that would increase total track length.
Solution Approach 2:
The patent optimizes specific focal length ratios between surfaces (f1/fe = 0.5-1.5, f2/fe = -1.0 to -1.5, f3/fe = -0.5 to 0.5) and uses high refractive index materials (n1=1.7088, n2=1.6203, n3=1.7545). These parameter changes enable compact design with ultra-short total track length while maintaining excellent MTF performance through precise control of optical power distribution.
2Measurement precision
If wafer-level lens increases number of lens surfaces to improve MTF, then modulation transfer function is improved, but manufacturing complexity increases
Solution Approach 1:
By using aspherical surfaces on just three lens elements, the patent achieves high MTF performance without increasing the number of surfaces. The aspherical profiles provide the necessary optical correction in a compact three-surface design, avoiding the manufacturing complexity of assembling multiple spherical lens elements while achieving superior image quality.
3Measurement precision
If conventional 3-D lens is used to achieve good MTF, then modulation transfer function is improved, but miniaturization is limited
Solution Approach 1:
The patent transitions from conventional three-dimensional lens design to a wafer-level 2.5D stacked architecture. Multiple lens elements are stacked vertically on thin substrates with precise spacing, enabling ultra-short total track length. This dimensional reorganization allows compact form factor while maintaining excellent MTF through optimized optical paths in the vertical dimension.
Solution Approach 2:
The use of high refractive index materials (n>1.6) and optimized focal length ratios enables the wafer-level lens to achieve conventional MTF performance in a dramatically reduced volume. The compact design fits within 1.5-2.0 times the focal length, compared to much longer conventional lenses.
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 achieves an ultra-short total track length and improved MTF, addressing the limitations of conventional wafer-level lenses by optimizing the lens design with aspherical surfaces and specific focal length conditions.
Implementation Method 1
a wafer-level lens system, including a first surface disposed on a first substrate, a second substrate with a first side bonded to the first substrate, a second surface disposed on a second side of the second substrate, and a third surface disposed on a third substrate
Data Source
AI summary
A miniature image capture lens is disclosed comprising an aperture diaphragm having an aperture through which an image is captured and a wafer-level lens system, including a first surface disposed on a first substrate, a second substrate with a first side bonded to the first substrate, a second surface disposed on a second side of the second substrate, and a third surface disposed on a third substrate, wherein the first surface, the second surface and the third surface are aspherical and the following conditions are satisfied:L/fe<1.7;f1/fe=0.5˜1.5;f2/fe=−1˜−1.5; and−2<f3/fe<2, whereinL: total track length (TTL) from the first surface to an image plane,fe: effective focal length of whole lens system,f1: effective focal length of the first surface,f2: effective focal length of the second surface, andf3: effective focal length of the third surface.