Solid-State Autofocus Using Chromatic Aberration
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Solution Overview
Problem
Conventional two-dimensional area imagers with moving parts for auto-focus suffer from wear-and-tear, increased battery drain, and recalibration needs, and require expensive electronics to utilize chromatic aberration for improved depth of focus.
Innovation Solution
A solid-state auto-focusing system that leverages inherent chromatic aberration in optical lenses with a broadband light source to focus different colors at distinct focal planes, using a color filter array and a range finder to construct a luminance plane for autofocus without moving parts, allowing for accurate distance measurement and image reconstruction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a moving lens or moving image plane is used for auto-focus, then the focal plane can be physically changed to accommodate different reading distances, but the system suffers from wear-and-tear, increased battery drain, and recalibration needs
Solution Approach 1:
The patent replaces the mechanical moving lens or moving image plane system with a solid-state sensor array that captures images at multiple focal planes simultaneously. The auto-focus function is achieved through electronic processing of multi-planar images rather than mechanical movement, eliminating wear-and-tear while maintaining adaptability to different reading distances.
Solution Approach 2:
The patent introduces a third dimension by capturing images at multiple focal planes (z-axis) simultaneously using a stacked sensor architecture. This multi-planar imaging approach allows the system to accommodate various reading distances without mechanical movement, as all focal planes are captured in a single shot.
2Adaptability or versatility
If a moving lens or moving image plane is used for auto-focus, then the focal plane can be physically changed, but the system experiences increased drain on batteries when implemented in portable devices
Solution Approach 1:
The patent eliminates the need for mechanical actuators, motors, and power-consuming moving components by using a solid-state stacked sensor array. The auto-focus functionality is achieved through simultaneous multi-planar image capture and electronic processing, dramatically reducing power consumption in portable devices.
Solution Approach 2:
The system performs preliminary action by capturing all necessary focal plane information simultaneously in a single shot before any processing occurs. This eliminates the need for sequential focusing adjustments that would consume additional energy, as all depth information is obtained upfront.
3Adaptability or versatility
If a moving lens or moving image plane is used for auto-focus, then the focal plane can be physically changed, but the system requires recalibration of the moving parts
Solution Approach 1:
The patent replaces mechanical moving parts with a fixed stacked sensor array, eliminating recalibration needs entirely. The solid-state structure has no moving components to drift or misalign, and the multi-planar geometry is inherently stable and factory-calibrated.
Solution Approach 2:
Instead of moving components to achieve focal plane changes, the patent inverts the approach by having fixed components capture multiple planes simultaneously. The calibration is performed once during manufacturing and remains valid throughout the device lifetime, reversing the traditional recalibration requirement.
4Adaptability or versatility
If chromatic aberration is used for improved depth of focus, then the depth of focus is improved, but expensive electronics are needed to implement this type of reader
Solution Approach 1:
The patent converts the typically harmful chromatic aberration (color fringing) into a beneficial effect for depth encoding. By using a broadband light source and capturing images at multiple focal planes, the chromatic dispersion naturally creates distinct focal planes for different wavelengths, which are then used to encode depth information without requiring expensive specialized electronics.
Solution Approach 2:
The patent makes the chromatic aberration, which is normally a defect to be corrected, into a useful feature for depth sensing. The same optical path and sensor array that capture standard images also capture depth information through chromatic focal plane separation, eliminating the need for separate expensive depth-sensing electronics.
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
This solution enables efficient auto-focusing in two-dimensional imaging systems without mechanical parts, reducing wear and battery consumption, while maintaining effective depth of focus and image quality across various distances, and is cost-effective by utilizing existing components.
Implementation Method 1
chromatic aberration is a lens distortion that arises due to dispersion, i.e., a variation of the refractive index of the lens material as a function of wavelength. As a result, the lens focuses different wavelengths of light at different focal distances.
Implementation Method 2
The distance from the imaging system to the object to be imaged can be determined by an independent light beam.
Data Source
AI summary
An imaging system having a solid-state auto focusing system advantageously images broadband light reflected from an object to be imaged using a lens objective having chromatic aberration, which focuses different colors of light at different focal planes. Using the color information in the focal planes in conjunction with an object distance determined by a range finder, a luminance plane is constructed that has a focused image of the object. The system provides the focused image of the object without the use of any moving parts.