Compact Wide-Angle Autofocus Lens with Liquid-Lens Focusing
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Solution Overview
Problem
Existing imaging systems for machine vision face challenges in achieving wide-angle field of view, high resolution, and compact size while avoiding mechanical failures and high costs due to mechanical lens movements and complex electromechanical components.
Innovation Solution
An optical assembly comprising three lens groups and a liquid lens that corrects for spherical aberrations, optical field curvature, and distortion, using plastic and glass aspheric lenses, and a variable power liquid lens to achieve autofocus without mechanical movement, reducing system size and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical lens movement is used for autofocus, then focus adjustment is achieved, but system size increases and mechanical failures occur
Solution Approach 1:
The patent replaces mechanical lens movement with a liquid lens that changes focal length through fluid pressure control. The liquid lens element can vary its optical power from -5 to +15 diopters by adjusting the pressure of liquid contained within it, eliminating motors and mechanical moving parts while achieving autofocus functionality.
Solution Approach 2:
The liquid lens changes its optical parameters (focal length from 76.2mm to infinity) by changing the physical state of the liquid inside it through pressure control. This allows continuous variation of focal length without mechanical movement of the lens elements.
2Measurement precision
If multiple lens elements are used for high resolution imaging, then image quality improves, but lens cost increases
Solution Approach 1:
The optical assembly uses a composite structure combining plastic aspheric lenses (first and second lens groups) with a liquid lens (third lens group). This combination achieves high-resolution imaging while reducing manufacturing cost compared to using multiple precision glass lens elements.
Solution Approach 2:
The optical system is divided into three lens groups: first lens group for wide-angle field of view, second lens group for correction of optical aberrations, and third liquid lens group for autofocus. This segmentation allows each group to be optimized for its specific function while using cost-effective plastic materials.
3Volume of moving object
If compact size is achieved with small sensors, then portability improves, but active alignment requiring air gap increases system complexity
Solution Approach 1:
The liquid lens provides built-in autofocus capability that automatically maintains proper focus without requiring external alignment mechanisms. The liquid lens element self-adjusts its focal length to compensate for variations in sensor positioning, eliminating the need for complex active alignment systems.
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 enables high-resolution imaging with a wide field of view and compact size, improving reliability and reducing costs by eliminating mechanical failures and complex components.
Implementation Method 1
a liquid lens disposed along the optical axis configured to receive the light from the first lens group and further configured to variably focus an image at distances from 76.2 millimeters to infinity
Implementation Method 2
a first lens group disposed along an optical axis configured to receive light from the object of interest and configured to correct for spherical aberrations of an image projected by a third lens group
Implementation Method 3
a second lens group disposed along the optical axis configured to receive the light from the liquid lens and further configured to correct for optical aberrations, and to magnify an image projected by the third lens group
Implementation Method 4
the third lens group disposed along the optical axis configured to receive the light from the second lens group and further configured to correct for optical field curvature and distortion of the image projected by the third lens group
Data Source
AI summary
A method and apparatus for capturing an image of at least one object appearing in a field of view (FOV). A housing has an image sensor an autofocusing lens assembly fixedly mounted relative thereto. The autofocusing lens assembly employs multiple lens groups and a liquid lens. The lens groups, liquid lens, and the image sensor are aligned such that light received within the FOV passes through the lens groups and liquid lens and impinges onto the image sensor. The image sensor generates an electrical signal indicative of the received image.