Liquid Lens Calibration via Pattern Focus Evaluation
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Solution Overview
Problem
Existing photographing systems using liquid lenses struggle to accurately focus on desired positions due to the lack of a reliable method for determining the correspondence between focal positions and control values, especially in applications requiring precise depth information for capturing focused images.
Innovation Solution
A photographing system that photographs multiple patterns at different focal positions, evaluates the focus of each image, and establishes a correspondence relationship between focal positions and control values, allowing for precise focusing by adjusting the focal position based on the evaluated data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a liquid lens is used to change focal position by voltage control, then the optical system can focus on multiple depth positions, but the correspondence between focal position and control value becomes uncertain
Solution Approach 1:
The system performs preliminary calibration by photographing calibration patterns at multiple focal positions and pre-establishing the correspondence relationship between focal positions and control values before actual use. This allows accurate focusing without requiring complex real-time calculations during operation.
Solution Approach 2:
The system uses feedback from focus evaluation of calibration patterns to iteratively determine the accurate correspondence relationship between focal positions and control values. By evaluating the focus degree of images at different focal positions and comparing with expected pattern positions, the system refines the mapping relationship.
2Measurement precision
If multiple images are photographed at different focal positions for calibration, then the correspondence relationship can be established, but the calibration process becomes time-consuming
Solution Approach 1:
The calibration process is segmented into distinct phases: photographing calibration patterns at multiple focal positions, evaluating focus degrees, and determining the correspondence relationship. This segmentation allows for systematic processing and optimization of each step to reduce overall calibration time while maintaining accuracy.
Solution Approach 2:
The system changes parameters such as focal position and control value systematically during calibration. By varying the focal position through controlled voltage changes and recording the corresponding images, the system efficiently maps the relationship between control values and focal positions without requiring exhaustive testing.
3Ease of operation
If the focal position is changed manually, then focusing can be adjusted, but the operation becomes complex and error-prone
Solution Approach 1:
The system performs self-calibration and self-adjustment by automatically determining the correspondence relationship between focal positions and control values and using this relationship to automatically focus on desired subjects. This eliminates the need for manual calibration procedures and simplifies operation while reducing control system complexity.
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
Enables accurate and efficient focusing on desired positions by determining the optimal control values for the liquid lens, reducing the need for manual adjustments and improving image quality in applications like biometric authentication and industrial imaging.
Implementation Method 1
The liquid lens is a type of lens that changes focus by using a technique called electrowetting in which a curvature of a droplet changes according to a voltage value to be given
Implementation Method 2
a forming position of an image can be changed by refracting an incident light beam into the optical system
Data Source
AI summary
A photographing system according to one example embodiment includes a hardware photographing device configured to photograph each of a first pattern and a second pattern; at least one memory storing instructions; and at least one processor configured to execute the instructions to: set, for the hardware photographing device, a control value for changing the focal position; evaluate degrees of focus of a plurality of images of the first pattern and select an image having a maximum evaluation value, as well as evaluate degrees of focus of a plurality of images of the second pattern and select an image having a maximum evaluation value; and acquire a correspondence relationship between a focal position of an optical system and a control value, based on the control values used in capturing the images of the first pattern and the second pattern, and subject distances of the first pattern and the second pattern.