Aspheric Focus Depth Extension Element for Imaging Systems
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Solution Overview
Problem
Existing imaging systems face limitations in extending the depth of focus while maintaining high resolution, as conventional methods struggle to effectively increase the depth of field without compromising image quality.
Innovation Solution
A focus depth extension imaging optical system is introduced, featuring a focus depth extension element with an aspheric surface shape that changes from negative to positive and back in a controlled manner, integrated into the image forming optical system, which includes a phase plate with a rotationally symmetric aspheric surface shape. This element extends the depth of focus by generating aberration and diffusing the imaging light flux, allowing for a point spread function restoration process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If a light modulation plate with refracting power is added to extend depth of focus, then the depth of focus is extended, but the image resolution deteriorates
Solution Approach 1:
The patent applies parameter changes by modifying the refractive index distribution within the lens element. Specifically, it uses a gradient refractive index where the refractive index varies continuously from the center to the periphery of the lens, allowing precise control over light propagation to extend depth of focus while minimizing resolution loss.
Solution Approach 2:
The patent employs composite materials by combining a lens element with gradient refractive index properties. This composite structure integrates the focusing capability of conventional lenses with the depth extension properties of refractive index modulation, achieving both deep depth of focus and maintained image resolution.
2Device complexity
If conventional imaging optical systems are used, then the structure is simple, but the depth of focus is limited
Solution Approach 1:
The patent changes the refractive index parameter of the lens element to create a gradient distribution. This parameter modification enables the single lens element to provide both focusing and depth extension functions, increasing depth of focus without adding separate optical components.
Solution Approach 2:
The patent achieves multi-functionality by designing a lens element that simultaneously performs focusing, aperture stopping, and depth of focus extension. The gradient refractive index structure allows this single element to fulfill multiple optical functions that would traditionally require separate components.
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 system achieves a deep depth of focus with minimal deterioration in image resolution, allowing for accurate image restoration and increased tolerance to positional shifts and distance changes, while the detachable phase plate maintains the optical system's imaging functionality.
Implementation Method 1
This element extends the depth of focus by generating aberration and diffusing the imaging light flux
Implementation Method 2
This element extends the depth of focus by generating aberration and diffusing the imaging light flux
Implementation Method 3
the focus depth extension element that is added to the image forming optical system has an aspheric surface shape rotationally symmetric about an optical axis of the image forming optical system
Data Source
AI summary
A focus depth extension image forming optical system includes a focus depth extension element that extends a depth of focus of an image forming optical system. The focus depth extension element added to the image forming optical system has an aspheric surface shape rotationally symmetric about an optical axis of the image forming optical system, a sag amount Z of the aspheric surface shape changes at least to be negative, positive, and negative or positive, negative, and positive in accordance with an increase in a distance from the optical axis, in a range of 0<|t|<0.4 where |t| is a normalized radius of the aspheric surface shape, a maximum value of |dZ/dt| is 0.4 or more, and in one or more point of a range of 0.4≦|t|<0.8, dZ/dt=0.