Erect Life-Size Lens Array With Aperture For Deep Focal Depth
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Solution Overview
Problem
Current techniques fail to effectively realize a long-focal-depth erect life-size lens array, with existing patents either lacking specific implementation details or being unable to achieve the desired optical performance.
Innovation Solution
The proposed solution involves a configuration of a first lens array with convex surfaces, a second lens array with corresponding convex surfaces, and an aperture with circular holes, where the refractive index, thickness, and distance between lens surfaces are optimized to satisfy specific conditions related to the modulation transfer function (MTF) and defocus amount, ensuring a deep focal depth and high MTF performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional lens array configuration is used, then the structure is simple, but the focal depth is short and MTF performance deteriorates with defocus
Solution Approach 1:
The optical system is divided into multiple lens arrays (first lens array, second lens array, third lens array) with different optical functions. Each lens array segment handles specific optical tasks, allowing the system to achieve long focal depth while maintaining manageable complexity through modular design
Solution Approach 2:
A light-shielding plate with aperture holes is introduced as an intermediary element between the lens arrays. This mediator controls light paths and prevents stray light, enabling the complex multi-array configuration to achieve the desired optical performance without proportionally increasing overall system complexity
2Illumination intensity
If the aperture radius is increased to improve light gathering, then illumination intensity increases, but MTF performance deteriorates due to increased defocus effects
Solution Approach 1:
The patent optimizes the aperture radius parameter to a specific range (0.03mm to 0.06mm) that balances light gathering capability with MTF performance. This parameter optimization ensures that the aperture is large enough to gather sufficient light but small enough to minimize defocus effects and maintain high MTF values across the focal depth range
Solution Approach 2:
The light-shielding plate with precisely positioned aperture holes provides localized light control. Each aperture is strategically positioned to allow only the desired light paths through the lens arrays, creating local quality control that maximizes both illumination and image quality
3Reliability
If the distance between lens arrays is increased to reduce interference, then cross-talk between adjacent lenses decreases, but the overall device length increases
Solution Approach 1:
Multiple lens arrays are arranged in close proximity with identical or similar lens configurations. The light-shielding plates with aperture patterns are positioned to create corresponding light paths through each array, allowing the system to achieve interference reduction through precise geometric copying rather than large separations
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 configuration achieves a deep focal depth and maintains high MTF values across various defocus amounts, enhancing the optical system's ability to maintain image clarity even with document movement, as demonstrated in the provided design examples.
Implementation Method 1
a first lens array in which plural first lenses each having a convex incidence surface and a convex exit surface are arranged in a direction orthogonal to an optical axis, a second lens array in which plural second lenses each having a convex incidence surface and a convex exit surface are arranged to correspond to the plural first lenses
Data Source
AI summary
An erect life-size lens array having a deep focal depth is realized. The erect life-size lens array includes a first lens array, a second lens array and an aperture, and when a thickness of the second lens is ξ1, a refractive index of the second lens is n, a distance between an exit surface of the second lens and a design image surface is ξ2, a radius of a circular hole of the aperture is ra, and a defocus amount is ξ3, the erect life-size lens array is for causing an MTF at a spatial frequency (line-pair/mm) ν to become MTFtarget or more, and satisfies (J1(2π·ra·((n/ξ1)+(1/ξ2))·ν·ξ3))/(π·ra·((n/ξ1)+(1/ξ2))·νξ3)≧MTFtarget, where J1 is a first type first-order Bessel function.