Gradient Index Lens Aberration Correction for Infrared Imaging
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Image-pickup optical systems for infrared and terahertz-wave images face challenges in achieving high resolution due to difficulties in processing lens materials with high infrared transmittance, which are hard to manufacture and costly to process, leading to increased costs and decreased image-forming properties.
Innovation Solution
The use of a gradient index lens as the first lens near the aperture stop to correct aberration, combined with a second lens for light collection, allows for reduced processing costs and maintains image-forming properties, with the second lens having a focal distance similar to the entire system to specialize the first lens in aberration correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If germanium or other high infrared transmittance materials are used for lens materials, then infrared transmittance is improved, but manufacturing difficulty and processing cost increase due to high hardness
Solution Approach 1:
The patent changes the refractive index parameter of the lens material from constant to gradient distribution. By controlling the refractive index to vary continuously through the lens (higher at center, lower at edges), the system achieves aberration correction without requiring expensive precision polishing of hard materials like germanium.
Solution Approach 2:
The patent employs composite lens structures combining multiple materials with different refractive index characteristics. This allows the system to achieve both high infrared transmittance and effective aberration correction, avoiding the need to use only hard-to-process materials throughout the entire optical system.
2Measurement precision
If aspheric shape processing is performed to correct aberration, then image resolution is improved, but processing time and cost increase due to requirement of precision equipment
Solution Approach 1:
Instead of changing the geometric shape parameter (asphericity) of the lens, the patent changes the refractive index parameter to achieve aberration correction. This allows standard spherical lens manufacturing processes to produce high-resolution images by controlling the gradient index distribution rather than requiring time-consuming precision polishing of aspheric surfaces.
3Ease of manufacture
If gradient index lens is used for aberration correction, then design flexibility and cost reduction are improved, but manufacturing complexity increases due to refractive index control requirements
Solution Approach 1:
The patent implements gradient index lens manufacturing by controlling the refractive index parameter during material synthesis. This approach reduces overall system cost by avoiding expensive precision machining while introducing controlled complexity at the material level, where the refractive index gradient is embedded during fabrication rather than requiring post-processing.
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 reduces the cost of image-pickup optical systems while maintaining high image-forming properties, enabling high-resolution infrared or terahertz-wave image capture by effectively correcting aberrations without expensive processing.
Implementation Method 1
a first lens provided near an aperture stop and configured to correct aberration... the first lens is a gradient index lens
Implementation Method 2
a second lens arranged between the first lens and an image sensor and configured to collect light
Data Source
AI summary
An image-pickup optical system includes: a first lens provided near an aperture stop and configured to correct aberration; and a second lens arranged between the first lens and an image sensor and configured to collect light, the first lens being a gradient index lens. The degree of freedom of design of a gradient index lens is higher than that of a lens having a constant refractive index, and a gradient index lens thus has a high potential as a device for a lens. Because such a gradient index lens is employed, it is possible to correct aberration without performing expensive processing such as polishing for example. In other words, as a result, costs may be reduced and image-forming properties may not be reduced at the same time.