Achromatic Gradient Index Singlet Lens Design
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Solution Overview
Problem
Current optical systems require multiple lenses to focus light of different colors equally, leading to increased complexity and size, as traditional lenses suffer from chromatic aberrations due to varying refractive indices with wavelength.
Innovation Solution
A single achromatic gradient index singlet lens is designed using gradient index materials with a refractive index varying linearly along the optic axis, balancing chromatic aberrations through a combination of surface curvature and refractive index distribution, allowing for equal focusing of light across a wide color range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional lenses are used to focus light of different colors, then chromatic aberrations occur due to varying refractive indices with wavelength, but using multiple lens elements increases device complexity and size
Solution Approach 1:
The patent applies gradient index materials where the refractive index varies continuously through the lens body rather than being uniform. This parameter change allows a single lens element to correct chromatic aberrations by controlling the spatial distribution of refractive index, eliminating the need for multiple lens elements while maintaining accurate focusing across different wavelengths
Solution Approach 2:
The invention uses composite gradient index materials that combine multiple material properties within a single lens structure. These composite materials enable simultaneous control of refraction and dispersion characteristics, allowing one lens to perform the function that traditionally required multiple separate lenses
2Reliability
If multiple lens elements are used to correct chromatic aberrations, then chromatic focusing performance improves, but the optical system becomes larger and heavier
Solution Approach 1:
The patent merges the functions of multiple lens elements into a single gradient index lens. By combining refraction and dispersion control within one integrated structure, the invention reduces the total number of components, thereby decreasing the overall weight and size of the optical system while maintaining effective chromatic aberration correction
3Ease of manufacture
If uniform refractive index materials are used, then manufacturing is simpler, but chromatic aberrations cannot be corrected
Solution Approach 1:
The invention transitions from uniform refractive index materials to gradient index materials where the refractive index varies continuously through the lens. This parameter change enables chromatic aberration correction while maintaining manufacturing feasibility through established gradient index material fabrication techniques
Solution Approach 2:
The patent applies different refractive index values at different locations within the lens body rather than using a uniform index. This local variation in material properties allows specific regions to correct chromatic aberrations while maintaining overall lens functionality and manufacturability
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 approach reduces the number of lenses needed by up to a factor of two, enabling smaller, lighter optical systems with improved chromatic performance, effectively addressing chromatic aberrations in imaging applications.
Implementation Method 1
The variation of refractive index as a function of wavelength is referred to as optical dispersion. A highly-dispersive material is one whose index of refraction changes greatly as a function of wavelength.
Implementation Method 2
Because of material dispersion, lenses do not focus light of different colors equally.
Implementation Method 3
The higher the refractive index contrast between two materials, the more light will bend at a curved interface between them.
Implementation Method 4
One lens is strongly focusing, fabricated from a glass with weak dispersion. The second lens is a negative lens, which means that it weakens the focusing from the first lens, but is designed so that the overall two-lens system still focuses light.
Data Source
AI summary
A method of making an achromatic gradient index singlet lens comprising utilizing a gradient index material with a curved front surface in which light does not follow a straight line as it travels through the material and wherein different color rays traverse different curved paths, utilizing the natural dispersion of the curved front surface as a strong positive lens, and developing a weakly diverging GRIN distribution within the lens to balance the chromatic aberrations of the curved front surface.