Apochromatic Lens System Using Limited Glass Types
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Solution Overview
Problem
Wideband apochromatic lens systems require a large number of lens elements and various glass types, leading to increased complexity, cost, and susceptibility to glass obsolescence, making it difficult to achieve effective color correction over a wide spectrum.
Innovation Solution
An apochromatic lens system is designed with a configuration of three optical groups, each comprising specific numbers of optical elements formed from no more than three different types of glass, optimizing the arrangement of powers, Abbe numbers, and partial dispersions to achieve color correction across a wide spectral band using fewer elements and glass types.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a large number of lens elements and various glass types are used to achieve wideband apochromatic correction, then color correction performance is improved, but device complexity and cost increase
Solution Approach 1:
The patent applies parameter changes by carefully selecting and optimizing the Abbe numbers, partial dispersions, and powers of a limited number of lens elements. By changing the optical parameters (Abbe numbers V1, V2, V3 and partial dispersions ΔP1, ΔP2, etc.) within a constrained design, the system achieves wideband apochromatic correction without requiring a large number of elements. The specific relationships between parameters (e.g., V1/V2 > 1.05, ΔP1/ΔP2 < 0.95) enable effective color correction across a broad spectrum using only three to seven lens elements.
Solution Approach 2:
The patent employs composite materials by combining a small number of lens elements made from different glass types, each with specific optical properties. The system uses multiple glass materials with carefully selected Abbe numbers and partial dispersions to create a composite optical system that achieves apochromatic correction. This approach allows the patent to eliminate secondary spectrum and achieve diffraction-limited performance over a wide spectral band (400-700 nm) using far fewer elements than conventional designs.
2Manufacturing precision
If more glass types are used to achieve better color correction, then optical performance is improved, but susceptibility to glass obsolescence increases
Solution Approach 1:
The patent reduces susceptibility to glass obsolescence by changing the design approach from using many different glass types to using a limited set of glass materials with specific parameter relationships. By optimizing the Abbe numbers and partial dispersions within a constrained material selection, the system achieves wideband apochromatic correction while minimizing the number of unique glass types required. This makes the system more reliable and less susceptible to obsolescence, as fewer material sources need to be maintained.
3Manufacturing precision
If a conventional wideband apochromatic design is used, then color correction is achieved, but cost and manufacturing complexity increase
Solution Approach 1:
The patent reduces manufacturing cost by changing the design parameters to use a minimal number of lens elements (three to seven elements) with specific Abbe number and partial dispersion relationships. This parameter optimization allows the system to achieve wideband apochromatic correction without requiring complex multi-element designs, thereby reducing manufacturing complexity and cost while maintaining diffraction-limited performance across the visible spectrum.
Solution Approach 2:
The patent applies segmentation by dividing the optical system into three distinct optical groups with specific power configurations. This segmentation allows each group to contribute to chromatic aberration correction in a coordinated manner, achieving apochromatic performance with fewer total elements. The segmented design simplifies manufacturing compared to conventional monolithic approaches while maintaining excellent color correction across a wide spectral band.
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 solution allows for effective color correction over a wide spectral band with reduced complexity and cost, achieving near-diffraction quality images across the field of view, while minimizing the risk of obsolescence due to the limited number of glass types used.
Implementation Method 1
Chromatic dispersion in a glass lens element occurs because the index of refraction (n) of the glass varies with the wavelength of light transmitted through the glass
Implementation Method 2
Chromatic dispersion in a glass lens element occurs because the index of refraction (n) of the glass varies with the wavelength of light transmitted through the glass
Data Source
AI summary
A wideband, e.g., 550 nm to 940 nm, apochromatic lens system for use with an external aperture stop, includes first, second, and third optical groups having, in order, positive, negative, and positive powers. The first group includes four optical elements having, in order, negative, positive, negative, and positive powers. The second group includes one element of negative power; and the third group includes two elements each having positive power. In another embodiment for use with an internal stop, the system includes first, second, and third optical groups having, in order, positive, positive, and negative powers. The first group includes four optical elements having, in order, positive, negative, positive, and negative powers. The second group includes one element of positive power, and the third group includes one element of negative power. In either embodiment, all of the optical elements are formed from not more than three different types of glass material.