Apochromatic Optical Design Using Anomalous Dispersion Glass
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Solution Overview
Problem
Optical systems with a narrow field of view, such as refracting telescopes, face challenges with chromatic aberration due to the dispersive properties of glass, leading to mechanical cumbersome designs and high costs with the use of highly anomalous glass types for effective color correction.
Innovation Solution
An apochromatic optical design using a small number of lenses, including an object-side lens group with flint glass, a middle lens group with a combination of normal and moderately anomalous glass, and an image-side lens group, which reduces chromatic aberration without requiring highly anomalous glass types, thereby achieving superior optical performance with reduced cost and complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If highly anomalous glass types are used for effective color correction, then chromatic aberration is reduced, but cost and manufacturing difficulty increase
Solution Approach 1:
The patent changes the parameters of the optical system by using a specific combination of glass types (flint glass with positive refractive power and anomalous dispersion glass with negative refractive power) and their respective refractive indices and dispersive properties. This parameter optimization achieves effective color correction without requiring highly anomalous glass, thereby reducing manufacturing difficulty and cost.
Solution Approach 2:
The patent employs a composite optical system combining flint glass and anomalous dispersion glass in a specific configuration. This composite material approach leverages the complementary properties of the two glass types to achieve superior color correction while avoiding the need for expensive and difficult-to-manufacture highly anomalous glass alone.
2Manufacturing precision
If more lens elements are added to reduce chromatic aberration, then image quality improves, but device complexity increases
Solution Approach 1:
The patent merges the functions of multiple lens elements into a more compact arrangement by strategically positioning the flint glass and anomalous dispersion glass elements. This combining approach reduces the total number of lens elements while maintaining effective color correction and image quality, thereby reducing device complexity.
3Manufacturing precision
If a very slow focal ratio is used to reduce chromatic aberration, then color correction improves, but device length and mechanical complexity increase
Solution Approach 1:
The patent changes the optical parameters by using glass materials with specific refractive indices and dispersive properties that enable effective color correction at faster focal ratios. This parameter optimization allows the system to achieve superior chromatic aberration correction without requiring a very slow focal ratio, thereby reducing device length and mechanical complexity.
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 design provides excellent color correction with a shorter track length and improved Strehl ratios, reducing the need for expensive and difficult-to-fabricate anomalous glass types, resulting in a more efficient and cost-effective optical system.
Implementation Method 1
Dispersion of an optical substrate causes the refraction of a lens to vary with wavelength, so that, for conventional optical glass, the index of refraction is higher for short wavelengths and decreases as wavelength increases.
Implementation Method 2
Dispersion of an optical substrate causes the refraction of a lens to vary with wavelength
Data Source
AI summary
An apochromatic imaging system has an object-side lens group having at least an object-side lens element with positive refractive power and formed from a flint glass material with deviation of relative dispersion −0.013<ΔPg,F<+0.013 and an Abbe number less than 50. A middle lens group has at least a second lens element and a third lens element, wherein, one of the second and third lens elements has deviation of relative dispersion −0.013<ΔPg,F<0.013 and the other of the second and third lens elements has deviation of relative dispersion 0.013<ΔPg,F<0.04. An image-side lens group has at least a fourth lens element.