Diffractive Optical System for Compact Wavelength Aberration Correction
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Solution Overview
Problem
Existing optical systems generate aberrations that differ for each wavelength, and increasing the number of lenses to correct these aberrations results in a larger system size.
Innovation Solution
An optical system with a front group and a rear group, featuring a light shielding member with an elongated opening and a diffraction surface that disperses light into multiple wavelengths, combined with aspherical surfaces and asymmetric optical elements to correct aberrations while maintaining a compact size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the number of lenses is increased to correct aberrations, then the aberration correction capability is improved, but the size of the total system is increased
Solution Approach 1:
The patent applies parameter changes by modifying the grating spacing of the diffraction surface to include an extremum value at the center portion, and by designing aspherical surfaces with specific curvature variations. These parameter optimizations enable effective aberration correction while maintaining a compact system configuration without requiring additional lenses.
Solution Approach 2:
The patent employs asymmetry principles through the design of asymmetric optical surfaces, including the diffraction surface with non-uniform grating spacing and aspherical surfaces with specific curvature distributions. These asymmetric designs allow for corrected aberrations across different wavelengths while keeping the overall system size small, avoiding the need for multiple symmetric lens elements.
2Measurement precision
If a diffraction grating is used to disperse light into multiple wavelengths, then the spectral resolution is improved, but aberrations that differ for each wavelength are generated
Solution Approach 1:
The patent applies local quality by designing the diffraction surface with locally varied grating spacing, where the spacing changes from the center portion toward the peripheral portion to include an extremum value at the center. This local variation in grating spacing allows different regions of the optical system to handle different wavelength components with optimized aberration correction, maintaining both spectral resolution and aberration uniformity.
Solution Approach 2:
The patent uses spheroidality through the incorporation of aspherical surfaces with specific curvature profiles. The aspherical surfaces are designed with curvature variations that compensate for wavelength-dependent aberrations generated by the diffraction grating, allowing uniform aberration correction across multiple wavelengths while maintaining high spectral resolution.
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 system effectively corrects aberrations for different wavelengths while keeping the overall size small, enhancing image quality and flexibility in design.
Implementation Method 1
a diffraction surface that disperses a light flux that has passed through the opening into a plurality of light fluxes of mutually different wavelengths
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
An optical system 10 includes a front group 11, a light shielding member 4, and a rear group 12 disposed in order from a side of an object to a side of an image. The light shielding member 4 has an opening elongated in a first direction. The rear group 12 has a diffraction surface 5 that disperses a light flux that has passed through the opening into a plurality of light fluxes of mutually different wavelengths in a first section perpendicular to the first direction, and an aspherical surface 6 disposed closer than the diffraction surface 5 to the side of the image. The aspherical surface 6 in the first section has a non-circular-arc shape. The grating spacing of the diffraction surface 5 in the first section changes from a center portion toward a peripheral portion to include an extremum value at the center portion. In the first section, the shape of at least one of a base surface of the diffraction surface 5 and an optical surface disposed closer than the diffraction surface 5 to the side of the object is asymmetric with respect to a normal line at a vertex thereof.