Diffractive Optical Element with Varying Grating Heights
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Solution Overview
Problem
Existing diffractive optical elements in telescopic lenses suffer from increased flare light due to chromatic aberrations, particularly red flare light, which affects optical performance and image quality.
Innovation Solution
A diffractive optical element with a blazed diffraction grating having varying grating heights in central and peripheral regions, optimized to reduce flare light by controlling diffraction efficiency and wavelength dependence, where the grating height in the central region is smaller than in the peripheral region, and the diffraction efficiency is tailored to minimize unwanted diffracted light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a diffractive optical element with a diffraction grating is used in a telescopic lens, then chromatic aberrations are reduced, but flare light intensity increases
Solution Approach 1:
The patent applies local quality by making the grating height vary across different regions of the diffraction grating. Specifically, the grating height in the central region is set to be smaller than that in the peripheral region, allowing different parts of the optical element to have different diffraction characteristics. This resolves the contradiction by locally optimizing each region to reduce flare light while maintaining chromatic aberration correction.
Solution Approach 2:
The patent changes the physical parameter of grating height from a uniform value to a spatially varying value. By controlling the grating height distribution across the central and peripheral regions, the patent optimizes the diffraction efficiency and wavelength dependence to minimize unwanted diffracted light while preserving the chromatic aberration correction function.
2Reliability
If the grating height is increased to improve diffraction efficiency, then optical performance improves, but flare light and chromatic aberrations worsen
Solution Approach 1:
The patent applies local quality by differentiating the grating height between central and peripheral regions. The central region has a smaller grating height to reduce flare light generation, while the peripheral region has a larger grating height to maintain adequate diffraction efficiency. This spatial differentiation resolves the contradiction between overall diffraction efficiency and local flare light reduction.
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 effectively reduces flare light intensity and chromatic aberrations, improving optical performance and image quality by optimizing the grating structure to manage the diffraction efficiency across different wavelengths.
Implementation Method 1
a diffractive optical element including a blazed diffraction grating so that the diffractive optical element serves as a lens
Implementation Method 2
The diffractive optical element has at least two regions that provide different diffraction efficiencies on a wavelength basis
Implementation Method 3
a grating height of the diffraction grating in a central region around an optical axis is smaller than the grating height of the diffraction grating in a peripheral region
Data Source
AI summary
There are provided an excellent diffractive optical element having a small amount of flare coloring and unaffected optical performance with a decrease in diffraction efficiency minimized and an optical system and an optical apparatus using the diffractive optical element. A diffractive optical element GD used in an optical system OL of a camera 1, which is an optical apparatus, and including a diffraction grating so that the diffractive optical element GD serves as a lens is so configured that the grating height h0 of the diffraction grating in a central region Ac around an optical axis Z is smaller than the grating height hmax of the diffraction grating in a peripheral region Ap.