Light Modulation Element Phase Control for White Light Color Reproduction
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Solution Overview
Problem
Existing light modulation elements struggle to reproduce a desired light image with high visibility using white light, as they either disperse light across the visible spectrum, leading to iridescent images, or require specific wavelength filters that limit light sources and increase costs, and fail to suppress the visibility of 0th-order diffracted light, which can obscure the image.
Innovation Solution
A light modulation element with an uneven surface that modulates the phase of incident light, featuring a diffraction efficiency peak within a specific wavelength band (380-780 nm) and a full width at half maximum of 200 nm or less, allowing it to reproduce a specific color image without additional filters, and reduces the influence of 0th-order diffracted light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a light modulation element diffracts light over the entire visible light wavelength band, then it can reproduce a light image, but the reproduced image becomes iridescent and loses definition due to chromatic dispersion
Solution Approach 1:
The patent applies parameter changes by designing the uneven pattern with specific height values (0.2-2.0 μm) and duty ratios (0.3-0.7) that create a diffraction efficiency peak at a specific wavelength. This selective parameter optimization enables the light modulation element to diffract only a specific wavelength band effectively, preventing chromatic dispersion while maintaining image reproduction capability.
2Use of energy by moving object
If the 0th-order diffracted light is not suppressed, then the light modulation element can transmit light efficiently, but the 0th-order light obscures the reproduced image and reduces visibility
Solution Approach 1:
The patent applies local quality by creating regions with different optical characteristics within the light modulation element. The uneven pattern is designed with specific local geometries (height, duty ratio variations) that selectively suppress the 0th-order diffracted light in certain areas while maintaining diffraction efficiency for the reproduced image in other areas, thereby improving image visibility without sacrificing overall light transmission.
3Manufacturing precision
If additional wavelength filters are added to reproduce a specific color image, then the image can be reproduced in a specific color, but the light source options are limited and manufacturing cost increases
Solution Approach 1:
The patent applies the taking out principle by extracting the wavelength selection function from separate filter components and integrating it directly into the light modulation element's uneven pattern design. By embedding the wavelength-selective diffraction capability within the modulator itself, the system eliminates the need for additional filter layers, reducing structural complexity while maintaining accurate color reproduction.
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 enables clear reproduction of a desired light image in a specific color, even with white light, reducing chromatic dispersion and enhancing visibility, suitable for design and security uses by providing high-definition images without additional filters and suppressing 0th-order diffracted light.
Implementation Method 1
a light modulation element including a factor element that reproduces a light image by modulating a phase of incident reproduction light
Implementation Method 2
the factor element has an uneven surface, and a maximum diffraction efficiency in a wavelength band of not less than 380 nm and not more than 780 nm in wavelength distribution of first-order diffracted light with respect to diffraction efficiency
Data Source
AI summary
A light modulation element reproduces a light image in a specific color other than iridescence where white light is incident, without a layer that selectively transmits or reflects a specific wavelength band, and clearly reproduces a desired light image by reducing an influence of 0th-order diffracted light, and an information recording medium including the same. The light modulation element includes a factor element that reproduces a light image by modulating a phase of incident reproduction light, and has an uneven surface. A maximum diffraction efficiency Dmax in a wavelength band of between 380 nm and 780 nm in wavelength distribution of first-order diffracted light and of negative first-order diffracted light with respect to diffraction efficiency for the factor element has a local maximum value with a full width at half maximum FWHM of 200 nm or less in wavelength distribution with respect to diffraction efficiency having the maximum diffraction efficiency.