Subwavelength Grating Optical Element for Authentication Verification
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing optical elements that change color with observation angle, such as subwavelength gratings, require manual rotation to verify authenticity, making the verification process inefficient and prone to errors due to the need to align the specular reflection direction, which can be difficult for users to achieve.
Innovation Solution
A multilayer optical element comprising a resin layer with a subwavelength grating, a dielectric layer with asperities, and a relief layer with reflective surfaces, where the subwavelength grating displays a colored image in the specular reflection direction and the relief layer displays a monochromatic image in other directions, allowing for easier verification by changing the observation angle to switch between these states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If subwavelength gratings are used to specify observation angle and color, then measurement precision is improved, but ease of operation deteriorates because manual rotation is required to align the specular reflection direction
Solution Approach 1:
The optical element is divided into two distinct functional layers: a subwavelength grating layer for color specification and a relief layer for directional light reflection. This segmentation allows each layer to perform its specialized function independently, eliminating the need for manual rotation while maintaining precise color specification.
Solution Approach 2:
The combined optical element performs multiple functions simultaneously: the subwavelength grating provides precise color specification while the relief layer provides automatic directional light reflection. This multi-functionality eliminates the need for separate verification steps involving manual rotation, improving both precision and ease of operation.
2Manufacturing precision
If subwavelength gratings are used to emerge light only in specular reflection direction, then manufacturing precision is improved, but loss of time increases because the observer must rotate the optical element to find the correct observation angle
Solution Approach 1:
The verification process is segmented into two automatic functions: the relief layer automatically directs light to the observer without requiring rotation, and the subwavelength grating automatically specifies the color. This eliminates the time-consuming manual rotation step while maintaining manufacturing precision.
Solution Approach 2:
The relief layer is pre-configured with reflective surfaces oriented at specific angles to automatically redirect light from the subwavelength grating to the observer's position. This preliminary arrangement of light paths eliminates the need for time-consuming manual rotation during verification.
3Ease of operation
If diffraction gratings or multilayer interference films are used to change color with observation angle, then ease of operation is improved because no special verifier is needed, but measurement precision deteriorates because multiple colors are observed and it is difficult to clearly define the colors that should be observed
Solution Approach 1:
The optical element separates the functions of color specification and light direction: the subwavelength grating layer precisely defines the color at a specific angle, while the relief layer directs light to the observer. This segmentation provides both ease of visual observation and precise color definition, resolving the contradiction.
Solution Approach 2:
The subwavelength grating is designed with a specific grating period to produce a predetermined color at a specific observation angle. This localized color specification, combined with the relief layer's directional reflection, ensures that the observer sees a clearly defined color without the ambiguity of multiple colors, maintaining both ease of operation and measurement precision.
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
Facilitates easier and more efficient authenticity verification by clearly distinguishing between colored and monochromatic images, reducing subjective interpretation and simplifying the verification process compared to traditional methods.
Implementation Method 1
The subwavelength gratings have characteristics of causing only the light with a specific wavelength to emerge in a specular reflection direction
Implementation Method 2
The subwavelength gratings have a microstructure with a period of not more than the wavelength of visible light
Implementation Method 3
the relief surface displays a reflection image in monochromatic reflected light, i.e., a monochromatic image, in reflection directions including a direction different from the specular reflection direction
Implementation Method 4
The second layer is a dielectric layer having a second refractive index which is higher than the first refractive index and having a second surface contacting the first surface of the first layer, the second surface having asperities conforming to the subwavelength grating
Data Source
AI summary
A subwavelength grating displaying a colored image exhibiting a color corresponding to a grating period of a subwavelength grating in reflection directions including a specular reflection direction. A relief surface displaying a reflection image in monochromatic reflected light in reflection directions including a direction different from the specular reflection direction. An optical element has a first state in which neither a colored image nor a reflection image is displayed, a second state in which the colored image is mainly displayed, and a third state in which the reflection image is mainly displayed. A plane in which the optical element is disposed and a plane including a line of sight of an observer form an observation angle therebetween. The optical element is observed in any of the first, second and third states according to the observation angle.