Diffraction Grating Recording Medium with Dual Pitch Regions
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current diffraction gratings used for forgery prevention, such as those on credit cards, can be easily replicated due to their relatively coarse grating pitch, making them less secure.
Innovation Solution
A diffraction grating recording medium is designed with a first recording region having a grating pitch greater than the wavelength of visible light and a second, smaller recording region with a grating pitch less than the wavelength of visible light, where the second region is formed in a parallel linear fashion, allowing the hidden image to be visible only under specific observation conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a diffraction grating with a relatively rough grating pitch is used, then it can be easily fabricated by double beam interferometry or dot matrix method, but it can be easily replicated and forged
Solution Approach 1:
The recording medium is divided into multiple recording regions with different grating pitches. The first recording region has a coarse grating pitch suitable for standard viewing, while the second recording region has a fine grating pitch that is difficult to replicate. This segmentation allows the medium to provide both ease of manufacture in the coarse region and high security in the fine region.
Solution Approach 2:
Different regions of the recording medium are assigned different grating pitch characteristics. The first recording region uses a coarse grating pitch for normal visibility, while the second recording region uses a fine grating pitch less than the wavelength of visible light to prevent replication. This local differentiation resolves the contradiction between ease of manufacture and security.
2Reliability
If a diffraction grating with a fine grating pitch less than the wavelength of visible light is used, then security against forgery is enhanced, but the image becomes invisible in standard viewing conditions
Solution Approach 1:
The recording medium is segmented into at least two recording regions: a first recording region with a coarse grating pitch that is visible in standard viewing conditions, and a second recording region with a fine grating pitch that provides security. This segmentation ensures that the fine pitch region does not compromise standard visibility while maintaining security enhancement.
Solution Approach 2:
The patent introduces a dimensional distinction between recording regions - one region operates in the visible light dimension for standard viewing, while the other region operates at a finer scale below the wavelength of visible light for security. This dimensional differentiation allows both functions to coexist without interference.
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
This design significantly enhances forgery prevention by ensuring that the hidden image is not visible in the standard viewing state, thereby increasing the security of the diffraction grating recording medium.
Implementation Method 1
a first recording region including viewing image unit cells having a light diffraction structure, and a second recording region including hidden image unit cells having a light diffraction structure
Data Source
AI summary
A diffraction grating recording medium (3) that enhances the ability to prevent forgery and make security more reliable. The diffraction grating recording medium (3) comprises a first recording region (31) including viewing image unit cells (11a), (12a), (13a) having a light diffraction structure, and a second recording region (32) including hidden image unit cells (2a). The viewing image unit cells of the first recording region (31) has a grating pitch more than the wavelength of visible light, and the hidden image unit cells of the second recording region (32) has a grating pitch less than the wavelength of visible light.