Thermal Dwell Optimization to Retain Micro Embossed Geometry under Storage
Thermal dwell matching polymer glass transition arrests micro embossed geometry loss, preventing stack creep from flattening diffraction peaks under pallet storage.
Optical Diffraction
Light Interaction
Wavefront interference occurs when light encounters a periodic structure with dimensions similar to its own wavelength. The phenomenon of optical diffraction is used in security printing to create holographic effects and color shifting patterns on high value packaging. By etching microscopic lines or pits into a substrate or a coating, the surface splits incident light into its constituent colors.
Pattern Authentication
Diffractive optically variable image devices utilize precise patterns to produce images that change appearance based on the angle of observation. This application of optical diffraction provides a strong defense against unauthorized photocopying because the color effects cannot be reproduced by standard pigments or toners. Labels and foils incorporating these structures are applied to pharmaceutical cartons and luxury goods to verify authenticity.
The effectiveness of the feature depends on the precision of the master tool used to emboss the pattern into the plastic or lacquer layer.
Surface Smoothness
Production of high quality diffractive effects requires a surface that is exceptionally smooth and dimensionally stable. If the base paper or film is too rough, the microscopic ridges are lost and the optical diffraction becomes blurred or invisible. Manufacturers often use a smoothing undercoat or a metallized layer to provide the necessary reflective base for the grating.