Imaging-Based Metrics Drawn from Visual Perception of Haze and Clarity of Materials. I. Method, Analysis, and Distance-Dependent Transparency
Open access
Date
2021-05Type
- Journal Article
Abstract
A versatile imaging-based method is presented for quantifying the transparency of materials based on “illumination diffusion” (ID), representing scattering- and refraction-induced change in the spatial distribution of transmitted light intensity. Samples are backlit through a graticule mask, with analysis performed by comparative evaluation of graticule images recorded as-is and viewed through a sample, mimicking visual perception. ID-haze is quantified as the reduction of contrast, while ID-sharpness is derived from imaged knife-edge acuity. Measurements are performed for diverse materials, including clarified polyolefins, silica-filled amorphous polymers, semicrystalline films, and etched polymer sheets. Comparisons with the respective haze and clarity values obtained using a common ASTM D1003 haze-meter are made in terms of their quantitative correlation and suitability for applications. In particular, unlike conventional instruments, ID-based analysis captures the variation of transparency with sample-to-object “airgap” distance. Gratifyingly, ID-haze generally features a one-to-one correlation with standard ASTM haze, when determined at a specific distance. The presented method also enables sensitive detection of local defects—differentiating them from large-area characteristics—and accurately extracts the contribution of luminescence to loss of transparency. ID-based method therewith offers unique opportunities for application- and airgap-specific transparency analysis, and advanced options for optical process- and quality control. Show more
Permanent link
https://doi.org/10.3929/ethz-b-000485896Publication status
publishedExternal links
Journal / series
Macromolecular Materials and EngineeringVolume
Pages / Article No.
Publisher
WileySubject
Clarifying agents; clarity; Haze; light scattering; optical properties; roughness; transparencyMore
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