Experimental studies of the transmission of light through low coverage regular or random arrays of silica micropillars supported by a glass substrate

TL;DR

This study experimentally investigates how light transmits through low coverage arrays of silica micropillars on glass, revealing diffraction, scattering, and guiding effects, and validates measurement techniques with haze calculations.

Contribution

It provides detailed angle-resolved measurements of light transmission through regular and random micropillar arrays, demonstrating the ability to resolve diffraction orders and scattering effects, and compares these with haze measurements.

Findings

Diffraction orders are resolvable in regular arrays.

Scattering and guiding effects are observed in both array types.

Haze measurements agree well with angle-resolved transmission data.

Abstract

The transmission of light through low coverage regular and random arrays of glass supported silica micropillars of diameters 10 to 40 \micro\meter and height 10 \micro\meter is studied experimentally. Angle-resolved measurements of the transmitted intensity are performed at visible wavelengths by either a goniospectrophotometer or a multimodal imaging (Mueller) polarimetric microscope. It is demonstrated that for the regular arrays, the angle-resolved measurements are capable of resolving many of the densely packed diffraction orders that are expected for periodic structures of lattice constants 20 to 80 \micro\meter, but they also display features that are due to the scattering and guiding of light in individual micropillars or in the supporting glass slides. These latter features are also found in angle-resolved measurements on random arrays of micropillars of the same surface coverage. Finally we perform a comparison of direct measurements of haze in transmission for our patterned glass samples with what can be calculated from the angle-resolved transmitted intensity measurements. Good agreement between the two types of results are found which testifies to the accuracy of the angle-resolved measurements that we report.