Bidirectional reflectance measurements over a micrometric surface area using a goniospectrophotometer

Dipanjana Saha*, Lou Gevaux, Jeppe Revall Frisvad, Gael Obein

*Corresponding author for this work

Research output: Contribution to journalReviewpeer-review


The increasing use of a spatially varying bidirectional reflectance distribution function (svBRDF) to describe the appearance of an object raises the important question of how BRDF values change when measured on a small scale. For this reason, we present a new goniospectrophotometer with the ability to measure the BRDF at the micrometer scale (μBRDF). The instrument produces BRDF measurements with a measurement surface diameter of 31 µm. This device is designed to aid in the extension of the BRDF metrological scale from centimeter to micrometer size. We support the credibility of our μBRDF measurements using a specially made test sample with uniform diffuse white dots on a uniform black background, measuring its bidirectional reflectance in one geometrical configuration at many spatial locations. This sample can easily be modeled using a few unknown parameters. The agreement between our measurements and the model demonstrates the credibility of the measurement technique.

Original languageEnglish
Article number055114
JournalReview of Scientific Instruments
Issue number5
Number of pages13
Publication statusPublished - 2024


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