Characterization of the Reflectivity of Various Black Materials

TL;DR

This paper measures and compares the total and specular reflectance of various black materials across ultraviolet to near-infrared wavelengths to evaluate their effectiveness in reducing stray light in optical systems.

Contribution

It provides comprehensive reflectance data for different black materials, aiding in the selection of optimal surfaces for stray light suppression in optical instruments.

Findings

Black materials vary significantly in reflectance properties.

Specular fraction helps distinguish between diffuse and mirror-like surfaces.

Data supports improved design of optical baffling systems.

Abstract

We present total and specular reflectance measurements of various materials that are commonly (and uncommonly) used to provide baffling and/or to minimize the effect of stray light in optical systems. More specifically, we investigate the advantage of using certain black surfaces and their role in suppressing stray light on detectors in optical systems. We measure the total reflectance of the samples over a broad wavelength range (250 < lambda < 2500 nm) that is of interest to astronomical instruments in the ultraviolet, visible, and near-infrared regimes. Additionally, we use a helium-neon laser to measure the specular reflectance of the samples at various angles. Finally, we compare these two measurements and derive the specular fraction for each sample.