Presentation
27 April 2020 Mid-wave and long-wave IR angular scatter of random anti-reflective nanostructured surfaces on ZnS, ZnSe, and GaAs (Conference Presentation)
Karun Vijayraghavan, David Gonzalez, Jesus Meza-Galvan, Menelaos Poutous
Author Affiliations +
Abstract
Fresnel reflections at boundaries between layered media can be suppressed using anti-reflective randomly-nanostructured surfaces (rARSS). Previous studies have shown that rARSS can result in spectral broadband transmission enhancement and polarization insensitivity, in the specular direction, compared to unstructured optical windows. However, specular reflectance can be suppressed through scattering mechanisms, resulting in an angular redistribution of the reflected irradiance. In those cases, specular transmittance is adversely affected as well. We characterized ZnS, ZnSe, and GaAs windows with rARSS treatment on both surfaces, by measuring the specular transmittance and reflectance, as well as, the directional angular reflective scatter, in the mid-wave and long-wave infrared bands (2 - 12 μm). The incident light was directed off-normal incidence, and the angular reflectance distribution was measured over a ±30° cone, centered on the specular reflection angle. An accurate determination of the redistribution of the reflected energy was obtained, by comparing the scatter of the structured surfaces to the pre-processed, optically flat, substrate performance. Surface roughness was determined using a UV-confocal microscope and a scanning electron microscope. The rARSS feature dimensions were correlated to the overall optical performance. The results show reflective specular and scatter intensity suppression, along with specular transmission enhancement.
Conference Presentation
© (2020) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Karun Vijayraghavan, David Gonzalez, Jesus Meza-Galvan, and Menelaos Poutous "Mid-wave and long-wave IR angular scatter of random anti-reflective nanostructured surfaces on ZnS, ZnSe, and GaAs (Conference Presentation)", Proc. SPIE 11388, Image Sensing Technologies: Materials, Devices, Systems, and Applications VII, 1138806 (27 April 2020); https://doi.org/10.1117/12.2558706
Advertisement
Advertisement
KEYWORDS
Gallium arsenide

Long wavelength infrared

Mid-IR

Reflectivity

Zinc

Nanostructuring

Transmittance

Back to Top