Optical super-resolving phase filters with random anti-reflection subwavelength surface structures

Praneeth Gadamsetti; Markus E. Testorf; Paolo Batoni; Menelaos K. Poutous

doi:10.1117/12.2576985

5 March 2021 Optical super-resolving phase filters with random anti-reflection subwavelength surface structures

Praneeth Gadamsetti, Markus E. Testorf, Paolo Batoni, Menelaos K. Poutous

Proceedings Volume 11682, Optical Components and Materials XVIII; 1168214 (2021) https://doi.org/10.1117/12.2576985
Event: SPIE OPTO, 2021, Online Only

Abstract

Superresolution phase pupil filters (SRPF) are diffractive optical elements used to direct coherent laser light to spot sizes below the diffraction limit, at the expense of an exponentially reduced Strehl ratio. They can be fabricated as binary or multiphase elements, and have varying transverse-feature pixel dimensions. Because of the wide range of pixel sizes and groupings, ranging from possibly 100’s of microns to submicron, anti-reflection thin-film layered coatings are difficult to implement on SRPF topography without impacting the filter’s phase-distribution function and overall performance efficiency. SRPF elements were implemented on fused silica wafers using standard microlithography, to produce laser beam spots below 50% of the nominal diffraction-limited diameter (Airy spot). Anti-reflection random nano-structures (rARSS) were added on the SRPF substrate surface to enhance the component’s transmittance by reducing Fresnel reflectivity. The SRPF were tested at three laser wavelengths: 543 nm, 594 nm, and 633 nm, using a CCD 2D-array beam profiler before adding the random nanostructures, in order to validate design performance, as well as, after adding rARSS, to quantify transmission enhancement and the impact on beam spot quality and size. An overall reflectance suppression was measured in the illumination pattern, and the superresolution beam spot was not affected by the presence of the rARSS.

Conference Presentation

Citation Download Citation

Praneeth Gadamsetti, Markus E. Testorf, Paolo Batoni, and Menelaos K. Poutous "Optical super-resolving phase filters with random anti-reflection subwavelength surface structures", Proc. SPIE 11682, Optical Components and Materials XVIII, 1168214 (5 March 2021); https://doi.org/10.1117/12.2576985

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