Microscope design for direct optical characterization of various microlens technologies

Zachary Kranefeld; Emily Carlson; Denis Nothern; Abigail Licht; Thomas Vandervelde

doi:10.1117/12.3002955

11 March 2024 Microscope design for direct optical characterization of various microlens technologies

Zachary Kranefeld, Emily Carlson, Denis Nothern, Abigail Licht, Thomas Vandervelde

Proceedings Volume 12893, Photonic Instrumentation Engineering XI; 128930F (2024) https://doi.org/10.1117/12.3002955
Event: SPIE OPTO, 2024, San Francisco, California, United States

Abstract

Microlens arrays (MLA) are a critical component of avalanche photodiode (APD) technology, but their performance is rarely characterized or investigated independent of the photodetector. To understand how best to improve coupling, the MLA must be characterized and compared to other technologies on a fair and consistent basis. In order to investigate new designs and compare different types of microlens technologies, a custom microscope was built. This microscope was designed to image the MLA surface as well as its focused beam which required solutions to the following challenges: 6-axis manipulation of the sample, sub-micron positional resolution, perpendicular travel to the optical axis, brightfield imaging, multispectral imaging, image processing, uniform irradiance over the sample area, and calibrated absolute optical power measurements. This microscope design enables the focal length range to be mapped with sub-micron accuracy along the paraxial ray. The imaged beam spot is quantitatively analyzed in MATLAB for 1/e² diameter and encircled energy, as well as qualitatively with complementary data sets. It was shown that Fresnel lens and plano-convex refractive MLA designs from various material groups could be compared equally in a side-by-side comparison.

Conference Presentation

(2024) Published by SPIE. Downloading of the abstract is permitted for personal use only.

Citation Download Citation

Zachary Kranefeld, Emily Carlson, Denis Nothern, Abigail Licht, and Thomas Vandervelde "Microscope design for direct optical characterization of various microlens technologies", Proc. SPIE 12893, Photonic Instrumentation Engineering XI, 128930F (11 March 2024); https://doi.org/10.1117/12.3002955

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