POKEMON: print optimization for kilo-fiber experiments using micro-optics and nanostructures

Abstract

The most pressing problems in modern astrophysics have often required the largest telescopes. With the cost scaling of mirror diameters, the field as a whole is faced with a challenge -- how to replicate or improve on the collecting area and sensitivity of the current generation of ELTs, which already boast 30 m class apertures and are multi-billion dollar facilities. One such approach is being pursued by the Large Fiber Array Spectroscopic Telescope (LFAST) -- a scalable array telescope. Each element of the array will consist of multiple mirrors each feeding to an individual fiber; with those fiber feeds feeding optical and infrared spectrometers. Coupling fiber bundle to spectrometer slit input must be optimized to take full advantage of the photon collecting ability of the telescope array, requiring precise alignment of microlenses to each fiber. Advances in two photon polymerization processes (2PP) now allow for optical quality microlenses with wavefront aberrations as small as $\lambda/20 to be created, opening up the design parameter of bespoke optical design and custom fabricated lenses. We present our approach to tackling these coupling problems with rapid prototyping and detailed quantification of the tolerances of the lenses. Our approach leverages our access to the Nanoscribe GT2 system at Penn State, enabling tests of new optically transparent resins like IPX-Clear to explore multiple design approaches. Our goal is to share our results and enable wider use of these techniques for astronomical applications.