Kilopixel silicon microlens arrays for PRIMA detector arrays

The optical coupling of detectors to telescope optics is a challenge for future far-infrared astrophysics observatories. The PRobe far-Infrared Mission for Astrophysics (PRIMA) collaboration has developed monolithic silicon microlens arrays for superconducting detector arrays spanning wavelengths from 24 to 261 microns. These custom-microfabricated lens arrays meet the stringent surface accuracy and roughness requirements that are necessary at PRIMA’s shortest wavelengths. Grayscale lithography is used in combination with deep silicon plasma etching to create arrays of three-dimensional lens profiles. This fabrication process generates highly uniform and accurate microlenses across a roughly 80 by 10 millimeter 1008-element array. The kilopixel microlens arrays are bonded to matching PRIMA detector arrays with a thin and uniform layer of epoxy. In this presentation, we report on the status and performance of PRIMA’s microlens fabrication and microlens-detector array hybridization processes.