SBIR Phase I: High-power laser compatible MEMS deformable mirrors for confocal and two-photon microscopy

This Small Business Innovation Research Phase I project will enable video-rate three-dimensional (3D) imaging within two-photon microscopes (TPMs) through the use of an electrostatically actuated deformable membrane mirror (DMM). As a subset of laser scanning microscopes (LSMs), TPMs achieve very high spatial resolution by using a focused, high-power laser beam to excite fluorescence via the simultaneous absorption of two low energy infrared photons to stimulate emission in the visible. Because of the increased resolution, and increased penetration of infrared light into tissue compared with other LSM methods, TPMs have become widely accepted for use in the medical industry, specifically for dermatology and neurology. The technology developed for this project will address the $500 million LSM market by delivering a low-cost, electrically tunable optic capable of simultaneously controlling focus and aberrations while operating an order of magnitude faster than competitive technologies. The 3D imaging capabilities enabled by this technology will result in an advancement of microscopy techniques and diagnostic methods, thereby reducing diagnostic time and patient discomfort. Other markets that can easily be addressed by this technology include laser marking and engraving, endoscopes, optical coherence tomography, and machine vision. The intellectual merit of this project will be the development of high-power capable coatings for micro-electro-mechanical systems (MEMS) based deformable mirrors. Because these mirrors consist of a thin membrane with a reflective surface, standard glass coating processes for solid substrates are incompatible. Instead, the surface material for the mirror must be deposited within one of the many fabrication steps for the DMM. This project will address the unique challenges of developing high-reflectance coatings and incorporate them into the existing DMM fabrication process. The project involves four key objectives: 1) developing gold coated deformable mirrors, 2) developing protected silver coated deformable mirrors, 3) measuring key performance parameters, and 4) measuring and defining the power handling capability and damage thresholds of gold and silver DMMs. The anticipated result will be a fully characterized DMM capable of long operation under the high-power femtosecond laser illumination regime used in two photon microscopes.