Pixel-by-pixel aberration correction for scanned-beam micro-optical instruments

Variable aberration compensation elements designed to correct the primary aberrations, and capable of sufficient speed for on-the-fly correction, can significantly extend the diffraction-limited field of view of scanned-beam instruments using practical microlens systems. In this paper we review the relevant aberration theory and discuss the requirements for compensation elements as well as appropriate architectures for correction of a scanned-beam instrument. We report correction of astigmatism and field curvature in an F/20 optical system using deformable polysilicon reflective membranes. Devices were successfully demonstrated that compensated more than 1.5 waves of defocus and more than 1 wave of astigmatism with less than 1/10 wave of spherical aberration, and with a bandwidth in excess of 20 kHz, which is suitable for high speed beam scanning applications such as video-rate imaging.