Improved micro-optoelectromechanical systems deformable mirror for in vivo optical microscopy

Micro-optoelectromechanical systems (MOEMS) deformable mirrors are being developed for focus control in miniature optical systems including endoscopic microscopes and small form-factor camera lenses. A new process is described to create membrane mirrors made from the photoset polymer SU-8. The SU-8 also serves as the adhesive layer for wafer bonding, resulting in a simple, low cost fabrication process. The process details and the optical properties of the resulting focus control mirrors, which have a diameter of 2 mm, a stroke in excess of 8 μm and very low residual aberration, are described. Multiple actuation electrodes allow active control of more than 1.4 μm peak-to-peak of wavefront spherical aberration. The MOEMS mirror is demonstrated in a confocal microscope in which it provides focus control during capture of in vivo images.