An improved focus control mirror using SU-8 wafer bonding process

We are developing MEMS deformable mirrors for focus control in miniature optical systems, including endoscopic microscopes and small form-factor camera lenses. This paper describes a new process to create 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 paper describes 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. Multiple actuation electrodes allow control of more than 0.4 μm peak-peak of spherical aberration.