Design and test of a microfabricated SU-8 optical scanner

Abstract

The use of SU-8 in recent years has spawned new developments in MEMS technologies due to its low cost and well characterized mechanical and optical properties. SU-8 is a high contrast, negative tone, chemically amplified, epoxy based photoresist. Considered the poor man's LIGA, the resist is recognized for its high aspect ratio (~15:1), great for vertical sidewalls. Designs of ink jets, micro fluidic devices, and optical devices are a few examples that the material has been used for. Written here is the fabrication and test analysis of a MEMS optical scanner. The scanner is a new stage development to the previous microfabricated Si/SiO 2 cantilever beam which was fabricated for the purpose of endoscope examination. The current design has improved performance and “ease of use” with the implementation of SU-8 as the foundation to the optical waveguide or scanner. With this new device, larger thicknesses were achieved as compared to the previous method. Fabrication of the SU-8 waveguide was measured to be ~85μm as compared to the silixon oxide method of ~3μm. An overall larger device makes coupling a fiber into the waveguide much easier and increases the amount of light coupled into the beam. The optical scanner consists of a cantilever beam with a U-shaped groove for optical coupling. In this paper, we will discuss the image scanning capabilities of the device.