Use of an Acousto-optic Deflector to Improve the Speed of the Stereolithography Process

In the stereolithography (SLA) additive manufacturing (AM) process, a laser system creates part geometries by using galvanometric mirrors and field lenses to locally polymerize raw materials. Small features require a small laser spot size, while large parts require longer scan times. Improving the speed of the SLA process currently requires increasing the laser spot size, sacrificing spatial resolution. An acousto-optic deflector (AOD) is a solid-state optical component wherein the angle and intensity of the first order beam is governed respectively by the frequency and amplitude of a radio-frequency signal. The use of an AOD to steer the beam in conjunction with a galvo will reduce the time required to make parts with desirable spatial resolutions.

Here, we present our work on the development of a system using an AOD to raster perpendicular to the regular galvo scan. This allows for the use of dynamic high-speed beam position control in the build plane while preserving part resolution and preventing cure-through problems associated with the Gaussian beam shape. In our early work, we developed a simulation to examine the effects of our processing parameters, and we developed an experimental system using a single galvo and AOD scanning perpendicular to one-another. More recently, we have developed a 2D system using two galvos and two AODs to enable scanning vectors of arbitrary lengths and orientations.