Photolithographic 3D Printing System

Example 3

To print structures, a custom built system shown schematically in FIG. 1 was used, equipped with a 405 nm light source. A three-dimensional CAD model was sliced vertically into a series of layers. Using a spatial light modulator (SLM) as a dynamically reconfigurable digital photomask, each two-dimensional image slice was sequentially transmitted to the SLM which took on the pattern of the image. UV light illuminated the SLM from a photodiode, and a patterned beam was reflected. The patterned beam was reflected by a galvanometer mirror pair onto a flat-field scan lens which flattened the images and acted as a reduction optic before passing the light onto the photoresin. Where two-dimensional image hit the resin a solid forms. The galvanometer mirror and scan lens allowed the patterned 2D image to be scanned over a large area, creating a mosaic of highly detailed cells. Subsequently, the substrate on which the layer rests was lowered, reflowing a thin film of liquid over the cured layer. The image projection was then repeated, with the next image slice forming the subsequent layer.