Dog diptych (IMAGE) Dartmouth College Caption A two-dimensional light engraving (left) suspended in a polymer film. The original photo (right) was projected into the film using a red- and blue-light projector that activates a photosensitive additive in the polymer. Applying heat to the film will erase the image and make it ready to use again. Credit Ivan Aprahamian/Sara Patch Usage Restrictions N/A License Original content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.