The idea is to illuminate a piece of clear acrylic from the edge and etch the acrylic so that the light reflects forward showing the image. I planned to use the Epilog Laser Cutter at Techshop to etch the image into the acrylic. Since the light entering from the LEDs is the same intensity for all areas of the image, we need some means of getting multiple gradations of brightness. I’ve previously described methods for turning photos into half-tone images and that’s what I did here as well. I took a photo and turned it into a monochrome bitmap using a 45-degree linear halftone.
One important difference in this case is that we want to etch the acrylic where we want light to shine. The laser cutter acts like a printer, and etches wherever there are dark pixels in the halftone image. So dark pixels in the image equates to light shining in the final product, which means I needed to invert the colors in the halftone which is why the picture looks spooky.
Doing anything with the laser cutter starts with finding the magic combination of speed, power and resolution that will give the best results with the material you’re etching. After a few test runs I found settings that gave me reasonable results.
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