Making [etched] holograms with a pen plotter
I found a pen-plotter on eBay that was broken when it arrived and spent my savings to fix it. I enjoy creating things with the pen plotter that would be impossible with a printer or hand, like gold ink postcards of a fossil. Recently, I've been experimenting with using the pen plotter to create holograms. William Beaty has a detailed guide on how to make hand-drawn holograms, which I found fascinating.
The secret to hand-etched holography lies in smearing greasy fingers on a screen and observing the highlights that reflect off the ridges left by the smudge. By moving the camera around the phone, the highlight moves, demonstrating the key insight of hand-etched holography. This phenomenon is similar to the rainbow pattern on CDs and the windshield-wiper streaking effect.
To control the direction and speed of the highlight, the radius of curvature of the ridges must be considered. By rendering a 3D scene where each point becomes a reflective ridge with a radius of curvature inversely proportional to its distance from the camera, depth information can be communicated to the viewer. The best materials for this experiment turned out to be old CD jewel cases, which were surprisingly effective despite being used and dirty.
The results were initially underwhelming in photos, but the experience of seeing the hologram in person was truly magical.
Written by urgent.news from Lobsters's reporting — not their text. Machine-written — may contain errors; check the original before relying on it.
