HOPE XII: Make Your Own Holograms

Author: Mike Szczys / Source: Hackaday

Prior to this weekend I had assumed making holograms to be beyond the average hacker’s reach, either in skill or treasure. I was proven wrong by a Club-Mate box full of electronics, and an acrylic jig perched atop an automotive inner tube. At the Hope Conference, Tommy Johnson was sharing his hacker holography in a workshop that let a few lucky attendees make their own holograms on site!

The technique used here depends on interference patterns rather than beam splitting. A diffused laser beam is projected through holographic film onto the subject of the hologram — say a bouquet of flowers like in the video below. Photons from that beam reflect from the bouquet and pass back through the film a second time.

Since light is a form of electromagnetic radiation that travels as a wave, anywhere that two peaks (one from the beam the other from the reflected light) align on the film, exposure occurs. With just a 1/2 second exposure the film is ready to be developed, and if everything went right you have created a hologram.

Simple, right? In theory, at least. In practice Tommy’s been doing this for nearly 30 years and has picked up numerous tips along the way. Let’s take a look at the hardware he brought for the workshop.

The Laser and the Film

Tommy is using a 100 mW laser meant for a machine that etches aluminum printing plates for offset printers. He described this as “a laser printer on steroids”. Apparently a bunch of these hit the used market and the cost was reasonable. I didn’t get more info than this and my eBay-fu failed me but if you have more info please leave a comment below.

Here we see the laser inside its cardboard enclosure (click for the full size image). The laser module is the gold box to the right. The beam shines to the left, through the white box that has electrical tape on it, through two lenses that spread the size of the beam, and out of a hole in the box which is just out of frame (top edge of this image).

The module in the middle connects to the control circuitry for the laser, and to the left is a power supply board.