(26 July, 2007)
This pageset describes my attempts at making holograms with pulsed lasers. Pulsed holography is convenient, because it can enable you to make holographic portraits if your pulses are reasonably short. It also eliminates the need for vibration-damping and specialized stable setups.
Frequency-doubled Nd+++ lasers are commercially used, and are probably the “workhorses” of most portraitists at this time; ruby has been used, but it has two drawbacks. First, it is a very inefficient laser, so you need fairly massive power supplies and energy storage capacitors. Second, human skin is quite translucent at the ruby wavelength, which is very red (694.3 nm), so people look very waxy in holograms made with ruby lasers. It is also somewhat difficult to sensitize a silver-halide emulsion to the ruby wavelength, but there are certainly ways to accomplish that, and commercial films and plates are (or were) available.
I have two approaches in mind for a DIY effort. One is fairly standard: a small Nd:YAG laser built from surplus commercial parts, with a doubling crystal. I am not yet sure whether I will put the doubler inside the cavity or outside it, but either way I will probably Q-switch the laser. This has some drawbacks, depending on the setup. For one thing, if you expect to put the beam through a spatial filter, you must limit the peak power so you don’t get an air-spark inside the pinhole. For another, even if the doubling crystal is outside the cavity, a Q-switched pulse has higher probability of damaging it.
My second approach involves trying to coax some coherence
length out of
a flashlamp-pumped organic dye laser.
This is unlikely to succeed, but should be ...interesting.
My email address is a@b.com, where a is my first name (just jon, only 3 letters, no “h”), and b is joss.
My phone number is +1 240 604 4495.
Last modified: Sat Oct 20 09:51:08 EDT 2007