As a recap: over the past few weeks I’ve been working on this fogsaber concept. The idea is to project a lightfield into a diffusor such as milky water or fog and create a beam-sword. I’m happy to say that I’m done with an initial version which does well in milky water and sort of OK in fog. I compiled the results into the video below:
In milky water, the result looks great. I believe this is due to the light rays scattering in the uniform medium, causing the rays at the end to be darker than the rays at the beginning. Furthermore, the optical setup has a greater ray-density at the beginning of the blade than at the end. You can see that in the following simulation done in Matlab using Optical Bench. The rays flare out at the end, so the density of the light is less bright.
The result below shows that it definitely works in milky water (water gets milkier as the gif goes on):
But here is the result in fog. On the left you can see a standard focused flashlight (rays focused at inifity), and on the right is the fog-saber:
In fog, the results are similar to low-milk-concentration water. This indicates that the scattering properties of the fog are not nearly as strong as that of the milky water, so the same saber effect isn’t as strong.
At this point we may be saying to ourselves: well, why don’t we just make the fog stronger. And I would agree, that maybe that is the key to getting it to work as well as the milky-water result. However, the foggier the environment, the more difficult it is to take a picture. The general visibility of the environment will decrease, and make for a less-fun experience. However, here’s what it looks like when the fog is strong:
Two paths forward:
The name of this game is Signal to Noise Ratio (SNR). The beginning of the beam needs to be much brighter than the end of the beam. I’m beginning to think that producing a pattern of rays using lenses and a single light-source may not be enough. I’m impressed by the brightness of a single focal spot compared to the fog surrounding it. If that focal spot were translated over time, it may be able to “build out” the saber in the fog. I’m imagining something like this:
Another way to restrict the end of the beam would be to spray out a diffusive medium from the lightsaber itself, instead of immersing the lightsaber in a diffusive medium. I’m thinking that spraying an aerosol or water solution for a few feet in front of the saber could allow for a compelling experience, and you could walk around with it outdoors. The optics could still be used to create a focused, narrow beam. In fact, the two could be combined to produce effects such as bright inner parts of the saber, and the saber extending from the hilt on activation.