Culture: Art: Visual
Laser bolts that you can see   (+2)  [vote for, against]
Shoot lasers and watch them move

The rolling shutter effect is how lasers are traditionally seen to move in bolts across the screen of your favorite sci-fi action flick. Lasers are rapidly pulsed such that the screen only picks up the laser in certain places. When the camera matches a multiple of the laser pulse speed the laser can look like it's moving slowly. This is the same reason a car wheel or helicopter rotor looks like it's moving slowly, stationary, or moving backwards on screen, unless tricks with shutter speed or post-processing changes it to what a human would see in real life. For a laser to be see as a bolt in real life it would need to be moving far too slowly to actually be a laser.

The idea is to use constructive interference between multiple laser beams. The laser beams would be of a wavelength invisible on the spectrum of visibility. When they meet they would change via diffraction into the visible wavelength, but only where they meet. If you use a wide beam or rapidly wave it back and forth you can make bolts appear to move in real physical space.

Now that I think about it, this is a hologram that could be used practically without anything more than a fog machine to make volumetric projections of any type, size, or color.
-- Voice, Aug 08 2021

Similar? Laser rule
//I'm not following the physics here...// — [MaxwellBuchanan], Apr 28 2017 [pocmloc, Aug 08 2021]

This idea, but without changing the wavelength http://jointhemovem...rojector-using.html
[Voice, Aug 08 2021]

Particle size analysis with laser diffraction method https://www.sympate...20ring%20structure.
[Voice, Aug 08 2021]

It turns out diffraction doesn't change the wavelength, only ther amplitude. (no idea why I thought it would be otherwise)And you end up with interference patterns in 3D space https://physics.sta...terference-patterns
[Voice, Aug 08 2021]

Pulsed laser interferometry with sub- picometer resolution using quadrature detection https://tsapps.nist...f.cfm?pub_id=920757
[Voice, Aug 08 2021]

Spatial Light Modulators https://holoeye.com...l-light-modulators/
[Voice, Aug 08 2021]

Made in MIT https://newatlas.co...xpensive-mit/28029/
It looks like this has been done, but just the fact there isn't one on the market tells me it's probably in patent hell and won't be available until the patent expires, 2024 at the earliest [Voice, Aug 08 2021]

random, halfbakery