Laser Light Cannon - a review
In the second episode of the Steven Universe series, the heroes must find a long-lost laser light cannon so they may defeat a destructive eye that has appeared floating in the sky. The episode introduces key elements of character backstory and begins to set the overarching plot in motion, but as a laser scientist, I'm more interested in the laser light cannon.
The laser light cannon is, specifically, long-lost in the back of Steven's dad's storage unit, and is being stored upright without any evidence of a dust cover or lens cap. This will undoubtedly result in the accumulation of dust that will be incredibly hard to clean off later, and will burn into the optics when the laser is fired. I'm not saying you won't find optics stored like this in a laser lab, but it is bad practice.
Steven and his dad do not handle the laser cannon as if it's made of precious optics. They drop it on the ground (mechanical shock).
They drag it along the ground (extreme mechanical vibrations).
At one point Steven looks back at the highly precious optics being subjected to the kind of shock and vibe profile that most aerospace equipment isn't even required to handle. "Is it gonna be okay?" he asks his dad. The dad shrugs. Neither of them has apparently read the shock/vibe specs for this laser. Let's see how this works out for them!
They choose to deploy the laser on a beach, which means opportunities for sand to get into the mechanisms, and onto the (still uncovered) lens itself.
And... nobody knows how to get the laser working. This part, at least, is familiar from laser labs. As is the frantic dance that ensues, as they try everything they can think of.
There's a kind of laser called a modelocked laser, which is supposed to emit its light in incredibly short pulses. To get it to shift into short-pulsed mode, you have to inject chaos so that one laser wavelength stops dominating, and a bunch of laser wavelengths can share the laser cavity. These laser wavelengths can work together to support powerful short pulses of light. In older modelocked lasers, injecting just the right amount of chaos can be tricky, and often involves repeatedly jolting one of the mirrors hoping that THIS time it will take. If you want to catch laser scientists being superstitious, show up while they're modelocking a tricky laser. Eventually they'll get to the point where they believe it works better if a certain person is doing the honors, or if they're using their left or right hand, or if they're saying a certain catchphrase while they do it.
They all assume the laser starts working because Steven is in contact with it and saying the right catchphrase, but it's probably pure chance.
The end of the laser opens like a flower, so I guess there WAS some kind of protection for the laser optics after all. But the aiming mechanism immediately gives way and the laser bonks to the ground, so they must have damaged it in all that rough handling. There's no way a real laser weapon would require someone to manually grab the laser and aim it, especially if it was this large.
Still, the heroes make do.
This is where the laser gets weird. The beam starts with an asparagus shape and, as it travels, evolves into a rose shape with twining thorny branches and finally a giant woman surrounded by additional asparagus.
Try not to worry about why we can watch the beam evolve as it travels at the speed of light. The asparagus shape beam is weird, but that's nothing compared to the spiral helix thorny vines surrounding the curving stem of some sort of flower. Logically it would be a rose since that's this laser's theme, but it really looks more like a globe amaranth. The final stage, the one that hits the weird eye, is of a giant woman with long hair and outstretched hand (presumably this is Rose Quartz herself), surrounding by at least nine of those asparagus spears.
That's unusual! But not unheard of. A laser beam doesn't have to be a single uniform beam, but can have multiple bright spots. Programmable holograms called spatial light modulators (cool name, right?) are one way laser scientists can turn a uniform beam into a weirdly shaped one. These are some example cross sections of beam shapes made by a laser with a spatial light modulator inside. A single laser could make beams with a variety of shapes. If I were to guess, Rose Quartz's laser light cannon has something like a spatial light modulator inside.
A spatial light modulator can also make a laser beam that changes shape as it travels. A beam can split into multiple spots, and the spots can even do a spiral helix rotation around each other. Here's an example of a popular beam called a Bessel beam, which can maintain a super-intense focused central spot for longer than a plain laser beam.
The fancy laser beam shapes are sometimes used for industrial machining, or sometimes in biology research. They can help make cleaner laser cuts and welds, or help a microscope see deeper into skin. I've never seen someone make an asparagus/giant woman laser beam, but I'm not going to rule it out.
The episode ends with the laser light cannon making short work of the menacing space eye, which breaks into shards and plummets to Earth. That tracks, too. Eyes are extremely vulnerable to laser light cannons.
If you want to read more, have you considered which of the Steven Universe characters would make good laser materials? Check out my analysis: Do They Even Lase?
Perhaps you are now fired up (ahem) about lasers and want to wear laser themed stuff on your body? WELL YOU ARE IN LUCK! I have a laser themed merch store.
It's a tank top that says lasers on it!
I feel like Garnet in particular would have rocked the blue-and-red laser tank top (which you will understand if you've read my Do They Even Lase? article). Neon get out of the way so they can see the shirt!
