Lasers travel at the speed of light,

and the only way that a blaster bolt, or a disruptor shot, or a phaser beam

can take this long to cross a room

is in science fiction, so the audience can understand what's going on.

But... this is real.

Over there– and I can't look at it

unless I'm wearing these incredibly-stylish laser safety goggles–

but over there is a class 4 laser generator,

the sort of thing that will burn your retinas out if you treat it the wrong way.

But lasers can't do this.

They certainly can't start moving back and forth, like it's a tennis match,

and they absolutely can't behave like they do in Star Wars,

when Kylo Ren uses the Force

and stops one in mid-air.

But this is not being added by computer afterwards.

This is happening in-camera.

I can interact with this and show you.

So how's it being done?

To explain that,

we need to talk to the person who programmed that laser.

- I'm Seb Lee-Delisle, and I'm a digital artist and laserist.

Definitely a real job!

I make a lot of primarily large, outdoor installations.

I project onto buildings and have lots of interactions with the public

with musical instruments that I made.

This laser is a really good three-watt laser.

It's fairly compact, but it's got really fast scanners in.

The big laser is an 11-watt laser made by a company called Lightspace.

The scanners aren't quite as good as the ones in here,

but they're still perfectly acceptable and what most people use.

- Alright, so...

Can this burn me? - Yeah.

- Okay.

- You're ruining my test now. - Oh, sorry.

- It's actually a very simple concept,

and it didn't take me that long to get it working.

All of my code is C++.

In this case, I had to tweak it at a really low level

because there were some really fine timing adjustments that I needed to make.

Here's the trick,

and it's something you've probably seen on Science YouTube before:

rolling shutter.

See, modern cameras don't take a single frame all at the same time–

boomph– like an old-school photograph, they scan.

It takes just a fraction of a second for it to go from the top,

all the way to the bottom of the camera,

and it registers each line one at a time.

So what we've done is we've turned the camera 90 degrees on its side,

so now that rolling shutter effect is going horizontally,

and this laser is being turned on and off incredibly quickly and incredibly precisely,

so that as the camera scans by for every frame,

the laser is on when it needs to be and off when it needs to be.

That takes a lot of maths and a lot of precision,

but the result... is this.

- The harder thing about programming this particular trick

is to start thinking in a different coordinate space...

Right? Because you're no longer dealing with X and Y particularly.

Instead, you've got one of your axes, which is the Y axis,

which is now time.

One of the things I had to take into account is obviously when you start the app,

when you start the camera, those things aren't gonna be in line,

so I had to add the capability to be able to

actually shift that start point at the frame backwards and forwards in time.

I'm certainly not the first person to exploit the rolling shutter effect

to make laser beam effects.

In fact, you can pretty much just run any traditional laser queue

and just start to see some weird things happening

if you mess around with your shutter speed and frame rate.

You might have seen some really good uses of it, in the past,

with Adam LaBay and his work with YouTube,

and then subsequently with Saturday Night Live.

What I'm doing here is a little bit different from that,

because we're literally taking the area of the frame in time,

and using that as a specific Y-position that we want something to appear in.

When we're all together, and we're just seeing it for the first time,

that was pretty special to get that surprise,

'cause I've only been testing this effect out with some much smaller lasers in my studio,

so when we got it actually with the bigger laser in such a big space,

yeah, it came to life.

And I'm a bit surprised how it looked.

- Oh, what?!

Oh, that looks good! That looks so good!

- I'll be preparing a video especially with more of the behind-the-scenes stuff.

More of the nerdy details.

I'll be putting that in a separate video on my channel.

- I want to be clear, Seb did all the hard work here.

I am just the guy who went: "What if we turn the camera on its side?"

But while we've got all this setup, and all this equipment, and these glasses,

there is one effect I wanna try:

the bullet dodge from The Matrix.

Catch is... we can't do this in slow motion,

so I've... just gotta fake it.

How hard can it be?

That is hot. That is very hot!