And today we're going to show you how to make your very own home-made, DIY microscope

using just a laser pointer and a syringe.

A microscope works by using a series of lenses to magnify an image.

And you can make one at home by using just a droplet of water to act as your lens.

Now this laser pointer is a little bit stronger than your garden variety laser,

so I'm keeping this well away from my eyes.

But you should be able to see, if we turn the laser on,

the light hits the droplet of water, refracts through it and spreads out onto the screen.

To show you how this works, Will I'm going to need some of your saliva.

If you can take a sip, swill it around a bit

and spit it back into the cup.

Lush.

Okay, if we suck it up into our syringe,

and take down the lights. Fire our laser through it...

There's our image!

Oh wow! Before you go thinking this is

just my breakfast, these are human cheek cells

that have been washed off in the water, and now you can see them with the laser here.

Each one of these tiny epithilial cells is about

30 micrometers across, so that's

30 millionths of a meter.

And using the laser, we've managed to project up their shadow onto the screen.

Now this is just been from inside my mouth using some tap water but

let's see if we can find a bit more microbiological life out and around Bristol.

Robbie, I need you to take a trip down to the harbourside and get a sample of the water there.

But whatever you do, do not swill that around your mouth!

And just one small droplet of river water is teeming with life.

When we magnify it, we can see thousands of microbes.

So that's how to make a microscope. Why don't you have a go,

build one at home, and see what kind of life you can find.

If you'd like to see more scientific tricks of the light

check out last week's video where we looked at how to make a macro lens.

And for more science every week, click subscribe, thanks for watching!