The

Volcano

logists

LENS

sensors, in the visible range they’re really

sensitive, the quantum efficiency could

be 70–80%, which is incredible, but you’d

expect that efficiency to drop in the UV,

mostly because of all these filters, but the

quantum efficiency of the Raspberry Pi

version 1 camera at 310 nanometres is

40%, so it’s absolutely unbelievable.

It’s comparable or better than some of

the commercial systems. I’ve seen one

quoted at 8% at 310 nm. Which is why

this has worked so well. There are other

issues to do with noise as

well. That is just absolutely

amazing. It’s why it’s

worked. It shouldn’t have

worked, but it did.

HS What’s next?

TP We’ve bought in some

stuff from Pimoroni. The

Enviro+ has all sorts of

interesting applications. There’s a mini

gas sensor on it, which I’m not sure will

be useful for us, but the thing that will be

useful is that particulate matter sensor

that you can add on to it. That’s looking

at the size of particles in air pollution, but

I don’t see any reason why we can’t use it

to detect ash particles on a drone flying

through a plume.

A lot of work I’ve been doing recently

has been on using mini cameras, flying

through gas plumes at the same time

with mini gas samplers.

The other massive advantage of all

this, from a volcano perspective, is that

things get blown up. Just this summer

there was an explosion and loads

of kit got wiped out. If that kit costs

thousands of dollars less to replace, it

just makes sense.

in lower-cost units, but maybe sending

multiple rover units to the moon. They

reached out to us to say that they had

an application that requires a very low

weight UV sensitive detector; would you

like to partner with us?

We developed

some sensors for

them. With Raspberry

Pi sensors, they’ve

developed prototypes for

spectrometers to go to

the moon.

There’s a limit to what

I can reveal, but the

whole unit that they’ve

built is about 150 × 100 × 100 mm in size,

and it’s got to come in under 60 grams,

so it needs to be really lightweight. I

suspect it isn’t 3D-printed, like ours.

But our contribution has been to deliver

the sensor module. With the project,

they’ve got to technology readiness level

4, so it’s already reasonably mature in

terms of where it’s got, and it’s passed a

whole series of tests. But the amazing

thing about it is that NASA asked us to

look at the quantum efficiency of the

sensor. If you get 100 photons falling

on the detector, how many electrons

are generated? With these kinds of

”

”

The quantum efficiency of the

Raspberry Pi camera version 1

is absolutely unbelievable – it’s

comparable or better than some

of the commercial systems

Left

On the right, the Raspberry Pi Camera module in its

natural state; on the left, the module with its lens and

Bayer filter removed to expose the sensor

Left

Tom’s written a GUI for the software, so you don’t

need to be an expert in Python programming on

Linux filesystems to study volcanoes