Near IR webcam

Introduction
Public summary: 

There's a whole spectra of light beyond the visible, why not see one side of it through a modified webcam?

Use a modified webcam to see into the near infrared.
Useful information
Kit List: 

Laptop
Small grey box containing:
Webcam (modified)
Lights (Incandescent and compact fluorescent)
Coke
CD
Shaver (blades removed)
Paper with CHaOS logo written with different pens
small white remote control

Packing Away: 

Store the laptop (and its power supply/lock) in the appropriate laptop case. All other equipment, including the webcam itself, should be carefully packed into the experiment box.

Frequency of use: 
4
Explanation
Explanation: 

What it it?

Take a normal webcam, remove the IR filter and replace it with crossed polars or a piece of exposed colour film and hey presto you have a near IR camera. Practical point:- the webcam has a focusing ring in front of the lens, which may be turned during an event, causing the image to become blurred. If this happens, ask a committee member to show you how to focus it (there is a knack, and if you it wrong you can jam the focus).

What is light/ IR light?

The light most of us are really familiar with is white light. But that's actually a mixture of different colours. Most of the time we can't tell that, but sometimes we can see these colours split up, like in a rainbow.

Do you know the colours of the rainbow? Ask them to tell you!
[Red -> Orange -> Yellow -> Green -> Blue -> Indigo -> Violet (basically purple!)]

It turns out that there are more kinds of light than our eyes can see. Some kinds of light are "redder" than red is - we call that kind of light "infra-red" . You might have seen images from cameras that can detect this kind of light, perhaps watching animals at night on TV, or police chase criminals with helicopters. At the other end of the rainbow there are other kinds of light that we can't see. These are more blue/ more purple than violet, and we call this kind of light "ultra violet".

It's weird to think that there's kinds of light we can't see, but not all kinds of eyes detect the same light. For example, some people can't tell red and green apart, which is called "colour blindness". Another example: some insects, such as bees, can see UV light. Some types of flowers have extra patterns in UV, so this helps them find the nectar in the middle of a flower! (How cool is that?!)

But what about wavelength/ spectra?

Add this extra level of detail with caution: it can be too much detail to take in if they've never thought about IR/UV before, and you can overwhelm them. You can come back to this later on once you'rve showed them some of the cool things you can see with the IR camera!

EM Spectrum: we call all the kinds of light (including UV, IR, visible) "electromagnetic radiation". One way of understanding this is to say that all these kinds of light have different sizes of wavelength. There's some charts in the box that you can point at when you explain this. Start with the rainbow: Red light waves are wider/longer than blue light waves. Following on from that, infra-red has longer waves than red light; UV has a shorter waves than blue. If you go further outside that you can see microwaves (that you can cook with) and radio waves (which can hold information. like music). These have a longer wavelength, much longer than infra-red. If you go the other way you get to X-rays- these have smaller waves than UV!

What do I look at with the camera?

Firstly, plug the new camera into a laptop and use VLC player (open up the video devices settings and select USB input owtte).
[Or maybe do ->Open Capture Device (Ctrl+c)-> PC Camera this sometimes also works]
[The camera often lags or gets stuck, the best solution is closing and reopening VLC]

Things to look at:

Coke is transparent, as are some plastics (shaver casing, sample of smoked glass).

Bank notes have lines. Try looking at the Queen's head on a £5 (old ones or new polymer ones both have the same effect!) or £20 note.

CD can be used as a diffraction grating to produce a 'rainbow' - shifted position.

Incandescent vs compact fluorescent - about the same luminosity in visible, former is much brighter under IR (Note: This looks more convincing if you give the fluorescent bulb 30 seconds or so to reach full brightness).

Different materials - some black clothing appears white under IR, often patterns on clothing disappear.

On the paper with the CHaOS logos, one shows up in IR and the other doesn't (written in different pens) - there is also the Normal/IR vision one with the same effect.

The laptop screen appears blank.

Remote control- uses IR, point at the camera while pressing buttons. Many camera phones lack IR filters so can test this on parents phone use it to see light from the end of the remote control.

There are lots of cool things to look at according to this:
http://www.hoagieshouse.com/IR/

Link to UV

This experiment often links well if placed near UV or demonstrated as a pair. You'll find the lights in IR can be too bright to see UV florescence. If separate demonstrations try and place slightly further apart or use the boxes as a screen if paired then switch off when moving across.

Risk Assessment
Date risk assesment last checked: 
Fri, 12/01/2018
Risk assesment checked by: 
Josh Garfinkel
Date risk assesment double checked: 
Wed, 17/01/2018
Risk assesment double-checked by: 
lucyhart.042
Risk Assessment: 

Using a webcam sensitive to near infrared light to look at various objects.

Risks:

* 1. Bedside lights contain glass bulbs.
* 2. Incandescent light gets hot if left on.
* 3. Compact fluorescent bulb contains (very small) quantity of mercury.
* 4. Lightbulbs can appear very bright when just switched on in dark room. Eyes are not used to that brightness.
* 5. Electrical cables present trip hazard
* 6. Coke is out of date.

Actions to control risks:

* 1. Take reasonable level of care with lamps.
* 2. Do not allow children to touch lamps, do not place too near the darkroom wall, or any flammable object.
* 3. Ensure lamp is stable and not easy to knock over.
* 4. Warn childen/visitors not to look directly into the lamps when you switch them on.
* 5. Try to keep cables out of thoroughfare. If cables must be placed somewhere people are likely to be walking, tape them down.
* 6. Do not let children drink the coke.

What to do if an accident still occurs:

* 1. In the event of broken glass, move public away and clear up mess carefully as soon as possible. In the event of injury, call first aider.
* 2. In the event of a burn call first aider. In the event of fire, follow procedures in venue RA (raise alarm, evacuate,...).
* 3. If lamp becomes broken, keep the public well away from the area, and ventilate area where breakage occurred. Take usual precautions for collection of broken glass. Do not use a standard vacuum cleaner for cleaning up dust; instead, pick up pieces/dust with a damp cloth or damp paper towels. Place materials, including the cloth/towels, in a sturdy closed container to avoid generating dust. After you have picked up all that you can, then vacuum the area. Finally, ventilate the room where the breakage occurred.
* 4. This is not really a major risk, tell first aider if child seems too dazzled about light.
* 5. In the event of injury, call first aider.
* 6. In the event of drinking, call first aider,

This experiment contains mains electrical parts, see separate risk assessment.
This experiment is sometimes run in a darkroom, see separate risk assessment.
Images
Publicity photo: 
Experiment photos: