See the unseen

Science can let us see the unseen, so make your own special glasses to reveal hidden images and even create secret messages.
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Picture of lots of red and green lines and patterns on top of each other


At the Crick our scientists need to see things that are often mixed up with lots of other stuff that they’re not interested in. They sometimes use colours, light, and even x-rays to help them see things they otherwise might not be able to. Although your glasses won’t use real x-rays, you will be able to filter out useless information to find the useful stuff, like pictures, or messages. 

Can you see the image here? Soon you will be able to...

What you will need

What you will need

●    Red plastic sweet wrappers (the kind you can see through)
●    A light green pencil
●    A red pen or pencil
●    White Paper
●    Cardboard (a cereal box is perfect)
●    Scissors
●    Tape or glue
●    A printed out template (optional - download here

Safety tip

  • Get an adult to help you with the scissors.

What you need to do

To make your glasses:

  • Either print out the template or draw your own glasses onto some cardboard

  • Cut them out, including the space for your lenses

  • Using tape or glue fix your red sweet wrappers across the lens holes in your glasses

  • Wear your glasses, or hold them in place and everything should look red

  • Take a look at that picture above again, can you see it now?

  • Now to try making your own hidden images and messages

  • To make your hidden images:

  • Test your pens and pencils by drawing with them on white paper and looking at them through your glasses. Red lines should disappear and green lines turn dark

  • With your green pencil draw a picture or write a message. Try not to press too hard, draw lightly and your lines will be more easily hidden

  • With your red pen or pencil draw random lines all over your green drawing. Try and keep your lines separate and don’t colour in big blocks of red

  • Now your green picture is hidden behind the red lines, reveal it with your filtering glasses

  • The science:

    The science:

    Your glasses are a red light filter, and a filter is something that lets some things through, but not others.

    So a water filter lets water through, but not dirt. Your glasses let red light through, but not other colours. That might sound strange because it’s the red lines that are disappearing, isn’t it? To answer that we need to understand a bit more about light and colours.

    To see things we need light sources, things like the Sun, or the lights in your house.

    The light from them bounces, or reflects, off of the things around us, goes into our eyes and we can ‘see’ them. We normally use light sources that give off a bright white light, but not everything we look at is white.

    The science

    Diagram to explain how light reflects off different surfaces, and how we see colour

    Most things don’t reflect all of the light that shines on them, just some of it.

    White light is actually made up of all the colours of the rainbow, (literally, we see the colours in a rainbow when they are separated out from the white light of the Sun). A red object, like the red pencil, only reflects the red parts and the green pencil is reflecting just the green parts.

    But what about the white paper? That’s reflecting all the light, including red, green and all the other colours of the rainbow, but mixed together so our eyes see it as white.

    Diagram to explain how the red light is filtered

    When we use the glasses the red filter lets the red light from the red lines through and you can actually see them.

    The white paper is reflecting all the colours of light, but only the red can get through the filter, so the paper looks red.

    Red marks on red paper don’t stand out, so we feel like the red lines have disappeared.

    Diagram to demonstrate how different objects are seen through different filters

    At the same time...

    The green light, from the green lines, is blocked by the filter so we see darkness where they should be.

    So in a weird way, it’s actually the green lines that are disappearing, not the red.

    Science at the Crick:

    It probably won’t surprise you that microscopes are used in the Crick labs.

    Microscopes capture and magnify images so we can look at incredibly small things, even single cells.  

    You may also know that you can’t see all types of light, some are invisible like X-rays. This type of light can be used to look inside objects and see things like the skeleton of your body. 

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