(Not quite industrial) light and magic
Playing with polarising film — what you can see and do with it.
A few days ago I posted the story below about polarisation, in it I attempted to explain what it is and some of the things it can do. And I showed a simple way to see polarisation effects using things you might well have in your home i.e. a laptop; a pair of cinema 3d glasses; bits and pieces of clear plastic.
This post takes things a step further after I got a sheet of polarising filter. It behaves in the same way as the polarised 3d cinema glasses but it’s bigger and after cutting it in half you can overlap it. This allows you to do some really cool things.
The filter is polarising in one direction, so if both sheets are oriented the same way light passes through. But turn one of the sheets and the area of overlap darkens, turn it by 90º and very little light to no light gets through, as you can see in the clip above.
When the sheets are positioned so no light can pass and the area of overlap is black, if you then place something else that can polarise the light, like 3d specs you can see something quite mind-bending… (see clip above).
Polarised filters are used to analyse stress in plastics, you can see why in the clip above and below.
The clips here all show how different bits of plastic react depending on their thickness, what stresses they have been subjected to and/or how they have been produced.
The lovely thing about having the sheets of filter is that you can see these effects so directly. My boy (7) has really got a kick out of playing with them, I think the appeal for him (and it’s the same for me) is that you get so much magic from something so simple.
I’m going to test what else is possible and then will develop a workshop for kids so they can explore this phenomena themselves. And there might be potential to create a simple kit to encourage people to take a look at home.
A friend at work had an old LCD monitor I could have in exchange for beer. It comes with a polarising filter glued to its screen. Remove the filter and the screen will appear white until you put a piece of polarising filter near it. This looks magical—see the video below. You can also make the colours change by rotating the piece of film. I love how this dramatically brings to life the role of polarising film on screens such as these, including most smart phones and tablets.
My next job is to cut lens shapes out of the film I removed from the screen and put them into the frame of an old pair of glasses. That way you’ll be able to see what’s on screen while wearing the glasses.
The Instagram post below shows the step-by-step process for removing the polarising filter from an old monitor screen, should you fancy giving it a go. Please make sure it’s the right kind of screen, and you’re happy to risk destroying it before making a start as this process is pretty irreversible. Have fun!
