The day I thought I discovered Birefringence


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  1. I tried to make an LCD panel with sugar water
  2. You can't make an LCD panel with sugar water
  3. Plastic glass looked more colourful than sugar water
  4. Boom! Birefringence!

It was July 2020, I had just graduated, and bought a polarisation filter lens from Amazon, hoping to fit it on my telescope. It didn't fit, but polarising filters are too cool to be just stowed away, so I was looking for fun things to do with it.

The most common encounter with Polarisation in daily lives is LCD displays; they emit polarised light, and enable all kinds of fun shenanigans right at home! After playing around with LCDs for a while, I wanted to create one. I would need a source of polarised white light, an optically active medium, and a polarising filter.

My source of polarised light was, ironically, an LCD displaying a white image. And the optically active medium was Sugar water. Table Sugar turns light Clockwise (Dextro / To the Right). And the polariser was, well the polariser.

Read tangent about Dextricity sugars.TODOOOO


In a real LCD, there is a source of white light, and an optically active medium (the Liquid Crystal) sandwiched between two polarising filters set at 90 degrees to each other, followed by a colour filter.

The amount by which the active medium rotates the Light can be controlled by applying an Electric field to it. (Which is applied via transparent electrodes made of Indium Tin Oxide. Cool stuff.)

Anyway, we don't have cool electrodes and fancy crystals, so I decided to just rotate the polarisation filter manually. That should have the same effect.

Except, I couldn't find a container made of glass, so I grabbed a plastic drinking glass, and filled it with water and a couple of spoons of sugar. There are two errors I made here, using a plastic container, and adding too little sugar.

The degree by which light is rotated depends on

  1. The length of the

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