Posted on 01 October 2011 at 16:04h

I was wasting time in Singapore airport, I think it was, cruising round the duty free shop seeing if there were any free samples on offer when I noticed this advertisment. Images of people playing golf were being projected onto a bottle of whisky standing in a glass pyramid. Quite an impressive display so I started wondering how the images were being projected. Must be a laser. Holograms maybe. On closer inspection I realised it was just a piece of angled glass reflected the image from a projector. The bottle was placed in the position of the image so they not appeared t the same place. Just like the old no parallax experiments to locate images in mirrors. I was quite taken aback by how such old technology was still able to catch peoples attention. It didn't make me buy a bottle of whisky though, free samples are a much better way of doing that.

While on the subject of optics I often use crocodile physics for doing ray diagrams in class, like the one below. I have quite an old version of the programme but it does everything I want. One problem however is that all the drawings are white rays on black background. If I want to make one to print out  take the image into paint and invert the colours.