Depth of Field:

In my daily scan of BBC News, I spotted a story about a holographic display device. It is noteworthy because it is reusable, and apparently can be driven by input from a control device to show multiple images in fast succession. There is some buzz about this as potential for another try at 3-D TV, but given that it is currently only monochromatic, and has a slow refresh rate for TV images, it has some way to go.

The positives are that we are much better now at getting laser light in multiple colours - the Blu-Ray explosion being our shortest wavelength mass-produced example, so there is technical know-how out there for an RGB attempt.

I bet this will produce some killer headaches for spectators...

The story caught my eye because as a high school project in the late 1970's, I produced holographic images at the Ontario Science Centre. Don Cooper and I spent hours trying to make sure no stray light from the two laser beams made it onto the emulsion plate, so I can attest to the difficulty of doing these properly. I forget the scientists' name who supervised, but he was an elderly Hungarian, and I can still hear him saying "light goes from heersh, to thersh." It was a lot of effort for a single image on a piece of rather thick film, which could never be reused.

The story also caught my attention because every once in a while, I find an image that is strangely three-dimensional. Have a look at the following image from the BBC site:

Now I'm not sure what it is supposed to be, but I found that if I gazed at the center-lower glint for a bit, suddenly I got a 3-D sensation. I'm not quite sure what causes this. I have some slides that do this too, even when projected.