Hello,

I have a question that may be a bit off the beaten path. I am an artist and am working with polarized filters. My question, is there a polarized filter that can go from a polarized to a non-polarized state. Such as, if you want the polarized filter to cycle on and off. Is there such a device? Any help would be greatly appreciated.

Regards, Todd

-- Todd (contacttodd@yahoo.com), January 22, 2001

Answers

Well, maybe I'm missing something, but if you rotate it it controlls the degree of polorization (well, the angle, but same difference) effectively turning it on and off. Wouldn't just rotating do the trick. But why? are you still or motion? Dean

-- Dean Lastoria (dvlastor@sfu.ca), January 22, 2001.

The straight answer is no. AFAIK there is no device that's switchable from a polarising to a non-polarising state.
BUT, having said that, LCD displays work by twisting the plane of polarisation electrically, as does a device called a 'Kerr cell'. LCDs have a polarising filter in front of a liquid crystal trapped between glass. This liquid crystal can act like a quarter-wave retardation plate when electrically excited.
It's a bit too complex to explain in detail here. I suggest you read up on the workings of a Kerr Cell, and LCD displays.

-- Pete Andrews (p.l.andrews@bham.ac.uk), January 23, 2001.