Which mechanisms will move with a ray of light?

By a mechanism, I mean a simple mechanical system... not something
complex like i.e. an electronic circuit that detects light and powers
a step motor. But it could be something like a metal allow, a plastic,
a material produced by chemical reactions, something coated by a
chemical, something organic like a bacteria or plant, etc. Also, the
mechanism must take the energy to move from the light source.

Please tell me what kind of light is required to move the mechanism:
laser, ir, uv, solar, bulb. The easiest to generate the light, the
best.

The mechanism should return to it's original state as soon as the light is off.

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Clarification of Question by cronodragon-ga on 04 Jul 2005 20:47 PDT

If possible, but not neccesary, I would like to know this data: angle,
distance, force, speed and frequency... maybe that would make the
question not worth $2.

For $2 you are supposed to get just a few links
- not an essay-  so I will give you few different examples

(there are not many  such things anyway)

1) Rotor of Crooks radiometer
" A Crookes' radiometer has four vanes suspended inside a glass bulb .."
http://science.howstuffworks.com/question239.htm

(First link to a pic is not working, but this one does
http://science.howstuffworks.com/framed.htm?parent=question239.htm&url=http://www.sciencemuseum.org.uk/collections/treasures/crooke3.asp
)

2) Solar sail
arge and lightweight mirrors that are pushed through space by sunlight
http://www.solarsails.info/

(There are many links on this)

3) laser rocket engine (a bonus link)

  This one wants laser - but mainly to keep the beam focused and so hit
 a target at distance. It is not exactly light here which moves the structure.
 It is a 'normal' racket and light just supplies the energy:
http://www.nasatech.com/Briefs/May00/MFS31272.html

It is also listed under 'exotic propulsin' here:
http://www.hobbyspace.com/Links/LaunchPropulsion1.html

 
 
 


 
   




 
 
 


 
   



A Crookes' radiometer has four vanes suspended inside a glass bulb

http://science.howstuffworks.com/framed.htm?parent=question239.htm&url=http://www.sciencemuseum.org.uk/collections/treasures/crooke3.asp

Great, thanks a lot!

To the examples hedgie has already given, you can add "optical
tweezers".  See, for instance,
<http://www.ipass.net/brianrodr/tweezers.html> (A Google search on
optical tweezers will provide you with lots of additional references.)

That's REALLY COOL! Thanks!