Projects to undertake Using Lasers I need an economically feasible physics project that would use lasers in any manner preferably with respect to optics for a school projects class XII . Any suggestions are welcome no matter how crazy it sounds ! 
 A: There are loads of things you can do with lasers. However, maybe this one might be of interest?

It's called "Laser Audio Interferometer" I tried this and it's simple.
  The mirror reflects the laser beam back down the bore of the HeNe
  laser tube, forming a second optical cavity external to the laser. Or
  use a laser pointer instead; I've been told that most will work. A
  small photovoltaic cell (solar cell or photodiode) collects some of
  the spill-light from the beam, and the PV cell output is sent to an
  audio amp and loudspeaker. If you move the wall (or the laser) a tiny
  bit, then as the "cavity" changes length, it sweeps across hundreds of
  resonant lengths located every 1/2 wavelength of the light. The light
  intensity sequentially grows dimmer and brighter, generating a
  sinewave signal. The frequency is proportional to the velocity of the
  wall. Connect the PV cell to the microphone input of an audio system,
  and when the wall is pushed, you hear moans and squeals.

Check out the site above for more ideas
A: What about a double-slit experiment? If your laser's spatial coherence is long enough, you should be able to place the screen far enough away to get a nice image.
Or go a step further and use a ballpen spring instead of a double slit, and reproduce the diffraction image of a helix (similar to what one sees with DNA)!
