There are many uses for even a 1 mW helium-neon laser. Most of these same sorts of things can also be done with a collimated diode laser (though some laser diodes may not have the needed coherence properties for applications like interferometry and hologram generation).
Below are just a few possibilities.
(Portions from: Chris Chagaris (email@example.com).)
- Basic optical experimentation such demonstrating the principals of refraction, reflection, diffraction and polarization.
- Interferometer construction: With a small laser and a few simple optics, this device will allow you to perform many interesting experiments.
- Free-space optical communications: using some basic electronics for modulation.
- Fiber Optic Experimentation.
- Viewing of holograms.
- Hologram generation: However, I’d suggest a slightly higher powered laser for this.
- Construction of a basic laser light show. A higher power laser could be substituted when budget constraints allow. 🙂
- Laser surveillance.
- Laser tachometer.
- Laser burglar alarm.
- Laser gyroscope.
- Studying fluid dynamics.
- Applications in construction for calculating distance, leveling, aid in pipe laying, etc.