5. Functional Hard Drive OscilloscopeThis strange project uses a laser mounted on the HDD's body to produce an oscilloscope effect -- when the output is bounced off a mirror.
We have all seen an oscilloscope hooked up to a speaker output to allow us to “watch” the music. Well now you can see a standard oscilloscope and a Hard Drive Oscilloscope side by side![Source]
4. Home Built Laser ProjectorFor those who've always wanted a professional grade laser projector, check out this nifty home built version.
The most important component used for laser projectors is the laser unit, He-Ne laser had been used in early days, multi-colored mixed gas laser is currently used for high end laser projector and solid state laser is one of the brand-new laser device that has been recently used. However the laser unit was very expensive and junk He-Ne gas laser cannot be modulated directly, so that I could not resolve to obtain the laser unit with a modulator[Source]