This is a simple and cheap laser show project where a laser is reflected onto a mirror physically attached to a speaker membrane. Sound waves are produced as the speaker vibrates which also causes the mirror to vibrate, producing multiple patterns and shapes on the walls and ceiling as they get projected, as shown in the image below.
This version of laser show can be seen in action on the ceiling as shown in the videos. The only logical step after building was to increase the power and number of beams since it only covers a small portion of the wall and was not bright enough. The resulting is a hypnotizing effect since it is quite easy to zone out and become completely absorbed in the music. When fog or smoke screen is employed in the room, the multiple vibrating beams coming out of the unit also look amazing.
Other cool stuffs can also be done on the unit such as connecting a microphone and watching the patterns made by the voice. To be able to spread the effect around even more, a disco ball or mirrors on the ceiling can be implemented.
The image below shows how one strong beam is split into several smaller parts which avoids buying 200 lasers that would all bounce off one mirror to perform diffraction grating where the little parts of the laser light interfere with each other because of the wave0like nature of light. Another video shows a powerful laser reflecting off a mirror mounted on a speaker which then goes through a diffraction grating as it creates hundreds of laser patterns based on the vibration of the speaker.
The design of the unit includes the laser module, power supply and housing, optics, and audio. The assembly initially begins by providing power to the laser itself and providing any easy method to turn it ON and OFF by using a switch. the laser modulation comes next where the mirror needs to be attached in the middle of the speaker. The laser then needs to be aligned correctly so it bounces off the mirror. The laser being reflected off the speaker will be intercepted by the diffraction grating to produce hundreds of beams by breaking it up. The final testing and assembly would look like the image below.