Laser Sky Effect using Arduino
Bouncing a laser beam off a spinning mirror can create an amazing light show as illustrated in this Laser Sky video by Youtube channel Normal Universe. The spinning mirror sweeps out a laser plane, which illuminates the cross sections of smoke or fog in the room and let you visualize how the air medium is moving around you in a very cool way. The spinning mirror is built out of 8 pcs of tiny plane mirrors installed on an spinning motor assembly made of a PC fan and a 3D printed mount part. The Arduino Uno is used as the main brain in the project. It not only controls the power to the laser, but also monitors the speed of the spinning mirror with a closed loop feedback system made of an optical switch (basically made of an LDR and an LED). A 3D printed casing provides a nice look and adds safety to its operation.
Laser Sky effect using Arduino, laser pointer, and spinning mirror
Following video describes the build process in detail.