This compact laser transmitter module outputs a focused, bright red dot beam at a wavelength of 650nm. Designed with a built-in current-limiting resistor, it can be powered directly from a 5V digital pin on microcontrollers like Arduino. When combined with an LDR or photo-detector module, it creates long-range optical tripwires. Widely used for laser security alarm systems, optical target indicators, alignment tools, and free-space optical data link experiments.