Sky Beacon: Optical SETI Laser Transmitter

**ELM – Emittrix Laseris Modulata** is a DIY optical SETI laser transmitter designed to send modulated signals into the sky, exploring the possibilities of **extraterrestrial communication**. It combines a green 532 nm laser, a TTL-modulated driver, and a custom power supply to create a functional optical beacon.

I built ELM – "Emittrix Laseris Modulata" to explore optical SETI and the engineering challenges of sending structured laser signals into space. Detecting or being noticed across interstellar distances depends strongly on transmitter power and beam focus — higher power (or narrower beams) makes a signal visible much farther away. For context, professional searches include radio facilities such as the Allen Telescope Array and large radio telescopes used by Breakthrough Listen, while optical searches use fast detectors on optical telescopes (for example, the Automated Planet Finder can detect ~100 W-class laser flashes from nearby stars). These real SETI efforts show both the promise and the scale of the problem: you can experiment on a DIY scale to learn the techniques, but reaching truly long distances requires much higher power and precision. Safety is paramount — never point high‑power lasers at aircraft or people.

I am using "ELM – Emittrix Laseris Modulata", a DIY optical SETI transmitter, to send modulated laser signals into the sky. I am using a green DPSS laser connected to a 3 W TTL-modulated laser driver, which can safely drive lasers up to 3 W using its adjustable voltage and current potentiometers.

I am modulating the laser by sending a TTL signal into the driver’s TTL input either from a signal generator/oscilloscope or a microcontroller, producing structured light pulses. I power the driver and laser with a 12 V Li-ion battery through a ZK SJVA booster. A push button switches the system on/off, and an LED indicates when the transmitter is active.

This DIY setup demonstrates optical SETI transmission principles: sending modulated laser pulses toward the sky, similar in concept to professional optical SETI experiments, but on a safe, small-scale platform.

“Complete setup showing the ELM optical SETI laser transmitter powered by a 12 V Li-ion battery and ZK SJVA 4× power supply module. The signal generator provides the TTL modulation input to the 3 W laser driver, producing modulated green laser pulses for optical transmission experiments.”

Uses and Applications

This project demonstrates a simple optical transmitter and SETI-inspired beacon system using a modulated laser source. It can be used for:

* Testing optical data transmission and light-based signaling.

* Educational demonstrations of **laser modulation and TTL control

* Experimental **optical SETI beacon concepts** and communication research.

Future Improvements

This project is open for experimentation and further development.

Anyone interested is welcome to improve or expand it — possible upgrades include:

* Using a microcontroller or Raspberry Pi to generate and encode modulation signals.

* Adding programmable transmission patterns (like Morse code or data bursts).

* Integrating automatic power regulation and cooling for higher laser output.

* Improving beam control and optics for longer-range transmission.