Αστεροσήμα : Sky Beacon — Optical SETI Laser Transmitter

An Optical SETI (Search for Extraterrestrial Intelligence) transmitter is a device designed to send signals using light—usually laser light—into space with the aim of contacting or being detected by intelligent extraterrestrial civilizations. It’s the optical (light-based) version of the more traditional radio SETI, which uses radio waves.

This project is Although titled an Optical SETI Laser actually a small-scale METI ((Messaging to Extraterrestrial Intelligence) setup

I have named it "Αστεροσήμα (Asterosima)" 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 have named it "Αστεροσήμα (Asterosima)" is a DIY optical SETI laser transmitter designed to send modulated signals into the sky, exploring the possibilities of e xtraterrestrial communication. It combines a green 532 nm laser, a TTL-modulated driver, and a custom power supply to create a functional optical beacon.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 "Αστεροσήμα (Asterosima)"a DIY optical SETI transmitter, to send modulated laser signals into the sky. I am using a 532 nm(green)DPSS laser (100mW) 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.

Role of Optics:

A laser beam spreads out naturally as it travels. By using well-designed, precise, and collimated lenses, the beam stays narrow and focused, which increases the distance it can travel. In principle, a High-power laser , with well-collimated optics could transmit signals across very long distances, even into space.

“Could advanced civilizations detect our laser signals? ----

{In theory, a well-collimated laser beam can be detectable at orbital or interplanetary distances if the receiving system has highly sensitive optical detectors. Modern space missions already use faint laser pulses for communication and ranging, so an advanced extraterrestrial probe or intelligent civilization equipped with quantum-level sensors could potentially detect even low-power, modulated optical signals. This makes optical SETI transmission an interesting concept for experimental research}.

“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.

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

“It can also be used to monitor potential optical responses from atmospheric or aerial anomalies under controlled observation.”

Note

This optical laser transmitter can be utilized for controlled experiments in atmospheric and space-based optical signal propagation studies. Its precisely collimated, high-intensity, and modulated laser output enables research into long-distance optical communication, beam stability under varying environmental conditions, and potential signal transmission beyond Earth’s atmosphere. In theory, any advanced spacecraft or extraterrestrial civilization equipped with sensitive optical detection instruments scanning the optical spectrum could detect such a signal. However, to achieve detectable interstellar transmissions, much higher optical power—on the order of megawatts or gigawatts—would be required

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).

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