LaserSETI is a project that could give evidence of intelligent life beyond Earth as it searches for technosignatures in the form of these laser pulses or high intensity monochromatic light sources.

Optical SETI is a subset of those searches looking for visible light signals that could be attributed to extraterrestrial intelligence, often presumed to be lasers because a narrow beam is essential if you’re going to send light a long distance efficiently.

It has long been speculated that powerful lasers might be used by advanced societies for interstellar communication. Messaging by light has a fundamental advantage over radio in that it can, in principle, convey far more bits per second – typically a half-million times as many. This increased bandwidth is a characteristic that would make lasers useful for communicating with off-world colonies, for example.

For decades, a small number of so-called optical-SETI projects have examined star systems for extremely brief (nanosecond) flashes of light that may indicate E.T. communication. However, the instruments used for these projects have all relied on photomultiplier tubes to detect the flashes, making them essentially one-pixel cameras. As a result, very little of the sky has been examined.

LaserSETI is trying to change that! Each LaserSETI detection device consists of two identical cameras. Each LaserSETI device uses cameras with a commercial lens that images approximately 75 degrees of sky onto off-the-shelf solid-state detectors. Therefore, with multiple LaserSETI observatories around the globe, all-sky monitoring is in reach.

These devices can tell monochromatic laser-like sources from natural sources by looking at their spectra. Behind each lens is a grating that transforms any light source in the camera’s field-of-view into a double rainbow-like spectrum. While stars will produce a complete spectrum from blue to red, a laser will only show up at its characteristic wavelength (think of your red laser pointer). Currently, there are no known monochromatic optical sources produced by nature, so any positive detection of laser-like sources would either indicate the presence of E.T., or just as important, a new type of astrophysical phenomenon. In this way, LaserSETI is paving the way for a new type of optical SETI search that watches the whole sky, all the time.