Image: Laser test bench

This ESA test bench is usually shrouded in darkness, except for the laser beam being projected across it.

Human eyes are not normally supposed to witness the laser being fired – for this photo, it was fired at the lowest possible energy level, while the camera was switched to its highest light-sensitive settings for an exposure time of half a second.

Lasers are versatile tools for space, variously used for remote sensing, interferometry and communications. ESA's Opto-Electronics Laboratory, at the Agency's ESTEC technical centre in Noordwijk, the Netherlands, specialises in assessing devices that generate, detect and manipulate light.