Illustration: ikonaut

3 — Two mirrors ensure that the photons multiply in this alignment. The result is a powerful, monochrome, synchronous beam with many possible applications.

2 — If this photon hits another excited atom, the latter produces a photon that travels in the same direction, oscillating in synch.

1 — A laser can be created by a crystal whose atoms are excited by light. When one of these atoms returns to its resting state, it emits a photon of a specific wavelength.

E — Analysis in a mini-chip of glass
Cassio-P Alpha, an EPFL spin-off, has miniaturised laser analysis. Their oscillator, hardly bigger than the palm of your hand, shoots a billion pulses a second into a glass chip. This enables samples to be analysed on site, out in the field.

D — Getting more data
When several multicoloured lasers are superimposed, fibre optic cables in data centres become more efficient. Enlightra, an EPFL spin-off, is developing the frequency combs needed to combine and separate their colours.

C — Efficient cancer recognition
Lasers in microscopes can help us to examine samples layer by layer and create 3D images. The ETH spin-off Imai has developed a process for preparing many tissue samples at once, using appropriate dyes.

B — A death-ray for weeds
Caterra, an ETH spin-off, has been collaborating with Agroscope to build a robot that destroys weeds without herbicides. It detects weeds among crop plants, then burns them with its targeted laser.

A — 3D-printers for metal
A powerful laser beam can melt metal powder at a precise point, thereby enabling the creation of complex 3D structures, layer by layer. A-Metal, a spin-off of ETH Zurich, has simplified this process.