Basic elements › Units of measurement

LIGHT

Light is an electromagnetic radiation whose frequency varies. The human eye perceives light with wavelengths between 400 and 780 nm. However, from a physical standpoint, light is not limited to the visible spectrum (infrared, ultraviolet, black light, etc.). Like electric current or sound, light is characterized by its luminous flux, measured in lumens (lm), and its intensity, measured in candela (cd). Besides illuminating us and making the world around us visible, light travels in a straight line through a vacuum, at a rigorously constant and extremely high speed.

A reference framework in physics and science

It has thus become one of the main reference standards in physics and science. The second is defined as the duration of 9,192,631,770 periods of radiation from a cesium 133 transition (atomic clocks). The meter is defined as the distance traveled by light in vacuum in 1/299,792,458 s.

Luminescence

In our watches, light is present on the hands and the dials, which frequently feature luminescent material. Nowadays, superluminova is available in different degrees (grades) of intensity.

Light as a tool

Watchmaking and light are intimately linked. The quality of the light in the Jura mountains encouraged the settlement of Huguenot watchmakers there. Light, as illumination, is therefore essential to the practice of watchmaking. But it is also present in many manufacturing processes. Light is involved in all photolithographic processes (chemical engraving, DRIE (Deep Reactive Ion Etching) engraving, UV-LIGA) but also in additive technologies (electroforming, selective laser melting) and, more recently, in machining (laser engraving, femtosecond laser machining). Finally, light is now omnipresent in quality testing, many measurements are now carried out optically (dimensions, counting, profile, etc.)