The A. Lange & Söhne "Lumen" series
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The A. Lange & Söhne "Lumen" series Luminous displays

Auroras rank among our planet’s most awe-inspiring natural phenomena: Fluorescent light cloaks the nocturnal darkness with mysterious green veils. With three of its most spectacular models, A. Lange & Söhne embarked on a journey to Iceland for a first-hand encounter with one of Mother Nature’s most fascinating extravaganzas. Breathtaking impressions between light and darkness in primeval natural surroundings.

The interplay of opposites

 

The interplay of opposites culminates in perfection with the northern lights in the Arctic sky above Iceland. They are the ideal setting for the luminous A. Lange & Söhne models that master the contrast of light and darkness in a spectacular way: the ZEITWERK “Luminous” (in a limited 100-watch edition), the GRAND LANGE 1 “Lumen” and the GRAND LANGE 1 MOON PHASE “Lumen” (both in a limited 200-watch edition). All three models feature a dial made of semi-transparent sapphire crystal. Its light-permeable coating allows the numerals to absorb enough daytime light energy to uniformly glow in the darkness for several hours..

Luminous outsize date: the GRAND LANGE 1 “Lumen”

The GRAND LANGE 1 MOON PHASE presents itself in daylight. Suddenly the light switches off. The watch’s noctilucent displays appear in glowing green. With the hours and minutes hands’ movement speeded up, the luminous large date advances from 25 to 26. The light comes on again. We examine the details on the semi-transparent dial and then the complete movement. A last press of the light switch causes the Lange logo to change from grey to luminous green.

How luminous displays work

 

Watches with luminous displays need a light source that charges the luminous compound applied to the display elements and allows them to glow. Thanks to the semi-transparent black-tinted dial, the displays of the GRAND LANGE 1 MOON PHASE “Lumen” and of the other A. Lange & Söhne “Lumen” models can be permanently charged with light energy

The displays of the GRAND LANGE 1 MOON PHASE “Lumen”

 

The dial is made of blackened silver with generous apertures and a semi-transparent black-tinted sapphire-crystal glass wafer. The special coating applied to the glass blocks most of the visible light but not the UV spectra that “charge” the luminous pigments on the outsize date mechanism and cause them to glow in the dark. The tens cross is coated with a white luminous compound and printed with black numerals. Conversely, the units disc, also featuring black numerals, is made of transparent glass and rotates in front of the luminous background of the date aperture. The lunar disc is made of glass as well. First, the glass surface is coated with a patented process. Then 1164 stars and the moon are cut out with a laser beam. The luminous compound behind the lunar disc makes the moon and the stars shine.

Anthony de Hass, Director of Product Development, about the GRAND LANGE 1 MOON PHASE "Lumen"

Why the northern lights are green

 

The rare natural phenomenon can be observed in the polar region merely during a few days between September and March. Complex physical processes create the polychrome auroras in the upper strata of the earth’s atmosphere. The green light, to which our eyes are particularly receptive, occurs at an altitude of about 100 kilometers. Here, oxygen atoms collide with the electrically charged particles of the solar winds. These collisions emit light with a wavelength of 557.7 nanometers, which the human eye perceives as green.

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