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A Visit from Clara Candela

Dear readers,

PTB is very large and there’s always something new to discover – sometimes you’ll even meet a long-lost family member. That’s exactly what happened when we ran into the brilliant and friendly Clara Candela at our Press Office. We were quick to invite Clara to make an appearance in our blog, which bears her name.
So who is this glow worm exactly? Clara hatched in our media design office one day and symbolizes the SI unit* of the Candela.

Clara Candela should be instantly recognizable to young guests and is here to teach them about the unit of luminous intensity, for example, how the light of a light source is distributed in a room. »The candela is the luminous intensity, in a given direction, of a source that emits monochromatic radiation of frequency 540 THz and that has a radiant intensity in that direction of 1/683 watt per steradian.«**

You’re probably wondering why news from PTB’s International Cooperation has been sent out with the name Candela since 2002. It has always been and still is our goal to bring news that often remains in the background into the spotlight.

Formerly known as »Technical Cooperation«, International Cooperation has a long tradition at PTB: For almost 60 years, PTB has been sharing its experience with developing and emerging countries and actively providing assistance for the establishment and expansion of their quality infrastructure. The second meaning of the term points directly to the heart of PTB; Candela is the term for the unit of measurement used to determine the light intensity of a light. The exact characterization and dissemination of the units of all quantities (such as the kilogram, the meter and the second) is a fundamental prerequisite for guaranteeing the quality of products and is the core task of PTB, the national metrology institute of Germany. We’ve designed the Candela to provide you with a glimpse into this area at PTB and hope that we can spark your interest.

Note: since we’re not blogging about science but just reporting from the world of development cooperation, we recommend that you check out more precise information from the Luminous Intensity Working Group in the Photometry and Spectroradiometry Department of the Optics Division at PTB.

Have a brilliant day!

The Candela editors