Happy second of Advent!

We’re lighting the second candle on our scientific Advent wreath. 

It’s time to light the second candle on our scientific Advent wreath. Each Sunday, researchers from the DOLPHIN group, led by Andreas Döpp, light up a candle – a weakly ionized plasma – to showcase techniques normally applied to their high-power laser experiments at the Centre for Advanced Laser Applications (CALA).

To capture the second candle, the students used a hyperspectral camera. Unlike a normal camera, which records only three color channels (red, green and blue) , a hyperspectral camera captures a full spectrum of light at each single pixel, spanning a continuous range of various wavelengths.

From this rich dataset, a variety of key properties can be derived – such as the temperature. Based on the fact that heated objects behave approximately like a black body, the researchers fitted a black-body curve to the spectrum of every pixel in the image and created a two-dimensional color temperature map.

 

The result: The flame is hotter at the outer edges. That’s because the outer edges are closest to the oxygen in the air, which is needed for the burning process.

Stay tuned for next week, as we'll reveal the next method! 

Pictures: Advent candles: AI-generated / Nina Beier; High-Speed Measurement: Matilde Nunes, Johannes Altmann and Marguerite Dion