Om anvendelse medicinen af koncentrerede kemiske lysstraaler.

Finsen was the founder of modern phototherapy. He demonstrated the value of invisible light, the actinic or chemical ray, the ultra-violet ray, as therapeutic measures. Digital facsimile from wellcomecollection.org at this link. 

In 1903 Finsen received the Nobel Prize for Physiology or Medicine "in recognition of his contribution to the treatment of diseases, especially lupus vulgaris, with concentrated light radiation, whereby he has opened a new avenue for medical science."