Finsen

Niels Ryberg Finsen (1861–1905) was a Danish physician and a pioneer of phototherapy. He is best known for developing early ultraviolet (UV) radiation therapies and for receiving the Nobel Prize in Physiology or Medicine in 1903 for his work in the medical application of light.

Finsen studied medicine at the University of Copenhagen and conducted experimental work on the therapeutic use of sunlight and UV radiation. He built devices, notably the Finsen lamp, which used a carbon arc lamp and filters to produce concentrated UV light. The aim was to target disease processes with light while limiting exposure to damaging radiation. In clinical practice, Finsen used the lamp to treat conditions such as lupus vulgaris (skin tuberculosis) and other skin infections, arguing that UV exposure could enhance healing and destroy microbial invaders.

His approach helped establish phototherapy as a legitimate medical modality and influenced dermatology and infectious-disease treatment in the late 19th and early 20th centuries. The methods were innovative for their time but also raised concerns about safety and the precise dosing of UV radiation, issues that subsequent researchers addressed as phototherapy evolved.

Finsen’s legacy lies in formalizing the idea that light can have therapeutic effects and in introducing apparatuses that made controlled radiation possible. He died in 1905 in Copenhagen. Today, phototherapy remains a core technique in dermatology and related fields, with Finsen’s early work frequently cited as a foundational milestone in medical light therapy.