The Body Photonic

01 November 2023
By Gwen Weerts

2023 was a big year for awards in optics. When I sat down to write this editorial, the Royal Swedish Academy of Sciences had just awarded the 2023 Nobel Prize in Physics to Pierre Agostini, Ferenc Krausz, and Anne L’Huillier for experiments with attosecond pulses of light. Within hours of the physics prize announcement, X (née Twitter) was abuzz over the omission of Paul Corkum, long expected to win a Nobel for laser methods that led to the creation of the field of attoscience.

Controversy, it seems, is embedded in the Nobel Prizes. In fact, the earliest Nobel Prize related to biophotonics was awarded to Dane Niels Finsen in 1903 for his use of ultraviolet (UV) light to successfully treat lupus vulgaris, a devastating bacterial infection that caused grotesque disfiguration of the face. After Finsen’s award was announced, dissidents pointed out that the bactericidal effects of UV light had been known for some time before Finsen applied them to treat tubercular skin; moreover, he had little theoretical understanding about why his light therapy worked. “No fair!” they cried.

Nonetheless, Finsen’s discovery kicked off decades of enthusiasm for  phototherapy, for everything from rickets to varicose veins. There was no illness, it seemed, that a little light could not help heal. One devotee of Finsen’s work, a prominent English journalist and physician, Caleb Saleeby, loudly championed “helio-therapy” in his 1923 book Sunlight and Health, which dedicates 183 pages to florid advocacy for sun baths. Soon after, he established the whimsically named Sunlight League, “formed to point to the light of day, to advocate its use for the cure of disease…and, immeasurably better, for preventive medicine and constructive health…” This would seem a charming historical sidenote if not countered by the sobering fact that Saleeby was also a vocal advocate for the eugenics movement, which is further evidence that monsters can lurk in the sunshine.

These early explorations of light as a therapy for the human body were a mere foreshadowing of the sophisticated science of biophotonics that would emerge toward the end of the 20th century. This issue of Photonics Focus explores the intersection of photonics and the human body. We learn about microfluidics, most commonly recognized by laypeople in at-home Covid-19 tests, a technology that promises to play an exciting part in the holy grail of personalized medicine. Another story explores the sophisticated suite of optical components and sensors built into modern smartphones and details their current and near-future capabilities for low-cost point-of-care medical testing. Finally, readers are gifted a very personal story about one woman’s experience with a brain tumor and the medical imaging technologies that helped enable its removal.

Fortunately, antibiotics now cure lupus vulgaris, and Finsen’s original UV lamps reside in London’s Science Museum. Finsen’s Nobel-worthy discovery launched a new field dedicated to the investigation of light’s ability to diagnose, treat, and cure diseases of the human body.

 Gwen Weerts, Editor-in-chief


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