Arthur Ashkin
1922–2020, Brooklyn, New York, USA, Rumson, New Jersey, USA
American physicist, inventor of 'optical tweezers' that use a laser beam to hold atoms, viruses and living cells.
Ashkin worked at Bell Labs from 1952 to 1991. He realized radiation pressure — the 'push' of photons — could act mechanically on small particles; in 1986 he showed a single strongly focused laser beam could hold a particle in 3D: optical tweezers. With softened beams he showed they could even grasp living cells and bacteria without damage.
Nobel-winning work
Optical tweezers (Ashkin, 1986) exploit the gradient force near a laser focus: photons deflected by a particle transfer momentum pulling it to the beam center. The instrument measures piconewton forces and nanometre motions — becoming biology's 'hand': stretching DNA, measuring kinesin molecular motors, and trapping cold atoms.
Workplaces: Bell Laboratories
United States