Laser Interferometry

Technology Review -- By Jennifer Chu

"In contrast, Feld and his colleagues have been able to image live, untreated cells by using an optical technique based on interferometry: a laser beam passed through a sample is compared with a reference beam of similar wavelength that is not passed through the cell. For example, it takes longer for light to travel through a cell than through, say, water. Researchers can measure that time delay, or phase shift, and then can map the cell and its motions on the scale of nanometers."