Laser light painting of exhaled droplets: imaging with accessible, lower-power lasers

The spatial distribution of exhaled droplets produced during speech, singing, and playing wind and brass instruments is characterized and compared. Rather than using a stationary laser with a flat-and-wide profile, droplets are imaged in a long exposure during which a narrow laser beam is scanned vertically across the field of view with a technique we think of as "light painting". The advantage of this method is that the same illumination can be obtained with a lower-power laser (such as a class IIIb or less).