photokymograph

pho·to·ky·mo·graph

(fō'tō-kī'mō-graf),
A device for moving film at a constant speed so that a continuous record of a physiologic event may be obtained, as by a beam of light shining on the film.
[photo- + G. kyma, wave, + graphō, to record]

photokymograph

(fō″tō-kī′mō-grăf) [″ + kyma, wave, + graphein, to write]
A device for making continuous photographs of a physiological event.