Photoacoustic spectroscopy, using a PZT transducer, is a quick, direct, and accurate technique to measure ink colors from the absorption region and maximum absorption position.
© 1989 Optical Society of America
R. S. Ram, Om Prakash, S. P. Varma, and A. N. Pandey, "Photoacoustic determination of the color of inks," Appl. Opt. 28, 1965-1967 (1989)