THE CORRELATION OF APPLIED VOLTAGE ON PIEZOELECTRIC TRANSDUCERS (PZT'S) TO DISPLACEMENT. Chris Wottawa, Harold Metcalf, John Noe, Laser Teaching Center, Department of Physics and Astronomy, SUNY at Stony Brook.

Plumbum Zirconium Titanate (PZT) is a ceramic material with the unique ability to transform an applied voltage into a small (typically nanometer) mechanical displacement, or vice versa. This property, the Piezoelectric Effect, which was discovered by Pierre and Jacques Curie in 1880, now has applications in almost all fields of science and technology. Because of this effect, these special ceramic materials have become known as piezoelectric translators or transducers (also PZT).

The purpose of this project is to measure the minute displacements of various PZT disks as a function of applied voltage. The PZT samples (PIC-155, PIC 151, etc) were obtained from the PhysikInstrument Company in Auburn, Mass. The tiny displacements are measured using light waves as a ruler with the help of a Michelson Interferometer. Light from a He-Ne laser (wavelength = 632.8 nm) is projected with the help of two adjustable mirrors through a diverging lens and then into the interferometer. The interferometer consists of two mirrors and a beam splitter, which, when aligned perfectly, forces laser beams to travel over two perpendicular paths and interfere as they recombine. This results in circular fringes (alternating rings of light and dark), caused by the alternating constructive and destructive interference. The radius of the fringes is directly related to the separation of the mirrors (the difference in path length of the two beams).

Up to now, the Michelson interferometer has been assembled and successfully aligned to produce good circular fringes. It was found that the instrument is extremely sensitive to vibrations transmitted through the optical table and surrounding air. We are now trying various methods to reduce these vibrations. After stable fringes are achieved a PZT will be mounted to one of the mirrors. Voltages applied to the transducer will cause displacements which will be measured by the shifts in the fringes.

This project was supported by a Symbol Technologies Fellowship and grants from ARO and ONR.

Chris Wottawa 3-August-2000