| Popis: |
Photo-electromotive-force effect induced by an oscillating speckle pattern of light onto photorefractive CdTe: V and Bi 12 TiO 20 is studied. The light pattern is produced by the reflected laser beam on a vibrating surface. As a result of the photo-emf effect, a photocurrent signal in the material arises that is related to the vibrating surface amplitude and frequency. This electric signal is first pre-amplified by an op-amp in transimpedance regime and then the first temporal harmonic component is measured using a phase selective frequency tuned lock-in amplifier. This harmonic shows a maximum value occurring for certain value of the normalized vibration amplitude. This technique is been developed to be used for the measurement of transverse mechanical vibrations. |
