| ABSTRACT: | MULTICHANNEL PHOTOREFRACTIVE LASER ULTRASONIC SENSOR
P. Delaye, F. Grappin, and G. Roosen
Laboratoire Charles Fabry De L'institut D'optique, Orsay, France
The development of laser ultrasound requires the use of sensors with high throughput that can collect light
from scattering surfaces, and detect ultrasound with high efficiency. One recently proposed solution, the
Photorefractive Laser Ultrasonic Sensor, is based on the registration of an hologram in a dynamic materials
that, after its reading, generates a local oscillator perfectly matched to the detected signal beam, leading to a
high field of view homodyne detection. We will present here an evolution of this system that uses at best the
imaging properties of holography, the Multichannel Photorefractive Laser Ultrasonic Sensor. The target is
illuminated by several beams (giving several measurement points), and the light collected is send on an
unique photorefractive crystals where they interfere with a single pump beam to write simultaneously
several holograms, that are used to demodulate all the ultrasonic signals at the same time.The different
possible architecture used to implement the multichannel sensor will be described as well as their properties
regarding cross-talk between the channels and detection sensitivity.
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