High speed single charge coupled device Cranz-Schardin camera.

This article describes an ultrahigh speed visualization system based on a miniaturization of the Cranz-Schardin principle. It uses a set of high power light emitting diodes (LEDs) (Golden Dragon) as the light source and a highly sensitive charge coupled device (CCD) camera for reception. Each LED is fired in sequence and images the refraction index variation between two relay lenses, on a partial region of a CCD image sensor. The originality of this system consists in achieving several images on a single CCD during a frame time. The number of images is 4. The time interval between successive firings determines the speed of the imaging system. This time lies from 100 ns to 10 micros. The light pulse duration lies from 100 ns to 10 micros. The principle and the optical and electronic parts of such a system are described. As an example, some images of acoustic waves propagating in water are presented.

Development of a new ultrasonic technique for bone and biomaterials in vitro characterization.

Classical techniques based on bone imaging allow visual examination or provide quantitative parameters like bone mineral density, which is a mass per unit of surface. Unfortunately, these techniques are generally expensive. A new method of bone characterization that uses ultrasound techniques is presented in this article. This method is able to evaluate mechanical properties like Young's modulus E and cortical bone thickness with low-frequency transducers and does not require the use of a coupling medium. Some results of Young's modulus measurements are presented and compared to the literature values and the pulse echo method.