Real-time visualization of dynamic holographic interferometric images using photorefractive crystals

摘要

Holographic interferometry of vibrating specimens using two-wave mixing in photorefractive Bi_(12)SiO_(20) (BSO) crystals is achieved in real-time. Real-time acquisition (30 frames per second) of holographic interferograms from vibrating objects is performed using repetitive sequences of separate record and read-out times synchronized with the ccd acquisition rate. In this two-wave mixing experiment, the reference beam is collinear with the optical imaging system (the object beam) and an external AC electric field is applied onto the BSO crystal. This configuration improves the diffraction efficiency and keeps the time response to a minimum, compared to configurations where the reference and object beam interfere with a large writing-beam angle, θ. The performance of the photorefractive holographic interferometer using on-axis reference beam (θ=0°) and off-axis reference beam (θ=30°) are compared. Example of real-time acquisition with good fringe contrast is demonstrated.