Abstract by John Nigliazzo
Physics and Astronomy
Application and Design of a Single-shot Ptychographic System for Ultrafast Lensless Diffractive Imaging
Ptychography is a lensless imaging technique used in coherent diffractive imaging. In ptychography, a coherent laser beam is scanned over a sample. The diffraction patterns that result from the scans are collected on a CCD screen and recorded. An image is then reconstructed using a Fast Fourier transform based algorithm which yields the internal structure of the object. Because of the time required to take each scan, traditional ptychography is not suitable for imaging samples in extreme environments, such as under dynamic compression. In such cases it is impossible to get an accurate reading. For this reason, we propose an experimental single-shot ptychographic system. Rather than a single coherent beam, this system utilizes a pinhole array to diffract the beam into hundreds of partially overlapping beams that then illuminate the object. The diffraction patterns from each of these beams is then collected on the CCD screen and an image is generated using a slight variant of the FFT. With this method, images have been taken with as little as 180 ms exposure time. We propose to speed up this exposure time by more than trillion times by applying it to ultrafast lasers sources.