Broadband ptychographic imaging with an accurately sampled spectrum

Abstract

Ptychography, a lensless imaging technology with large field of view (FOV), has been extensively developed in the past decades. However, the demanding coherence of the light source restrains its application in the field of ultrafast imaging, as short light pulses have broad spectral bandwidth and thus poor temporal coherence. Here, we demonstrated the implementation of ultrafast imaging with large FOV by monochromatizing the polychromatic ptychographic diffraction patterns. This scheme relaxes the requirement of bandwidth and successfully realizes the millimeter-scale FOV imaging using ultrashort pulses, while maintaining the good spatial resolution of the order of diffraction limit. Due to the use of a precisely sampled spectrum, the illumination information can be accurately captured allowing more reliable imaging process. Experimental results show that satisfactory spatial resolution can still be achieved even for a relative bandwidth up to 20%. Our work demonstrates the potential of ultrafast diffraction imaging with a large FOV.