Periodic Reporting for period 3 - TIMP (Ultrahigh-speed nanometer-scale microscopy)
Reporting period: 2022-03-01 to 2023-08-31
Ultrahigh-speed microscopy at THz frame rate is essential for exploring ultrafast non-repetitive events, for which the pump-probe technique is inapplicable. The spatial resolutions of such microscopes is to date limited to the micrometer scale [1]. In this project, we develop an ultrahigh speed microscope with nanometric scale resolution, for exploring laser-induced ultrafast phase transitions (e.g. femto-magnetism).
The new microscope is based on a new approach for ultrahigh-speed imaging that we recently proposed: time-resolved imaging by multiplexed ptychography (TIMP) [2]. In TIMP, multiple frames of the object are recovered algorithmically from data measured in a single CCD exposure of a single-shot ptychographic microscope [3] (we recently demonstrated experimentally reconstruction of 36 complex-valued frames [4]). A burst of ultrashort pulses (finite pulse train) illuminates the object. For each pulse, the imaging system (single-shot ptychograpic microscope) produces a diffraction pattern on the CCD. The diffraction pattern is highly redundant: it contains more information than needed to determine uniquely the object at high resolution. This redundancy is critical because the CCD is slow, and so integrates over all the overlapping diffraction patterns and records the sum of them – the multiplexed diffraction pattern. Thanks to the redundancy, the recorded multiplexed pattern can determine all the frames, without decreasing the spatial resolution of the single-shot ptychographic system (the cost for multi-framing can be in other quantities, e.g. field of view or setup complexity). In order to arrange the frames in the correct order, each pulse in the burst should be different from all the other pulses (e.g. in their spectrum, polarization or spatial mode). The number of recovered frames corresponds to the number of pulses.
J. Liang and L. Wang, Single-shot ultrafast optical imaging, Optica, 5, 1113, 2018.
P. Sidorenko, O. Lahav and O. Cohen, Ptychographic ultrahigh-speed imaging, Optics Express, 25, 10997 (2017).
P. Sidorenko and O. Cohen, Single-shot ptychography, Optica, 3, 9 (2016).
O. Wengrowicz, O. Peleg, B. Loevsky, B.K. Chen, G.I. Haham, S. Sainadh Undurti and O. Cohen, Experimental Time-Resolved Imaging by Multiplexed Ptychography, submitted to Optics Express.
The new microscope is based on a new approach for ultrahigh-speed imaging that we recently proposed: time-resolved imaging by multiplexed ptychography (TIMP) [2]. In TIMP, multiple frames of the object are recovered algorithmically from data measured in a single CCD exposure of a single-shot ptychographic microscope [3] (we recently demonstrated experimentally reconstruction of 36 complex-valued frames [4]). A burst of ultrashort pulses (finite pulse train) illuminates the object. For each pulse, the imaging system (single-shot ptychograpic microscope) produces a diffraction pattern on the CCD. The diffraction pattern is highly redundant: it contains more information than needed to determine uniquely the object at high resolution. This redundancy is critical because the CCD is slow, and so integrates over all the overlapping diffraction patterns and records the sum of them – the multiplexed diffraction pattern. Thanks to the redundancy, the recorded multiplexed pattern can determine all the frames, without decreasing the spatial resolution of the single-shot ptychographic system (the cost for multi-framing can be in other quantities, e.g. field of view or setup complexity). In order to arrange the frames in the correct order, each pulse in the burst should be different from all the other pulses (e.g. in their spectrum, polarization or spatial mode). The number of recovered frames corresponds to the number of pulses.
J. Liang and L. Wang, Single-shot ultrafast optical imaging, Optica, 5, 1113, 2018.
P. Sidorenko, O. Lahav and O. Cohen, Ptychographic ultrahigh-speed imaging, Optics Express, 25, 10997 (2017).
P. Sidorenko and O. Cohen, Single-shot ptychography, Optica, 3, 9 (2016).
O. Wengrowicz, O. Peleg, B. Loevsky, B.K. Chen, G.I. Haham, S. Sainadh Undurti and O. Cohen, Experimental Time-Resolved Imaging by Multiplexed Ptychography, submitted to Optics Express.
• We demonstrated experimentally the concept of TIMP. Specifically, we reconstructed 36 complex-valued frames from data recorded in a single exposure of the CCD (Wengrowicz et al., Opt. Exp. 2019)
• We designed and constructed a TIMP microscope in the visible spectral range. We expect that it will allow us to generate movies of ultrafast non-repetitive processes consisting of 16 frames, THz frame rate and ~5 microns spatial resolution. We are about to start testing the microscope.
• We develop a deep learning reconstruction algorithm for single-shot ptychography (Wengrowicz et al., Opt. Exp. 2020), and currently extend it to TIMP.
• We designed and currently construct a TIMP microscope in the extreme UV spectral region.
• Collaborating with Manuel Guizar-Sicairos from Paul Scherrer Institute (PSI), we experiment to demonstrate single-shot ptychography in the x-ray spectral region. Analysis of experimental results is ongoing.
• We designed and constructed a TIMP microscope in the visible spectral range. We expect that it will allow us to generate movies of ultrafast non-repetitive processes consisting of 16 frames, THz frame rate and ~5 microns spatial resolution. We are about to start testing the microscope.
• We develop a deep learning reconstruction algorithm for single-shot ptychography (Wengrowicz et al., Opt. Exp. 2020), and currently extend it to TIMP.
• We designed and currently construct a TIMP microscope in the extreme UV spectral region.
• Collaborating with Manuel Guizar-Sicairos from Paul Scherrer Institute (PSI), we experiment to demonstrate single-shot ptychography in the x-ray spectral region. Analysis of experimental results is ongoing.
We aim to develop TIMP microscopes with visible, extreme UV and x-ray radiation and apply them to various applications.