title: All-passive pixel super-resolution of time-stretch imaging.
abstract: Based on image encoding in a serial-temporal format, optical time-stretch imaging entails a stringent requirement of state-of-the-art fast data acquisition unit in order to preserve high image resolution at an ultrahigh frame rate - hampering the widespread utilities of such technology. Here, we propose a pixel super-resolution (pixel-SR) technique tailored for time-stretch imaging that preserves pixel resolution at a relaxed sampling rate. It harnesses the subpixel shifts between image frames inherently introduced by asynchronous digital sampling of the continuous time-stretch imaging process. Precise pixel registration is thus accomplished without any active opto-mechanical subpixel-shift control or other additional hardware. Here, we present the experimental pixel-SR image reconstruction pipeline that restores high-resolution time-stretch images of microparticles and biological cells (phytoplankton) at a relaxed sampling rate (≈2-5 GSa/s)-more than four times lower than the originally required readout rate (20 GSa/s) - is thus effective for high-throughput label-free, morphology-based cellular classification down to single-cell precision. Upon integration with the high-throughput image processing technology, this pixel-SR time-stretch imaging technique represents a cost-effective and practical solution for large scale cell-based phenotypic screening in biomedical diagnosis and machine vision for quality control in manufacturing.
authors.affiliation: Department of Electrical and Electronic Engineering, the University of Hong Kong, Pokfulam, Hong Kong.
authors.forename: Antony C S
authors.initials: AC
authors.lastname: Chan
authors.affiliation: Department of Electrical and Electronic Engineering, the University of Hong Kong, Pokfulam, Hong Kong.
authors.forename: Ho-Cheung
authors.initials: HC
authors.lastname: Ng
authors.affiliation: Department of Electrical and Electronic Engineering, the University of Hong Kong, Pokfulam, Hong Kong.
authors.forename: Sharat C V
authors.initials: SC
authors.lastname: Bogaraju
authors.affiliation: Department of Electrical and Electronic Engineering, the University of Hong Kong, Pokfulam, Hong Kong.
authors.forename: Hayden K H
authors.initials: HK
authors.lastname: So
authors.affiliation: Department of Electrical and Electronic Engineering, the University of Hong Kong, Pokfulam, Hong Kong.
authors.forename: Edmund Y
authors.initials: EY
authors.lastname: Lam
authors.affiliation: Department of Electrical and Electronic Engineering, the University of Hong Kong, Pokfulam, Hong Kong.
authors.forename: Kevin K
authors.initials: KK
authors.lastname: Tsia
mesh_terms: D000465:Algorithms; D005434:Flow Cytometry; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D053758:Nanoparticles / Q000648:ultrastructure*; D019047:Phantoms, Imaging; D010839:Phytoplankton / Q000648:ultrastructure*; D014867:Water / Q000737:chemistry
chemical_list: D014867:Water