This study presents a time-resolved imaging technique for detecting ultrafast events in the sample with tunable tick-tock pulses in common-path digital holographic microscopy. The tick-tock pulses are generated from the same single femtosecond pulse source and manipulated through a spatial-multiplexing encoding/decoding scheme with two complementary binary codes for digital hologram recording and reconstruction. The spatial-multiplexing encoding/decoding scheme with compressive sensing on the Fresnel digital hologram is used to recover missing data and achieve high-fidelity wavefront reconstruction. The elapsed time of tick-tock pulses can be adjusted by changing the optical path difference between the pulse pair arms for dynamic observation at various timescales. The proposed method is applied to explore the ultrafast physical phenomenon by quantitative phase imaging with a stopwatch-like tunable timescale ranging from nanoseconds to femtoseconds.
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