Temporally structured illumination for ultrafast time-stretch microscopy

Abstract

This work developed a temporally structured illumination scheme to conquer the detector bandwidth limitation that is increasingly becoming a stumbling block of ultrafast single-pixel measurement. Inspired by structured illumination microscopy and space-time duality, an electro-optic modulator resembling the temporal counterpart of a spatial grating is used to impart a sinusoidal pattern onto the time-stretch signal before detection. Consequently, the detector bandwidth is equivalently doubled based on three measurements and a subsequent reconstruction, thereby capturing the high-frequency components originally beyond the detector bandwidth. As a proof of concept, this method is applied to an ultrafast single-pixel imaging modality, the time-stretch microscopy, to verify its capability to surpass the resolution limit imposed by the detector bandwidth. High-quality images with ∼4.0 μm spatial resolution are acquired at ∼30 MHz frame rates by merely half of the detector bandwidth, compared to the traditional system. This Letter provides a simple and economical solution for high-speed signal acquisition, which is demanded in a variety of applications, ranging from ultrafast imaging to single-shot spectroscopy.