Toward video-rate compressive spontaneous Raman imaging via single-photon avalanche diode arrays.

Spontaneous Raman microscopy is well-known for its remarkable chemical contrast yet suffers from slow acquisition speeds. Recently, the compressive Raman microspectroscopy framework has shown that a significant speed advantage is brought by leveraging shot-noise-limited detection using a single-photon avalanche diode (SPAD). However, current imaging speeds of compressive Raman architectures are fundamentally limited by SPAD sensitivity and dead time. Here, we demonstrate an efficient and scalable compressive Raman parallelization scheme based on SPAD arrays. We show that parallelization using line excitation, instead of spatial multiplexing, allows to reach effective pixel dwell times (τ _pdt ) of 0.8 µs. Such fast speed represents over one order-of-magnitude speed-up over previous demonstrations. This effective parallelization not only allows for demonstrating unprecedented chemical imaging speeds using the otherwise weak spontaneous Raman effect but also paves the way for true video-rate inexpensive molecular microspectroscopy.