Fast and artifact-free excitation multiplexing using synchronized image scanning

We present the Resonator, a simple optical device that provides quasi-simultaneous fluorescence imaging with multiple excitation wavelengths. The device uses a resonant scanning mirror to periodically displace the sample image on a camera sensor at a rate that is much faster than the image acquisition rate. The excitation light is synchronized with the scanner motion to create two laterally shifted copies of the image, each containing the fluorescence excited by a single wavelength. The additional information is then encoded either into the point-spread function of the imaging or as multiple distinct images. Since this multiplexing is performed at very high rates, our design can eliminate or mitigate artifacts caused by temporal aliasing in conventional sequential imaging. We demonstrate the use of our system for the monitoring of fast light-induced dynamics in single quantum dots and for the imaging of Ca 2+ signalling in hippocampal neurons.