We present our latest advances in multi-wavelength label-free imaging using quantitative phase imaging. Basic QPI designs usually incorporate a single, coherent or partially coherent light source. The introduction of off-axis geometry allows for calculation of phase information from a single-exposure interferogram. For multi-wavelength imaging, it has been previously required to take sequential interferograms with different wavelengths, effectively reducing imaging throughput, or to use color cameras that have cross-talk between the color channels and artefacts caused by Bayer pattern. Alternatively, it was suggested to use spatial interferometric multiplexing in order to provide multi-wavelength data, where multiple interferograms of different off-axis angles are acquired in a single exposure. We introduce an external module for label-free QPI capable of multi-color imaging using spatial interferometric multiplexing of multiple color channels, with self-referencing that significantly reduces mechanical vibration noise. This technique has various applications such as interferometric spectroscopy of live cells and multiple wavelength phase unwrapping.
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