Multispectral digital holographic microscopy with tunable supercontinuum lasers

Supercontinuum (SC) lasers in combination with tunable acousto-optic filters facilitate multiwavelength digital holographic microscopy (DHM) with a broad spectral range. However, to achieve optimized quantitative phase imaging (QPI) in off-axis DHM the coherence properties of the tunable light source and the holographic carrier interference fringe pattern formation have to be considered as they are wavelength dependent. We thus determined experimentally the wavelength dependency of coherence length and off-axis carrier fringe frequency in a Michelson interferometer-based multi-spectral DHM setup with a continuously tunable SC laser and moreover analyzed the impact of both parameters on hologram formation and QPI image quality. The results are found in good agreement with theoretical predictions and provide essential information for a reliable adjustment of SC laser based multispectral off-axis DHM systems. Finally, the application of multispectral-DHM for reduction of coherence induced disturbances in quantitative phase images of living pancreatic tumor cells in illustrated.