Adaptive dynamic range shift (ADRIFT) quantitative phase imaging

Abstract: Quantitative phase imaging (QPI) is often used for label-free single cell analysis with its high-contrast images of optical phase delay (OPD) map. Contrary to other imaging methods, sensitivity improvement has not been intensively explored because conventional QPI is sensitive enough to see surface roughness of a substrate which anyway restricts the measurable minimum OPD. However, emerging QPI techniques which utilize, for example, differential image analysis of consecutive temporal frames, such as mid-infrared photothermal QPI, mitigate the minimum OPD limit by decoupling the static OPD contribution and allow to measure much smaller OPD. Here, we propose and demonstrate super-sensitive QPI with expanded dynamic range. It is enabled by adaptive dynamic range shift with combination of wavefront shaping and dark-field QPI techniques. As a proof-of-concept demonstration, we show dynamic range expansion (sensitivity improvement) of QPI by a factor of 6.6 and its utility for improving sensitivity of mid-infrared photothermal QPI. This technique can also be applied for wide-field scattering imaging of dynamically changing nanoscale objects inside and outside a biological cell without losing global cellular morphological image information.