Color-coded LED microscopy for quantitative phase imaging: Implementation and application to sperm motility analysis.

Color-coded light-emitting diode (LED) microscopy (cLEDscope) is a novel computational microscopy technique capable of multi-contrast and quantitative phase imaging of biological specimens using color-multiplexed illumination. Using specially designed LED patterns, it is capable of recording multiple differential phase contrast (DPC) images in a single exposure and employs a computational algorithm to retrieve the phase distribution of the specimens. Herein, we describe the detailed procedures in the cLEDscope implementation for quantitative phase imaging. Several notable features and caveats in the cLEDscope setup and image processing are also outlined. The imaging model is derived for our specific configuration, and the associated phase-retrieval algorithms are presented on the basis of a weak-object transfer function. As an illustrative application of the quantitative cLEDscope, we demonstrate its utility as a sperm-motility analyzer by exploiting its real-time quantitative imaging capability.