Field-portable lensfree holographic color microscope for telemedicine applications

We report a field-portable lensfree on-chip holographic microscope that can image confluent color samples, with sub-micron resolution over a wide field-of-view (FOV) of ~ 20 mm². This color microscope is suitable for field use as it weighs less than 150 grams and its dimensions are smaller than 17×6×5 cm³. The unique design of this lensfree microscope utilizes three computational methods, namely: (i) pixel super-resolution to achieve sub-micron resolution with unit magnification over a large FOV, (ii) multi-height phase-recovery that enables imaging of confluent samples, and (iii) YUV color space averaging that mitigates `rainbow´ like color artifacts, typically observed in holographic imaging. To demonstrate the performance of our computational color microscope, we imaged a 1951 USAF test chart and Papanicolaou (Pap) smear samples. This holographic color microscope with its light-weight, cost-effective design, and wide FOV could be useful for tele-pathology applications including for example diagnosis of cervical cancer or malaria.