Field-portable wide-field microscopy of dense samples using multi-height pixel super-resolution based lensfree imaging

We report a field-portable lensfree microscope that can image dense and connected specimens with sub-micron resolution over a large field-of-view of similar to 30 mm(2) (i.e., similar to 6.4 mm x similar to 4.6 mm) using pixel super-resolution and iterative phase recovery techniques. Weighing similar to 122 grams with dimensions of 4 cm x 4 cm x 15 cm, this microscope records lensfree in-line holograms of specimens onto an opto-electronic sensor-array using partially coherent illumination. To reconstruct the phase and amplitude images of dense samples (with >0.3 billion pixels in each image, i.e., >0.6 billion pixels total), we employ a multi-height imaging approach, where by using a mechanical interface the sensor-to-sample distance is dynamically changed by random discrete steps of e. g., similar to 10 to 80 mm. By digitally propagating back and forth between these multi-height super-resolved holograms (corresponding to typically 2-5 planes), phase and amplitude images of dense samples can be recovered without the need for any spatial masks or filtering. We demonstrate the performance of this field-portable multi-height lensfree microscope by imaging Papanicolaou smears (also known as Pap tests). Our results reveal the promising potential of this multi-height lensfree computational microscopy platform for e. g., pathology needs in resource limited settings.