Comparison of mobile phone microscopes.

<p>A) <i>Left panel:</i> Cartoon schematic of a ball lens mobile phone microscope. Red brackets indicate microscope attachment optics outside of the phone (a ball lens), and blue brackets indicate mobile phone camera optics inside the phone (a lens group and CMOS sensor). <i>Middle panel:</i> Image of stained cheek epithelial cells taken with a 6 mm ball lens. <i>Right panel:</i> Enlargement of the area indicated within the dashed line in the middle panel. B) <i>Left panel</i>: Cartoon schematic of a standard finite objective microscope attachment to a mobile phone, consisting of an objective and an eyepiece. <i>Middle panel:</i> Image of stained cheek epithelial cells taken with a 4X/0.10 NA objective and a 20X eyepiece. <i>Right panel:</i> Enlargement of the area indicated within the dashed line in the middle panel. Note that despite the image being in-focus at the center of the field of view, some image degradation due to field curvature is detectable at the edge of the field. C) <i>Left panel:</i> Cartoon schematic of the reversed lens microscope presented in this paper, with opposing identical lens groups outside the phone (red brackets) and inside the phone (blue brackets). <i>Middle panel:</i> Image of stained cheek epithelial cells taken with the opposed lens group setup. <i>Right panel:</i> Enlarged area of the area indicated within the dashed line in the middle panel. Note that despite the image being focused at the center of the field, no field curvature is detectable in the reversed lens microscope image, in contrast to the ball lens A) and standard finite objective B) microscope images.