A smartphone-based petrographic microscope.

Photomicrographs of thin sections provide a swift and efficient means of sharing information for consultation, education, documentation and publication within the Geosciences and related areas. In general terms, the main way to capture digital microscopic images involves the use of a mounted camera unit on a high-end costly benchtop microscope. However, freehand methods to capture microscope-scale images using a smartphone, as well as smartphone adapters that can be attached to a microscope have emerged during recent years. This paper presents the design features of a costless system able to obtain photomicrographs without requiring a conventional microscope. The imaging device is comprised of a mini-objective lens attached to a smartphone and a structure that allows it to focus as well as to rotate the stage and to insert/remove a polarized sheet. The quality and magnification of the images attainable from the new design is comparable to the images normally obtained by a conventional petrographic microscope using a ×4 objective and a ×10 ocular (total magnification ×40).