Fig. 1.

Design details of the smartphone-based SFDI device. (a) The light-emitting diode and patterned slide projected the spatial pattern onto the sample, while the phone camera collected the resulting image. Crossed polarizers were placed in front of the light source and camera in order to minimize capturing specular reflections. The measurement area was approximately 4 × 4 cm. (b) The 3D printed attachment consisted of the phone case, the projection unit, which housed the light source with spatial pattern slide, and the shroud which provided a fixed measurement distance and blocked ambient light. (c) The handheld device was approximately 9 × 15 × 7 cm and weighed 260 grams.