  We report on a method to obtain confocal imaging through multimode fibers
using optical correlation. First, we measure the fiber's transmission matrix in
a calibration step. This allows us to create focused spots at one end of the
fiber by shaping the wavefront sent into it from the opposite end. These spots
are scanned over a sample, and the light coming back from the sample via the
fiber is optically correlated with the input pattern. We show that this
achieves spatial selectivity in the detection. The technique is demonstrated on
microbeads, a dried epithelial cell, and a cover glass.
