Extending depth of field of MOF imaging probes

2 March 2018:

A fully computational method for extending the depth of field of multicore optical fibers (MOF) imagers has been demonstrated by CNBP researchers in a new paper published in the journal ‘Optics Express’. The work shows that the depth of field can be more than doubled for certain spatial frequencies. Lead author on the publication is CNBP Research Fellow Dr Antony Orth from RMIT University.

Journal: Optics Express.

Publication title: Extended depth of field imaging through multicore optical fibers.

Authors: Antony Orth, Martin Ploschner, Ivan S. Maksymov, and Brant C. Gibson.

Abstract: Compact microendoscopes use multicore optical fibers (MOFs) to visualize hard-to-reach regions of the body. These devices typically have a large numerical aperture (NA) and are fixed-focus, leading to blurry images from a shallow depth of field with little focus control. In this work, we demonstrate a method to digitally adjust the collection aperture and therefore extend the depth of field of lensless MOF imaging probes. We show that the depth of field can be more than doubled for certain spatial frequencies, and observe a resolution enhancement of up to 78% at a distance of 50μm from the MOF facet. Our technique enables imaging of complex 3D objects at a comparable working distance to lensed MOFs, but without the requirement of lenses, scan units or transmission matrix calibration. Our approach is implemented in post processing and may be used to improve contrast in any microendoscopic probe utilizing a MOF and incoherent light.