This paper demonstrates multiphoton excited fluorescence
imaging through a polarisation maintaining multicore fiber (PM-MCF)
while the fiber is dynamically deformed using all-proximal detection.
Single-shot proximal measurement of the relative optical path lengths of all
the cores of the PM-MCF in double pass is achieved using a Mach-Zehnder
interferometer read out by a scientific CMOS camera operating at 416 Hz.
A non-linear least squares fitting procedure is then employed to determine
the deformation-induced lateral shift of the excitation spot at the distal tip of
the PM-MCF. An experimental validation of this approach is presented that
compares the proximally measured deformation-induced lateral shift in
focal spot position to an independent distally measured ground truth. The
proximal measurement of deformation-induced shift in focal spot position is
applied to correct for deformation-induced shifts in focal spot position
during raster-scanning multiphoton excited fluorescence imaging.