rescale/resample of optics 

The premise is that the wavefront size needs to stay the same and the optic should be scaled up or down to match it.  Thus, an oversize optic will be cropped and only the central portion which overlaps the incident wavefront will be used, similarly, a too small optic will be zero padded and light will not be transmitted beyond the boundary of the optic.
So far in testing this has been robust, however, a variable other users may need to adjust is the order of the spline interpolation used by scipy.ndimage.interpolation.zoom, here it is set to zero rather than the default (three).