IMAGING IN FLUORESCENCE DIRECT-VIEW MICROSCOPY

We derive a general theory of imaging for the fluorescence direct-view microscope (DVM) in terms of the system's incoherent optical transfer function. Particular attention is given to both the form of the in-fo cus transfer function and the optical sectioning capability of the ins trument in the presence of (i) a spatially incoherent source and (ii) a spatially coherent (laser) source. Unlike its brightfield counterpar t, the imaging properties of the fluorescence DVM are shown to be rela tively insensitive to the source coherence, provided the pinhole spaci ng-to-radius ratio is kept sufficiently large. This suggests that the use of a laser source in fluorescence direct-view microscopy could pro ve to be extremely beneficial as regards increased light throughput an d cost-effectiveness. (C) 1998 Elsevier Science B.V. All rights reserv ed.