Microscopy is an important tool in biology and medicine, but it is often limited to optical
imaging structures with high numerical aperture(NA) with a short working distance(wd), for
example NA = 0.6 and wd <1 mm are usual. The common microscope objective is inadequate for
imaging of living cells in culture as an optical imaging structure with both high numerical aperture
and long working distance is required. In this study, a novel optical design has been developed to
meet the long working distance and high resolution power imaging of living cells in a vessel with a
high culture solution thickness, where cells need to be developed in about 48 hours or a week. The
developed optical design was characterized by an ultra-long working distance (wd >13.5 mm) and
high numerical aperture (NA = 0.7). This optical imaging system is not only good for the
subcellular imaging of free-floating cells in culture, but also for the imaging of cells attached at a
surface of vessel.
Calculation of the vectorial field distribution in a stratified focal region of a high numerical aperture imaging system