[Phase contrast microscopy].

This special section on phase contrast microscopy was pre-ceded by an international conference on phase contrast (PhC) and differential interference contrast (DIC) held in Warsaw, Poland, October 19—21, 1992, and is coincident with the 60th anniversary of Frits Zernike's invention of the PhC method, the 40th anniversary of Zernike's Nobel Prize in physics for PhC microscopy, andthe40th anniversary ofNomarski's DIC system. To be exact, however, only the second of these anniversaries is truly coincident with this special section, while the others occur about a year before or after. The PhC/DIC conference included invited lectures and about 30 regular papers on theories, developments, and appli-cations of PhCIDIC methods and related techniques. Fifteen contributions dealt with accepted for publication in this special section. supplemented by three other archival papers prepared by the guest editor himself. Such a guest-editorial practice is rather unconventional, but I have been strongly interested in PhC microscopy for nearly 40 years, and these anniversaries offer an extraordinary opportunity to present my own contributions. In self-justification I would only note that this special section is the first (and possibly also the last) occasion to present soot phase contrast microscopy in detail (and free from mysteries or secrets) in a distinguished international journal on applied or engineering optics. The special section begins appropriately with a paper by H.