Colin Sheppard is Honorary Professorial Fellow at the University of Wollongong, Australia. Previously, he has been Senior Scientist in the Nanophysics Department at the Italian Institute of Technology, Genoa; Professor in the Departments of Bioengineering, Biological Sciences and Diagnostic Radiology at National University of Singapore; Professor of Physics at the University of Sydney; and University Lecturer in Engineering Science at the University of Oxford. He obtained his PhD degree from University of Cambridge. He has held visiting positions at many universities, including MIT, Stanford, UC-Berkeley, EPFL, TU-Delft, University of Jena, University of Erlangen, UNSW, Melbourne, UWA, Queensland, Tsinghua, Zhejiang and Tokyo. He developed an early laser microscope (1975), patented scanning microscopy using Bessel beams (1977), gave the first demonstration of scanning two-photon microscopy (SHG) (1977), proposed two-photon fluorescence and CARS microscopy (1978), launched the first commercial confocal microscope (1982), and developed the first confocal microscope with computer control and storage (1983). In 1988, he proposed scanning microscopy using a detector array with pixel reassignment, now known as image scanning microscopy.
Fundamental resolution limits in lithography and inspection
The classical fundamental limit to resolution in optical lithography and optical mask and wafer inspection is set by diffraction. The background to this fundamental limit is reviewed. Within this framework, solid immersion lenses, the proximity effect, phase-shifting masks, superoscillations, and the exploitation of partial coherence and nonlinearity are all approaches to improve upon the simple classical limit. Nowadays, it is usually regarded that it is not resolution itself that is limited, but the information capacity of the optical system. This means that resolution can be improved by trading off some other factor. Recent approaches to superresolution in microscopy may have applications in both optical lithography and optical inspection.