ABSTRACT
No scientific optical instrument has had greater impact across disciplines than the optical microscope. Invented in the seventeenth century, the optical microscope had reached near perfection (optically speaking) by the end of the nineteenth century. The past century has seen an explosion in the use of the microscope in various fields and the continued development of specialized techniques, the incorporation of new light sources such as the laser, the introduction of electronic image detection, and advancements in chemical markers for visualizing the structure and function in biological specimens. Even with the vigorous development during the past 100 years, the fundamental microscope architecture is remarkably similar to the models made by Ernst Abbe and Carl Zeiss at the end of the nineteenth century. This entry describes the architecture of the basic optical microscope, discusses its image-forming properties, and provides a brief overview of the types and uses of various microscope objectives. Several common mechanisms for producing or enhancing contrast in samples are introduced, including amplitude, phase, and polarization contrast as well as fluorescence imaging. Some useful extensions of the basic microscope are also introduced, including video enhancement, the confocal-scanning microscope, and the near-field microscope. Subsequent entries provide more details on fluorescence microscopy, scanning confocal microscopy, and microscopy of living systems.
