Chapter 1 : Light Microscopy

Abstract:

Light microscopy is made easy, interesting, and useful for bacteriological purposes if at least four different kinds of instruments are readily available, permanently set up for work, and maintained in good order. An additional instrument, a stereoscopic “dissecting” microscope, is valuable for undertaking the isolation of bacteria from nature on agar plates when colonies early in growth are small and close together. The chapter outlines the principles of basic microscope. Achieving high resolution as well as freedom from chromatic and spherical aberration requires attention to basic principles. Unfortunately, light of the most effective wavelength (namely, UV light of about 365 nm) is not perceived by the eye and does not pass through glass. The Koehler system of illumination is useful for high-resolution microscopy because it provides appropriate illumination of the field and makes good use of high-quality optics. The chapter outlines the steps allowing achievement of Koehler (nearly optimum) illumination for an oil-immersion objective. The chapter also focuses on dark-field microscopy, phase-contrast microscopy, interference microscopy, fluorescence microscopy, and photomicrography.