Chapter 10 - Amplitude Modulation Contrast Microscopy

Abstract

In this chapter I discuss the amplitude modulation contrast microscope and how it converts an optical path length gradient in a transparent would-be invisible object into a difference in intensity that results in a visible pseudorelief or shadow cast image. Amplitude modulation contrast optics is commonly known as Hoffman modulation contrast (HMC) optics. The relationship between the object and the image in an amplitude modulation contrast microscope, like that in a differential interference contrast microscope, can be described mathematically since the spatial gradient in the optical path length is mathematically equivalent to the first spatial derivative of the optical path length. Since the amplitude modulation contrast microscope is not based on polarized light passing through the specimen, it can be used with birefringent specimens and specimen holders. The depth of field in an amplitude modulation contrast microscope is so small, we say that it produces optical sections.