Fundamentals of microscopy

Microscopy is the study of the fine structure and morphology of objects with the use of a microscope. Microscopes range from optical microscopes, which resolve details on the micrometer level, to transmission electron microscopes that can resolve details less than one nanometer across. The size and visibility of the polymer structure to be characterized generally determines which instrument is to be used. For example, the size and distribution of spherulites can be observed by optical techniques, but a study of their internal structure requires electron microscopy. Combinations of the various microscopy techniques generally provide the best insight into the morphology of polymer materials [1]. Table 2.1 shows the basic properties of the different microscopes, for the purpose of comparison. 

It is already apparent from this general description of microscopy that resolution and contrast are key parameters. Resolution is the minimum distance between two object features at which they can still be seen as two features. The contrast of a feature is the fractional change in image brightness that it causes. If two features have high contrast but are separated by less than the resolution, they will appear as one object, visible but not resolved. If their contrast is very low. 

Can observe surface, or bulk if transparent surfaces only bulk , but very thin films, less than 0.2 pim 

Specimen environment ambient high vacuum high vacuum 

Specimen preparation easy easy very difficult 

1 Lens-Imaging Microscopes. ... . 29 233 Atomic Force Microscopy 47 

It is beyond the scope of this text to describe the design features and operation of specific microscopes and their attachments. Any attempt to discuss microscope operation or construction in detail would rapidly become outdated. Manufacturers representatives or Web sites are the best source for information on their instruments. Lists of manufacturers are given in Appendices VI and VII. 

Key parameters of microscope images are resolution and contrast. Two object features closer together than the resolution will appear as one feature, not two, in the image. The contrast is the fractional change in image intensity that a feature causes. Small features in the specimen that have low contrast, below about 0.05, 

Can observe Surface, or bulk if transparent Bulk. but thin films, 0.2 tm Surfaces Surfaces 

Specimen environment Ambient, or transparent fluid High vacuum High vacuum (4kPa in HPSEM) Ambient, high vacuum or fluid 

Microscopes are commonly identified by the radiation used, as optical or electron microscopes. A more fundamental distinction is whether the image is formed all at once, by lenses, or sequentially, point by point, by scanning. In computer terms, these would be described as parallel and serial transmission of information respectively. A TV image is an example of an image formed by scanning. The conventional optical microscope and the trans- 

Instrument Optical microscope OM lens-imaging Transmission electron microscope TEM Scanning electron microscope SEM scanning-imaging Atomic force microscope AFM 

Specimen environment ambient, or transparent fluid high vacuum high vacuum (30 torr in HPSEM) ambient, high vacuum or fluid 

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Table 2.1 Properties of various types of microscope Fundamentals of microscopy ... 

Chapter 1 provides a brief introduction to polymer materials, processes, morphology and characterization. Chapter 2 is a concise review of the fundamentals of microscopy, where many important terms are defined. Chapter 3 reviews imaging theory for the reader who wants to understand the nature of image formation in the various types of microscopes, with particular reference to imaging polymers. All of these chapters are mere summaries of large fields of science, to make this text complete. They contain many references to more specialized texts and reviews. Chapters 4 and 5 contain the major thrust of the book. Chapter 4 covers specimen preparation, organized by method. 

Chapter 1 provides a brief introduction to polymer materials, processes, morphology and characterization. Chapter 2 is a concise review of the fundamentals of microscopy, where many important terms are defined. Chapter 3 reviews imaging theory for the reader who has not had fundamental training in physics and... 

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