Comparison of microscopic techniques/application

Introduction
Microscopes are instruments used for viewing objects often too small to be seen distinctly by the unaided eye. When comparing different types of microscopes one main difference between them is their application.

Optical microscopes
An optical or light microscope uses visible light and a system of lenses to magnify image samples.

The main areas for optic microscopy are biotechnology, microbiology, microelectronics, pharmaceutic research, nanophysics and medicine. Medical applications include tests on free cells or tissue fragments, termed as smear tests, such as in most fields of histology.

A reflected light-microscope is used for opaque preparations as well as in the fluorescence microscopy.

In medicine it is used in the dermatoscopy, where the doctor examines skin lesions of a patient through a dermascope. Eye specialists use this technique in the form of a binocular slit lamp to examine the anterior and the posterior segment of the human eye.

Fluorescence microscopy
Fluorescence microscopy is an optical microscope that uses fluorescence and phosphorescence to study properties of organic or inorganic substances.

This microscopic technique is widely used in biology. The most important applications are based on the specific staining of individual cell components. From the resulting image then the cell components can be visualized through specific proteins. There can also be observed interactions between proteins or the tracking of individual processes in living cells.

Confocal microscopy
Confocal microscopy is an imaging technique that allows increased optical resolution and contrast of a digital image. Today commonly used the confocal laser scanning microscope (CLMS) are point scanner (a focused laser beam scans the preparation).

In medicine it is widely used for studies in neurophysiology, neuroanatomy and for morphological studies including a broad spectrum of tissues and cells.

It is a non-invasive technique that enables studying the corneal structure of the eye, by mapping the conjunctiva and cornea.

Electron microscopy
Electron microscope use a beam of electrons to create a surface image of a given sample. There are two types, the transmission electron microscope and the scanning electron microscope.

Electron microscopes are used in a variety of industrial applications, for example for clothing and apparel, pharmacology or aeronautics. It is used for detection and characterization of particles and experiments dealing with dynamic materials. SEMs are also used in forensic science for microscopic analysis of clothing fibers or blood samples. Worldwide TEMs are used by nanotechnology centers, research laboratories or universities, affecting the normal daily life in many different areas due to the immense magnification and resolution possibilities.

In life science electron microscopes are applied for visualization of 3D architectures of cells and tissues. For the observation of individual viruses as wells as macromolecular complexes shown in their natural biological context and cancer research. Electron microscopes are used to explore the molecular mechanisms of diseases.

The application in medicine and biology include the localization of proteins, analysis of particles or the electron tomography (detailed 3D structure of macro-molecular objects belonging to a cell). It is also used in cryobiology (effects of low temperatures on living organisms) and toxicology (effects of chemicals on living organisms).

Atomic force microscopy
Atomic force microscopy (AFM) is a high resolution type of scanning which makes use of Van-der-Waals forces to produce a surface image.

In chemistry it is used to explain the interactions of chemical substances.

A major application of AFM is the force spectroscopy. By measuring the forces directly at the interactions between the tip of the cantilever and the surface of the sample, a digital image can be created. This technique enables the measurement of atomic bounding’s as well as showing the interactions during Van-der-Waals forces. In biophysics this technique is used for the measurement of mechanical properties of living material.