A microscope is an optical instrument capable of producing a magnified image of an object by using magnifying lenses. Depending on construction structures or functions, there're a wide range of microscopes developed. They include scanning electron microscope, atomic force microscope, light microscope, compound microscope, scanning tunneling microscope, x-ray microscope, and binocular microscope, etc. A scanning electron microscope (SEM) scans a specimen with electron beams, detects secondary electrons emitted from the specimen as the result of bombardment by electron beams, and displays a secondary electron image representing-the scanned objects on a display screen. A laser scan microscope has a laser scanning observation optical system which scans a laser beam over a sample (focal surface), and detects the beam transmitted through the sample by use of a detector. Scanning probe microscope (SPM) provides a microscopic analysis of the topographical features or other characteristics of a surface by causing a probe to scan the surface. It employs a technique of mapping the spatial distribution of a surface property, by localizing the influence of the property to a small probe. Scanning tunneling microscope is a scanning probe microscope in which a tunneling current flows between the probe and the sample surface. Scanning tunneling microscope produces a magnified image by moving a tiny tungsten probe across a specimen. Scanning force microscope (also known as atomic force microscope) is a scanning electron microscope which senses the topography of a surface by detecting the deflection of a cantilever as the sample is scanned. Confocal microscopes use a visible originating radiation source which is directed to a beam splitter. A confocal scanning microscope generally comprises a light source, a focusing optical system with which the light of the source is focused onto a pinhole, a beam splitter, a beam deflection device for beam control, a microscope optical system, a detection pinhole, and the detectors for detection of the reflected or fluorescent light. There are ultraviolet microscopes through which a specimen is observed by using light in the ultraviolet range or in the deep ultraviolet range (collectively referred to as ultraviolet light).
