Microscope and its development
A microscope is an instrument used to see objects that are too small
for the naked eye. The science of investigating small objects using such an
instrument is called microscopy. Microscopic means invisible to the eye unless aided
by a microscope.
There are many types of
microscopes, the most common and first to be invented is the optical microscope which uses light to image the sample. Other major types
of microscopes are the electron microscope (both the transmission electron microscope and the scanning electron microscope) and the
various types of scanning probe
microscope.
A microscope is an instrument that produces a clear
magnified image of an object viewed through it. A microscope must be able not only to magnify objects
sufficiently but also to resolve, or separate, the fine details of the object
that are of interest to the viewer. In the optical microscope visible light
rays, reflected from or transmitted by the viewed object, pass through a series
of lenses and form an enlarged image of the object. This image is produced at
the normal distance of clearest vision, which is about 10 inches, or 25 centimetres, from the eye of the viewer.
The degree to which the
fine details of an object can be resolved is limited by the wavelength of the
light that is used. Thus, finer details can be resolved if ultraviolet light is
used instead of visible light, and even more detail can be resolved by using X
rays. The greatest magnification and resolution are provided by the electron
microscope. In this device a beam of electrons is used instead of rays of
visible light for examining the object.
The basic form of microscope is the simple optical microscope. It consists of a single convex lens, or magnifying glass, or of a combination of lenses that has the same effect. The compound microscope, which is the most common type of optical microscope, consists of two separate lens systems. Each system is a simple microscope and may be either a single lens or a group of lenses. The object being viewed is placed close to one lens system, called the objective, which forms an image, called the primary image. This image in turn is the object that is magnified by the second system of lenses, called the eyepiece. The image seen by the eye is produced by the eyepiece at the normal distance of clearest vision.
The basic form of microscope is the simple optical microscope. It consists of a single convex lens, or magnifying glass, or of a combination of lenses that has the same effect. The compound microscope, which is the most common type of optical microscope, consists of two separate lens systems. Each system is a simple microscope and may be either a single lens or a group of lenses. The object being viewed is placed close to one lens system, called the objective, which forms an image, called the primary image. This image in turn is the object that is magnified by the second system of lenses, called the eyepiece. The image seen by the eye is produced by the eyepiece at the normal distance of clearest vision.
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