A microscope is an optical device used to examine tiny, hard-to-see objects. Depending on the type of microscope, this instrument can be used to inspect a variety of biological, mechanical, or geological samples. It is also used in medical and forensic applications. Whether you are looking to purchase a microscope, or want to know how one works, a general understanding of its components will help you choose the best microscope system for your needs.
The basic parts of a microscope are the body, the objective lenses, and the eyepieces. These three main components work together to create the virtual image that is visible to the user. Each part of a microscope is designed to perform a specific task. For instance, the objective lens relays the real image of an object to the eyepiece. In addition, the ocular lens magnifies the image.
The ocular lens is located in the upper portion of the microscope. This lens is made of glass, and is designed to magnify the image of an object. Most microscopes feature three or four objectives. However, there are many more types of objectives to choose from. Higher power objectives are spring-loaded to keep the slide from breaking. Other objectives are used for other purposes.
Most quality microscopes have parfocal lenses, which are achromatic. This allows the lens to magnify a specimen by changing the wavelength of the light. Some quality microscopes use colloidal crystals to increase the image quality. They are also available with tip and electron microscopy.
The objective lenses are the main optical lenses. The focal length of these lenses can vary from 4x to 100x. There are also doublet lenses that are a pair of lenses that are "welded" together. Doublet lenses are often found in widefield eyepieces for improved color performance.
An illuminator, or light source, is typically located on the base of the microscope. It is used to provide backlight illumination, which is more effective than direct light illumination. Light is then focused to the sample through the aperture, which is a hole in the stage. Many microscopes have an iris diaphragm, a disc with several holes that controls the amount of light reaching the specimen.
The illuminator is usually controlled by a switch or on/off switch. Illumination is usually 110 volts in the United States. Another option for illumination is mirrors, which can reflect light from an external source.
The Abbe condenser is typically found in high-quality microscopes. It has a rotating disc with different-sized holes, which helps to adjust the light that passes through the specimen. With higher magnification, the iris diaphragm is especially useful.
An iris diaphragm is typically found on microscopes with high power. During higher-magnification examinations, the diaphragm is particularly helpful in controlling the amount of light that is passed through the specimen. Several other features are present on higher-power microscopes.
The final image is formed by the combined magnification of the Objective and Ocular lenses. This is referred to as the field of view.
