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A light microscope uses visible light and lenses to view small objects, magnifying them up to 1000 times. It consists of an objective, ocular lens, stage, light source, condenser, tube, and focusing system. Most microscopes today are compound microscopes with multiple lenses. The concept of lenses was discovered by the Romans, and Anton Von Leeuwenhoek is credited with perfecting lens making and introducing the microscope as a vital tool in biology.
A light microscope, also called a light microscope, is an instrument for observing small objects using visible light and lenses. It is a widely used and well recognized microscope in the scientific community. The device can be used to view live or dead samples and can maximize these samples up to a thousand times (1,000 times) their actual size. Light microscopes include almost all compound and stereo microscopes.
This type of microscope consists of an objective, an ocular lens, a stage, a light source, a condenser, a tube, an arm to hold the tube, and a focusing system. The sample is placed on the stage, a platform usually equipped with metal arms to hold the sample or slide it into place. The light bulb is located under the stage so that light shines through the sample. The tube focuses the stage so that the ocular lens, or eyepiece, is at the end of the tube and the objective lens is at the end closest to the specimen.
The objective lens is a small round piece of glass that collects light from a small area of the sample at a short focal length and directs the light into the tube. The image is then magnified by the ocular lens, which is placed up to the eye. Since the objective lens is convex, it focuses and directs light into its center. Conversely, the concave shape of the ocular lens serves to scatter light as it meets the eye, thus making the image larger. The condenser is a lens, often implanted into the stage or located just below it, that condenses light rays from the light source onto the spot being examined on the specimen above.
A simple light microscope uses only one magnifying glass, but most microscopes today use two or more lenses to magnify the image. Most microscopes today are compound microscopes that use more than one magnifying glass. The eyepiece typically magnifies to 2x, 4x, or 10x the actual size, and the eyepiece loupe can magnify 4x, 5x, 10x, 20x, 40x, 50x, and 100x. A microscope usually comes with three eyepiece lenses of different magnification levels set on a revolver. There may also be a fourth lens used for oil immersion viewing of specimens, where a drop of oil is placed on the slide to further refract the light and the oil immersion lens is lowered until it touches the oil drop .
The relationship between glass and magnification and the concept of a lens were discovered by the Romans in the 1st century AD. Lenses were finally used in the late 1200s as eyeglasses. This may have set the stage for Zaccharias and Hans Jannsen, Dutch eyeglass makers who, in the year 1590, are said to have invented the first compound microscope by experimenting with several lenses in a tube. The validity of the Jannsens’ claim to this invention, however, is highly disputed. Many historians credit Tuscan scientist Galileo Galilei with developing the compound microscope and technologically similar telescopes in the early 1600s.
Later, a Dutch apprentice named Anton Von Leeuwenhoek perfected lens making to achieve a steep curvature on a small lens, allowing him to bring much smaller specimens into focus than ever before. He is often referred to as the father of microscopy as he introduced the microscope as a vital tool in biology. Among other discoveries, Anton Von Leeuwenhoek was the first to see bacteria, yeast and organisms in a drop of water.
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