Transcript Microscopes
Microscopes A Historical Perspective The Microscope Through the Years Zacharias Janssen (15801638), a Dutch eyeglass maker, is generally credited with developing the first compound microscope in the 1590’s with his father, Hans. Because the lenses were not ground perfectly, they only saw fuzzy blurs. Anton van Leeuwenhoek (1632-1723) Dutch fabric merchant. His unusual hobby was to make tiny lenses out of glass. He perfectly ground lenses that could magnify objects about 270X in 1676. Leeuwenhoek: Early Pioneer of the Microscope observed “animacules” in a drop of water. found that his own blood cells were round, and the blood cells of fish and birds were oval. described the appearance of bacteria from scraping his teeth. Robert Hooke (1635-1703) English scientist who refined the compound microscope with two lenses. His most famous discovery showed that cork is made of cells in 1665. Hooke used the name cell because what he saw reminded him of little rooms in a monastery. Schleiden-German botanist who studied plant tissue under the microscope Schwann-German zoologist who examined animal tissue under the microscope. Virchow-hypothesized that cells divide to form new cells. These ideas became the cell theory: All living things are made of cells. Cells are the basic unit of life. Cells come only from other cells. Schleiden and Schwann (1830’s) Louis Pasteur (1822-1895) He used the microscope to discover that microorganisms were the cause of disease. This became the GERM THEORY. Discovered vaccines for anthrax and rabies. Most well-known for a process used to kill bacteria in milk with high heat, protecting us against diseases like tuberculosis and typhoid fever. Microscopes are instruments that produce larger-than-life (magnified) images, pictures, or even videotapes. Most microscopes use light rays to produce a magnified image of an object. These microscopes are called optical microscopes. (optical refers to light) Different Kinds of Microscopes Compound microscopes only magnify up to about 1000 times. not powerful enough to show viruses. Problem solved in 1930s with electron microscope. Can magnify objects nearly one million times. Using electron microscope, individual atoms and molecules can be observed. Advantages of New Technology The Microscope Today Research is done using electron microscopes. Uses a beam of tiny particles called electrons instead of light rays. Beam of electrons is not focused through a lens, but through magnets. Common Types of Electron Microscopes TEM (Transmission Electron Microscope)useful for observing the inside of an object, such as the structures found in a cell. SEM (Scanning Electron Microscope)useful for observing the outer structure of an object, such as the arrangement of atoms in a solid. Incredible Views SEM view of a moth’s head region. Incredible Views SEM pictures of tiny globules used on scratch and sniff stickers. More Incredible Views What is this? The hook that makes up velcro. Still More Notice the unmagnified pollen grains visible on the flower. (top) Then look at pollen grains that have been magnified 60 times. (center) The 3-D image of pollen grains (bottom) has been magnified 378 times. Scanning Tunneling Microscope A new type of electron microscope took this photograph of individual silicon atoms. What is this? Needle and thread In Conclusion Over 400 years ago, the microscope was invented. This instrument changed our entire view of the world. Although the discoveries of the first uses of the microscope seem simple compared with the discoveries made today, your knowledge of this tool will illustrate why these were so earthshaking.