A microscope is a device which allows one to view something which is too small to be seen by the naked eye. Items which are often studied under a microscope can include a single hair, blood or skin cells. With the naked eye these are hard to see, and impossible to view in any detail. However, by using a microscope the intricacies of these and any other object are much more clearly revealed. This kind of detail is often required in science and so those who use microscopes most in their work are often scientists of some shape or form. Knowing what a microscope is used for is only half of the story though. It is also interesting to consider how the technology works. The technical alignments of the components of a microscope are very detailed and can be incredibly hard to get right. However the basic principles of the function of a microscope are actually surprisingly simple. A magnifying lens is situated in the part of the microscope which is placed near to the object being studied. This lens creates an enlarged image of the subject just inside the tube from the light which it reflects. This is quite a complex area of physics but the image of the object which is created inside the microscope is what is actually enlarged to enable a more in depth view of the subject. Most microscopes actually contain two lenses, one at each end of the eye tube. Between them is an air separated couplet. This is known as a compound lens microscope. The image of the subject is created between the two lenses. The one closest to the subject is used to bring the image into focus while the one closest to the eye is used to help the eye focus on that image. When viewing an object through a microscope correctly your eye should be focused to infinity. For those who use a microscope frequently, or for prolonged periods of time, and experience headaches or tired eyes it is usually as a result of incorrect focusing of the microscope. If it is focused correctly there should be no adverse affects to using a microscope often and for long periods at a time. The invention of the microscope is shrouded in mystery as many have claimed to have been responsible for it but there is no real evidence to confirm any one individual. Names such as Galileo Galilei and Zacharias Janssen have been suggested but nobody knows for certain who it should be attributed to.