The Microscope is used for looking at objects that are too small to be seen by the naked eye.
The first compound microscope is thought to have been invented by Hans and Zacharias Janssen of Holland in around 1600. Their work became well known through Englishman Robert Hooke's publication `Micrographia' in 1665.
In 1830 the microscope saw many improvements. The simple lens was replaced by a high-quality achromatic and aplanatic system. This means that the image has no false colours round the image parts and from other defects that obscure details.
Over the next 50 years many people worked at perfecting the microscope and in 1880, Ernst Abbe had established and used a framework which meant that the microscope could give a range of magnification from approx. x30 to x2000.
The microscope has a group of lenses called the `objective', these focus rays of light from the object and produce a larger image of it about half way up the draw tube. At the top of the draw tube are a group of lenses, these are called the eyepiece and these magnify the object even more.
The object to be magnified is placed on a glass slide on a platform below the objective lens. The microscope has `coarse' and `fine' adjustment controls, these can move the draw-tube allowing more precise focusing. The image of the object is seen as a result of an artificial light source being passed through or onto it. Older microscopes utilised daylight and a mirror to achieve the same effect.
