Since its invention, compound microscopes made a remarkable contribution to the advancement of science. Compound means that microscope uses more than one lenses. Microscope is a combination of two Greek words, micron which means small and skopein meaning to look at. The modern compound light microscope was widely known for its importance in the field of biology. The discovery of bacteria and microorganism paid the way to one the greatest inventions of all time. Another equally important discovery was by Robert Hooke who was credited by his discovery of cell. In the world of medicine, Louis Pasteur of France discovered a yeast fungus and in the middle of the 19th century a German Bacteriologist, Karl J. Ebert made his discovery of Eberthella Thyphosa. Similar instrument was used by Robert Koch when he discovered tubercle and cholera bacilli. Composed of two optical elements this extraordinary instrument has a primary magnifying lens and a secondary lens system which is similar to a telescope which commonly referred as the ocular.

The primary or the objective lens is located close to the object which forms a magnified picture of the specimen and then the secondary lens will serve as the eye piece will act as a magnifier and produces an enlarged image of the image produced by the objective lens. Images produced by a compound microscope are two-dimensional and most images are upside down and backward compared to the actual reflection of the object. The same basic construction is being used in today’s microscope except that the primary and the secondary lenses are not single simple lenses but more are made of two or more optical elements. It maybe inverted or upright, compound microscopes can magnify through several of its objectives from about 4x to 100x, and its eyepieces can result to 10x to its total magnifications of 40x to 1000x (Objective x Eyepiece). A compound light microscope with a 2000x magnification can view bacteria, algae, protozoa and a range human/animal cells.

There are special types of compound microscopes; the first one is stereoscopic microscope which gives three-dimensional erectal image of the object. It’s like giving the viewer a different perspective of the specimen. These types of compound microscope are widely used in biological laboratories in experimenting tiny biological specimens. Another type is metallurgical microscope; this instrument illuminates normal specimen thicknesses of metals, minerals and ores. Since they are all opaque to brightness and cannot transmit light, all of them can reflect to a greater or lesser extent of light. To illuminate such specimens, there’s a light source attached to the body and to the other parts of the microscope. Next is polarizing microscope; this type has two additional elements – a polarizer and an analyzer. The polarizer send out light whose waves vibrate in one direction and the analyzer which is located between the specimen and the eye piece, is a second polarizing element.

This two elements block out the light coming from the specimen that does not affect the state of polarization. Fluorescence microscope made it possible to see biological specimens through mercury-vapor lamps. These lamps are loaded with light in the blue region of the spectrum and equipped with special light filters. The last type is the phase contrast and differential interference contrast (DIC) microscope, this type made it possible to see practically invisible structures without any deceptive chemical treatment and often times reveal better results than any conventional techniques.

Historically speaking, it all started during the 1st century AD when glass was invented. It was the Romans who discovered that if you put an object in front of the glass it would look bigger than its original size. This crystal has thin edges and was thick in the middle; the same crystal was used by Phoenicians when they tried to set a fire by focusing the rays of the sun in a piece of parchment. These burning glasses or magnifiers are the early “lenses”; derived from the Latin word lentil because they are shaped like the seeds of a lentil. The invention of spectacles during the end of the 13th century gave way to the birth of microscopes. It was uncomplicated then, so simple like a cylinder with a cover for the object and a lens on the other side that focuses six to ten times bigger than the actual size. It was used to examine tiny insects and fleas that’s why it was dubbed as “flea glasses”. It’s been like around 500 years since the invention of the first real and authentic microscope. It all started in Netherlands in the year 1590 when a Dutch spectacle maker Zaccharias Janssen and his father Hans had an accidental discovery while experimenting a tube with several lenses in it.

But the first person behind the invention of microscope as a device whose key function was to present a magnified image of an object probably occurred in the year 1600 was Galileo. He designed the compound microscope that has two separate lenses that served as an objective and the eyepiece although studies of great significance were carried out later who evolved into a simple microscope equipped with only one lens. The two giant names behind the 17th century microscopy were Anton van Leeuwenhoek, the father of microbiology from Holland and Robert Hooke of England. Leeuwenhoek was a craftsman from Amsterdam who invented the earliest simple microscope, a powerful one-lens microscope. He was inspired by the glasses used by the drapers to examine the quality cloth because of this, he developed a new method for grinding and polishing tiny lenses and out of this he made his first invention. His microscopes are made of silver or copper metal frames holding hand-ground lenses, and those who survived through the years can magnify up to 275 times.

His interest in microscope and expertise with glass processing led to one of the most significant discoveries in the history of science. Today, only nine out 500 to 600 microscopes are being used. Hooke, is one of the outstanding English scientist who played an important role in the discovery of microscope. In 1665 he published the book Micrographia which contains all his microscopic and telescopic observations. During this time he contributed three significant features of today’s microscope: coarse and fine adjustments, illumination systems, and a stage to hold the specimen. The gradual development of microscopes led to the breakthrough of other discoveries using the “achromatic” microscope towards the end of 19th century. Achromatic microscope allowed the observation of bacteria, microbes and other microorganisms which scientist came to understand the causes and treatments of many illnesses around the world.