An optical instrument used for viewing very small objects such as minerals samples or animal or plant cell typically magnified several hundred times. The optical microscope, which utilises light to image the material, is the most common and the first to be created. Other major types of microscope include electron microscope including scanning and transmission electron microscope, ultra microscope and various types of scanning probe microscope.
Microscopy is the scientific discipline which involves magnification of objects which may or may not be seen with naked eyes. The aim of this branch is to render these objects visible for studies allowing the researches to learn more about them and how they work.
Often referred to as light microscope is the one which uses visible light and the system of lenses to magnify the images of small sample. The optical microscopes were one of the oldest design of microscope and possibly invented in their present compound form in the 17th century.
The rules of microscopy lie in 1600 when the scientist and engineers first started to develop lenses which were capable of significant magnification allowing people to see things which were invisible before.
• First microscope was about six feet then, 1590 Zacharias Janssen and Hans Janssen manufactured the first compound microscope.
• 1660 Marcello Malpighi one of the great Microscopist considered as the father of embryology and early histology observed capillaries.
• 1665 Robert Hooke an English physicist looked at the cork through the microscope lens and noticed some kind of pores or cells in it. Hooke was the first person to use the term cell in order to identify microscopic structure. The book named Micrographia was published by him in the 1665.
• Anton van Leeuwenhoek in 1673. He has correctly called as inventor of microscope. He created a simple microscope that could magnify 245x and published his drawings of microorganisms in the 1683.
• George Adams senior made many microscopes from about 1740-1772 but was pre-dominantly just a good manufacturer and not an inventor.
• Giovanni Battista amici in 1813 designed reflecting microscope using curved mirrors rather than lenses. He recognized the importance of the thickness of cover slip and developed the concept of water immersion.
• Ernst abbe with Carl Zeiss published a paper in the 1877 in which define the physical law that determined resolving distance of an objective known as abbe law.
• 1903 Richard Zsigmondy develop the ultra microscope that could study objects below the wavelength of light. He won the Nobel Prize in the 1925 in chemistry.
• Ernst Ruska co-invented the electron microscope in 1931, for which he was awarded the Nobel Prize in Physics in 1986.
• Gerd binning and Heinrich Rohrer 1981 invented the scanning tunneling microscope which gave three dimensional images of the objects even to the size of atomic level. The stem is one of the strongest microscope still date.
The microscope is made up of three structural components, namely:
2. Base, and,
• Head – Also known as the body, it holds the optical components in the upper portion of the microscope.
• Base – It serves as a support for microscopes. It also has microscopic illuminators on board.
• Arms – This is the part connecting the base and to the head and the eyepiece tube to the base of the microscope. It gives support to the head of the microscope and it is also used when carrying the microscope.
Optical parts of a microscope and their Role:
The optical components of a microscope are used to examine, magnify, and generate an image from a specimen put on a slide. These parts include:
• Eyepiece – also known as the ocular. This is where you view through the microscope. It found at the top of the microscope. It has a standard magnification of 10x and an alternative eyepiece with magnifications ranging from 5X to 30X.
• Eyepiece Tube – it’s the eyepiece holder. It carries the eyepiece just above the objective lens. In some microscopes such as the binoculars, the eyepiece tube is flexible and can be rotated for maximum visualization, for variance in distance.
• Objective Lenses – These are the major lenses used for specimen visualization. They have a magnification power of 40x-100X. There are about 1- 4 objective lenses placed on one microscope, in that some are rare facing and others face forward.
• Nose Piece – also known as the revolving turret. It holds the objective lenses. It is movable hence it call revolve the objective lenses depending on the magnification power of the lens.
• The Adjustment Knobs – These are knobs that are used to focus the microscope. There are two types of adjustment knobs i.e; fine adjustment knobs and coarse adjustment knobs.
• Stage – This is the section on which the specimen is placed for viewing. They have stage clips that hold the specimen slides in place. The most common stage is a mechanical stage, which allows the control of the slides by moving the slides using the mechanical knobs on the stage instead of moving it manually.
• Aperture – This is a hole on the microscope stage, through which the transmitted light from the source reaches the stage.
• Microscopic illuminator – This is the microscopes light source, located at the base. It is used instead of a mirror.
• Condenser – These are the lenses that gather and concentrate the light from the illuminator into the specimen. They are found under the stage next to the diaphragm of the microscope.
They play a major role in ensuring clear sharp images are produced with a high magnification of 400X and above. The higher the magnification of the condenser, the more the image clarity.
• Diaphragm – it’s also known as the iris. It is found under the stage of the microscope and its primary role is to control the amount of light that reaches the specimen.
It’s an adjustable apparatus, hence controlling the light intensity and the size of the beam of light that gets to the specimen. For high-quality microscopes, the diaphragm is coupled with an Abbe condenser, and combined they are able to control the light focus and light intensity that reaches the specimen.
• Condenser Focus Knob – this is a knob that moves the condenser up or down thus controlling the focus of light on the specimen.
• Abbe Condenser – this is a condenser specially designed on high-quality microscopes, which makes the condenser to be movable and allows very high magnification of above 400X. High-quality microscopes normally have a high numerical aperture than objective lenses.
• The Rack Stop – It controls how far the stages should go preventing the objective lens from getting too close to the specimen slide which may damage the specimen. It is in charge of preventing the specimen slide from rising too high and colliding with the objective lens.
• General Criminal Science
Microscope are essential for the purpose of investigations they can magnified through great details.
• Forensic Epidemiology
It is the study of how disease are spread. Presence strains of bacteria can be observed under a microscope.
• Forensic Anthropology
It is used for study tissues, bones and other remains in order to determine factors causing death.
• Pen marks on paper
When the line is drawn on paper the pointed tip of the pen alters the papers fibers leaving a mark. The shape of the indentation can differ depending upon the pen which is used, the user style of writing as well as the quality of the paper
• Analyzing the pen indentation on the paper
Analysis of pen indentation on the paper can provide a better understanding about the possible identity of the author.