Just as the telescope opened mankind the door of the infinitely large, the microscope made. It is possible to know the worlds of tiny dimensions, including the cell, base of life. They had the foundations of modern science biological well into the modern age had been based on direct observations.
Microscopes are laboratory apparatus or instruments or devices that, under the laws of formation of images through increased optical converging lens, allow observation of small details of a sample given to the naked eye does not perceive.
The compound microscope is an optical instrument that is used to increase or magnify images of objects and organisms not visible to the naked eye. Common optical microscope consists of three systems:
The system consists of a mechanical parts sene in which they are installed lenses that allow the movement for focusing.
The optical system comprises a set of lenses arranged in such a way that produces the increase of the images seen through them
The system of illumination microscope comprising the parts that reflect, transmit and regulate the amount of light needed to make the observation through the microscope.
The following sections describe each of the systems named in order to have a knowledge of the entire microscope.
3. Part mechanical Microscope
Part mechanics of the microscope includes: foot, pipe, revolver, the handle, deck, truck, coarse adjustment knob and fine adjustment. These elements hold the optics and lighting also allows the displacement necessary to approach the object.
Foot: It is the basis on which rests the microscope usually has a Y-shape or a rectangular.
The tube: It is cylindrical and is internally blackened to avoid the discomfort glare of light. At its upper end are placed eye.
The revolver: It is a rotating part provided with holes which are threaded on the objectives . Turning the gun, the targets passing through the axis of the tube and placed in a position to work , which is noted by the noise of a pinion is fixed.
The column: It is also called a handle or arm is a piece placed on the back of the device. Holding the tube in its upper and lower end conforms to the foot.
The platen: It is a flat metal piece that fits in the preparation or object being observed. Has a hole in the optical axis of the tube that allows passage of light rays to the preparation. The plate can be fixed, in which case it remains stationary, in other cases it may be spinning, ie by side screws can focus or produce circular motion.
Carro: A device placed on the slide deck that allows the preparation orthogonal movement front to back and from right to left.
The coarse adjustment knob: By turning this screw, climb or descend the tube of the microscope slide vertically through a zipper. These large movements allow rapid development approach.
The micrometer screw: By almost imperceptible movement produced by sliding the tube or plate, accurate focus is achieved and clear preparation. Coupled to a drum graduated in divisions of 0.001 mm which is used to refine their movements and can measure the thickness of objects.
The optical system is responsible for reproducing and enlarging the images by the set of lenses which compose it. It consists of eyepieces and objectives.
The eyepieces: The eyepieces are generally made two lenses arranged on a short tube. The eye generally used is the following: 8X, 1OX, 12.5X, 15X. The X is used to express in shorthand increases.
Objectives: The objectives leading to increased images of objects and bodies and, therefore, are close to the preparation being examined. The commonly used targets are of two types: dry objectives and goals of immersion.
The objectives are used dry without placing any substance between them and the preparation. On the outside are a series of indices that indicate the increase occur, the numerical aperture and other data . For example, if a goal has these data: Plan 40 / 0.65 160 / 0.17, meaning that the goal is planachromatic, its increase 40 and its numerical aperture 0.65, calculated for a tube length of 160 mm. The number of targets varies with the type of microscope and its intended use. Increases in dry objectives most frequently used are: 6X, 1OX, 20X, 45X and 60X.
The immersion objective is composed of a complicated system of lenses. To look through this lens is necessary to place a drop of oil of cedar between the target and the preparation, so that the front lens in contact with the oil of cedar. Generally, these objectives are 1 OOX and are distinguished by one or two circles or rings of colored black around its lower end.
The objectives are arranged in a so-called swivel gun.
This system is intended to direct sunlight or artificial lights so that the preparation or object to be observed under the microscope. It includes the following elements:
The mirror: It has two faces: one concave and one flat. Has movement in all directions. The concave surface is preferably used with artificial lighting, and flat, natural lighting (sunlight). In modern times it dispenses with the mirror in the manufacture of microscopes, and they bring a lamp built into the axis of the microscope.
Capacitor: The capacitor is formed by a lens system, whose purpose is to focus light rays on the level of preparation. The condenser is located beneath the deck. The capacitor can slide on a rack with a screw that determines its movement up or down.
Diaphragm: Generally, the condenser is provided with an iris diaphragm, which regulates the opening and controls the quality of light that must pass through the condenser.
Light ray path through the microscope
Light beam from the lamp passes through the diaphragm directly to the condenser. Through the lens system that has the condenser, the light is concentrated on the preparation to observe. The beam penetrates the target and continues through the tube into the eyepiece, which is captured by the eye of the beholder.