Tuesday, 3 July 2012

Parts of Light Microscope

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Microscope Parts and Functions
A microscopes function is to see things at different levels, magnifications e.g. cells that can not be seen with a naked eye.
1. Eyepiece: The eyepiece (sometimes called the 'ocular') is the lens of the microscope closest to the eye that you look through. It is half of the magnification equation (eyepiece power multiplied by objective power equals magnification), and magnifies the image made by the objective lens... sometimes called the virtual image. Eyepieces come in many different powers. One can identify which power any given eyepiece is by the inscription on the eyecup of the lens, such as "5x", "10x", or "15X". Oculars are also designed with different angles of view; the most common is the wide field (W.F.).
2. Eyepiece Holder: This simply connects the eyepiece to the microscope body, usually with a set-screw to allow the user to easily change the eyepiece to vary magnifying power.
3. Body: The main structural support of the microscope which connects the lens apparatus to the base.
4. >Nose Piece: This connects the objective lens to the microscope body. With a turret, or rotating nose piece as many as five objectives can be attached to create different powers of magnification when rotated into position and used with the existing eyepiece.
5. Objective: The lens closest to the object being viewed which creates a magnified image in an area called the "primary image plane". This is the other half of the microscope magnification equation (eyepiece power times objective power equals magnification). Objective lenses have many designs and qualities which differ with each manufacturer. Usually inscribed on the barrel of the objective lens is the magnification power and the numerical aperture (a measure of the limit of resolution of the lens).
6. Focusing Mechanism: Adjustment knobs to allow coarse or fine (hundredths of a millimeter) variations in the focusing of the stage or objective lens of the microscope.
7. Stage: The platform on which the prepared slide or object to be viewed is placed. A slide is usually held in place by spring-loaded metal stage clips. More sophisticated high-powered microscopes have mechanical stages which allow the viewer to smoothly move the stage along the X (horizontal path) and Y (vertical path) axis. A mechanical stage is a must for high-power observing.
8. Illumination Source: The means employed to light the object to be viewed. The simplest is the illuminating mirror which reflects an ambient light source to light the object. Many microscopes have an electrical light source for easier and more consistent lighting. Generally electrical light sources are either tungsten or fluorescent, the fluorescent being preferred because it operates at a cooler temperature. Most microscopes illuminate from underneath, through the object, to the objective lens. On the other hand, stereo microscopes use both top and bottom illumination.
9. Base: The bottom or stand upon which the entire microscope rests or is connected.
Compound light microscope:
Microscope Part Function
Eyepiece (ocular lens) The part you look through. It has a lens that magnifies the object, usually by ten times (10x). The magnifying power is engraved on the side of the eyepiece. Tube Holds the
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eyepiece and the objective lenses at the proper working distance from each other. Revolving nosepiece Rotating disk holds two or more objective lenses. Turn it to change lenses. Each lens clicks into place. Objective lenses Magnify the object. Each lens has a different power of magnification, such as 10x, 40x, and 100x.The magnifying power is engraved on the side of each objective lens. Be sure you can identify each lens. For example, the low-power objective lens is usually 10x. Fine-adjustment knob Use with medium- and high-power magnification to bring the object into sharper focus. Coarse-adjustment knob Moves the tube or stage up or down and brings the object into focus. Use it only with the low-power objective lens. Stage Supports the microscope slide. Clips hold the slides into position. A hole in the center of the stage allows the light from the light source to pass through the slide. Condenser lens Directs light to the object being viewed. Diaphragm Use this to control the amount of light reaching the object being viewed. Light source Shining a light through the object being viewed makes it easier to see the details. (Your microscope might have a mirror instead of a light. If it does, you will adjust it to direct light through the lens.) Overall, the function of a microscope is to view specimens too small to be viewed by the human eye. and the other four are not here

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