The-microscope.pdf

What is a Microscope? A microscope is a scientific instrument used to see things that the naked eye cannot see. Some microscopes show things at the cellular level, such as organelles, while other more advanced microscopes see things at the atomic level, such as electrons. Microscope...

What is a Microscope? A microscope is a scientific instrument used to see things that the naked eye cannot see. Some microscopes show things at the cellular level, such as organelles, while other more advanced microscopes see things at the atomic level, such as electrons. Microscopes can see these things due to their special lenses.  Parts of a Microscope 1. The lenses help to magnify the object. 2. The head of the microscope is located below the ocular lenses. It includes the revolving nosepiece and has prisms inside. 3. The microscope's base is the bottom, solid structure used for support. A strong base is necessary to ensure the microscope is steady and the items seen are not moving. 4. The arms of the microscope are the carrying handle in many microscopes. It connects the head of the microscope to the base. When carrying a microscope, one should hold the arm in one hand and the base in the other to ensure it is stable and secure. Microscope Lens There are two types of microscope lenses. One is called the objective lens, while the other is called the eyepiece or ocular lens.  The objective lenses are below the nose piece, situated above the stage, and directly above the object to be viewed. The light microscope many times has three objective lenses. Each lens has a different level of magnification. The typical magnification of each objective lens is 4x, 10x, 40x, and 100x. When combined with the objectification of the eyepiece lens (10x), each objective lens magnifies the image to 40x, 100x, 400x, and 1000x. The 4x lens is known as the scanning lens. The 10x lens is the low-power lens. The 40x lens is the high-power lens, and the 100x is typically the oil immersion lens. These lenses work by bringing in light and focusing it on the object. The oil immersion lens is unique because it requires a special immersion oil to help the lens focus and refract to a higher magnitude. Microscope Eyepiece At the top of the microscope is the eyepiece. The eyepiece contains the ocular lens. Some microscopes have two eyepieces, and some have only one. The ocular lens inside the eyepiece has a 10x magnification multiplied by the chosen power in the objective lens. Nose Piece The nose piece is what holds the objective lenses. It helps rotate to which lens the user needs at the moment. Sometimes this piece is called the revolving turret. Stage The stage, located below the nose piece, contains clips to hold a microscope slide with and has a hole in the center to allow light to come through the specimen. After clipping the slide with a specimen on it in place, the lenses utilize the light to help bring the magnification into focus. Aperture The aforementioned hole in the stage under the microscope slide is the aperture. Users can change this hole to allow more or less light through the microscope slide. Each specimen has a different level of opaqueness, which would help users determine how much light is necessary to see the specimen clearly. Adjustments A user can make two types of adjustments on a microscope. The first type is the coarse adjustment- This adjustment is a quick movement and allows the stage to move up and down. Users can only use this adjustment on the lowest power objective lens, typically the 4x lens, to alleviate the possibility of the lens moving too close and breaking the lens or the microscope slide.  The other type of adjustment is the fine adjustment- Users should do this much slower and steadily. This type of adjustment brings the specimen into focus. The diaphragm controls the amount of light that is let through the aperture. This is also known as the iris as it is similar to the iris of the eye. The microscopic illuminator is the light source of a microscope. The condenser is composed of lenses under the stage and near the diaphragm. It is used to help collect and focus the light from the illuminator. What is the use of slide in laboratory? typically 75 by 26 mm (3 by 1 inches) and about 1 mm thick used to hold objects for examination under a microscope. Typically the object is mounted (secured) on the slide, and then both are inserted together in the microscope for viewing.  Cover slips typically measures between 18 and 25 mm on a side, and 0.085 to 0.25 mm thick keeping any solid or liquid specimens placed flat and evenly so as to allow high resolutions microscopes to focus within their limited region in which they can focus. What is a prepared slide for a microscope? Prepared microscope slides refer to a set of slides that have been previously mounted by an individual who is a professional in the field.  How do you store prepared slides? Store slides in a dry place with constant room temperature to prevent condensation Preparation Techniques: Dry Mounts, Wet Mount, Squash, Staining The main methods of placing samples onto microscope slides are wet mount, dry mount, smear, squash and staining. Dry Mount: The dry mount is the most basic technique: simply position a thinly sliced section on the center of the slide and place a cover slip over the sample. A cover slip is placed over the sample.  Example specimens: hair, pollen, dust and insect parts can be viewed whole, whilst muscle/plant tissue can be sectioned and then viewed. Wet Mount: Used for aquatic samples, living organisms and natural observations, wet mounts suspend specimens in fluids such as water, brine, glycerin and immersion oil. A wet mount requires a liquid, tweezers, pipette and paper towels. 1. Place a drop of fluid in the center of the slide 2. Position sample on liquid, using tweezers 3. At an angle, place one side of the cover slip against the slide making contact with outer edge of the liquid drop 4. Lower the cover slowly, avoiding air bubbles 5. Remove excess water with the paper towel Smear Slides: The edge of a slide is used to smear the sample, creating a thin, even coating on another slide. A cover slip is then placed over the sample. Example specimen: viewing blood cells. Squash slide A wet mount is first prepared. A lens tissue is used to gently press down the cover slip. To avoid damaging the cover slip, two microscope slides can be used to 'squash' the sample. Good for soft samples. Example specimens: Root tip squashes are used to look at cell division. The following rules, cautions, and maintenance hints will help keep your microscope in good operating condition. 1. Use both hands when carrying the microscope: one firmly grasping  the arm of the microscope; the other beneath the base. Avoid jarring your microscope. To keep the microscope and lens systems clean: 2. Never touch the lenses. If the lenses become dirty, wipe them gently with lens tissue. (lens tissue or a cotton swab) 3. If blurred specks appear in the field of view this may be due to lint or smears on the eyepiece. If the specks move while rotating the eyepiece, the dust is on the eyepiece and cleaning the outer lens of the eyepiece is in order. If the quality of the image is improved by changing objective lenses, clean the objective lens with lens paper. 4. Never leave a slide on the microscope when it is not in use. 5. Always remove oil from the oil-immersion objective lens after its use. If by accident oil should get on either of the lower-power objective lenses, wipe it off immediately with lens tissue. 6. Keep the stage of the microscope clean and dry. If any liquids are spilled, dry the stage with a piece of cheesecloth. If oil should get on the stage moisten a piece of cheesecloth with xylol and clean the stage, then wipe it dry. 7. When not in use, store your microscope in its cabinet. Put the low power objective lens into position at its lowest point above the stage. Be sure that the mechanical stage does not extend beyond the edge of the microscope stage. Wrap the electrical cord around the base. 8. To avoid breaking the microscope: 9. Never force the adjustments. All adjustments should work freely and easily. If anything does not work correctly, do not attempt to fix it yourself, immediately notify your instructor. 10. Never allow an objective lens to jam into or even to touch the slide or cover-slip. 11. Never focus downward with the coarse adjustment while you are looking through the microscope. Always incline your head to the side with eyes parallel to the slide and watch the objective as you move it closer to the slide. This will prevent you from smashing the objective into the slide. 12.Never exchange the objective or eyepiece lenses of different microscopes, and never under any circumstances remove the front lenses from objective lenses. 13.Never attempt to carry two microscopes at one time