Parts of A Microscope [PDF]

Citation preview

PARTS OF A MICROSCOPE



PARTS OF A MICROSCOPE PARTS OF A MICROSCOPE AND THEIR FUNCTIONS Eyepieces: The eyepieces are the lenses at the top that the viewer looks through; they are usually 10X or 15X. To get the total magnification level, multiply the magnification of the objective used (ex: 10X eyepiece * 40X objective = 400X total magnification). Tube: Where the eyepieces are dropped in. Also, they connect the eyepieces to the objective lenses. Coarse Adjustment Knob: The coarse adjustment knob located on the arm of the microscope moves the stage up and down to bring the specimen into focus. The gearing mechanism of the adjustment produces a large vertical movement of the stage with only a partial revolution of the knob. Because of this, the coarse adjustment should only be used with low power (4X and 10X objectives) and never with the high power lenses (40X and 100X) Body Tube: The body tube is a hollow tube through which light travels from the objective to the ocular. It contains a prism at the base of the tube that bends the light rays so they can enter the inclined tube Arm: Structural element that connects the head of the microscope to the base. Fine Adjustment Knob: This knob is inside the coarse adjustment knob and is used to bring the specimen into sharp focus under low power and is used for all focusing when using high power lenses. Nosepiece: This circular structure is where the different objective lenses are screwed in. To change the magnification power, simply rotate the turret. Low Power Objectives: Cover a wide field of view and they are useful for examining large specimens or surveying many smaller specimens. This objective is useful for aligning the microscope. The power for the low objective is 10X. High-Power Objective: Lens that magnifies 40x, with total magnification 400x if the eyepiece lens is 10x power, and it is ideal for observing very fine detail, such as nerve cells in the retina or the striations in skeletal muscle.  Stage clips: Hold the slides in place. Stage: The horizontal surface upon which the slide is placed is called the stage. The slide is held in place by spring loaded clips and moved around the stage by turning the geared knobs on the stage. The stage has two perpendicular scales that can be used to record the position of an object on a slide. This is useful if you want to quickly relocate an object. Condenser Diaphragm- This diaphragm controls the amount of light entering the lens system. This feature is useful for viewing unstained biological specimens that are translucent. Reducing the amount of light improves contrast, making the specimen "stand out" against the background. Some microscopes have an annular condenser, which is a plate under the stage that can be rotated. The plate consists of holes of different diameter. As the plate is rotated, the different holes click into place, blocking out different amounts of light. Other microscopes have an iris diaphragm with a lever that opens and closes the diaphragm to let in varying amounts of light. Use the condenser diaphragm to reduce the amount of light and increase the contrast of the image. Condenser Focusing Knob: This control is used to precisely adjust the vertical height of the condenser. Condenser Lens: This lens system is located immediately under the stage and focuses the light on the specimen. Control knobs located just behind and underneath the condenser control the up and down movement of the condenser. Inclination Joint: A joint at which the arm is attached to the pillar of the microscope. It is used for tilting the microscope. Mirror: It is either attached to the lower end of the arm or to the pillar. It contains a plane mirror on one side and a concave mirror on the other side. Mirror is used to reflect light rays into the microscope. Pillar: A small, strong vertical projection developing from the foot or base. Foot or Base: It is the basal, horse shoe-shaped structure. It provides support to all the remaining parts of the microscope.



SPECIAL PRECAUTION IN HANDLING A MICROSCOPE 1. Handle with care Improper handling is a common cause of many problems that occur with microscopes. When carrying a microscope, hold it by the base and the metal support arm. The stage on a microscope is the flat plate where the slides are placed for observation. Avoid picking your microscope up by the stage or the eyepiece holder, as this can cause misalignment. 2. Look after lenses When using your microscope, the objective lens is lowered to adjust the focus. However, be careful not to let the lens touch the slide you’re looking at, as this can damage the lens. Furthermore, dirty lenses are notoriously difficult to clean. 3. Keep covered Microscopes should always be sold with dust covers. Whether transporting or storing your instrument, make the most of the microscope bag and remember to keep your microscope covered when not in use. The microscope’s eye tubes also need to be kept dust free. If the eyepieces need to be removed, cover the tubes with caps and store them with the microscope. 4. Store safely Ensure you store your microscope in a clean, dry space with good ventilation. Salt air or damp, for example, can cause damage to equipment over time. Expensive, precision equipment should not be stored next to solutions that may leak. Similarly, keep your microscope away from areas with potentially corrosive chemical fumes. Such fumes can destroy lenses or corrode metal parts. 5. Keep clean Oil immersion is a technique used to increase the resolving power of a microscope. Both the objective lens and sample are immersed in a transparent oil of high refractive index so that high magnifications can be achieved while still maintaining good resolution. It is essential to ensure careful cleaning takes place immediately after using immersion oil and do not use damaging solvents. 6. Take care of bulbs After using your microscope, turn off the illuminator and wait for it to cool down before putting it away. Allowing the bulb to cool will extend its life and avoid the unnecessary cost of expensive replacements. Similarly, if used constantly on full power, the bulb will overheat and blow. Remember too, to turn the illuminator off when not in use. 7. Clean carefully Microscope lenses are delicate. Treat them carefully to avoid any scratches. Use an aspirator to remove dust. Moisten special lens paper with distilled water or appropriate cleaning solution. Rubbing gently in a circular motion will remove any sticky residue. Never use anything abrasive on microscope lenses. 8. Refer to the user’s manual Your microscope should be sold with a user’s manual and specialist spanners as required. Always refer to the manual when making any adjustments to the microscope and use the supplied spanners. Never use force, inappropriate tools or over-tighten when making adjustments to your microscope, as this will only result in equipment damage. 9. Maintain your microscope An annual maintenance check of microscopes is always a good idea. Moving parts should be cleaned and lubricated. Similarly, inspect the power cords and plugs for safety. 10. Consider a professional service



Contact Edulab’s friendly team today for a range of products to help keep your laboratory microscopy equipment in tip top condition



PARTS OF A MICROSCOPE AND THEIR FUNCTIONS 1. 2. 3. 4. 5.



6. 7. 8. 9. 10. 11. 12.



13.



14.



Foot or Base: It is the basal, horse shoe-shaped structure. It provides support to all the remaining parts of the microscope. Pillar: A small, strong vertical projection developing from the foot or base is called pillar. Arm: It is a curved and strong structure used for handling the entire instrument. Inclination Joint: A joint at which the arm is attached to the pillar of the microscope is called inclination joint. It is used for tilting the microscope. Stage: It is a flat rectangular plate attached to the lower end of the arm. Slide or object is placed on the stage and studied. A hole is present in the centre of the stage. Light rays pass through this hole. Clips: Two clips are attached on the upper part of the stage. These are used for holding the slide in position. Diaphragm: It is attached beneath the stage. It regulates the intensity or amount of light entering into the microscope. It may be of two types viz., iris diaphragm and disc diaphragm. Body Tube: It is the tubular, hollow part attached to the upper part of the arm of microscope. It can be moved up and down with the help of adjustment knobs. Nose Piece: It is a circular and revolving metalic part attached to the lower end of the body tube. It has three holes in which objective lenses can be fitted. Coarse Adjustment Knob: It is a large-sized knob used to move the body tube up and down for bringing the object into focus. Fine Adjustment Knob: It is a small-sized knob. It is used for fine and sharp focussing of the object. Exact focussing is done by this knob. Eyepiece or Ocular: It is a lens fitted at the top of the body tube. It is always marked with a number (5X, 10X, 15X) on its rim. This number shows its magnification power. Magnified image of the object is seen with the eyepiece. Objective Lenses: Three objective lenses are attached to the revolving nose piece at the bottom of the body tube. These are low power objective (10X), high power objective (45X) and oil immersion objective (100X). Mirror: It is either attached to the lower end of the arm or to the pillar. It contains a plane mirror on one side and a concave mirror on the other side. Mirror is used to reflect light rays into the microscope.



SPECIAL PRECAUTION IN HANDLING A MICROSCOPE 1. Clean the eyepiece and objective lenses with lens paper or clean silken paper before use. 2. Do not tilt the microscope while working with it. 3. Always study the material first under low power and then only under high power of microscope. 4. After completing all observations, leave the low power objective in place. 5. Never allow an objective lens to strike either the slide or the stage while focusing. 6. While studying with high power objective, use only the fine adjustment knob. 7. All wet-mount preparations should be covered by a coverslip before making any observation under microscope. 8. Avoid habit to remove the parts of the microscope. 9. Always hold the microscope with both the hands while carrying it. 10. Keep the microscope back into its box after using it. 11. In dim light use only the concave side of the mirror. 12. Never use oil immersion lens without oil.