March 2, 2008
Information On A Light Microscope
Light microscope, as the name denotes, uses a light source to illuminate the specimen under examination. It can be of many types, like simple (single lens), compound (multiple lens), stereo microscopes, and digital microscopes. It is available with different levels of magnification, usually ranging between 20X and 1500X. The stereo microscopes however have a lower magnification range between 20X and 200X, as it is primarily used to study the surfaces of larger specimens.
Its Parts
- Base- The microscope rests on this and this provides free standing
- Stage- This is where the specimen or sample slide is placed for viewing. The slide is held with two metal clips
- Aperture - Small opening on the stage. The sample is placed over the aperture for viewing and is held by the clips of the stage
- Light source- It is situated below the stage. The light shines through the aperture and illuminates the sample.
- Nosepiece- It is located above the stage. It holds the lenses, which are used to magnify the sample. The viewer can rotate the nosepiece for his convenience
- Objectives- This is held by the nosepiece and have different magnification powers, usually from 2X to 15X or 20X
- Arm- Connects the base to the upper parts of the microscope and can be used to carry the microscope
- Coarse adjustment knob- It is located on the side of the microscope. It is used to focus the sample. The knob is used to move either the stage or the upper parts of the microscope.
- Fine Adjustment Knob- It is located on the side. It is used to fine tune the image of the sample
- Body- It holds the eyepiece and connects it to the nosepiece lenses.
- Eyepiece- The sample is viewed by looking into this. It has a magnifying power of 10X
Guidelines to Follow While Using the Microscope
- Eyes- Eyepieces should rest just below the eyes. The eyes should face downward at 30-45 degrees below the horizontal; interocular distance of eyepieces have to be adjusted to ensure that both the eyes focus comfortably
- Back- The individual should sit erect; the entire body leans forward with the lower back and shoulder blades supported by the chair
- Neck- Neck and head should be bent as little as possible, not more than 10 to 15 degrees below the horizontal
- Arms/Wrist- Upper arms should be perpendicular to the floor, elbows to be close to the body; forearms parallel to the floor and wrists should be straight.
- Legs- Feet should rest firmly on the floor or on a footrest. There should be equal pressure applied by the chair to the back of the thighs.
Care of the Microscope
A Light microscope can be quite expensive; hence, good amount of care should always be taken…
- The microscope should be held by the stand only and never by the eyepiece holder
- When unplugging the illuminator, hold the plug and not the cable
- Turn the light off when not in use, as bulbs are quite expensive
- The stage and lenses should be cleaned before putting away the microscope
- Do not use a paper towel or any other material for cleaning. Use a good quality lens tissue or a 100% cotton swab to clean the optical surface.
- Keep the instrument covered with a dust jacket when not in use
- Focus smoothly. Do not try to speed up the process of focusing.