Parts and Functions of a Light Microscope

• A light microscope uses two lenses to magnify objects.
• The lenses bend or refract light, which makes the objects appear closer.
• The microscope is a very powerful magnifying glass that helps you see things like cells up close.

Microscope Parts:

• Eyepiece: Used to view the specimen.
• Body Tube
• Revolving Nosepiece
• Objective Lens
• Arm
• Stage
• Stage Clips
• Coarse Focus
• Fine Focus
• Diaphragm
• Light
• Base: The part where the microscope rests.

Stage clips & Objectives:

• Stage clips hold the slide in place.
• Low power objective (shorter) is used to focus the microscope.
• High power objective is used for fine details of a specimen.
• Coarse adjustment focuses first.
• Fine adjustment gives more detailed focus.
• The stage is where the slide rests.
• The mirror or light source directs light upwards onto the slide.
• The diaphragm controls the amount of light that passes through the microscope.
• The nosepiece is the rotating device that holds the objectives (lenses).
• The arm is the part to hold when carrying the microscope.

Types of Microscopes:

• Light
• Compound
• Stereo
• Inverted
• Fluorescence
• Atomic Force
• Confocal
• Retinal Imaging
• Laser Microdissection
• Electron

Magnification:

• Microscopes have scanning, low, high, and oil immersion objective lenses.
• Each objective has its magnification labeled.
• The eyepiece has a magnification.
• The total magnification is calculated by multiplying the ocular by objective.
• Scanning is 4x, low power is 10x and high power is 40x.
• The ocular lens magnification is 10x.
• The total magnification for scanning is 40x.
• The total magnification for low power is 100x.
• The total magnification for high power is 400x.

Using the Microscope:

• Clear backpacks and materials from aisles and desks.
• Microscopes are stored with the cord wrapped around and scanning objective clicked into place.
• Carry microscopes with both hands using the base and arm.

Focusing Specimens

• Always start with the scanning objective.
• Place the specimen in the center of your field of view.
• Use the coarse knob to focus.
• Use the fine knob until its clear.
• Switch to low power once you’ve focused on scanning.
• Repeat the coarse and fine knob focusing steps.
• Switch to high power.
• Only use the fine adjustment knob at high power to focus specimens.
• It could crack the glass slide or lens if the course knob is used under high power.

Field of View

• The field of view is the area a person can view through a microscope.
• It is represented by a circle.
• As magnification increases, field of view decreases.
• The area you see through the microscope gets smaller when going from scanning (40X) to high power (100X).
• There is better detail with higher powers of magnification, but less of the image can be seen.
• The microscopes lens inverts the image, the image appears upside down and backward compared with actual object.
• Move the slide in the opposite direction of how you want the image to move.
• If you move the slide to the right on stage, the slide appears to move left.

Making a Wet Mount Slide

• Get a clean slide and coverslip.
• Place one drop of water in the middle of the slide.
• Place the specimen into the water.
• Place the edge of the cover slip on one side of the water drop at a 45° angle.
• Slowly lower the cover slip on top of the drop to prevent air bubbles.

Drawing Specimens

• Drawings of specimens should be done in pencil to erase and shade.
• All drawings should include clear and proper labels and should be large enough to view details.
• Drawings should be labeled with the specimen name and magnification.
• Specimens should be drawn to scale, making your drawing reflective of how much of the viewing field it takes up.

Cleanup

• Microscopes need to be stored with the scanning objective in place.
• Wrap the cords and cover the microscopes, checking to ensure no slides have been left.
• Place microscopes in the designated location.

Troubleshooting

• Adjust the diaphragm and make sure your light is on, if your image is too dark.
• Use lens paper to carefully clean the objective and ocular lens if there is a spot in your viewing field, even when you move the slide.
• If you can't see anything under high power, make sure you have followed all focusing steps, starting at scanning.
• Ensure that your objective is clicked fully into place, if only half your viewing field is lit.