Microscope Parts and Usage

• A microscope is a precision instrument with optical, mechanical, electrical, and electronic subsystems.
• Microscopes produce highly magnified images of small specimens or objects.
• "Microscope" comes from the Greek words "micros," meaning small.
• Microscopy is the use of a microscope or investigation by a microscope.

Parts of a Microscope

• Eyepiece: A series of lenses mounted in a tube that magnifies the image projected by the objective lens.
• Tube: Reflects light up to the viewer's eyes.
• Rotating Object (Nosepiece): Holds multiple objective lenses of varying magnifications for quick changes.
• Objective Lenses: Gather light passing through the specimen and project the image into the microscope. Objective lenses can consists of:
• Low power objective: The first lens with magnification usually 4X.
• Medium power objective: The second lens with magnification usually 10X.
• High power objective: The third lens with high magnification usually 43X.
• Stage Clips: Hold the slide in place.
• Stage: The platform beneath the objectives where the slide is placed.
• Light Source
• Condenser
• Arm: Contains the focus mechanism, supports the stage and body.
• Fixed: Integral parts connected solidly to the base.
• Pillar (Post): A single post allows body rotation and vertical movement.
• Boom (Universal): Allows microscope to be aligned.
• Coarse Adjustment: Makes large changes in focus.
• Fine Adjustment: Makes small adjustments in focus.
• Base: Provides balance and rigidity.
• Head (Body): Connects the eyepiece to the nosepiece, may be fixed or allow tilting.
• Monocular: A single eyepiece.
• Binocular: Two eyepieces, one for each eye.
• Trinocular: Binocular head with an additional port for a third eyepiece.

Light Sources

• Fluorescent: Cool temperature, bright white light, good for observing live specimens, typically 5-10 watts.
• LED: Light emitting diodes, bright and cooler light, often battery operated and cordless.

Types of Microscopes

• Most microscopes are light (bright field) microscopes, relying on light to observe the magnified image.
• Compound (high power) microscopes
• Stereo or dissecting (low power) microscopes
• Phase Contrast
• Fluorescence
• Metallurgical
• Electron Beams
• Digital.

Compound Microscope

• The most common type, also known as a biological or research microscope.
• High power microscope with magnification from 40x to 1000x (some up to 2000x).
• Much serious work of a compound microscope is done at 400x to 500x.
• Principle:
• A single light path passes through a series of lenses, each lens magnifying the image.
• The image appears as if it's 10" (250mm) from the eye.
• Light illuminates the specimen for viewing.
• The objective lens has three to five lenses on a rotating nosepiece for changing power.
• The image is two-dimensional (2-D), reversed, and upside down.
• Trans-illumination (light projected from below) is the most common method.
• At 400x, much detail can be seen at the cellular level.

Stereo Microscope

• The second most common type, also known as dissection or inspection microscopes.
• Low power microscope with magnification from 10x to 80x (10x to 40x is most popular).
• Zoom models are available from about 10x to 60x.
• Principle:
• There are two separate light paths (opposed to a single light path) which produce a true stereo.
• Provides a three-dimensional (3-D) image of the specimen.
• Stereo microscopes have both top and bottom built-in or attached illumination.
• Stereo microscopes use light sources (desk lamps, sunlight, built-in lamps) to illuminate the specimen.