Microscope Parts and Functions

Compound Microscope Invention

• Zacharias Janssen is credited with the invention of the compound microscope around 1590.

Objective Lens Function

• The objective lens is responsible for magnifying the specimen. It is the lens closest to the specimen.

Microscope Light Source

• The illuminator provides a steady light source for illuminating the specimen.

Total Magnification

• The total magnification of a compound microscope is calculated by multiplying the magnification of the objective lens by the magnification of the eyepiece.
• Using a 40x objective lens with a 10x eyepiece results in a total magnification of 400x.

Slide Holder

• The stage is the platform where the slide is placed and held in place by slide clips.

Mechanical Stage

• The mechanical stage allows for precise movement of the slide using knobs.

High Magnification Resolution

• Immersion oil, a special type of oil with a refractive index close to that of glass, is required to achieve good resolution at 1000x magnification. It helps to minimize light scattering and improve image clarity.

Shortest Objective Lens

• The 4x objective lens, with the shortest length, generally has the lowest magnification power.

Condenser Lens Purpose

• The condenser lens focuses light from the illuminator onto the specimen, enhancing illumination for clearer viewing.

Rack Stop Function

• The rack stop is a mechanical feature that prevents the objective lens from making contact with the slide, protecting both the lens and the specimen.

Quality Microscope Feature

• All good quality microscopes have a parfocal mechanism, which enables the user to switch between objective lenses while maintaining focus, minimizing the need for extensive refocusing.

Condenser Lens Benefit

• A condenser lens with a numerical aperture (NA) of 0.65 or greater, while beneficial for all objective lenses, is particularly useful when using high power objective lenses (40x and 100x).

Thin Slide Focus Adjustment

• When using very thin slides and difficulty focusing on a specimen at high power, the condenser lens can be raised or lowered using its adjustment knob to bring the light into proper focus.

Condenser Lens Feature at 1000x

• For 1000x magnification, the condenser lens must have an adjustable iris diaphragm to control the amount of light reaching the specimen, improving image contrast and clarity.

Diaphragm Function

• The diaphragm, also known as the iris, regulates the amount of light entering the microscope, influencing the image brightness and contrast.

Retractable Objective Lens Feature

• Retractable objective lenses, commonly found in high power microscopes, have a spring-loaded mechanism designed to prevent the lens from contacting the slide during focusing. This protects both the lens and the slide.