Everyday Science Academy

Microscope: An Introduction

 

Virtual Microscope

 

 Types of Microscopes

 

1. Light Microscopes (Optical Microscopes)

  • Compound Microscope: Uses multiple lenses to achieve high magnification, suitable for viewing thin specimens like cells and tissues.

  • Stereo Microscope (Dissecting Microscope): Provides a 3D view of larger, opaque specimens, ideal for dissection or circuit board inspection.

  • Fluorescence Microscope: Utilizes fluorescence to visualize specific structures within cells, often used in molecular biology.​

2. Electron Microscopes

  • Transmission Electron Microscope (TEM): Transmits electrons through ultra-thin specimens to reveal internal structures at atomic resolution.

  • Scanning Electron Microscope (SEM): Scans a focused electron beam over a specimen's surface to produce detailed 3D images of surface topography.

  • Scanning Transmission Electron Microscope (STEM): Combines TEM and SEM techniques for high-resolution imaging and analysis.​Wikipedia+1Wikipedia+1

3. Specialized Microscopes

  • Confocal Microscope: Uses laser light to scan specimens and produce high-resolution images at various depths, creating 3D reconstructions.

  • Atomic Force Microscope (AFM): Measures surface topography at the nanoscale by "feeling" the surface with a mechanical probe.

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 Parts of a Compound Microscope and Their Functions

 

  1. Eyepiece (Ocular Lens): The lens you look through, typically with 10x magnification.

  2. Objective Lenses: Primary lenses that magnify the specimen. Common magnifications include 4x, 10x, 40x, and 100x.

  3. Nosepiece (Turret): Holds the objective lenses and allows rotation to switch between them.

  4. Stage: The flat platform where the slide is placed.

  5. Stage Clips: Hold the slide in place on the stage.

  6. Illuminator: The light source, located beneath the stage, that illuminates the specimen.

  7. Condenser: Focuses light from the illuminator onto the specimen.

  8. Iris Diaphragm: Adjusts the amount of light reaching the specimen.

  9. Coarse Adjustment Knob: Moves the stage up and down for general focusing.

  10. Fine Adjustment Knob: Fine-tunes the focus for detailed viewing.

  11. Base: Supports the microscope and houses the illuminator.

  12. Arm: Connects the base to the head and is used for carrying the microscope.​MicroscopeMaster

 

 

 Objective Lenses: Types and Uses

Objective lenses are crucial for magnifying the specimen. Here's a breakdown:

  • Scanning Objective (4x): Provides a broad overview of the specimen, useful for locating areas of interest.

  • Low Power Objective (10x): Ideal for observing larger details and general viewing.

  • High Power Objective (40x): Used for examining fine details within the specimen.

  • Oil Immersion Objective (100x): Requires a drop of immersion oil between the lens and the slide to increase resolution by reducing light refraction.​Wikipedia+2Rs' Science+2Wikipedia+2

Note: Some microscopes also use water immersion objectives, which use water instead of oil to achieve high-resolution imaging, particularly useful for live specimens.​Wikipedia+1Wikipedia+1

 

 

 Immersion Techniques

  • Oil Immersion: Involves placing a drop of special oil between the 100x objective lens and the slide. The oil has a similar refractive index to glass, which minimizes light refraction and enhances image clarity. This technique is essential for observing minute details at high magnifications.​

  • Water Immersion: Uses water between the objective lens and the specimen. This method is beneficial when working with live specimens or when oil might damage the sample.​

 

 

 Additional Resources

 

  • NCBioNetwork Virtual Microscope: An interactive tool to explore microscope components and practice focusing techniques.

  • Khan Academy: Offers educational videos and articles on microscopy and cell biology.

  • Britannica: Provides in-depth articles on various types of microscopes and their applications.