Comprehensive Study Guide to Microscopy: Anatomy, Optics, and Magnification

Microscope Components and Structural Anatomy

• Ocular Lens / Eyepiece: The upper optical lens through which the observer views the specimen; provides a baseline magnification of $10\times$.

• Nosepiece / Revolving Nosepiece: The rotating turret mechanism that holds the various objective lenses, allowing rapid switching between different magnification powers.

• Objective Lenses: Primary optical lenses positioned directly above the stage on the revolving nosepiece, facing down toward the specimen.

• Stage: The flat horizontal platform upon which the prepared slide or specimen is mounted for observation.

• Stage Clips: Metal clips mounted on the stage used to hold the microscope slide firmly in position during viewing.

• Arm: The structural upright support that connects the optical head and nosepiece to the base; used for carrying the instrument.

• Coarse Focus Knob (Coarse Adjustment Knob): The larger control knob that moves the stage or lenses dramatically to achieve rapid initial focal alignment.

• Fine Focus Knob (Fine Adjustment Knob): The smaller precision control knob that makes subtle adjustments to bring the specimen image into sharp, detailed focus.

• Iris Diaphragm: An adjustable shutter located beneath the stage that regulates the angle and volume of light passing upward through the specimen.

• Light Source (Illuminator): The built-in lamp located at the bottom of the microscope within the base that emits light upward through the condenser, iris diaphragm, stage opening, and specimen.

• Power Supply: The electrical assembly that provides operational current to the light source.

• Base: The heavy bottom foundation providing structural support and stability for the entire microscope.

Microscopy Optical Definitions

• Field of View: The complete circular visible area observed when looking directly through the ocular lens.

• Diameter of Field: The transverse measurement or width across the circular field of view.

• Depth of Field: The vertical distance or axial measurement between the closest and farthest points of a specimen that remain sharply in focus at the same time.

• Total Magnification: The combined enlarging power of the optical system, calculated as the product of the ocular lens magnification and the objective lens magnification:   $\text{Total Magnification} = \text{Ocular Lens Magnification} \times \text{Objective Lens Magnification}$

Objective Lens Types, Specifications, and Total Magnification

• Scanning Objective Lens:

  • Lens designation: Scanning
  • Objective magnification rating: $4\times$
  • Lens etching / Numerical aperture rating: $4/0.10$
  • Eyepiece / Ocular lens magnification: $10\times$
  • Total magnification calculation: $4\times \times 10 = 40\times$
  • Resulting total magnification: $40\times$

• Low Power Objective Lens:

  • Lens designation: Low Power
  • Objective magnification rating: $10\times$
  • Lens etching / Numerical aperture rating: $10/0.25$
  • Eyepiece / Ocular lens magnification: $10\times$
  • Total magnification calculation: $10\times \times 10 = 100\times$
  • Resulting total magnification: $100\times$

• High Power Objective Lens:

  • Lens designation: High Power
  • Objective magnification rating: $40\times$
  • Lens etching / Numerical aperture rating: $40/0.65$
  • Eyepiece / Ocular lens magnification: $10\times$
  • Total magnification calculation: $40\times \times 10 = 400\times$
  • Resulting total magnification: $400\times$

• Oil Immersion Objective Lens:

  • Lens designation: Oil Immersion
  • Objective magnification rating: $100\times$
  • Lens etching / Numerical aperture rating: $100/1.25$
  • Eyepiece / Ocular lens magnification: $10\times$
  • Total magnification calculation: $100\times \times 10 = 1000\times$
  • Resulting total magnification: $1000\times$

Prepared Slide Anatomy and Reference Identification

• Slide Anatomy:

  • Specimen: The mounted biological or test material affixed to the slide for microscopic examination.
  • Cover Slip: A thin, transparent sheet of glass or plastic placed directly over the specimen to protect the lens, flatten the sample, and prevent desiccation.

• Reference Slide Labeling Details:

  • Academic Course Identification: BI 151 (Lab 2: Microscopy)
  • Author/Instructor Attribution: O'Malley
  • Specimen Title: Letter e
  • Product SKU: SKU B1201801A
  • Manufacturer Branding: eisco Made in USA