Microscopy Principles and Lens Functioning

Microscopy

• Microscopy is the use of microscopes to observe tiny objects invisible to the naked eye.
• It's crucial in biology, medicine, materials science, and chemistry.
• Microscopes are optical instruments using multiple lenses to magnify images.

Microscope Principles

• The word "microscope" comes from Greek words meaning "small" and "view."
• Microorganisms, very small, need magnification to be seen.
• Microscopy is essential for microbiology studies.

Lens Functioning

• Refraction occurs when light changes medium (e.g., from air to glass).
• Refractive index measures how a material slows light's speed.
• Glass has a higher refractive index than air.
• Light bends towards the normal when entering a denser medium (e.g., glass).
• Bending (refraction) is based on refractive indices of materials.

Lens Properties

• Lenses act like clustered prisms.
• Parallel light rays converge at a focal point (F) on a convex lens.
• Focal length (f) is the distance from the lens center to the focal point.
• Lens strength is inversely related to focal length. Shorter focal length means greater magnification.

Magnification and Resolution

• Magnification is enlarging an object's appearance.
• It's expressed as a ratio (apparent size / actual size).
• Resolution is the ability to distinguish separate, close objects.
• Higher magnification doesn't always mean better resolution.
• Resolution is limited by the wavelength of light and numerical aperture (NA).

Abbe Equation

• Abbe's equation (d = λ / (n sin θ)) defines the minimum distance (d) between two distinct objects.
• λ is the light wavelength.
• n sin θ is the numerical aperture (NA).
• Resolution increases with smaller d values.
• Shorter wavelengths (blue light) provide better resolution.