Phase-Contrast

• Variations in REFRACTIVE INDEX can cause variations in what?

  Light intensity
• Light intensity is also known as what?

  Contrast
• Refractive index: The ratio of the speed of light in a vacuum to the speed of light in a medium.
• Specimen: LIGHT to DARK with HALOES of varying intensity related to the THICKNESS of the component.
• What components produces LESS HALOING and thus a BEST-DETAILED IMAGE?

  Thin and flat components
• Phase-contrast microscopy is ideal for viewing what type of elements?

  Low-refractile elements or living cells
• What are the examples of low-refractile elements or living cells?

  Hyaline casts and mucus threads
• Refraction: bending of light as it passes from ONE MEDIUM TO ANOTHER.
• Diffraction: bending of light as it passes an OBSTACLE or through an APERTURE or an opening
• Low refractive index uses what?

  Phase-contrast
• Annular diaphragm or light annulus: condenser
• The annular diaphragm is adjusted until what?

  concentric and superimposed
• Phase-shifting element or dark annulus: objective