BLG 151 Chapter Notes - Chapter 2: Numerical Aperture, Bright-Field Microscopy, Chromophore
14 Sep 2015
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Refraction: when ray of light passes from one medium to another, ray is bent at interface. Refractive index: measure of how greatly subst slowly velocity of light, direction and magnitude of bending determined by refractive indices. Ex, light passes through air into glass, medium higher r index, slowed and bent toward normal. Light leaves glass, air has lower r index, it accelerates and bent away from normal. Light source is distant so that parallel rays of light strike lens, convex lens focuses ray at focal point, f, distance btw lens and focal point, focal length, f. Lens w/ short f magnifies object more than lens w/ longer f. Objective lens: lens closest to specimen, forms magnified image. Bright field microscope: examine both stained and unstained specimens. Light source located at base, 2 focusing knobs (fine and coarse) Substage condenser: mounted w/in stage and focuses cone of light to slide. Parfocal: image should remain in focus when objective lenses are changed.
