BLG 151 Chapter Notes - Chapter 2: Numerical Aperture, Eyepiece, Focal Length
1 Oct 2017
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Document Summary
The human eye contains fovea, portion of retina that contains photoreceptors. Fovea photoreptors/cone cells cn resolve images 100-200 micrometers (um) apart. Light is refracted (bent) when passing from one medium to another. Refractive index: a measure of how greatly a substance slows the velocity of light. When light passes from a medium with greater refractive index it is slowed and bent toward normal, when it passes through lesser refractive index it accelerates and bent away from normal. Focal point (f): focus light rays at specific place. Focal length (f): distance b/t center of lens/focal point. Lens with shorter focal length magnifies an object more than lens having larger focal length. Working distance: distance between the front surface/lens of cover glass/speicimen when it in sharp focus. Lens closest to specimen: magnification, working distance. Resolution: ability of lens to separate/distinguish small objects that are close together. Depends on wavelength of light used and ability of lens to gather light (na)
