Biology 2382B Lecture Notes - Lecture 2: Aldehyde, Point Spread Function, Scanning Electron Microscope
17 Jan 2017
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Compound microscope - more than 1 lense. Condenser lens - focuses light on specimen. Objective lens - collect light after it passes through the specimen. Ocular lens (eyepiece) - focus image onto eye. Only structures with a high refractive index (ability to bend light) are observable. The ability to distinguish between two very closely positioned objects as separate entities. Light microscope can resolve objectives up to 0. 2 (cid:541)m apart. Cannot see viruses (need an electron microscope) A more optimal resolution is a lower d-value. D is the minimum distance resolved between 2 points. N sin numerical aperture (higher is better) N refractive index of medium between the specimen and the objective lens. 1/2 angle of light entering objective. The limit of resolution is 0. 2 (cid:541)m=200 nm. Optimal resolution (d): is achieved by making it lower. Getting a better lens (high numerical aperture) Get a larger sin ( ), by increases . Electron microscope has light that goes to 1 nm.
