NATS 1575 Study Guide - Final Guide: Combined Dna Index System, Scanning Electron Microscope, Microsatellite
30 Aug 2016
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Document Summary
A microscope is an instrument used to magnify and observe finer details of an object. Virtual image the magnified image seen when looking through the microscope. Real image the actual image seen by the naked eye. Mechanical/structural system support microscope (6 parts: stage, arm, base, body tube, coarse and fine adjustment knobs. Optical/functional system illuminates and forms image (4 parts: condenser, illuminator, objective (lower) and eyepiece/ocular (upper) lenses. Used especially in firearm department: stereoscopic microscope. Useful for large and bulky items (requires less magnification; 10x-125x: polarizing microscope (see below) Used for birefringent materials: scanning electron microscope (see below as well) Types of illumination: transmitted when the light comes from below and is directed through the specimen, vertical/reflected when the light comes from above and reflects off the specimen. Magnification = power of objective lens x power of eyepiece lens. Depth of focus : thickness of the specimen, high magnification = low depth of focus.
