The Microscope

The Basics A microscope is an optical instrument that uses a lens of a combination of lenses to magnify and resolve the fine details of an object The earliest microscope is a single lens microscope: the magnifying glass The larger image you see when looking through a microscope is called a virtual image

The Basics You place an object under the lower of two lenses, called the objective lens, it is viewed through the eyepiece lens

The Basics The following are the types of microscopes used by forensic scientists Compound microscopes Comparison microscope Stereoscopic microscope Polarizing microscope Microspectophotometer Scanning electron microscope (SEM)

The Compound Microscope Base- ALWAYS CARRY WITH ONE HAND ON BASE Arm- supports the microscope, ALWAYS CARRY WITH ONE HAND ON ARM Stage- place you put specimen on, generally on a glass slide and placed under the clips Body tube- where the objective and eyepiece lens is Coarse adjustment- raises and lowers the stage, DO NOT use if you are on a high magnification

The Compound Microscope Illuminator- transmitted illumination when light passes up from the condenser and through the specimen. Condenser- lens system under the microscope stage to collect light and focus them on the specimen Objective lens- the lenses for magnification Eyepiece or ocular lens- lens closest to eye, can be monocular or binocular

The Compound Microscope Always focus your specimen on the lowest magnification first When you increase a compound microscope’s magnification, its field of view and depth of focus decrease Field of view- area of a specimen seen Depth of focus- the thickness of a specimen that is entirely in focus under the microscope

The Comparison Microscope Two compound microscopes in one unit Very useful for looking at two different things for comparison When you look into the comparison microscope you see both specimens at the same time Modern firearms examination began with the first comparison microscopes

The Stereoscopic Microscope Two monocular compound microscopes properly spaced and aligned to present a 3-D image of a specimen to the viewer Ideal for microscopic examination of big, bulky items