Microscope Flashcards
Real Image
an image that can be seen directly w/ the naked eye
Virtual Image
formed from light that has passed through a lens and distorted to make the object look larger or smaller
Field of View
the area of the specimen that can be seen when magnified
*decreases when you increase magnification
Depth of Focus
the thickness of the specimen that is entirely in focus
*decreases when you increase magnification
Transparent (Transmitted) Illumination
passes through the specimen from underneath (for transparent specimens)
Vertical (Reflected) Illumination
light source is above the specimen, and light is bouncing back (for opaque specimens)
Compound Light Microscope
- monocular
- uses transparent/transmitted illumination
- longer objective lens, greater magnification
- magnification is the ocular lens (10x) times the objective lens
- up to 400x magnification
Stereoscopic Microscope (Dissecting Microscope)
- 2 light sources for transmitted/transparent and reflected/vertical illumination
- wide field of view,great depth of focus, & large working distance makes it most versatile & most frequently used microscope
- good for locating evidence over a large surface (garments, weapons, tools)
Compound Microscope Image
creates an image that is upside down and backwards
Stereoscopic Microscope Image
gives an image that is right side up
Comparison Microscope
- binocular
- pioneered by army colonel Calvin Goddard
- used to compare bullets, bullet cartridges, hair, fibers, tool marks, etc. side by side
Polarizing Microscope
- used in the analysis of birefringence in soils and fibers
- made possible the examination of plane-polarized light with matter
Plane-Polarized Light
light confined to a single plane of vibration
Polarizer
a device that permits the passage of light waves vibrating in only one plane
Extinction
no light penetrates, total darkness, happens when analyzer and polarizer are “crossed”
