lab four Flashcards
light microscope
coordinated system of lenses arranged to produce an enlarged, focusable image of a specimen
magnification
increase in apparent size, accompanied with resolution
resolution
ability to distinguish 2 points as separate points
ocular eyepiece
uppermost lens/series of lenses, most have magnification of 10X
ocular tube
connects ocular to body tube
scanning objective lens
4x magnification, larger specimens
low-power objective lens
10x magnification, coarse/preliminary focusing
high-power objective
final/fine focusing, 40x magnification
oil-immersion objective lens
oil immersion helps magnify specimen, 100x magnification
mechanical stage
platform where slides are placed to accurately control movement of slides
stage clips
secure slide
coarse adjustment knob
adjusts microscope on 4x and 10x only
fine adjustment knob
adjusts specimen into final focus
condenser lens
lens system found beneath stage that focuses light
iris diaphragm
regulates light entering microscope
always start examination with…
low-power objective
magnification equation
product of power of ocular and power of objective
what does resolving power depend on
design and quality of objective lenses
depth of filed
thickness of the specimen in focus at any one time
first microscope
used by Robert Hooke in 1665 to observe cork
Anton van Leeuwenhoek
built simple microscope with one lens
- father of microscopy
- built over 240 microscopes
- first to see/describe microorganisms (tiny animalcules”
compound light microscope
allows light to pass through specimen and uses two lenses
- magnification
- resolution
parfocal
if one objective is in focus and a change is made to another objective, the focus will not be lost
what happens to DOF as magnification increases
it gets thinner
electron microscopes
- no light
- beam of electrons
- placed inside vacuum chamber so electrons don’t bounce off of gas molecules
- not used to view living cells
2 type of electron microscopes
- transmission
- scanning
transmission electron microscope
stream of electrons transmitted through thinly sliced specimen
- magnets guide stream of electrons
- image projected on photographic plate
- 200,000 magnification
what is magnification usually accompanied with?
resolution
contrast
the ability to discern detail and see difference between light/dark areas
