Presentation on theme: "02 Dissecting Microscope. A B Carrying a Microscope."— Presentation transcript:
02 Dissecting Microscope
A B Carrying a Microscope
Return the lowest power objective in place Wrap the cord around the base Return dustcover Storing The Microscope
Use lens paper on all glass parts of the microscope. Cleaning the Microscope
Dissecting Microscope & Parts Free standing illuminator
Pond Water Sample Paramecium Euglenia Volvox Clamydomonas Spirogyra RotiferDaphnia
Prepare wet mount for dissecting scope Pond water Look at specimen under high power and draw what you see. Use proper clean-up technique Activity
Phase Contrast Microscope Muscle tissueDowny mildew of grape
Imperfections in glass Peaks and troughs don’t line up These waves are in different phases PCM used to transform phase differences into intensity differences, thus increasing contrast Understanding Phase Contrast Microscopy light glass light waves
Dark Field Bright Field Phase contrast Comparison of Light Microscopy
Course adjustment knob Fine adjustment knob Y-axis knob X-axis knob Specimen holder ocular objective Light intensity lever Light intensity preset button stage Revolving nose piece Aperture iris diaphragm ring condenser
Use lens paper on all glass parts of the microscope. Clean oil immersion lens with chemicals provided by your instructor Cleaning the Microscope
Using the microscope Always observe using the LOWEST POWER objective first. Focus using the COARSE ADJUSTMENT KNOB to bring the object into focus. Bring the object into sharp focus by using the fine adjustment knob. Focus, and then move to a higher power objective, if needed. Use only the FINE ADJUSTMENT KNOB when using the HIGHEST (longest) POWER OBJECTIVE. Keep both eyes open to reduce eyestrain. Determine total magnification of the object by multiplying the power of the ocular (10x) the power by the power of the objective.
Preparing a slide Using a pipet or dropper, add a drop of water or another solvent to a clean microscope slide. Then, place the specimen in the water. Place the edge of a coverslip on the slide so that it touches the edge of the water. Slowly lower the coverslip to prevent the formation of air bubbles.
The effects of immersion oil on resolution
40x 100x Oil Immersion Lens
base ocular objective Illumination intensity stage Nose piece Specimen holder Course adjustment X-axis knob Condenser Iris diaphragm (aperture diaphragm ring) Fine adjustment y-axis knob
For Light Microscope use set to 0
Prepare wet mount Cheek cell Elodea cell Onion cell Bacterial cells in yogurt Look at specimen under high power and draw what you see. Use proper clean-up technique Activity
Epidermal Onion Cell
Dispose Biological material
Microscope Parts Quiz
Microscope Quiz 1. 1.Which objective uses oil? 2.If your ocular is 10x and your objective is 40x what is the total magnification of your image? 3.Why do you need a cover slip and how do you avoid an air bubble? 4.What is the difference between a light microscope and a dissecting microscope?
When looking through the ocular you will see 2 rings The may or may not be concentric. By turning the centering adjustment screws o the condenser, you align the rings so they become concentric Aligning rings
Brightfield –absorption Light is transmitted through the sample. Only useful for specimens that can be contrasted via dyes. Very little contrast in unstained specimens. Darkfield -scattering The illuminating rays of light are directed from the side so that only scattered light enters the microscope lenses, consequently the cell appears as an illuminated object against the view. Phase Contrast- phase interference Incident light [Io] is out of phase with transmitted light [I] and when the phases of the light are synchronized by an interference lens, a new image with greater contrast is seen
Dark-Field Microscopy Modified condenser contains disc in center Only light refracted by specimen can enter objective. Objects surrounded by halo. Advantage can see smaller objects like spirochetes, internal structures highlighted. Disadvantage objects look bigger than they actually are.
Phase Contrast Microscopy Light passes through annular diaphram. Causes light waves to become “in phase” or synchronized. Advantage can highlight internal cell structures and details. Disadvantage - none.