Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Microscope: instrument that magnifies small objects that cannot be seen by naked eye. * Microscope can be divided into 2 kinds: -simple microscope : consist of one lens (ocular lens) - compound microscope: consist of 2 lens (ocular +compound lens) (light microscope+electron microscope) *Light microscope can be divided into: bright field\dark field\phase contract \fluorescent microscope *Part of microscope: 1- ocular lens(eye piece): first lens element in microscope , it will show the final image 2- body tube : connect the objective lens with ocular lens 3- rotating nosepiece: carry the objective lens 4- objective lens: magnify the specimen 5- stage: support the slide 6- mechanical stage: move the slide horizontally and vertically 7- condenser: focus the light onto the specimen+control the amount of light 8- iris diaphragm: control the amount of light 9- coarse adjustment: get the picture out 10- fine adjustment: make the picture clear * Lenses and total magnification: - the magnification of the specimen depend on two lens system in light microscope: 1) ocular lense 2) objective lens - ocular lens magnify the specimen 10x - objective lens can be divided according to their magnification power into : 4x(red) 10x(yellow) 40x(blue) 100x(white) (oil objective lens) -what is the use of oil? (why?) *Total magnification = mag. of ocular lens x mag. Of objective lens *Working distance: distance between the objective lens and the slide - as the objective lens power increase the working distance decrease • • 1) bright field microscope: - Source of illumination is light - The specimen must be stained - We can see shape ,arrangement, size , color of m.o - We cannot see viruses - Specimen darker than background 2) Phase contrast: -Widely used to view the unstained living specimen by increasing the contrast between the object and background ,and this happen according to special condensers -No need to stain the specimen -Specimen darker than background 3) Dark field microscope: -Different from bright field or phase contrast microscope - Use special condenser with blocking disk - No light will pass into the objective lens if there is no specimen on the stage -Objects or particle on the stage will reflect the light into the objective lens and appear as bright object on a black background - No need to stain the specimen 4) Fluorescent microscope: - the specimen must be stained with fluorescent dye - source of illumination is u.v light * Electron microscope: - Source of illumination is beam of electron - We can see viruses - 2 kind of electron microscope: 1) scanning E.M: look at the surface of bulk object by scanning the surface with fine electron beam and measuring the reflection 2) Transmission E.M: - Passes electrons completely through sample - It can obtain detailed information of the sample