Transcript Slide 1
Parts Focusing Care Images Produced by Light Microscopes Amoeba Streptococcus bacteria Anthrax bacteria Human cheek cells Plant cells Yeast cells Eye piece Revolving Nosepiece Arm Objective Lens Mechanical stage control Stage Clips Coarse Focus Stage Disc Diaphragm Fine Focus . Light Base Parts of the microscope •Light source: Could be a mirror, but most likely it is a bulb built into the base •Disc Diaphragm: Adjusts the amount of light striking an object •Objective lens: Gathers light and magnifies image •Revolving nosepiece: turns to allow you to select different objectives. •Eyepiece: Magnifies objects 10x and focuses light to your eye •Stage clips Holds slide by the edges •mechanical stage controls: control knobs move slide up/down, right/left. •Base and arm: support for carrying the microscope Fine focus knob: moves stage slowly toward/away from objective lenses. •Course Focus knob: moves stage quickly toward/away from objective lenses. 1. Remove and fold dust cover, plug in and turn on microscope. 2. Click lowest power 4x objective down. 3. Put stage at lowest position 4. Place the prepared slide on the microscope and secure with stage clips. 5. Look into the Eyepiece 6. Use the Coarse Focus to bring stage up and stop when focused. 7. Use the Fine Focus knob 1. Once focused with 4x small objective click to 10x medium objective. Use the fine focus knob to clarify. 2. – 3. If you see nothing go back to the 4x objective While looking at the slide carefully click the 40x objective down. – – Use ONLY the fine focus knob to clarify. If it looks like the 40x objective will be hitting the slide when turned down DO NOT USE THE 40x! • The objective lenses are positioned so that once the focal length is correct for the smallest 4x objective the specimen should be almost clear when switched to the 10x objective – The course focus knob should only be used with the 4x objective. – Always proceed from 4x to 10x to 40x – Do not use the 40x if it will touch the cover slip – There is a black pointer line embedded in the eyepiece that will move when you twist the eyepiece. • Always center your specimen in the field of view. – Otherwise as you zoom in with increased magnification the specimen will be out of your field of view. 4x field of view ameoba is all there 40x field of view ameoba NOT in your field of view 10x field of view part of ameoba there Oil Immersion Lens 100x Do NOT use! Why we don’t use it: 1) Lens is very close to coverslip Drop of immersion oil connecting cover slip and lens. Keeps high magnification from being blurry. 2) Immersion oil should not get on other objective lenses. • Carry with two hands one supporting the base and one on the arm • Insert and remove slides with the stage in the lowest position and the short 4x objective down • Place dust cover on when not being used • Place in cabinet on the correct numbered slot. • DO NOT use the course adjustment knob when focusing with the 10x, 40x • DO NOT use the 100x objective. Beyond Light Microscopes • Light microscopes are limited by their resolution. – Light microscopes cannot produce clear images of objects smaller than 0.2 micrometers • The electron microscope was invented in the 1930’s by Max Knott and Ernst Ruska – Electron microscopes use beams of electrons, rather than light, to produce images – Electron microscopes can view objects as small as the diameter of an atom Types of Electron Microscopes • Transmission electron microscopes (TEMs) pass a beam of electron through a thin specimen • Scanning electron microscopes (SEMs) scan a beam of electrons over the surface of a specimen • Specimens from electron microscopy must be preserved and dehydrated, so living cells cannot be viewed Images Produced by Electron Microscopes Cyanobacteria (TEM) House ant Lactobacillus (SEM) Avian influenza virus Campylobacter (SEM) Human eyelash Deinococcus (SEM) Yeast References • http://www.cfkeep.org/uploads/microscope .ppt#256,1,Microscopy • http://education.denniskunkel.com/catalog/ product_info.php?products_id=1123 • http://micro.magnet.fsu.edu/ • http://inventors.about.com/library/inventors /blroberthooke.htm