Microscopes PDF

Microscopes Imaging technology  History of Microscopes Hans + Zacharias Janssen – Dutch lens makers – Invented the first microscope in 1595 – Overlaid two lenses Ocular lens Objective lens – First compound microscope Using more than 1 lens to...

Microscopes Imaging technology  History of Microscopes Hans + Zacharias Janssen – Dutch lens makers – Invented the first microscope in 1595 – Overlaid two lenses Ocular lens Objective lens – First compound microscope Using more than 1 lens to magnify objects – Magnifying power = 20X  History of Microscopes Robert Hooke – English scientist – Made a 3-lens compound microscope in 1665 – Light source (illumination) beam of light concentrated on the specimen by passing through a water filled glass flask – Identified “cell” structures in cork  History of Microscopes Antoni Van Leeuwenhoek – Dutch businessman – Used a single-lens microscope Similar to a magnifying glass – Magnification = 250X  extremely high-quality lenses! – First to observe movement of single-cell organisms Free-living cells Independent systems “animalcules”  Types of Microscopes Microscopes enabled most of our understanding of modern biology  Specimen A specimen is the object you are looking at  Magnification Magnification - How many times larger a microscope makes an object appear 10x 15x 20x 30x 40x  Magnification What do you notice about the amount of the coin that you see as the magnification increases? 10x 15x 20x 30x 40x  Light Transmission (Compound) Microscope 1 Ocular lens – Magnifies object – 10X magnification 3 objective lenses – Magnify and bring object into focus – Low  4X – Medium  10X – High  40X Image produced by light passing through specimen Protozoa, bacteria, individual  Parts of a Microscope Together let’s label the diagram of a microscope and complete the table describing the function of each part. (Workbook pg 109- 110) At home can use textbook pg 478 for reference Light Transmission (Compound) Microscope Ocular lens Connects eyepiece to Usually 10X objective lenses Support  Light Transmission (Compound) Microscope Holds and rotates through multiple objective lenses Usually low, medium, high powers (4X, 10X, 40X) Light Transmission (Compound) Microscope Where slides are Holds slides in place placed Can move up or down for focus  Light Transmission (Compound) Microscope Brings specimen into view quickly Changes the intensity of Brings specimen light into view slowly Regulate amount of light Used to fine-tune entering the scope focus Light Transmission (Compound) Microscope Steady illumination support  Electron Microscope Image produced by electrons rather than light Electron focused by electromagnets Magnification = up to 1.2 million times  Electron Microscope Scanning electron microscope Transmission electron (SEM) microscope (TEM) – Electrons reflected off – Electrons passing through specimen surface specimen – 3D image of the surface of – Internal structures of specimen specimen What’s that? What’s that? What’s that? What’s that? What’s that? Calculating Magnification Total Magnification = Eyepiece x objective lens (ocular lens)  Calculating Magnification Eyepiece = 5x Objective lens = 4x Total magnification = 5 x 4 = 20x The image you see is 20 times larger than the actual specimen  On Our Microscopes Total magnification = Ocular Lens x Objective Lens Ocular Lens: 10X Ocular Lens: 10X Ocular Lens: 10X Objective Lens: Objective Lens: Objective Lens: 10X 40X 100X Total Total Total Magnification = Magnification = Magnification = 100X 400X 1000X  Using a Microscope When carrying a microscope, one hand should be on the arm and one hand should be on the base.  Using a Microscope Lens paper should be used to clean lenses.  Focusing a Microscope 1. Turn the revolving nosepiece to the lowest objective.  Focusing a Microscope 2. Place the slide on the stage and fasten the stage clips.  Focusing a Microscope 3. Turn on the light source and adjust using the diaphragm.  Focusing a Microscope 4. Turn the screen on. Slowly turn the coarse adjustment knob to bring the slide into focus.  Focusing a Microscope 5. Use the fine adjustment knob to bring the slide into clearer focus.  Focusing a Microscope 6. Use the revolving nosepiece to change the magnification. You may need to refocus using the coarse and fine adjustment knobs. Measurement with the Microscope  Field of View Diameter (FOV) Field of view diameter is a measure of the width of the circular area seen through the ocular Focusing on a metric ruler + counting the number of mm  Sizes under Microscope: Micrometers (µm) The micrometer is the unit of measurement used to measure objects under a microscope 1/1000 of a millimeter (1000 µm = 1mm) 40X FOV _____ mm = _____ µm  Field of View (FOV) The diameter of the circle of light you see when you look into a microscope  Field of View (FOV) What is the FOV in mm? What is it in µm?  Let’s Try 0.018 mm =__________m 250 m =__________ mm 240 000 m =__________ mm 32 000 m =__________ mm 364 mm =__________ m 0.567 mm =__________ m 4.5 mm =__________ m 0.879 mm =__________ m 79 mm =__________ m 27.5 mm =__________ m  Fit Number The number of times a specimen will fit across the field of view Use the longest part of the specimen  Fit Number Fit Number – What is the fit number of the white blood cell shown below…?  Fit Number Fit Number – This cell will fit across the field of view approximately 5.3 times. – Fit number is 5.3  Calculating the Size of a Specimen Specimen size = FOV Fit #  Let’s Try The diameter of the low power field of view is 2 000 m. If four lily cells fit across the field of view, how long is each cell in mm? Field of view Lily cells 2000 m