Review of the microscope


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In this slide show i reviewed about the History,Basic principle, Parts and Use of the Compound microscope

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Review of the microscope

  1. 1. THREE GOALS: •produce a magnified image of the specimen, •separate the details in the image, •render the details visible to the human eye or camera.
  2. 2. The History • Hans and Zacharias Janssen of Holland in the 1590’s created the “first” compound microscope • Anthony van Leeuwenhoek and Robert Hooke made improvements by working on the lensesAnthony van Leeuwenhoek Hooke Microscope Robert Hooke 1632-1723 1635-1703
  3. 3. The History Zacharias Jansen The “First” Microscope 1588-1631
  4. 4. Types of microscopes Light microscopes  Bright field microscope  Dark field microscope  Phase contrast microscope  Fluorescent microscope Electron microscopes  Transmission electron microscope  Scanning electron microscope
  5. 5. Magnification• To determine your magnification…you just multiply the ocular lens by the objective lens• Ocular 10x Objective 40x:10 x 40 = 400 So the object is 400 times “larger” Objective Lens have their magnification written on them. Ocular lenses usually magnifies by 10x
  6. 6. RESOLVING POWER/ RESOLUTION• ability of a lens to separate or distinguish small objects that are close together• wavelength of light used is major factor in resolution shorter wavelength ⇒ greater resolution Actual What We Might See
  7. 7. WAVE LENGTH• Wave length of light – used for illumination – Visible range – 400 – 750nm (Shorter wave length – high resolution) E.g. Blue light has a shorter wave length than red light
  8. 8. NUMERIAL APERTURE• NA – of the objectives (property of lens that decides the quantity of light enter into it) – Two factors 1) Refractive Index 2)Angle
  9. 9. REFRACTION• The bending of light as it passes from one medium to another of different density• The bending of the light ray gives rise to an angle of refraction, the degree of bending• Index of refraction: A measure of the speed at which light passes through the material
  10. 10. ILLUMINATION• To collect and reflect the light – two devices – 1) Mirror 2) artificial Light• 1) Mirror – natural source or artificial source – Two side – reflective- plain – artificial light – Concave – natural source
  11. 11. Properties of Light:Light & Objects • Reflection: If the light strikes an object and bounces back (giving the object color) • Transmission: The passage of light through an object • Absorption: The light rays neither pass through nor bounce off an object but are taken up by the object
  13. 13. Ocular LensBody TubeNose Piece ArmObjectiveLenses StageStageClips Coarse Adj.Diaphragm Fine AdjustmentLight Source Base The Parts of a Microscope
  14. 14. Body Tube • The body tube holds the objective lenses and the ocular lens at the proper distanceDiagram
  15. 15. Nose Piece • The Nose Piece holds the objective lenses and can be turned to increase the magnificationDiagram
  16. 16. Objective Lenses • The Objective Lenses increase magnification (usually from 10x to 40x)Diagram
  17. 17. Lenses • focus light rays at a specific place called the focal point • distance between center of lens and focal point is the focal length • strength of lens related to focal length – short focal length ⇒more magnificationCopyright © The 18McGraw-HillCompanies, Inc.
  18. 18. Stage Clips • These 2 clips hold the slide/specimen in place on the stage.Diagram
  19. 19. Diaphragm • The Diaphragm controls the amount of light on the slide/specimen Turn to let more light in or to make dimmer.Diagram
  20. 20. Light Source • Projects light upwards through the diaphragm, the specimen and the lenses • Some have lights, others have mirrors where you must move the mirror to reflect lightDiagram
  21. 21. Ocular Lens/Eyepiece • Magnifies the specimen imageDiagram
  22. 22. Arm • Used to support the microscope when carried. Holds the body tube, nose piece and objective lensesDiagram
  23. 23. Stage • Supports the slide/specimenDiagram
  24. 24. Coarse Adjustment Knob • Moves the stage up and down (quickly) for focusing your imageDiagram
  25. 25. Fine Adjustment Knob • This knob moves the stage SLIGHTLY to sharpen the imageDiagram
  26. 26. Base • Supports the microscopeDiagram
  27. 27. How a Microscope WorksConvex Lenses arecurved glass used tomake microscopes(and glasses etc.) Convex Lenses bend light and focus it in one spot.
  28. 28. How a Microscope WorksOcular Lens Objective Lens(Magnifies Image) (Gathers Light, Magnifies And Focuses Image Body Tube Inside Body Tube) (Image Focuses)•Bending Light: The objective (bottom) convex lensmagnifies and focuses (bends) the image inside thebody tube and the ocular convex (top) lens of amicroscope magnifies it (again).
  29. 29. Caring for a Microscope• Clean only with a soft cloth/tissue• Make sure it’s on a flat surface• Don’t bang it• Carry it with 2 HANDS…one on the arm and the other on the base
  30. 30. Carry a MicroscopeCorrectly
  31. 31. Using a Microscope• Start on the lowest magnification• Don’t use the coarse adjustment knob on high magnification…you’ll break the slide!!!• Place slide on stage and lock clips• Adjust light source (if it’s a mirror…don’t stand in front of it!)• Use fine adjustment to focus
  32. 32. I. Dark field contrast microscopy takes advantage ofobjects that “scatter” light - this requires a specialcondenser that can “angle” the incident lightII. Phase contrast microscopy takes advantage ofobjects that alter the phase of incident light - Thisrequires “phase rings” in the condenser and in theobjective lensIII. Fluorescence microscopy take advantage ofinherently fluorescent Material of biologicalobjected that can be fluorescenlty labeled.
  33. 33. DARK FIELD MICROSCOPE Contrast Bright Field Phase Contrast Dark-Field
  34. 34. Dark field contrast microscopytakes advantage of objects that“scatter” light - this requires aspecial condenser that can“angle” the incident light
  35. 35. FLUORESCENT MICROSCOPEOptical System of a FluoresceinFluorescence -excited by blueMicroscope light (450-490) -emits green light (520-560)
  36. 36. [INSERT FIGURE 4.9]Fluorescence microscopy take advantage of inherentlyfluorescent Material of biological objected that can befluorescenlty labeled.
  37. 37. Microscopy [INSERT FIGURE 4.10]
  38. 38. Applications of differentmicroscopes  Bright field – Stained slides  Dark field – Live unstained cells  Fluorescent – Microbiological material