HISTORY OF MICROSCOPY
•
2 gefällt mir•801 views
This document discusses microscopy techniques. It begins with a brief history of microscopy and introduces Antonie van Leeuwenhoek, an early pioneer in microscopy. It then defines common terms used in microscopy like aberration, contrast, depth of field, immersion fluids, and numerical aperture. Specific microscopy techniques are described like dark field microscopy, which is used to view thin organisms. Phase contrast microscopy is also explained, which improves the visibility of transparent specimens without loss of resolution.
Empfohlen
Weitere ähnliche Inhalte
Was ist angesagt?
Was ist angesagt? (20)
Andere mochten auch
Ähnlich wie HISTORY OF MICROSCOPY
Ähnlich wie HISTORY OF MICROSCOPY (20)
Mehr von Riyaz Sheriff
Kürzlich hochgeladen
Kürzlich hochgeladen (20)
HISTORY OF MICROSCOPY
- 3. History of Microscopy • Born in Netherlands • Fabric Merchant • Surveyor • Wine Assayer • Minor City Official. • Learnt to grind lenses and started building simple microscopes by 1668 ANTONIE VAN LEEUWENHOEK
- 4. Animalcules
- 6. Common terms in Microscopy • Aberration Unwanted Artifacts – Dust or Oil on Optical Surfaces – Improper alignment – Improper aperture settings – Imperfections in lens system • Spherical aberration – Image in focus I n the centre and blurred at the periphery • Chromatic aberration – Colour fringes within image field
- 9. Contrast Difference in image luminance
- 10. Depth of field • Vertical distance between the nearest and farthest objects in specimen that appear to be in sharp focus. • Depth of field increases with numerical aperture of lens
- 12. Immersion fluid ( Oil ) • Any liquid that occupies space between the object and microscope objective lens • Required for objectives that have working distance of 3mm or less • Immersion fluid should have the same refractive index as that of slide (1.515) • Immersion fluid maximizes effective numerical aperture of objective lens • Minimizes light refraction
- 13. 40X
- 14. 100X
- 15. SEM
- 17. What else?
- 18. Numerical Aperture • Measure of light gathering capacity of Lens or Condenser Objective Mirror Condense r position Iris Diaphrag m Magnification Objective Eye Total Low Concave Lowest Partially closed 10 10 100 High power Concave Slightly raised Partially open 45 10 450 Oil immersio n Plane Fully raised Fully open 100 10 1000
- 21. I M.B.B.S
- 22. • 1590 by Dutch spectacle makers • OBJECTIVES – 4X – 10X – 40X – 100X
- 23. Differences • Field Diaphragm – Light source • Substage condenser – Gathers light and concentrates into a cone onto the specimen
- 24. How images are formed?
- 27. • Specialized illumination technique • View thin organisms like spirochetes & leptospira
- 28. Special Dark field condenser BRIGHT FIELD DARK FIELD
- 29. • BLOCKS CENTRAL PATH OF LIGHT & DIRECTS LIGHT AWAY FROM OBJECTIVE AT AN OBLIQUE ANGLE
- 30. • Bacteria have a refractive index slightly different from the surrounding. • Light passing through the bacteria enters objective • Light not passing through the bacteria does not enter objective • So , end result – Bright organisms against dark background
- 36. Why Phase Contrast? • Many unstained biological specimens are virtually transparent under bright field illumination • Visibility can be improved in wet mount and cell cultures by reducing the opening size of substage condenser and iris diaphragm Loss of resolution. Artifacts • Phase contrast improves the contrast in these specimens without loss in resolution
- 38. Working principle.. • The phase contrast microscope uses the fact that the light passing trough a transparent part of the specimen travels slower and, due to this is shifted compared to the uninfluenced light. • This difference in phase is not visible to the human eye. • However, the change in phase can be increased to half a wavelength by a transparent phase-plate in the microscope and thereby causing a difference in brightness. • This makes the transparent object shine out in contrast to its surroundings.
- 40. • When dealing with transparent and colorless components in a cell, dyeing is an alternative but at the same time stops all processes in it. The phase contrast microscope has made it possible to study living cells, and cell division is an example of a process that has been examined in detail with it. • The phase contrast microscope was awarded with the Nobel Prize in Physics, 1953.