THE MICROSCOPE Flashcards
The ratio of the apparent size of an object as seen through the microscope & the
actual size of the object
Magnification
- The ability of the lens to clearly separate or distinguish two points of two lines
individually in the image. - It is determined by the shortest wavelength of visible light & maximum numerical
aperture
Resolution/Resolving Power
- A measurement of the ability of the condenser and the objective lens to gather light.
- Scanner : 4x : 0.10
- LPO : 10X : 0.25
- HPO : 40X : 0.65
- OIO : 100X : 1.25
. Numerical Aperture
- Thickness of the object that maybe seen at one time under focus.
- Distance between the center of a lens or curved mirror and its focus
Focal length
- Distance between the front lens of the objective lens & the top of the cover glass when the
specimen is in focus.
Working distance
- Refers to quality of the objectives & eyepiece where practically no change in focus has to be
made when objective is substituted for another
Parfocal
- Bending of light rays away from the objective lens when light passes from the glass of the microscope slide to the air.
Refractive Index
• First microscope.
• Created in the 17th century by Antony van Leeuwenhoek, who combined a convex lens with a holder for specimens.
• 200 – 300x Magnification
• Not used often today because the introduction of a second lens led to the more powerful compound microscope
Simple Microscope
• Two lenses
• Better magnification than a simple microscope
• Bright field microscopes (the specimen is lit from underneath, and they can be binocular or monocular) provide a magnification of 1,000 times, which is considered to be high, although the resolution is low.
• Allows users to take a close look at objects too small to be seen with the naked eye, including individual cells.
Compound Microscope
- Stained tissue is examined with ordinary light passing through the preparation.
- The microscope includes an optical system and mechanisms to move and focus the specimen
Bright field microscopes
- Tissue sections are usually irradiated with ultraviolet (UV) light and the emission is in the visible portion of the spectrum.
- Fluorescent substances appear bright on a dark background
Fluorescence Microscopy
- uses a lens system that produces visible images from transparent objects and, importantly, can be used with living, cultured cells
Phase-Contrast Microscopy
-Allows the recognition of stained or unstained structures made of highly organized subunits.
-Tissue structures containing oriented macromolecules are located between the two filters, they appear as bright structures against a dark background.
Polarizing Microscopy
• Uses electrons rather than light for image formation.
• Samples are scanned in vacuum or near vacuum conditions, so they must be specially prepared by first undergoing dehydration and then being coated with a thin layer of a conducive material, such as gold.
Scanning Electron Microscope (SEM)
• Uses electrons rather than light for image formation.
• Samples are scanned in vacuum or near vacuum conditions, so they must be specially prepared by first undergoing dehydration and then being coated with a thin layer of a conducive material, such as gold.
• After the item is prepared and placed in the chamber, the SEM produces a 3-D, black-and white image on a computer screen.
Scanning Electron Microscope (SEM)
-uses electrons in creating a magnified image
- Uses a slide preparation to obtain a 2-D view of specimens, so it’s more suited for viewing objects with some degree of transparency.
- Offers a high degree of both magnification and resolution
Transmission Electron Microscope (TEM)
used to support and adjust the parts
Mechanical Parts
used to enlarge the specimen
Magnifying Parts
used to provide light
Illuminating Parts
bottom post portion that supports the entire
microscope, provides stability and support for the
microscope when it is upright. The base also typically
holds the illuminator, or light source
• Base
part above the base that supports the other parts
Pillar
allows for tilting for the convenience of the user
Inclination joint
connects the eyepiece tube to the base ,curve or slanted part which is held while carrying the microscope
Arm
is a platform for the slides, which hold the specimen.
Stage and stage clip
