Microscopes BIO 1114

Magnification

Ratio of the size of the image to the size of the object

Resolving power

Ability of an optical system to distinguish between two objects that are very close together

Rule

Objects closer than ½ (closer to each other) of the source wavelength can not be resolved

• The optical system cannot resolve that regardless of clarity and system operation

• 200nm or less space between objects will make them appear as one entity

-Light microscopes (400-700nm): blue/violet on visible light spectrum

Wavelength

Distance between 2 corresponding points on 2 adjacent waves (measured in nanometers)

Nanometer (nm)

One billionth of a meter

DPI, Megapixels, MP

• DPI in printers stands for dots per inch, everything is printed in dots to make a cohesive image

• Mega means 1 million, megapixels tells how many pixels are assigned to colors to make up an image

• MP stands for micro-print, signature link on checks aren’t a solid line, its print so small if a check was copied that link would appear solid

-More detailed=more pixels for colors=higher resolution

Stereo Microscope

Maximum magnification ~250x, can view any outside organism

• White light as a radiation source, larger working distance

Compound Microscope

Maximum magnification ~ 1,500 x

• White light as a radiation source, smaller working distance

• Advantage: Can get more magnification

• Disadvantage: Has to be small, stable organism

-Has to be thin enough to let travel through it

History/ Technology/ Electron Microscope

Early 1900s, look for improvement

• Beam of electrons for radiation source

• Electrons travel in waves- wavelength = 0.05nm (very short, can see different entities- right side of visible spectrum)

• Images are sharper, very detailed and able to see cell’s organelles (viruses couldn’t be seen until this)

• Knowledge greatly enhanced of specific cellular bacterial, viral and other “minute” functions

• Live specimen viewing not possible

Transmission Electron Microscope (TEM)

• Sample must be cut very, very thin

• Can see internal details

Scanning Electron Microscope (SEM)

• Whole samples can be used

• Ability to see external details (very fine)