Lesson 3 - Imaging using light microscopy

Question 1

What does a condenser lens do?

Answer 1

• focuses the light on the specimen and passes through to the objective lens

Question 2

What does and objective lens do?

Answer 2

• collects light after it has passed through the specimen

Question 3

What does a ocular do?

Answer 3

• focuses image onto the eye

Question 4

What is magnification determined by?

Answer 4

• the objective lens and the ocular lenses

- total collective magnification is the product of the magnifying ability of the lenses within the light path

Question 5

What is the resolution of microscope?

Answer 5

• ability to distinguish between two very closely positioned objects as separate entities
• we want resolution ot be as small as possible (a higher number of alpha is better)

Question 6

How can we help improve resolution?

Answer 6

• by using a selective wavelength of light

- we can use fluorochromes to help visualize certain things inside of the cell

Question 7

What happens if wavelengths of light are moving parallel? If light passes through a part of the cell that has a higher refractive property?

Answer 7

• if parallel, white light is visible
• if higher refractive property, it bends the wavelength and the waves will be out of phase (appears darker)
• flatline of wavelengths shows as completely black

Question 8

What is phase contrast microscopy?

Answer 8

• used to examine unstained cells
• small differenced in refractive index and thickness within the cell are further exploited and converted into contrast visible to the eye
• spots that are much darker, further artificially refracted the lights through the spots in the cell to give us better detail of intracellular components of the cell

Question 9

What does bright field microscopy show?

Answer 9

• the peak of the wavelength will be slightly reduced
• we don’t see much detail, a lot of the light passes through and is unhindered
• only structures with a high refractive index are observable

Question 10

What is a phase halo?

Answer 10

• the structures around the edge of the cell leads to an artificial superimposition of light (two peaks added together creating a brighter light) - disadvantage

Question 11

What is Differential interference contrast microscopy?

Answer 11

• used to examine unstained cells
• takes advantage of the polarity of light
• isolates vertical and horizontal wavelengths and combines them to create a form of interference that is related to the polarity of the polar plane of light that is going though the specimen
• creates a topographical image of the cell