Microscope Definitions

Measure of how much a substance slows velocity of light

Point a lens focuses light on

Distance from the center of the lease to the focal point.

25cm

Higher lens strength = shorter focal length

Bright background with a darker image of the sample

Below stage, focuses light on sample

Keeps image in focus when objective lenses are changed

Product of ocular and objective power

Ability of a lens to distinguish two objects from each other

N sin theta n=refractive index theta= half angle of the cone of light entering objective

= 0.5 wavelength of light / numerical aperture. (Smaller this is the better resolution and finer detail observed)

High quality magnification & resolution (high aperture)

Produces bright objects against a bright field (only light refracted by specimen enters objective due to hollow cone of light)

Relies on change of velocity of light in different media as it passes through the sample.

Living samples; creates contrast without staining

Directs ring of light to the condenser

Focuses undeviated light and advances by 1/4 wavelength to create required 1/2 wavelength separation between deviated and undeviated light

Excites a specimen with a specific wavelength of light, triggers the specimen to emit light

Fluorescent dyes used to tag specific cells or parts of cells so that they emit light at a specific wavelength.

Used laser beam to illuminate a fluorescent sample and remove stray light to produce higher resolution images

Process used to fix and preserve the internal and external structures of a sample

Application of heat to preserve and rice sample cells to a slide

Use of chemicals to fix a specimen. Protects fine cellular structure better than heat fixation, often used for electron microscopy