FIVS 215 Exam 1

Antony Von Leeuwenhoek

Created the first microscope, simple microscope, in 1600s

Hans and Zacharias Janssen

created the first compound microscope, had no stand

Hooke

First to use the term cell, first “mechanical stage”

Zeiss

worked with Abbe, the basic design of the microscope has not changed since then (1930s)

Kohler Illumination

• Used to make sure that the light is even and gives a clear image

• reduces stray light

• increases contrast

Electromagnetic Spectrum

• use visible light, UV, x-ray, infrared

• short wavelength = higher frequency

Least distance of vision

The minimum distance an object can be at to still be seen clearly (10 inches)

Visible Light

• red 660 nm

• blue 440 nm

• green 550-580 nm

Image formation in compound micrscope

• objective lens projects a real image to the field stop/ field diaphragm

• then the ocular lens projects that image as a virtual image 10in from your eye

Stereoscope

has 2 light paths that give a stereo image (used for dissecting)

infinity- optics

• The objective lens sends light out in parallel rays instead of immediately forming an image

• uses a tube lens to take those parallel rays and form an image

Numerical Aperture

• how much light an objective lens can collect and how much detail it can see

• Oil has a closer RI to glass than air does, which is why it is able to let in more light

• Angular aperture = how wide the cone of light is that the objective can accept

• Wider light cone → higher NA → more detail/resolution

Lamp Diaphragm/ Field Iris

• Lamp diaphragm: controls how much light is produced/passes from the lamp

• Field iris: controls the size of the illuminated area

Condenser

Focuses the light onto the specimen by making a cone

Substage Aperture

• Substage aperture is an opening below the specimen and condenser that helps control the cone of light going into the objective

objective lens

• The lens closest to the specimen

• Collects light from the specimen

• Creates the first magnified image

• Common magnifications: 4×, 10×, 40×, 100×

Ocular lens

• The lens you look through

• Magnifies the image produced by the objective

• Usually 10×

Objective markings

0.17 - cover slip thickness

pol - has no strain

oil - immersion medium

infinity - tube length

Airy’s Disk

• When a lens is illuminated by a beam of parallel light, the light does not focus to a point but creates a diffraction pattern that looks like a disk

• higher Na means a smaller disk

• Airy disk = the smallest blurry spot the microscope can make from a point of light.

Abbes rule of thumb

Want magnification to stay between 500xNa and 1000xNA

Abbes theory

• explaining how a microscope forms an image and why there is a limit to how much detail we can see

• A microscope can only distinguish two objects if it can collect enough of the diffracted light from them

Isotropism

• has no special effects on light

• appears dark under cross polarized light

Anisotropism

• effects light as is passes through

• refracts light in different directions

• appears colorful under cross polarized light

Calcite Rhombs

• Natural polarizer

• splits rays in half - birefringence

Double Refraction

• light splits into two

Birefrigence

• two rays have different RI and travel at different speeds

• when they interfere with each other under polarized loght you see the bright colors

• changes as you rotate specimen

Converging lens

• (+) wider middle

• convex lens

• bends rays toward eachother

Diverging Lens

• (-) thin middle

• concave lens

• makes rays spread apart

Real image

can be projected onto a screen or to the back focal plain of the objective

Virtual Image

• can’t be projected onto screen

• enlarged virtual image appears to lie on the same side of the lens as the object

Back focal plane

• plane in the objective where light is organized according to its angle

Conjugate Focal Planes

• different locations in a microscope's optical system where the light is focused to form related images

Image forming planes conjugate planes

• filed diaphragm, specimen, eyepiece field stop, and retina must be in common focus

Illuminating forming planes conjugate planes

• light source, substage condensers aperture diaphragm, back focal plane, and eye point of eyepiece must all be in common focus

angular aperture

width of the cone of light the object can collect

Color temperture

• in kelvin

• describes the color of light produced by a light source

Angle of incidence = angle of reflection

with true specular reflectance (mirror), the angle of incidence is always equal to the angle of reflection

Specular reflectance

• light hits a smooth, shiny surface and reflects in one main direction

Diffuse Reflectance

when light hits a rough or uneven surface and reflects in many different directions

Refraction

• light changes direction because it moves from one material into another.

Critical angle

• special angle that happens when light travels from a material with a higher refractive index to a lower refractive index

Dispersion curve

shows how the refractive index of a material changes with the wavelength (or color) of light

Becke Line

• halo moves toward higher RI medium on upward focusing

Oblique Illumination method

• object is illuminated by unilateral oblique

  transmitted light it will be asymmetrically shaded

• If the index of the particle is higher than that of the liquid, the

  particle appears to be shaded on the same side as the field. If the particle's index is lower than

  the medium, it appears to be shaded on the opposite side.

Calibrated ocular micrometer

• tiny ruler in eyepiece that helps you the size of the things you see under the micrscope

• changes at different objectives

Stage micrometer

• the ruler on microscope slide that has known measurements

Spherical Abberations

• variation of focal length with distance from the lens axis

• makes image blurry

• different rays focus at different points

Chromatic Abberation

Transparent materials do not refract all wavelengths equally

Curvature of field

• you can focus the image in one particular plane (F‐1 or F‐2)

• different parts of the image focus at a time

Distortion

• think magnification

• barrel: magnification decreases as you go further out

• pincushion: magnification increases as you go further out

Astigmatism

rays from different directions don't focus at the same point

Pleochroism

when a specimen appears to be different colors depending on the direction you look at it

Retardation

• retardation = Birefringence x thickness x 1000

• he difference in how far two light waves travel because they move at different speeds through a birefringent material

superior

above

inferior

below

medial

middle

lateral

away from middle

anterior

front

posterior

back

dorsal

towrads back - animals

ventral

towards belly “front'“ - animals

proximal

closer to body

distal

farther from body