Observation tools

Question 1

Microscope scales 2

Answer 1

• Provide information at differing scales ranging, micron to picometer scales
• mikrós - small, skopein - to look

Question 2

Observation tools - seeing small things in the body 6

Answer 2

• magnetic particle imaging
• magnetic resonance imaging (blodcirculation)
• near infra-red imaging (tumor scanning)
• ophthalmic microscopy (eye surgery)
• Flouroschopy/X-ray imaging
• ultrasound imaging (baby)

Question 3

Light

Answer 3

• radiant energy or electromagnetic radiation (EMR)

- has both electric and magnetic components

Question 4

EMR

Answer 4

electromagnetic radiation

• radio, microwave, infrared, visible, ultraviolet, x-ray, gamma ray
• visible 400-700

Question 5

The nature of light - reflection

Answer 5

Direction change of a wave front at an interface between two dissimilar media s.t. the wave front returns into the medium from which it originated (ex.mirror)

Question 6

The nature of light - refraction

Answer 6

Direction change of a ray of light from one transparent medium to another with different optical density.
- a less to a more dense medium –> bent perpendicular to the surface, greater deviation for shorter wavelengths.

Question 7

The nature of light - diffraction

Answer 7

• Light rays bend around edges - new wavefronts are generated at shape edges
• The smaller the aperture, the bigger the diffraction

Question 8

The nature of light - dispersion

Answer 8

Separation of light into its constituent wavelengths when entering a transparent medium - the change of refractive index with wavelength, such as the spectrum produced by a prism or by water droplets in a rainbow

Question 9

Contrast - Bright Field (normal) 3

Answer 9

• Full aperture is illuminated
• Does not reveal differences in brightness between
• Light absorption of sample is imaged

Question 10

Contrast - Dark Field 3

Answer 10

• A central obstruction blocks the central light cone
• Enhances contrast by indirect illumination
• Light scattering at sample is imaged

Question 11

Chromatic Aberration 3

Answer 11

• “focus all length to the same point”
• Dispersion: An optical lens has different refractive indices for different wavelength (Rainbow color) or…
• Achromatic lenses combine two or more lenses o correct chromatic aberration (single color yellowish)

Question 12

Spherical Aberration

Answer 12

• Aberration with a spherical lens

- If point spread function = blurriness

Question 13

Aberration

Answer 13

lenses that causes light to be spread out over some region of space rather than focused to a point.

Question 14

Aberration

Answer 14

lenses that causes light to be spread out over some region of space rather than focused to a point.

Question 15

Astigmatism

Answer 15

• Blurred vision

- Not axisymmetric (error in the shape of the optical surface or due to misalignment of the components)

Question 16

Flourenscene microscopy

Answer 16

• High energy beam (UV) to emit visible light
• down to 2-5nm
• filter for emission and excitation

Question 17

specimen

Answer 17

laboratorieprov

Question 18

resolution

Answer 18

defined as the shortest distance between two points on a specimen that can still be distinguished by the observer or camera system as separate entities

Question 19

NA

Answer 19

light gathering capacities of an obj

Question 20

depth of field

Answer 20

distance between the nearest and farthest obj that are acceptable in sharp focus in an image (without lossing sharpness) - depends on the resolution
- higher magnification smaller depth of field

Question 21

Bright field

Answer 21

area which absorb light (e.g. electrons) appear dark whereas the areas with a low interaction btw sample and light appear bright.

Question 22

Dark field

Answer 22

the light (e.g. electron beam) which barely interacts with the ample does not hit the detector (dark area). Only the light which is scattered at the sample can reach the detector. These appear brights