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Flashcards in Aberrations of optical system Deck (16)
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1
Q

why do monochromatic aberations happen

A

from the shapes and positions of optical surfaces and to the positions of limited aperatures

2
Q

why do chromatic aberrations happen

A

variation in refractive index w/ wavelength of light (dispersion)

3
Q

what are the seidel aberrationst hat are most relevant for the eye

A

SA
coma
radial astig

4
Q

which seidel aberr are mainly considered in the quality of ophthalmic lenses

A

curvature of field

distortion

5
Q

what is positive SA

what lenses does this happen for

A

marginal rays focus in front of the paraxial rays
marginal zones have more positive power than the central zone
-positive spherical lenses

6
Q

what is negative SA

what lenses does this happen for

A

marginal rays focus in back of paraxial rays meaning the marginal zones have less power than the central zone

  • positive aspheric surfaces that have a steeper curvature in the center than in the periphery
  • negative sph lenses
7
Q

what is longitudinal SA

A

the difference in positiion of the marginal and paraxial foci along the optic axis

8
Q

what is lateral SA

A

the difference in position of the marg and paraxial rays in the plane of the paraxial focus

9
Q

how are SA minimized in real eyes

A

small pupil diameter
aspheric surface
gradient refractive index of lens

10
Q

what is positive coma

A

marginal rays meet at a location further from the optic axis
brighttest image on bottom

11
Q

what is negative coma

A

marginal rays focus closer to the optic axis than the chief ray, brightest at top

12
Q

when does pincushion distortion happen

A

when an off axis ray falls beyond the chief ray

high plus

13
Q

when does barrel distortion happen

A

when an off axis ray falls closer to the optic axis than the chief way
high minus

14
Q

a stop in front of a positive lens will cause what kind of distortion

A

barrel

15
Q

a stop in back of the postivie lens will cause

A

pincushion

16
Q

what is chromosteropsis or chromatic steropsis

A

due to slight displacement of the natural pupil and the difference in visual and optical axes, some observers report ath red objects appear closwer than blue during binocular vision or the opposite