Geometric Optics Flashcards
Equation for Power of an SSRI
-which is positive/negative
F = (n2-n1)/r
r in meters and positive if surface is a “C” shape
Collimating lens
Rays leave at infinity
Nodal Point
Light passes undeviated
-Center of curvature for an SSRI
Snells Law
The ration of sines of the angles of incidence/refraction are equal to the ratio of indices (n)
Total Internal Reflection
Applies Snell’s Law to find a critical angle where angle of refraction = 90
Traveling from high to low n
Downstream Vergence
New = Old / ( 1 - dOld)
-downstream/closer to eye: becomes more minus
Equivalent Power
Approximates a thick lens as two thin lenses
Fe = F1 + F2 - (t/n)F1F2
Fe increases as n increases but decreases as t increases
Back Vertex Power
Plane waves entering
F = F2 + F1 / (1 - (t/n) F1)
F becomes more positive/ less negative as t increases
Aperture Stop vs Field Stop
Aperture Stop limits light and FOV
-Eyes AS is pupil, for most telescopes it’s objective lens
Field Stop limits FOV
Entrance Pupil vs Exit Pupil
Entrance Pupil is the image of the AS by all lenses in front of it
Exit Pupil is the image of the AS by all lenses in behind it
-Exit Pupil is inside a Galilean telescope but outside a Keplerian
Entrance Port vs Exit Port
Entrance Port is the image of the FS by all lenses in front of it
Exit Port is the image of the FS by all lenses in behind it
Focal Ratio
Indication of how much light will enter a system (camera speed/exposure)
Lower f = MORE light
f = focal length/entrance pupil diameter
Depth of Field vs Depth of Focus
Depth of Focus is an interval around the retina
Depth of Field is an interval in space (excludes accommodation)
-increases as focal length decreases
Angle of Half Illumination
Metric measurement for FOV
Field of Fixation
Angle made from optical axis by entrance port measured from eye’s center of rotation (usually 14 mm from cornea)
