Adv Imaging Flashcards
(7 cards)
how much light is contained in the airy disk? (what percentage?)
84%
SMALLEST PSF is when the pupil is what size? What’s the tradeoff? What’s the compromised size?
7mm - huge! tradeoff - aberrations. Compromised ~3mm
what’s the neural limit in cyc/deg? equal to what VA? equal to how many mins of arc?
-if frequency is greater than the neural limit, what phenomenon happens?
60 cyc/deg = 20/10 = 0.5min arc
aliasing! (anything greater >60cyc/deg)
-cones can’t discern dark/light b/c they run into each other
what’s the resolution limit needed for IMAGING cones (in cpd?) What’s this frequency called?
120cyc/deg - the width of ONE cone!
-SAMPLING frequency
any wavelength between ___-___nm WILL be transmitted to the retina
400-1200nm
cornea: anything goes.
lens: absorbs everything below 400nm
vitreous: absorbs infrared
retina: macular pigment: 400-550, esp 460! (blue)
SLO: scanning laser oscope - uses vertical scanning m___ across retina; uses __hole to select the depth you want
- SLO axial (delta Z) depends on the ___ stop
- give a couple examples of these:
mirrors, pinhole selects depth
- dependent on the F-stop
- HRT, GDx, optos
what limits LATERAL resolution of an OCT? (hint: it’s NOT a limiting factor in axial resolution)
-what limits AXIAL resolution of an OCT?
pupil diameter
bandwidth limits axial! determines L - the coherence length, which you want to be as SMALL as possible so you can differentiate layers
