retinal mosaic

Question 1

rods peak at ___ degrees

Answer 1

15

Question 2

adaptive optics

Answer 2

take images of individual cones
Adaptive Optics & Retinal Densitometry: shine light of different wavelengths, how much light reflects back = L, M, S cones
Random arrangement
Ratio of L and M variable
S: sparse (<10% of cones)

Question 3

resolution of phr

Answer 3

40-60 c/deg

Question 4

aliasing

Answer 4

inadequate sampling of continuous function
Signal differs from original (b/c sparse sampling)
Lower spatial Freq & different orientation

Question 5

avoid aliasing

Answer 5

nyquil limit N/2
Sampling Freq (N) should be 2x highest spatial frequency
E.g. 40 r.f to sample 20c/deg
Below: looks like smaller spatial resolution
Can’t tell it’s grating
Blurring eye’s optics helps PREVENT aliasing
Periphery: lower cone dens = aliasing REDUCED by disarray in sampling mosaic

Question 6

s cones sparse - why?

Answer 6

Chromatic aberration in eye blurs short wavelength
Sparse is ADEQUATE to capture retinal image seen by s
Blue out of focus on retina