Chromatic Aberrations In The Human Eye Flashcards Preview

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Flashcards in Chromatic Aberrations In The Human Eye Deck (79)
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1

What are the types of monochromatic aberrations

Defocus
Astigmatism
Coma
Trefoil
Spherical aberration

2

What are the chromatic aberrations

Longitudinal (LCA)
Transverse (TCA)

3

What are the two things we care about in LCA

-Chromatic difference of power (focus, defocus, blur..)
-chromatic difference of refraction

4

What two things do we care about in transverse chromatic aberration (TCA)

-Chromatic difference of position
-chromatic difference of magnification

5

What is said about the stimulus if red is focused on the retina

It is low stimulus, object far away

6

What is said of the stimulus of the blue is in focus

Object is close, high stimulus
-may cue accommodation

7

Significance of chromatic defocus (LCA) depends on what

Luminance

8

What does the autorefractor measure people

Hyperopic

9

What is the LCA average (distance from red to blue)

2.1D

10

At what wavelength do people become hyperopic

580nm

11

What happens to the refractive error with higher wavelengths

Increases

12

What do short wavelengths make people

Myopic

13

What do long wavelengths do to people

Make them hyperopic

14

The chromatic difference of focus (CDF) reduces retinal image contrast by _____ of defocus

0.2D
-relatively minor

15

What is the amount of defocus in the chromatic difference of defocus equivalent to

The amount of defocus is equivalent to the depth of field of the human eye

16

What does the chromatic difference of focus do for vision

Reduces contrast moderately

17

Effect of chromatic defocus on VA

-Minor effect on the VA
-any attempt to correct would only provide marginal benefit and surface new problems

18

The chromatic difference of magnification for two wavelengths of light has what kind of relationship with the axial distance (z) from the pupil to nodal point

Proportional

19

What is the equation for the chromatic difference of magnification

Change in mag=z(2D)

20

What is the change in mag usually

0.8%
Considered insignificant

21

What does the magnitude of the effect depend on

Axial distance Z

22

When can magnification be 0

Only if the pupil and nodal point are at the same place
0 axial length

23

What is the axial length we look at for magnification

Pupil to nodal point

24

When is magnification significant

Looking through optical instrument.
Depth perception (3D glasses)

25

CDM (chromatic difference in mag) and depth perception

Red and blue have different focuse and magnification.
-if one eye view through short wavelength light, the visual system may interpret the different sized retinal images as a difference in relative depth resulting in a distorted perception of 3D world

26

The chromatic difference of position is directly proportional to

-stimulus eccentricity (certain field angle)
-lateral displacement (foveal vision)

27

How much is the pupil decentered

0.5mm nasally

28

CDP (chromatic difference of postion) for stimulus eccentricity

For object points off the achromatic axis, the amount of TCA as a function of axial location of pupil z, CD-R, and the angle of eccentricity

29

What happens when you increase eccentricity to TCA?

Increases it just slightly

30

Equation for stimulus eccentricity

TCA=(z)sin(e)(2D)

Z=axial length
E=eccentricity
2=given, LCA