10 Photopic Vision

Question 1

13 . What is Point Spread Function?

Answer 1

Distribution of photons during a shutter catch.

Question 2

2. What are the basic units of photopic vision?

Answer 2

Photons

Question 3

3. T/F: The visible light spectrum is narrow.

Answer 3

True

Question 4

3. What is the approximate range of the visible light spectrum?

Answer 4

390 to 700 nm

Question 5

3. Most of energy from the sun is in the _____ range.A) InfraredB) Visible LightC) Ultraviolet

Answer 5

C) Ultraviolet

Question 6

13. When looking at a star how many cones are defining most of the image, and where are they located?

Answer 6

3-4 cones.Center.

Question 7

14. What do the bumps in Point Spread Function indicate?

Answer 7

Optical aberration

Question 8

15. T/F: Cones align towards the nodal point

Answer 8

True

Question 9

15. What helps to guide the photons to the chromophore?

Answer 9

The inner segment guides the photon to the chromophore located in the outer segment.

Question 10

16. T/F: Directional sensitivity of cones increases photon catch

Answer 10

False, directional sensitivity of cones decreases photon catch.

Question 11

16. Out of the 5500 photons entering the eye, how many actually hit the chromophore?

Answer 11

~2900 photons

Question 12

17. T/F: L/M cone ratio is 2:1.

Answer 12

False, L/M cone ratios vary.

Question 13

4. The number of photons that reach the photoreceptors has an INVERSE or DIRECT relationship to their frequency?

Answer 13

Inverse.

Question 14

4. How long is the “shutter time” for cones?A) 5 msecB) 100 msecC) 500 msec

Answer 14

B) 100 msec

Question 15

4. Photon catch is integrated over a _____ time span.A) LongB) ShortC) Medium

Answer 15

B) Short

Question 16

5. Which photoreceptor (rod or cone) is very sensitive and can respond to a single photon?

Answer 16

Rod

Question 17

Which photoreceptor (rod or cone) is very sensitive and can respond to a single photon?

Answer 17

Rod.

Question 18

7. Chromatic aberration can be described as a _______ on the retina.A) BlurB) RainbowC) Cloud

Answer 18

B) Rainbow

Question 19

7. Low frequency light (reds) focuses BEHIND or IN FRONT OF light?

Answer 19

Behind

Question 20

7. High frequency light (blue) focuses BEHIND or IN FRONT OF light?

Answer 20

In front of

Question 21

18. T/F: L cones are sensitive to short wavelengths?

Answer 21

False, L cones are sensitive to Long wavelengths.

Question 22

18. What is peak sensitivity to a cone?

Answer 22

Increased probability of a photon to be absorbed by a cone.

Question 23

19. T/F: L cones absorb 100% of all photons at different frequencies?

Answer 23

False, L cones absorb different frequencies of light at different percentages.

Question 24

19. At a frequency of 510 Hz, L cones respond to how many photons out of the 2900 that hit the retina?a.) 250b.) 170c.) 310

Answer 24

b.) 170

Question 25

20. What is the complex molecule that contains a chromophore and is found in the outer segment of a cone?

Answer 25

Rhodopsin

Question 26

20. T/F: Rhodopsin is a photon-catching molecule that contains chromophore.

Answer 26

False.

Question 27

20. T/F: Chromophore changes its shape from bent to straight when it absorbs a photon.

Answer 27

True

Question 28

21. Out of every 3 photons, how many end up hitting a chromophore?

Answer 28

2 photons

Question 29

21. T/F: Photoisomerzation is when a photon hits a chromophore isomer and changes it shape.

Answer 29

True

Question 30

22. T/F: If 700 photons cause photoisomerization of chromophore, only a fraction of photons are in the Point Spread Function.

Answer 30

True. Only 170 of photons are in point spread function

Question 31

9. ______ in the vitreous causes chromatic aberration secondary to difference in _______

Answer 31

Water, Index of refraction

Question 32

10. TRUE or FALSE:Brown circles contain ~25% of the photonsSmaller concentric circles contain ~ 50% of the photons

Answer 32

FALSEBrown circles contain ~50% of the photonsSmaller concentric circles contain ~ 25% of photons

Question 33

11. In the example from class, how many photons of a star’s light hit the retina?A) 58B) 684C) 1452

Answer 33

C) 1452

Question 34

12. Where is the image carried when the photons hit the cones? A) peripheryB) centerC) surrounding media

Answer 34

B) center

Question 35

8. Which of the following is out of focus?A) L cones B) M conesC) S cones

Answer 35

C) S cones