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Year 1 Optics Flashcards

1
Q

What is a equal to apical angle in Prentice Position?

A

i2

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2
Q

What is equal to apical angle in Frontal Position?

A

i1

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3
Q

What is equal to apical angle in Minimum Angle of Resolution? Are there any other equations we should know?

A

2i1’
i2’ = i1
i1’ = i2

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4
Q

What is the eV equation?

A

eV = Joules/e

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5
Q

What is Joules equivalent to?

A

DeltaE

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6
Q

What is the minimum angle of resolution equation?

A

Angle in seconds that it subtends by divided by the no. of units in the letter (usually 5 units)

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7
Q

How do we convert Snellen to logMAR?

A

E.g. 6/12 would be 12/6 = 2
log2 = 0.3 logMAR

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8
Q

How do we convert logMAR to Snellen?

A

Reverselog0.3 = MAR
MAR x5 = Total angle subtended
MAR x6 = Snellen Equivalent

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9
Q

What path does light travel along in relation to time?

A

The path of least time

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10
Q

How is frequency measured?

A

In the number of vibrations per second measured in Hertz or ‘cps’

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11
Q

What are the abbreviations for Speed?

A

C (in a vacuum)
V (not in a vaccum)

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12
Q

What is wavelength?

A

The gap between 2 troughs or 2 peaks

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13
Q

How is wavelength measured?

A

In nanometers (10 to the power of -9)

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14
Q

What is the constant of speed of light in vacuo?

A

3 x10 to the power of 8

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15
Q

What is the visible light wavelength range?

A

400 - 700nm

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16
Q

What is the equation for speed?

A

Speed = Wavelength x Frequency

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17
Q

How do we work out nmedium?

A

nmedium = speed in vacuo/speed in medium

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18
Q

Define refractive index

A

Speed of the ray as it changes as it passes from one to another which gives us refractive index

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19
Q

Where does light deviate in a prism?

A

Towards the base (image deviates towards the apex)

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20
Q

When going rare to dense, what direction does the light deviate?

A

Towards the normal

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21
Q

In parallel sided blocks what does i1’ = i2 mean?

A

Angle of refraction at the 1st surface is equal to the angle of incidence at the 2nd surface

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22
Q

What’s the formula for DTOT?

A

(i2’ + i1) - a (i1’ + i2)

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23
Q

What is the DTOT formula for then apical angle is equal to or <10PD?

A

a(n-1)

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24
Q

What is the equation for Curvature?

A

Curvature = 1/radius of curvature

R = 1/r

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25
What do we measure instead of the angle of incident of a curved surface?
Measure the radius (r) from surface of object point and then from surface to the image point
26
What is L'?
Image vergence (curvature of light wavefront leaving the focal surface or lens)
27
What is L?
Object vergence
28
What is Fsurf?
Measures how much the object changes the object vergence
29
What relationship is there between object distance and image distance and object and image vergence?
Inverse relationship so when object distance is closer there is a larger vergence
30
What relationship is there between rsurf and Fsurf?
Inverse relationship between radius of curvature of a focal surface and the focal power of a surface
31
If it's a real object what is a minus number?
l (little L)
32
What does a convex surface mean for figures?
That r (radius of curvature) is a positive value
33
What does a concave surface mean for figures?
That r (radius of curvature) is a negative value
34
How many outcomes are there for a real object adding curvature?
1) Image vergence is converging 2) Image vergence is diverging 3) image vergence is zero
35
If a real object, adding divergence = one outcome which is what?
Image vergence is diverging
36
How do we work out first and second focal lengths in a curved surface?
f = n/-Fsurf f' = neye/Fsurf
37
How do we work out first and second focal lengths in thin lenses?
f = 1/-Fsurf f' = 1/Fsurf
38
How do we know if an image is erect?
h' will be positive
39
How do we know if an image is magnified?
h' > h Or do h'/h and if higher than 1 then it's magnified
40
What does it mean if the image is <1 in magnification?
It means it's not magnified but is minified
41
What does it mean if l is before f on the axis (closer to surface)?
Virtual image
42
How to work out tanW?
h' / l' - r
43
How do we work out Flens in thin lenses?
F1 + F2 F1 = nlens - 1 / r1 F2 = 1 - nlens / r2
44
How do we work out F1 in thin lenses?
nlens - 1 / r1
45
How do we work out F2 in thin lenses?
1 - nlens / r2
46
If we have a strong lens, what do we not have to do as much in glasses?
If a strong lens (Flens) we don't have to decentre (c) as much as cFlens
47
What is neye's value?
1.333
48
What is f'eye?
Calculation of where the retina needs to be for this model eye to be focused for looking at the object at optical infinity. Where the retina needs to be looking at optical infinity.
49
What is conjugate focus?
Means there's a special relationship so will form an image at some point (B & B'). This is a retinal conjugate with the optical reversibility of light
50
If Feye is >+60D then what needs to be smaller to remain emmetropic?
f'eye
51
If Feye is <+60D then what does f'eye need to be?
Larger to account for Feye being smaller
52
When is an eye considered emmetropic?
When f'eye and Feye are satisfied
53
What is under active control?
f'eye
54
What is the distance from the anterior corneal surface to retina?
Axial length (k')
55
What is k?
Distance to retinal conjugate / far point
56
What is K'?
Axial length in D Represents required vergence for light to image on the retina
57
What is K?
Ocular refraction. Error between optical power and eye size.
58
What is Ametropia?
Not Emmetropia
59
When is someone considered Myopic?
When Feye > K' or f'eye < k'
60
When is someone considered Hypermetropic?
When Feye < K' or f'eye > k'
61
Where is the retinal conjugate of a myope?
Is in real object space when accommodation is relaxed. No incident ray parallel to optical axis so light comes out converging in a myope. k (retinal conjugate) is in real space as a minus value
62
Where is the retinal conjugate of a hyperopic?
Is in virtual space when accommodation is relaxed so beyond measure of the eyes No incident ray parallel to optical axis so light comes out diverging in a hypermetrope k (retinal conjugate) is a plus so is in virtual object space
63
What is diffraction?
Waves coming in straight bend around an edge. This happens around the edge and are propagated out but get cancelled before this; the surface acts as another light source
64
What type of light needs to be used to show diffraction?
Monochromatic
65
When do we get interference?
If 2 wavelengths are of the same speed with max and min displacements in time with each other we get interference
66
What is 'Constructive Interference'?
When in-phase wavelengths increase the maximum amplitude (sum of the two)
67
What is 'Destructive Interference'?
When the waves are 180 degrees out of phase of each other; the positive direction of one matches negative direction wavelength of another so they cancel each other out
68
When light travels from rare to dense medium, what happens to the reflected light?
Undergoes a "phase change" equal to 180 degrees so reflected light is also polarised if the wave is transverse
69
What is polarisation?
Due to vibrations of the electrical and magnetic fields being perpendicular to the direction of propagation, they need to be perpendicular to each other
70
What is polarisation EVIDENCE of?
Evidence of a transverse wave
71
What is wave nature shown by?
Dispersion Diffraction Interference Polarisation
72
In a thin lens, if f' is a minus number, what does it mean?
That the light is diverging
73
In a thin lens, if f is a minus number, what does this mean?
That the light is converging
74
What does it mean for Fsp to always be more negative than K?
Spectacle correction is always more negative than ocular refraction
75
What are we doing when we place a correcting lens?
Making the 2nd focal point of the correcting lens coincide with the far point (k) of the eye
76
In contact lenses what is K = 1/k equal to?
Fcl = 1 / f'cl

Optics Theory (1 decks)

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