Optics

Front 1

Speed of light

Back 1

c = vh

v = frequency

h = wavelength

C = 3x10^10 cm/s

Front 2

Energy of a photon

Back 2

E = hv

h = Planks constant = 6.6x10^34

v = frequency of light wave

Front 3

Shorter wavelengths = ________ energy and refract _______.

Back 3

more and more

Blue Bends More

Front 4

Critical angle (total internal reflection)

Back 4

sin(critical angle) = n'/n

n air = 1

n water = 1.33

Front 5

Vergence formula

Back 5

U + D = V

U = object vergence

D = Lens power

V = Image vergence

Front 6

Lens power

Back 6

D = 1/f

f = focal length (meters)

Front 7

Snell's Law

Back 7

nsin(i) = n'sin(r)

n = refractive index

i = angle of incidence

r = angle of refraction

Front 8

Prismatic power

Back 8

/\ = (image deflection cm)/meters

/\ = 100tan(B)

B = angle of deviation

Front 9

Prentice's Rule

Back 9

/\ = hD

h = distance from optical axis (cm)

D = lens power

Front 10

Reduced schematic of the eye

Back 10

Front 11

Calculation of retinal image size

Back 11

I/17mm = O/X

I = Retina image size

O = Object size

X = Distance to object

Set up like triangles

Front 12

Spherical equivalent

Back 12

SE = sphere + (cyl/2)

Front 13

Refracting power of a spherical surface

Back 13

Ds = (n' - n)/r

n = refractive index to left

n' = refractive index to right

r = radius of curvature of surface (m)

(+ is convex, - is concave)

Front 14

Reflecting power of a spherical mirror

Back 14

Dr = (-1/f) = (-2/r)

f = focal length = (r/2)

r = radius of curvature

(- is convex, + is concave)

Front 15

Power of thin lens immersed in fluid

Back 15

Dair/Daqueous = (niol - nair)/(niol - naqueous)

Front 16

Power of lens at new vertex distance

Back 16

D2 = D1 + S(D1)^2

D1 = original power of lens

D2 = new power of lens

S = change in vertex distance (m)

**S is + or - (V1 - V2)

Front 17

Linear Magnification

Back 17

ML = I/O

I = image distance or height

O = object distance or height

Front 18

Axial Magnification

Back 18

Max = (ML)^2

ML = linear magnification

Front 19

Angular Magnification

Back 19

Ma = xD

x = distance

D = power of lens

Front 20

Simple Magnifier (+ sphere lens)

Back 20

M+ = D/4

D = power of a simple plus lens

ex. 1x magnifier = +4 lens; 2x = +8 lens

Front 21

Telescope Magnification

Back 21

Mtele = -De/Do

De = eyepiece power

Do = objective power

Front 22

Total accommodatoin through telescope

Back 22

Atotal = An(Mtele)^2

An = normal accommodation required

Mtele = magnification of telescope

Front 23

SRK IOL power formula

Back 23

P = A - 2.5L - 0.9K

A = constant for type of IOL

L = axial length of eye

K = average keratometry value

Front 24

Antireflective coating on glass

Back 24

Is 1/4 wavelength thick

--> causes the reflecting light to be out of phase by 1/2 wavelength

--> negative interference

Front 25

Convex lens is a _____ lens and gives _____ vergence

Back 25

plus and plus

Front 26

Concave lens is a ______ lens and gives _______ vergence

Back 26

minus and minus

Front 27

Cylindrical lenses

power is ______ (@ or x)

axis is ______ (@ or x)

Back 27

power is @

axis is x

Power is @ 90 degrees from axis x

Front 28

How to convert from plus cyl to minus cyl notation

Back 28

1. add cylinder to sphere

2. switch the sign of cylinder

3. change axis of cylinder by 90 degrees

Front 29

What is the power cross for the following Rx:

-4.00 + 3.00 x 180

Back 29

-1.00

|

----------- -4.00

|

Front 30

Real image vs virtual image for a lens

Back 30

Real Image Virtual Image

- Right of lens - Left of lens

Front 31

Image characteristics of plus (converging) Lens

Back 31

Image is Real & Inverted most of time.

Exception: object distance < or = focal length will produce a virtual and upright image

Front 32

Image characteristics of a minus (diverging) lens

Back 32

Image is always virtual and upright

Image is always smaller than the object

Front 33

Real image vs virtual image for a mirror

Back 33

Real Image Virtual Image

- Left of mirror - Right of mirror

opposite of lenses

Front 34

Image characteristics of convex (-) mirror

Back 34

Always

- Virtual (right)

- Upright

- Minified

Front 35

Image characteristics of concave (+) mirror

Back 35

1. Object outside focal point

- Real (left), Inverted, Mag/Min or same size

2. Object on focal point

- No image

3. Object inside focal point

- Virtual, Upright, Magnified

Front 36

Total magnification of a lens system

Back 36

Mtotal = M1xM2xM3....

Front 37

Prism diopter =

Back 37

= cm of image displacement over a reference of 100 cm

Front 38

Galilean Telescope

Back 38

Eye piece: minus (high D)

Object piece: plus (low D)

Separation = subtract the two focal lengths

Upright image

Front 39

Keplarian Telescope

Back 39

Eye piece: plus (high D)

Object piece: plus (low D)

Separation = add the two focal lengths

Inverted image

Front 40

Which bifocal lens would you add to a + lens?

Back 40

Round top

- minimizes displacement

- still has jump

Front 41

Which bifocal lens would you add to a - lens?

Back 41

Flat top or executive

- minimized both displacement and jump

(always minimizes jump in both hyperopes and myopes)

Front 42

Spectacle lenses: Image size changes ____% for each 1D change in Rx

Back 42

2%

+ magnify

- minify

Front 43

Prism: Image is displaced in which direction?

Back 43

Front 44

Age 40 has _____ D of accommadation

Back 44

6D

Front 45

Up to age 40, accommodation decreases by _____D every ____ years.

Back 45

decreases by 1 D every 4 years

Front 46

Between age 40 to 48, accommodation decreases by ____ D every ____ years?

Back 46

decreases by 1.5D every 4 years

Front 47

Above age 48, accommodation decreases by _____ D for every _____ years?

Back 47

decreases by 0.5D every 4 years

Front 48

Snellen denominator = _____ arcmins at that distance

Back 48

5 arcmins

Ex. 20/60 >> letter subtends 5 arcmins at 60ft.

So, at 20 feet it is bigger by 3x (60'/20')

3 x 5 arcmins = 15 arcmins on the retina

Front 49

Good soft contact lens has _____ fit?

Back 49

3-point touch

Lightly touches apex and limbus on both sides

Front 50

Define aniseikonia

Back 50

Unequal magnification (size) of images projected on the retina due to difference in spectacle correction between eyes.

Can tolerate up to 7-8% difference in image size.

This is approximately 3D difference between each eye.

Front 51

List the methods to reduce cylinder-induced asthenopia and distortion

Back 51

1. Use minus cylinder form

2. Minimize the vertex distance

3. Decrease cyl power while keeping the proper spherical equivalent

4. Rotate the axis of the correcting cyl towards 90 or 180

Front 52

When performing retinoscopy, as neutralization is approached, the light beam becomes _______, _________ & __________.

Back 52

brighter, wider & faster

Front 53

AC/A ratio by Gradient Method formula

Back 53

AC/A = (deviation c lens - deviation s lens) / (lens power)

Front 54

Power of a thick lens

Back 54

Pfront + Pback - [(t/n) x (Pfront x Pback)]

t = thickness of lens in meters

n = refractive index of lens

Front 55

Zero order aberrations:

Back 55

Piston

Front 56

First order aberrations:

Back 56

Prism

Front 57

Second order aberrations:

Back 57

Myopia (positive defocus)

Hyperopia (negative defocus)

Regular astigmatism

Front 58

Third order aberrations:

Back 58

look these up

Front 59

Fourth order aberrations:

Back 59

look these up