Lecture 5 - Physical And Optical Characteristics Of Ophthalmic Lenses

Question 1

What will alter the properties of light striking through it in a predictable way?

Answer 1

An optical system (a lens)

Question 2

The altered property from an optical system

Answer 2

Vergence

Question 3

Measures the degree of converging or diverging of a light wave at a given point in space

Answer 3

Vergence

Question 4

Vergence characterizes the curvature of a wavefront of light in what?

Answer 4

Air

Question 5

Diverging light has what kind of vergence?

Answer 5

Negative

Question 6

Converging light has what kind of vergence?

Answer 6

Positive

Question 7

Img Vergence equation

Answer 7

Img Vergence = obj vergence + power

V=U+P

Question 8

Point img that is exiting light with a positive vergence

Answer 8

Real img

Question 9

Point img that is exiting light with a negative vergence

Answer 9

Virtual img

Question 10

Point obj that is incident light with a negative vergence

Answer 10

Real obj

Question 11

Point obj that is incident light with a positive vergence

Answer 11

Virtual obj

Question 12

Definition is incident rays are close to the optical axis, which yields point img’s for point obj’s

Answer 12

Paraxial Approximation

Question 13

Line joining the centers of curvatures of the 2 surfaces of a lens

Answer 13

Optical axis

Question 14

What does the optical axis pass through?

Answer 14

Lens at the optical center

Question 15

Optical axis is perpendicular to what?

Answer 15

Each surface, so light passing through the axis is undeviated

Question 16

Axis perpendicular to the muscle plane around which the eye rotates when acted on

Answer 16

Axis of rotation

Question 17

Change in vergence of light that occurs at different points along its path (related to vertex distance)

Answer 17

Lens effectivity

Question 18

2 lenses have the same effective power if what?

Answer 18

They form a real or virtual img of an obj at the same point (usually far point of the eye)

Question 19

Rays on the periphery, far from the optical axis

Answer 19

Marginal rays

Question 20

Rays in close proximity to the optical axis

Answer 20

Paraxial rays

Question 21

Limits on an optical system’s field of view

Answer 21

Stops

Question 22

Physical entity that limits the amount of light passing into an optical system when viewing an object

Answer 22

Aperture stop

Question 23

Does an aperture stop have to be an actual aperture?

Answer 23

No; it can be like an actual aperture, like a camera or another physical element, like the edge of a lens

Question 24

Limits the size of the object that can be imaged by the system

Answer 24

Field stop (it works with aperture stops)

Question 25

Refers to the interval surrounding the retina in which an eye sees an obj as in focus

Answer 25

Depth of focus

Question 26

If light is focused in the depth of focus, is the obj in focus?

Answer 26

Yes; the obj will be in focus as well

Question 27

A short focal length leads to what depth of field?

Answer 27

Large depth of field

Question 28

What test in clinic inc DOF?

Answer 28

Pinhole

Question 29

Interval surrounding the fixation plane in which an obj can reside and still be in focus

Answer 29

Depth of field

Question 30

If an object is located in the depth of field, will there be blur?

Answer 30

No; there will not be a perceivable blur

Question 31

An increase in aperture size does what do depth of field and depth of focus?

Answer 31

Decrease in both

Question 32

Optical systems create distortions in img quality or a deformation of the img plane. What are the 2 types of aberrations?

Answer 32

Monochromatic aberrations

Chromatic aberrations

Question 33

Wavelength independent aberrations

Answer 33

Monochromatic aberrations

Question 34

Monochromatic aberrations do what to img quality and img plane?

Answer 34

Distort img quality

Deform img plane

Question 35

3 ways monochromatic aberrations distort img quality:

Answer 35

Spherical
Coma
Radial astigmatism

Question 36

2 ways monochromatic aberrations deform the img plane:

Answer 36

Curvature of field

Distortion

Question 37

2 types of chromatic aberrations:

Answer 37

Longitudinal

Transverse