Corrected Curve Lens Design

Question 1

periscopic lens has a _ BACK curve

Answer 1

-1.25

Question 2

meniscus lenses have a _ FRONT curve

Answer 2

+6.00

Question 3

a _ design has a specific base curve to minimize aberrations

Answer 3

corrected curve lens

Question 4

chromatic aberrations occur due to: _

Answer 4

abbe number/lens material

Question 5

The 5 aberrations that occur when viewing peripheral objects are called?

Answer 5

Seidel (3rd order)

Question 6

What aberrations are experienced when peripheral rays focus @ different location than paraxial rays?

Answer 6

spherical aberrations

Question 7

What are the only aberrations that occur with points on the optic axis?

Answer 7

spherical aberrations

Question 8

What aberrations occur due to difference in image distance of off axis locations?

Answer 8

coma

Question 9

What aberrations occur when off axis light passes through spectacle lenses at an angle?

Answer 9

radial/oblique astigmatism (RA)

Question 10

What aberrations occur when the location of off-axis image points do not match the screen location?

Answer 10

curvature of field

Question 11

What aberrations occur due to changes in magnification in the periphery compared to the center?

Answer 11

distortion

Question 12

Distortion:
magnification (inc/dec) at periphery for plus lenses?
magnification (inc/dec) at periphery for minus lenses?

Answer 12

increases

decreases

Question 13

_ and _ are minimized by the pupil

Answer 13

spherical aberrations

coma

Question 14

_ and _ may be minimized individually by selecting appropriate base curve

Answer 14

radial astigmatism

curvature of field

Question 15

if RA is eliminated, then effects of curvature of field will _ (and vice versa)

Answer 15

be enhanced

Question 16

_ cannot be eliminated

Answer 16

distortion - not very problematic

Question 17

What are the 2 most important aberrations to control?

Answer 17

Radial astigmatism

curvature of field

Question 18

The locus of far points for all possible viewing angles is called _

Answer 18

far point sphere (FPS)

Question 19

the _ meridian contains the optical axis and the off-axis object

Answer 19

tangential

Question 20

with horizontal focus of radial astigmatism, _ will appear clear
with vertical focus of radial astigmatism, _ will appear clear

Answer 20

vertical boundaries

horizontal boundaries

Question 21

radial astigmatism is induced if lens are tilted:
pantoscopic tilt means:
faceform tilt means:

Answer 21

on horizontal axis - reading glasses

on vertical axis - sports lenses

Question 22

for pantoscopic tilt, 1mm OC drop for every _ degrees of tilt

Answer 22

2

Question 23

with curvature of field, the dioptric difference between the actual focal point and the desired focal point is called?

Answer 23

power error

Question 24

the more off axis you get, the _ the deviation

Answer 24

greater

Question 25

3 ways to construct a corrective curve lens:

Answer 25

point focal lens
percival form lens
minimum tangential error

Question 26

corrective curve lens design: correct radial astigmatism and leave power error uncorrected

Answer 26

point focal lens

Question 27

corrective curve lens design: minimize power error, but leave some residual RA

Answer 27

percival form lens

Question 28

corrective curve lens design: partially corrects both errors (compromise)

Answer 28

minimum tangential error (most common)

Question 29

What 4 parameters must you consider when constructing a lens? Which one is most important?

Answer 29

vertex distance, lens thickness, refractive index, front and back surface powers (most important)

Question 30

Tscherning ellipses does not eliminate RA for _ or _

Answer 30

aphakes or high hyperopes (high + powers)

Question 31

plano lenses generally have back surface curves of _

as lens become more minus, the back surface _ and front surface _

Answer 31

-6.00 D

steepens, flattens

Question 32

as plus lens power increases, the back surface becomes more _, and the front surface becomes _

Answer 32

flatter, steeper

Question 33

When 2 lenses call for different BC:
if both plus: choose _
if both minus: choose _
if one +, one -: choose _

Answer 33

steeper
flatter
higher numerical value (usually +)