Formulas and Optical Theory Flashcards
TP = sphere power + cylinder power x sin 2 (0)
Power in Oblique meridians
N1 sin i = N2 sin r
Snells’ Law
angle I =angle r
Law of reflection
Prism (^)=(hxD) / 10
Prentice Rule
D = 1/f
Focal length - Dioptic power
De = D1 +D2
Nominal Power
FPD = A +DBL
Frame PD
Dec = (FPD - PPD) / 2
Binocular decentration
Speed of light in air/ speed of light in medium.
Index of refraction
MBS = ED + (2 X Dec)
Minimum blank size
I need a lens with power +3.50D. If I use a lens blank with a front surface power of +8.00D, what back surface do I need?
De = D1 + D2 +3.50 = +8.00 + D2 D2 = -4.50
I have a lens with a front surface of +9.25D and a back surface of -2.25D. What is the power of the lens?
De = D1 +D2 De = +9.25 + -2.25 De = +7.00
I want my lens to have a power of -3.00D. What back surface do I need if the front surface is +8.00D?
De = D1 +D2 -3.00 = +8.00 +D2 D2= -11.00
What is the difference between a high index lens and a aspheric lens?
High index refers to the material of the lens; Aspheric refers to the surface design of the lens
What are the three things that can happen to a ray of light when it passes through a lens?
Absorbed, reflected, refracted
What is the difference between a monocular distance PD and a binocular distance PD?
Monocular PD: each eye is measured separately from the center line of the face
Binocular PD: the measurement is taken from the center pupil to center pupil