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Alicat38
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Curvature of surface
 the angle turned through per unit length of arc
 R = 1/r in Dioptre (D)

Refraction
Light passes through an interface b/t 2 optical media

Reflection
Light bounces at interface

Image
New wavefront curvature (vergence in air) L' gives distance to image

More curvature >
more vergence changing power

Lens gauge/clock/measure
measures surface power by measuring the sag of a lens of a specific refrative index

Centered or symmetrcal elements
elements positioned such that they have a common axis

Surface power
 Measure of the ability of the surface to change the vergence of light
 Fs = (n'n)/r = n'/f' = n/f
 in Dioptre

Chief ray of extended object through a spherical surface
ray passes through the center of curvature (it is undeviated because it is normal to the spherical surface)

Lens
has two refracting surfaces (both surfaces spherical or one surface may be plano (plane, no curvature, zero power))

Center thickness
Thickness at the vertex of the lens

Thin lens
negligible centre thickness, change in vergence as light passes through the lens is insignificant

Biconvex/concave
both surfaces are have the same sign but different powers

Equiconvex/concave
both surfaces have the same power

Meniscus
center of curvature is on the same side of lens for both surfaces

planoconvex/concave
zero power on one side, all power on other side

Lens form (bending)
any power of lens can be obtained by a combination of surface powers

Principal foci
 Light from infinity (parallel) passes lens and focuses at the SECOND prinicipal focus
 Light emerging from FIRST principal focus emerges from the lens parallel

Symmetric planes
 closest possible distance b/t a real object and its real image in a plus lens
 OR
 closest possible distance b/t a virtual object and its virtual image in a minus lens

Principal plane
location of object and image when m=+1

