Sphere, Cylinder Flashcards
Define meridian
Define a spherical lens
Optical lens with a symmetrically curved surface, resembling a portion of sphere
Power along all meridia is the same
Define a cylindrical lens
Optical lens that only has a curved surface in one direction along the axis of the lens
What is the axis of the lens
An imaginary line that runs through the centre of the lens perpendicular to its surface
What are the 3 types of toroidal surfaces
Tyre formation surface
Barrel formation surface
Capstan formation surface
What is a crossed cylinder
Two cylindrical surfaces with their axis perpendicular
What is the base curve and cross curve
Base curve- surface power in shallower principal meridian
Cross curve- surface power in steeper principal meridian (value numerically furthest from zero)