Lenses

There are many types of lenses which are mainly made of glass or plastic. They are used in spectacles, projectors, telescopes, microscopes, binoculars and many other optical equipments and instruments. However, the 2 main categories of lenses are "Converging Lenses" and "Diverging Lenses"

Types of Converging Lenses

• Biconvex Lens
• Plano-convex Lens
• Concavo-convex Lens

Types of Diverging Lenses

• Biconcave Lens
• Plano-concave Lens
• Convexo-concave Lens

Main features of a thin converging lens

Optical Centre, O is the point midway between the lens surfaces on its principle axis

Principle Axis is the line passing through the optical centre, O symmetrically.

Principle Focus, F is also known as the the focal point is the where all the rays close to and incident parallel to the principle axis converge after refraction. 

Focal Length, f is the distance betwen the optical centre and the principle focus.

Focal Plane is perpendicular to the principle axis. 

For more ray diagrams and their applications... ...

• Ray diagram of object distance equal to infinity
• Ray diagram of object distance greater than 2f
• Ray diagram of object distance equal to 2f
• Ray diagram of object distance in between f and 2f
• Ray diagram of object distance equal f
• Ray diagram of object distance lesser than f

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