Hammad TariqOptometrist

Isra Medical University Islamabad

Reflection

Conditions for reflection

Laws of reflection

Types of reflection

Ophthalmic Use

Luminous objects are those which give of there own light e.g. sun

Non-Luminous objects are those which don’t give of the own light e:g moon

Reflection is the change in direction of a wave front between two different media so that the

wave front returns into the medium from which it originated

When light rays traveling in a medium reaches the boundary of other medium, they turn

back to the first medium. This phenomenon of turning back of light into the same medium after striking the boundary of other medium is called

Reflection of Light

There should be some incident ray The surface should be polished

The INCIDENT ray, REFLECTED ray and the NORMAL all lies in the same PLANE

Angle of INCIDENT is always EQUAL to angle of REFLECTION

REFLECTED ray is always OPPOSITE to INCIDENT ray

Reflection is categorized into which is as follows Specular ReflectionDiffuse Reflection

If the reflecting surface is smooth the REFLECTION thought it will be called

SPECULAR reflection

When light strikes surface of non-metallic material it bounces off in all directions by the microscopic irregularities this is called diffuse

reflection Or

If the reflecting surface is rough the reflection thought it will be called diffuse refection

The anterior surface of cornea acts as a convex mirror.

It is used such by the standard instruments (Keratometer)