ABSTRACT
Visible light is electromagnetic radiation with a wavelength of between 390 nm (violet) and 780 nm (red). Important parameters of electromagnetic radiation are wavelength (
λ
), frequency (
ν
) and energy (
ε
). Light is an electromagnetic wave but can also be viewed as a stream of discrete wave packets of energy called
photons
. The relationship between the wavelength, frequency and photon energy are expressed as:
ν
= c/
λ
(2.1)
ε
= h
ν
= hc/
λ
(2.2)
Where, c
≈
×
m/s is the speed of light in a free space; h = 6.67
×
J.s is Planck constant. If the wavelength of light is small in comparison with the size of the
optical apparatus, corresponding to the limiting case
λ
→
,
one can use as a first approximation, the techniques of “ray optics” or “geometrical optics”.
