Unit 4 Lasers

Question 1

What is a LASER, and properties

Answer 1

light amplification stimulated emission radiation

Before Maser was present
first laser in 1960 (Ruby laser)
1961 He-Ne

ORDINARY
not very intense
Moderatly Monochromatic
non directional
High divergence
Moderately coherant

LASER
very intense
Highly Mono Chromatic
Directional
Low Divergence
Highly Coherent
(phi diff neither equal not constant)

HOW is light produced
interaction of atoms with EM radiation

1) Absorption
2) Spontaneous Emission
3) Stimulated emission(Einstien)
atom-> discrete energy levels

Spontaneous: makes atom go to higher energy/absorption once it happens 2 things can happen: if u dont interfere it drops and E is released in terms of photons
hv + E1=E2
2) when photon projected at atom it forces atom to jump down(photon not absorbed by atom) and hence it also releases hv, thus
hv+E2=E1+2hv(Stimulated emission)