1. Spectral line in a discrete spectrum as images of the entrance slit of a spectrograph

2. Discrete and continuous absorption spectra for atoms (a) and molecules (b)

3. Prominent Fraunhofer absorption lines within the visible and near UV spectral range

4. Continuous “bound-free” and discrete “bound-bound” flurescence transitions of the NaK molecule observed upon laser excitation at l=488 nm. (a) Spectrum (b) enlargement(vibration bands) (c) level scheme

5. E Ek E2 E1 E0 Recombination continuum collision induced transitions
fluorescent lines
collision induced transitions
Recombination continuum E0 E l
IFL
Discrete and continuous emission spectrum and the corresponding level diagram.

6. LASER RESONATORS
Perfectly parallel
Misalignment : escapes

7. A laser resonator with mirrors that are spherical surfaces

8. q
r(z) z
A ray is characterized by its displacement r and slope r’.

12. Stability condition

13. plane-parallel resonator
spherical resonator(concentric)
hemispherical resonator

14. confocal resonator
hemiconfocal resonator

15. Semiclassical description : absorbtionEa Eb

16. Perturbation theory
Eigen function of the unperturbed atom

17. dipole matrix element

19. Weak field approximation