Advanced Practical Courses

For the beginner or advanced practical courses please contact Dr. Dirk Luggenhölscher

The following experiments are offered there:

Nd YAG Laser: The laser experiment starts with collimation and adjustment of the pump radiation emitted by a diode laser. The Nd YAG rod is placed in the focus of the pump light and the Nd:YAG resonator is set up. The neodymium ions form the laser active material and are excited by optical pumping with the laser diode. They are embedded in a transparent host crystal (YAG = Yttrium Aluminum Garnet). The output power of the laser is optimized on the one hand by adjustment and on the other hand by temperature variation of the laser diode (wavelength). A number of experiments are carried out with the setup used:

  • Dependence of the diode laser wavelength on temperature and injection current
  • Measurement of the emission spectrum for calibration of the diode laser wavelength
  • Output power of the laser diode
  • Lifetime measurement of the lasing transition
  • Stability criteria of the resonator
  • Measurement of laser threshold and output power of the Nd:YAG laser
  • Transverse modes
  • Spiking
  • Frequency doubling with a KTP (potassium thio-phosphate) crystal
  • Q-switching for generating intense laser pulses

Zeeman-Effekt: The splitting of a spectral line of cadmium under the influence of an external magnetic field is observed by a Fabry Perot interferometer with high spectral resolution. After setting up and adjusting the optics, the interference pattern at different magnetic field strength is recorded by a CCD camera and further processed on the computer. Finally, the Bohr magneton is determined.

Optical Plasma Diagnostics: Low temperature plasmas, in particular radio-frequency (rf) discharges, are widely used for technological applications. Fundamental mechanisms are, however, not yet fully understood. Plasma diagnostic techniques are required for detailed investigations and monitoring technologically used plasmas. Optical measurements are a powerful diagnostic tool offering high spatial and temporal resolution. Optical emission spectroscopy (OES) provides a non intrusive access, to the physics of the plasma, with comparatively simple experimental requirements. Phase resolved OES (PROES), within the rf cycle, of rf plasmas is a rather new diagnostic technique providing information on various plasma parameters and characteristics. The basic principles of PROES will be discussed. A PROES diagnostic system will be set up and aligned. A typical experiment on a current research plasma will be carried out. A relatively simple analysis of the measured data, applying a collisional radiative model, yields information on the various power coupling mechanisms within the plasma.