**8.1 Optical method: using a Glan Thomson polarizer for laser intensity imbalance**

We introduced an optical method, previously developed for laser printers (Duarte, 2005), to study the effect of the laser intensity imbalance on the cloud formation. The method uses two Glan Thomson polarizers to produce a controlled imbalance between pump and probe laser. Each Glan Thomson polarizer was installed in front of the polarizing beam splitter cubes the produces the first division of the cooling and repumping laser respectively as seen in Fig.13. The laser intensity was controlled at will by rotating the Glan Thomson polarizer. The polarizing beam splitter cube contributes for further reduction of the laser intensity. We measured the intensity behind the beam splitter cube after each intensity reduction and recorded simultaneously the cloud with our camera. The laser polarization was slightly rotated after passing the beam splitter polarizing cube not affecting the overall functioning of the cloud. A more precise method could be realized by fixing the Glan Thomson polarizers for maximum transmission and rotating at will the field in front ofs each Glan Thomson polarizer by means of a half wave plate disposed in front of it. By this method the laser field polarization would be kept fixed after passing the Glan Thomson.
