چكيده به لاتين
One of the phenomena that occurs when a beam of laser beam passes through an absorbing environment is a thermal lens phenomenon. Since this phenomenon shows its effects on the environment in the form of changes in the temperature of the environment and, consequently, the change in the refractive index of the environment, the reaction of the environment during the passage of the beam will be like a divergent lens. This phenomenon also causes changes in the thermoepatic properties of matter. The main effects of this phenomenon will be the change in the quality of the laser beam passing through.
In this dissertation, the quality of the beam of a He-Ne laser (probe beam ) with the TEM00 mode is examined after passing through the liquid medium with the thermal lens phenomenon. The thermal lens process is created by a laser beam in a ethanol environment, and the He-Ne laser beam propagates uniformly with this beam in the thermal lens and changes its quality. The results of this study show that changing the laser beam power of the diode, the quality of the He-Ne laser beam changes, and in a threshold power, the shape of the He-Ne laser beam is similar to the ring-shaped beam .
Key words: thermal lens phenomena, pump and probe beam, beam quality, refractive index changes, temperature, adsorbent environment
