The liquid crystal to isotropic phase transition induced with 488 nm light in films of liquid crystalline azobenzene polyesters has been studied as a function of temperature, light intensity, and film thickness. That phase transition is associated with the photoinduced trans-cis-trans isomerizations of azobenzene molecules and it has been found that the 488 nm light power needed to induce the transition to the isotropic state increases when the film thickness decreases. The irradiation with the laser beam heats the film up and this seems to be responsible for the observed thickness dependence. Optical absorption measurements show that azobenzene aggregates present in one of the polymers are broken down in the photoinduced phase transition. The birefringence induced with low power 488 nm light in films before and after undergoing that photoinduced phase transition has also been studied. Birefringence shows a faster growing rate in films which have undergone the transition.