Chalcogenide glasses undergo various photoinduced effects under light irradiation in their band-gap and subband-gap range (refractive index, density, band-gap energy changes…). More specifically, the viscosity of these glasses can be tuned only by playing with the irradiation conditions, without any temperature increase. Because the photoinduced viscosity change (“photofluidity”) is athermal, it could allow glass forming at a micrometer scale (the size of a laser spot), and without risk of crystallization. Nevertheless, the photofluidity is poorly understood up to now, especially because few methods exist to properly assess the rheological properties under light irradiation. First because photoinduced changes occurs within time scales shorter than the time required to measure viscoelastic properties by static methods (creep or relaxation tests). Secondly, because we can assume that the light is homogeneously absorbed (and thus, the mechanical properties homogeneously changed) along the thickness of the glass only if its dimensions are very thin regarding the light absorption coefficient. We proposed here a dynamical method to track the kinetic of these change in glass thin films under light cycles. We describe here this method and investigate the influence of the wavelength and the power of the light source on the viscoelastic properties. We analyze the kinetic of the evolution of these properties and the influence of the glass composition.