New high purity glasses in the As42S58-G(42)S(58) and A(40)S(60)-Ga40S60 systems were synthesised and the solubility regions of Ga42S58 and Ga40S60 in the As-S matrix were determined. Illumination of glassy powders and thin films shifts the short wavelength absorption edge, changes the optical gap, E-g(opt), and changes their index of refraction, n. The sensitivity of Ga-containing films is higher than pure As-S. Annealing and illumination also changes the thickness of thin films, their density, the single oscillator energy, E-0, dispersion energy, E-d, of the Wemple-DiDomenico dispersion relationship and their Raman spectra. The changes in the Raman spectra are interpreted as photoinduced changes of short-range order in the structure of thin films. A microscopic model of the photoinduced changes is proposed.