Reflectivity spectra of CuAlS
2, CuAlSe
2 and CuGaSe
2 crystals have been investigated in the wave number range 50 - 4000 cm
-1 for the polarization Εllc and Ε⊥c. The fundamental phonon parameters, the limiting dielectric constants ε
o and ε
∞ and the reflectivity spectra contours have been calculating by using classical dispersion relations for both Εllc and Ε⊥c configurations. The Szigeti effective charges and the relative ion charges of Cu, Ga, Al, S, Se anions and cations have been calculated in dependence on the incident light polarization.
Raman scattering of CuAlSe
2 (at resonance excitment), CuAlS
2 and CuAl
xGa
1-xSe
2 has been investigated at 300 and 77K. The modes caused by Al - Se and Ga - Se vibrations have been determined for CuAl
xGa
1-xSe
2 solid solutions. We have found that the intensity of the modes B
12(Γ3) - 107.2 and 210.5 cm
-1 increases whereas the intensity of Ε(Γ5) - 157.3 cm
-1 mode decreases as the exciting energy approaches the band gap Ε
g.