By combining a tandem multipass Fabry-Pérot ͑FP͒ interferometer with a charge-coupled-device ͑CCD͒ imaging detector, we have successfully observed surface Rayleigh waves, longitudinal guided modes, and bulk acoustic modes in dilute magnetic semiconductors, Si-and Ge-based films and superlattices. The inelastically scattered light from acoustic modes is transmitted through the FP off-axis, and is focused on the CCD where it forms concentric rings. We also have demonstrated that the high sensitivity of our system allows the observation of weak bulk acoustic modes from opaque a-Si:H/a-SiN x :H superlattices.