A multi-channel laser measurement system based on a commercially available single-channel laser vibrometer has been developed to measure the vibrations of low mass flexible space structures. The first generation of the multi-channel laser vibrometer is bulk-optic based system with laser being switched by an acousto-optical modulator. To overcome some of its drawbacks, for instance, being physically large and cumbersome, requiring tedious alignment, the second generation of the system was developed which employs fiber-optic technique to distribute the laser signal to the desired fiber-optic laser head. The design of the fiber-optic switch minimizes the power loss of laser beam in such a way that the vibrometer can work in its optimal range. Both bulk-optic and fiber-optic multi-channel vibrometers were verified using accelerometers on a light weight communication satellite antenna reflector. The modal parameters of the reflector were identified using measured frequency response functions both from laser vibrometer and from accelerometers. The result show that the laser system gives virtually the same result as the accelerometers.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.