We present a novel method of extracting hydrodynamic information from a gas-solid fluidized bed. The proposed method involves measuring the fluctuations produced in a laser sheet that perpendicularly crosses the free bed surface. This non-local, non-intrusive technique can be applied to 2D and 3D gas-solid fluidized bed systems. Frequency domain and state space analysis were used in a complementary manner to characterize the fluidization regimes of these systems by monitoring E-WB, mu, D-2, lambda(max), and K. Finally, we evaluated the influence of H/L on attractor invariants in 3D fluidized beds. (C) 2003 Elsevier B.V. All rights reserved.