The work reported in this paper focuses on the design of optimal filters for fault detection in uncertain dynamic systems. A design procedure dealing with interval type parameter uncertainties is proposed for residual generation via a frequency domain approach. Robustness enhancement is based on the design of optimal detection filters maximizing the effect of faults while minimizing the influence of disturbances. In this framework, in order to cope with parameter uncertainties, Kharitonov polynomials and Dasgupta geometry are introduced and an extension of previous results to worst case situation is proposed. An example is also included to illustrate the method efficiency.