The importance of capacitively coupled radio frequency (rf) discharges has resulted in many attempts, by experiment and by simulation, to understand the dynamics of the discharge. Because of the time varying nature of the sheath potential, the sheath region is of special interest in these plasmas. Direct measurements are reported of the sheath electric fields in a helium plasma obtained using a laser induced fluorescence method. In the interpretation of these measurements, the time dependence of the fluorescence spectrum had to be considered. The measured electric field distributions can be used to deduce sheath widths. ©1995 American Institute of Physics.