Neutron bandpass-limiting disk chopper for implementing the time-of-flight (TOF) mode of measurements at reflectometers at steady flux sources is presented. A sufficiently compact multi-disk system cuts off the contaminant slow neutrons, allows to make measurements with different TOF resolutions and/or different TOF bases. A method of analyzing the effect of beam divergence on the disk chopper performance is proposed. The parameters of the disk chopper, which is designed for the neutron reflectometer SONATA (reactor PIK, Gatchina, Russia), are used for the model simulations.