A grid screen for an illumination device includes a honeycomb grid disc mounted in a component having an aperture. The protocol adaptation layer may lie above the MAC layer. When the command signals of more than two of the processing devices including the relevant processing device which determines are valid, the command signals are output according to priority while a control information blocking signal is output to a processing device other than those which are valid. Additionally, a light detector is located within the sensor housing, to detect light scattered by blood back into the housing. Such an optical deflector has a compact configuration and operates at high speed. Under control of the at least one producer, a second compare-double-and-swap operation within a spin loop is executed to atomically locate the first buffer and update the double pointer of the first buffer.