Abstract: Various embodiments describe time-multiplexing of optical channels in an air data sensor. At least one switch outputs a reference optical signal, and each of a plurality of backscattered optical signals to at least one common optical path at a time. Alternatively stated, the at least one common optical path is configured to receive the reference optical signal and at least one of the backscattered optical signals in sequence. In doing so, the extent of systematic bias present in the at least one common optical path can be compensated for and even reduced during sensor operation.