Abstract: A clockless time-of-flight interval timer includes a tapped delay line register comprising N buffers that each contribute a substantially identical incremental time delay. A latched version of a START pulse associated with an output of transmitted energy from a laser is propagated through the tapped delay line. A DATA signal representing a detected pulse returned from a target is coupled to a block of four comparators each having a different signal threshold. The output of each comparator block is provided as input to one of four channel registers, each register comprising N D-type flipflops separately but synchronously triggerable by tapped incrementally delayed outputs from the N buffers. Channel register outputs are multiplexed and decoded and interfaced with a microprocessor. The microprocessor determines first signal time over threshold (FOT) information and total time over threshold (TOT) information from the channel registers.