The photonic and optoelectronic communities have long been interested in the development of tunable delay systems for optical pulses. The various systems developed suffer from shortcomings such as limited delay range for high speed devices, low duty cycles and nonlinearity in optical path-length change, the inability to provide tens of centimeter scanning range and a repetition rate in the hundreds of hertz range, and low temporal resolution and optical loss. This invention is an instrumentation which uses an involute reflector and a pair of rotation mirrors to perform a time delay line for optical pulses.This delay line provides a long scan, high repetition rate, and linear range. The optical delay line is an essential part in time-domain terahertz technology, ultrafast optics research, time resolved detection, interferometric spectroscopy, optical coherence tomography, and other applications.