Patent ID: 7858940

Claim:
An information acquisition apparatus for acquiring information on an object by means of a terahertz wave, comprising: a pulse generator adapted to be excited by a first beam of light to generate a terahertz wave pulse; a detector adapted to be excited by a second beam of light coherent to the first beam of light to detect a reflected or transmitted terahertz wave from the object irradiated with the terahertz wave pulse; a first delay unit for altering a delay time of the second beam of light so as to enable the detector to detect a pulse signal contained in the terahertz wave from the object; a second delay unit adapted to be driven to oscillate with an amplitude not greater than a temporal width of the pulse signal detected by the detector at a predetermined frequency to modulate the delay time; and a computation unit for computationally determining information on a temporal position of a peak of the pulse signal contained in the terahertz wave from the object, using an output signal from the detector when the delay time is modulated by the second delay unit, by taking out a frequency component of the predetermined frequency from the output signal.