Patent ID: 8514399

Claim:
An information acquiring method for acquiring information of an object by using terahertz time domain spectroscopy, the method comprising: a first generating step of generating pulse-shaped pump light, first probe light and second probe light in synchronization with each other; a second generating step of generating pulses of terahertz radiation by using the pump light; a detecting step of detecting pulses of terahertz radiation from an object irradiated with the pulses of terahertz radiation; a first delay step of adjusting an optical path difference between an optical path of the pump light used in the second generating step and an optical path of the first probe light used in the detecting step, so that a field intensity of a predetermined fixed point on a time domain waveform of the pulse of terahertz radiation from the object is detected in the detecting step, following the predetermined fixed point; a second delay step of adjusting an optical path difference between the optical path of the pump light used in the second generating step and an optical path of the second probe light used in the detecting step by a sum of an additional optical path adjustment amount and the optical path difference adjusted in the first delay step, so that the time domain waveform of the pulse of terahertz radiation from the object is obtained in the detecting step; and a correction processing step of compensating for influence of a change in condition of the object on the time domain waveform obtained in the detecting step by using the field intensity of the predetermined fixed point, or an adjustment amount of the optical path adjusted in the first delay step.