Image forming apparatus

An image forming method of visualizing internal information of an object using time-domain spectroscopy, the method comprising:

• a detection step of detecting a terahertz wave from the object by a detection unit;
• a waveform generating step of generating a time waveform of the terahertz wave from an output of the detection unit in the detection step;
• a modulation step of sequentially performing spatial modulation of terahertz waves for each pixel, on a propagation distance from an emission of the terahertz waves until reaching the detection unit, by using a first modulation pattern and a second modulation pattern, wherein the terahertz waves each correspond to a pixel of an object in a direction substantially perpendicular to a direction in which the terahertz wave penetrates inside the object, and emitting a first terahertz wave and a second terahertz wave;
• an adjustment step of converting a change amount of the propagation distance of the terahertz wave for each pixel corresponding to the modulation pattern to a time amount, adjusting positions on a time axis of a first time waveform of a first terahertz wave and a second time waveform of a second terahertz wave generated in the waveform generating step based on the time amount, and calculating a third waveform and a fourth time waveform;
• and
• an addition step of performing an addition processing of the third time waveform and the fourth time waveform for each pixel.