METHOD AND DEVICE FOR IMAGING TERAHERTZ

摘要

PROBLEM TO BE SOLVED: To discriminate between different materials and environments by collecting transmission signals propagating through an object and processing the information contained in these signals for each point or 'pixel' on the object thereby analyzing the frequency dependency in time region. SOLUTION: An object 4 is set in the focal plane of a tera hertz(THz) beam and scanned in x and y directions in a zigzag pattern using a motor driven orthogonal conversion stage. A scan delay section 6 varies the delay of pulse between an optically gated THz transmitter 2 and a gated detector 5. A photocurrent generated from the detector 5 is fed through a preamplifier to an A/D converter and a DSP 7. An A/D converter for converting the speed and a DSP processor for Fourier transforming the waveform are employed. An FFT spectrum is represented by colored dots on the screen of a display 8 and the frequency components of THz are represented as a visible spectrum.