Biological material imaging using THz-echo analysis method

Ultrafast laser techniques have opened up a tremendous research opportunity in studying the interaction of short pulses of light with matter. With discovering of the picosecond photoconducting hertzian dipoles and high-brightness THz beams characterized with an ultrafast detector, we have seen more and more applications of ultrafast light in noninvasive imaging. Standard methods, when applied to the measurement of thin optical materials, doesnot independently determine the material's thickness and index of refraction. The proposed method is fundamentally different from other imaging such as contrast difference in optical coherent tomography (OCT) or the peak-to-peak intensity ratio as in THz imaging to determine index of refraction and thickness. We show that the application of ultrafast techniques allows simultaneous measurements of material thickness and optical constants in optical precision from transmission measurements. Such finding invites new perspectives in imaging and other applicable disciplines such as imaging processing after recording of the THz waveform of biological samples.