A method of investigating an object, comprising the steps of: (a) irradiating the object with an optically-generated pulse of electromagnetic radiation, said pulse having a plurality of frequencies in the range from 100 GHz to 100 THz; (b) detecting radiation transmitted and/or refle
A method of quantitatively analysing a sample, the method comprising: irradiating the sample with radiation having a plurality of frequencies in the range from 25 GHz to 100 THz; detecting radiation reflected from and/or transmitted by said sample to obtain a frequency domain waveform
