Display modes in time-resolved terahertz imaging

We have constructed a terahertz (THz) imaging system based on a conventional pump-and-probe setup. With a time-delay line in the probe beam we can record time-resolved THz waveforms at every image position. The resulting time-indexed set of images (the `THz movie') can be mapped to two-dimensional images with `display modes'. Several of these `display modes' are closely related to sample absorption and refraction, others are designed for very specific purposes such as gas detection. Some of the modes map specific features of the THz pulse without particular purpose, yet they prove to be useful in investigating features of THz images. Examples are provided.