Application of terahertz Gouy phase shift from curved surfaces for estimation of crop yield

The application of terahertz time-domain spectroscopy (THz-TDS) and imaging to differentiate flat and curved surfaces in reflection via the THz Gouy phase shift is demonstrated. For a THz-TDS system that is aligned for reflection from a flat surface, the presence of a curved surface displaces the image focal plane from the detector plane, resulting in a Gouy phase shift. The potential of utilizing this configuration for estimating the number and size of curved objects is discussed with particular emphasis on agriculture crop yield estimates. (C) 2009 Optical Society of America