THz near-field imaging employing synchrotron radiation

Terahertz scanning near-field infrared microscopy below 1 THz is demonstrated at an electron storage ring using coherent synchrotron radiation. Spatial resolution below the diffraction limit down to about λ/40 at 2 cm−1 is derived from the transmittance spectra of a conical aperture probe. The potential of the technique is exemplified by imaging wet biological samples. Strongly absorbing living leaves have been imaged in transmittance with a spatial resolution of 130 μm at about 12 cm−1. The THz near-field images reveal distinct structural differences in the mesophytic and xerophytic leaves investigated.