A proposed novel multiplexed near field terahertz microscope

There is burgeoning interest in the possibility that ‘terahertz’ measurements will yield novel biological information. This relates primarily to the fact that proteins and other large molecules have many low frequency modes which fall in the terahertz region and which may give structural information. Additionally there is interest in possible measurements of ‘mechanical’ resonance modes of membranes in structures such as liposomes. A fundamental problem with terahertz measurements is that, since one terahertz has a wavelength of three hundred microns, diffraction limited imaging can only yield a resolution of the order of half a millimetre, too large for items of biological interest. The solution is well known – scanning near field microscopy – which can yield resolution far below the wavelength. However the solution comes with a problem, namely very slow data rates and hence very long imaging times. We describe a proposed multiplexed near field microscope which can collect fully spectrally resolved information on up to ~100 pixels simultaneously using one high quality detector. Resolution of a few microns appears feasible (possibly rather better at the top end of the terahertz range.) The microscope is ideally suited for use with coherently enhanced synchrotron radiation sources provided they run in CW mode