title: Improvement of terahertz imaging with a dynamic subtraction technique.
abstract: By use of dynamic subtraction it is feasible to adopt phase-sensitive detection with a CCD camera to reduce long-term optical background drift. We report on a two-order improvement of the signal-to-noise ratio. The improved system is used to image terahertz field distribution generated by an optically rectified electro-optic crystal with a modulation depth as small as 10(-4). We also introduce a modified detection geometry that realizes near-field imaging capability with greatly improved spatial resolution.
authors.affiliation: Department of Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute, Troy, New York 12180-3590, USA.
authors.forename: Z
authors.initials: Z
authors.lastname: Jiang
authors.forename: X G
authors.initials: XG
authors.lastname: Xu
authors.forename: X C
authors.initials: XC
authors.lastname: Zhang