Terahertz multiwavelength phase imaging without 2π ambiguity

We present a terahertz phase imaging method with multiwavelengths. This novel approach can image an object with a larger optical length compared with using the largest wavelength in the terahertz spectrum and does not involve the usual phase unwrapping in the detection of phase discontinuity. Furthermore, this technique can effectively reduce the noise background. We present two examples to demonstrate the validity of this new method. Both measurements show that multiwavelength phase imaging is a straightforward and efficient phase data processing method in terahertz imaging applications.