Fast three-dimensional terahertz computed tomography using real-time line projection of intense terahertz pulse

Abstract

We demonstrated fast three-dimensional transmission terahertz computed tomography by using real-time line projection of intense terahertz beam generated by optical rectification in lithium niobate crystal. After emphasizing the advantage of intense terahertz pulse generation for two-dimensional spatio-temporal terahertz imaging, peak-to-peak amplitudes of pulsed terahertz electric field have been used to obtain a series of projection images at different rotation angles. Then a standard reconstruction algorithm has been employed to perform final three-dimensional reconstruction. Test samples including a medicine capsule have been investigated with a total acquisition time to only 6 minutes.

Development of a wavefront sensor for terahertz pulses

“…In the crystal, the spatial distribution of the broadband (0.1-2 THz) THz electric field modifies the intensity distribution of the probe beam that is finally captured by a 232x232 pixels CMOS camera after passing through an analyzer and a lens that images the crystal plane (magnification γ = −0.23). Similar optical arrangement was previously used for realtime 2D and 3D THz imaging [14]. For a given time delay between the THz and the probe pulses, the system is able to provide a 2D (x-horizontal and y-vertical directions) image at 800 nm corresponding to the distribution of the THz electric field at the crystal position.…”

Review of Terahertz Tomography Techniques

“…For a potential application, a long phase of feasibility must be envisaged because many experiments must be conducted with real samples and some tradeoffs are such as the optimal wavelength to combine transparency, resolution, and ability to fairly image the sample. The long acquisition time arising from use of THz time-domain spectroscopy has been overcome recently [176]. Nevertheless the technological development presented seems difficult to transfer because of the complexity and the cost of high power optical and terahertz sources.…”

A modified algebraic reconstruction technique taking refraction into account with an application in terahertz tomography

“…For an overview on the relatively new field of tomographic methods using THz radiation, see Wang et al [34], Guillet et al [17] and Ferguson [14,15]. Published results can be divided into transmission or reflection tomographic methods [20,25] to the THz range is widely distributed [7,13,15,18,26,34]. Here a very simplified propagation along straight lines is used with the Radon transform as mathematical model.…”