The restoration of CW THz images based on phase analysis

Abstract

The method about how to distinguish the object from the standing wave, eliminate the wave patterns in CW THz images based on phase analysis is reported. The standing wave of CW THz images result from the interference of the wave-front reflected from the object and other optics in the system. Therefore, the information of the surface of the object and the background is included in the interference pattern of the images. Because the objects have different Phase Gradients from the background, they could be extracted from the image by utilizing the phase information of the interferential waves. The waves of the image can be removed with Election-pass filter, and the result of the filtering would not deteriorate the result because there is no object in the image. At last, the image of object and the image without standing wave can be fused together to make the image better for eyes. The scope of CW THz imaging's application can be extended and the quality of images can be improved by applying this approach.

Interference elimination in terahertz imaging based on inverse image processing

“…The interference resulting from I 2 and the first signal I 1, transmitted through the sample, happens easily. In the THz reflection systems, interference occurs under a similar situation [16]. As can be seen from figures 1(d) and (e), respectively, there are two kinds of situations enabling interference from the signal I 1 reflected on the surface of sample and the undesired signal I 2 .…”

“…Thus, the fringes and sample information are removed simultaneously in the frequency domain or spatial domain with great blindness. Other methods based on phase analysis [16] and wavelet transform [23] can eliminate the fringes in the background, but the interference in the sample area still exists.…”