Terahertz interferometric synthetic aperture tomography for confocal imaging systems

Area of Science:

• Optics and Photonics
• Imaging Science
• Terahertz Technology

Background:

• Confocal imaging typically has a limited depth of focus.
• Extended objects pose challenges for high-resolution imaging techniques.
• Terahertz (THz) imaging offers unique material penetration capabilities.

Purpose of the Study:

• To demonstrate Terahertz (THz) interferometric synthetic aperture tomography (TISAT) for confocal imaging within extended objects.
• To adapt existing algorithms for THz imaging challenges.
• To achieve diffraction-limited resolution over an extended depth range.

Main Methods:

• Combined attributes of synthetic aperture radar and optical coherence tomography.
• Adapted interferometric synthetic aperture microscopy algorithms.
• Developed a frequency-swept two-dimensional TISAT confocal imaging instrument.

Main Results:

• Successfully demonstrated TISAT for confocal imaging of extended objects.
• Accounted for diffraction and defocusing effects on THz beam width.
• Achieved in-focus, diffraction-limited resolution over a depth 12 times larger than the instrument's depth of focus.

Conclusions:

• TISAT is a viable technique for extending the imaging depth in confocal THz imaging.
• The developed method can be readily extended to three dimensions and greater depths.
• This advancement has implications for non-destructive testing and material characterization.