Abstract
Terahertz (THz) imaging has been demonstrated in numerous applications from medical to non-destructive evaluation (NDE), but current systems require expensive components, provide slow frame-rates and low resolutions. THz holography offers a potentially low-cost, high-performance alternative. Here we demonstrate the first full video-rate THz digital holography system at 2.52 THz (118.8 µm) using low-cost optical components. 2D digital reconstructions of samples are performed at frame-rates of 50 Hz - an order of magnitude higher than previous systems, whilst imaging of samples concealed in common packaging types demonstrates suitability for NDE applications. A lateral resolution of 250 µm was determined using a 1951 USAF target.
Highlights
Terahertz (THz) radiation describes electromagnetic radiation with a frequency of between 0.1 and 10 THz
In order to perform a fast hologram reconstruction, the graphics processing units (GPUs) were used with the Matlab GPU functionality to improve processing speed
We have demonstrated a real time THz digital holography system capable of imaging moving objects at a frame rate of 50 Hz and resolving features smaller than 280 μm
Summary
Terahertz (THz) radiation describes electromagnetic radiation with a frequency of between 0.1 and 10 THz. The reflection mode has been previously demonstrated to be beneficial for imaging highly absorbent materials with THz radiation - biological samples [17] It allows for easy separation of the amplitude and phase information [18] and separation of the zero-order mode compared to in-line holography systems whilst providing further advantages such as noise reduction [19] and ability to measure sub-wavelength changes in optical thickness [20]. This detector distance allowed enough space for the reference beam to combine with the object beam at the detector without interacting with the sample object.
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