Paper
25 February 2016 Dynamic measurements at THz frequencies with a fast rotary delay line
Hichem Guerboukha, Andrey Markov, Hang Qu, Maksim Skorobogatiy
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Abstract
Fabrication, characterization, and applications of a fast rotary linear optical delay line (FRLODL) for THz time-domain spectroscopy are presented. The FRLODL features two reflective surfaces with spatially separated incoming and outgoing beams. It has been manufactured using CNC machining. A linear dependence of the optical delay on the rotation angle allows a straightforward extraction of the conversion factor between the acquisition time (in ms) and the terahertz pulse time (in ps). The FRLODL has been tested using rotation speeds of up to 48 Hz, corresponding to an acquisition rate of up to 192 Hz with four blades incorporated on the same disk. At high speeds we observe a decrease of the bandwidth due to the limitations of the electronics, in particular, the transimpedance amplifier. An error analysis is performed by experimentally evaluating the signal-to-noise ratio and the dynamic range. With regard to the applications of the FRLODL, we first present observation of the evaporation of liquids, namely water, acetone and methanol. We then demonstrate monitoring of the spray painting process. Finally, detection of fast moving objects at 1 m/s and their thickness characterization are presented.
© (2016) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Hichem Guerboukha, Andrey Markov, Hang Qu, and Maksim Skorobogatiy "Dynamic measurements at THz frequencies with a fast rotary delay line", Proc. SPIE 9747, Terahertz, RF, Millimeter, and Submillimeter-Wave Technology and Applications IX, 97470R (25 February 2016); https://doi.org/10.1117/12.2216308
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KEYWORDS
Terahertz radiation

Picosecond phenomena

Signal to noise ratio

Liquids

Spectroscopy

Photodiodes

Optics manufacturing

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