Professor Qing Hu
Real-time THz imaging
One attractive feature of THz radiation is that it can penetrate optically opaque materials. In combination with strong spectral fingerprints of many materials at THz, this feature allows noninvasive imaging in biomedical and security applications. Because of the low average power of time-domain systems (~µW), previously THz imaging was performed by mechanically scanning the object and the process takes many minutes to complete.
In this project, we demonstrate real-time THz imaging at video rate. It is made feasible with the high power levels of THz quantum-cascade lasers. Using a microbolometer camera with 240-by-320 pixels, we can perform real-time THz imaging, that is, making movies in T-rays.
W. M. Lee and Q. Hu, "Real-Time, Continuous-Wave Terahertz Imaging using a Microbolometer Focal-Plane Array," Opt. Lett. 30, 2563 (2005). [PDF]
Alan W.M. Lee, Benjamin S. Williams, Sushil Kumar, Qing Hu, and John L. Reno, "Real-Time Imaging using a 4.3-THz Quantum Cascade Laser and a 320´240 Microbolometer Focal-Plane Array," IEEE Photonics Technology Letters 18, 1415 (2006). [PDF]
Alan W.M. Lee, Qi Qin, Sushil Kumar, Benjamin S. Williams, Qing Hu, and John L. Reno, 'Real-Time Terahertz Imaging over a Standoff Distance (>25 meters)," Appl. Phys. Lett. 89, 141125 (2006). [PDF]
Sushil Kumar and Alan W. M. Lee, "Resonant-Phonon Terahertz Quantum-Cascade Lasers and Video-Rate Terahertz Imaging," IEEE Journal of Quantum Electronics, 14, 333 (2008). (Invited) [PDF]
Qing Hu and Alan Wei Min Lee, "Real-Time, Continuous-Wave Terahertz Imaging Using a Microbolometer Focal-Plane Array," U. S. Patent No. 7,692,147, issued on April 6, 2010.
Left: example of a T-rays movie: a pencil viewed at visible light and THz frequency.
Bottom left: pencil written note inside an envelope viewed at THz.