Real-time terahertz imaging with a single-pixel detector

Abstract

Terahertz (THz) radiation is poised to have an essential role in many imaging applications, from industrial inspections to medical diagnosis. However, commercialization is prevented by impractical and expensive THz instrumentation. Single-pixel cameras have emerged as alternatives to multi-pixel cameras due to reduced costs and superior durability. Here, by optimizing the modulation geometry and post-processing algorithms, we demonstrate the acquisition of a THz-video (32 × 32 pixels at 6 frames-per-second), shown in real-time, using a single-pixel fiber-coupled photoconductive THz detector. A laser diode with a digital micromirror device shining visible light onto silicon acts as the spatial THz modulator. We mathematically account for the temporal response of the system, reduce noise with a lock-in free carrier-wave modulation and realize quick, noise-robust image undersampling. Since our modifications do not impose intricate manufacturing, require long post-processing, nor sacrifice the time-resolving capabilities of THz-spectrometers, their greatest asset, this work has the potential to serve as a foundation for all future single-pixel THz imaging systems.

Terahertz radiation and the skin: a review

“…[33][34][35][36] At the same time, intensive research has been conducted on THz multipixel cameras and holographic or codedaperture imaging principles. 9,[37][38][39] The main THz spectroscopic approaches that are generally used in biological research are Fourier transform spectroscopy (FTS), photomixing spectrometry, TPS, and TPI. FTS commonly utilizes broadband CW-sources or pulsed sources and the Michelson interferometer scheme, in which the inverse Fourier transform of the recorded interferogram is used.…”

Improving the performance of ghost imaging via measurement-driven framework

“…Considering the difficulty of generating quantum entanglement source, it was proved in theory and experiment that GI could be implemented with thermal and pseudo-thermal light [2][3][4][5][6][7][8] . In recent years, with the proposal of various GI schemes 6,[9][10][11] , GI has a bright application prospect in many related fields, such as remote sensing 12,13 , imaging through scattering media [14][15][16][17] , optical encryption 18,19 and terahertz imaging [20][21][22][23][24] .…”

A new spin on single-pixel imaging: spatial light modulation at megahertz switch rates via cyclic Hadamard masks

“…Alternatively, our scheme may be generalized to other fields by using elements that convert from optics to the field of interest. For example, it has been demonstrated that illuminating a highly resistive silicon wafer with spatially modulated light can enable the spatial modulation of a terahertz beam transmitted through the wafer 21 . With recent advancements in terahertz SPI, the speed of such systems is currently limited by the rates of DMDs, and thus may be improved by using our scheme.…”

“…The signal from the detector is recorded for each pattern projected on the object, and the image is formed from the signals by an inversion algorithm. SLM-based SPI has been demonstrated in numerous applications in optics 9 , including visible and infrared microscopy 10 , 3D imaging 11,12 , fluorescence microscopy 13 , multi-spectral imaging 14 , multiphoton wide-field imaging 15 , viewing through scattering media 16 as well as in hybrid optically assisted techniques, such as optoacoustic imaging 17 , optical detection of ultrasound 18 and terahertz imaging [19][20][21] .…”