Light-Field Methods for Terahertz Imaging (T-Field)

• Applicant: Professor Dr. Ullrich Pfeiffer
• Subject Area: Electronic Semiconductors, Components and Circuits, Integrated Systems, Sensor Technology, Theoretical Electrical Engineering
• Term: from 2015 to 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 288230757

• Final Report Year: 2021

Final Report Abstract

The main objective of Light-field methods for THz imaging (T-Field) was to investigate the feasibility of light-field methods, commonly utilized in the visible light domain, for THz radiation. This was also the very first time that such a technique was proposed, let alone investigated, for THz. The funding allotted in this project was earmarked for investigating the capturing of THz light-fields with a silicon integrated CMOS-based THz camera. This included both theoretical and experimental investigations of the image formation, as well as proposing novel techniques for THz light-field imaging to rival the coherent imaging methods prevalent in lower frequencies (radio waves and millimeter waves). The project also aimed to design a new silicon integrated camera SoC for integration into a multi-chip array forming a video-rate THz plenoptic camera system. During the course of this study, we have discussed the mathematical and conceptual formulation of light-fields for THz sources and detectors. In Transmission mode, we were able to reconstruct the antenna pattern of a source and performed imaging without lenses. In reflection mode, we demonstrated the power of light fields in a confocal imaging setup where we could identify different objects. Using a toy gun as a target, we could show the increase of image quality solely based on post-processing of the data. In another experiment, we could extract the 3D profile of a curved metallic surface. These experiments validated our approach of utilizing incoherent methods together with light-fields for imaging applications, which were previously only possible with coherent system approaches. We also designed the world’s first fully digital camera SoC, with integrated power supplies, digital readout circuitry, and SPI-based control. Finally, we developed a 3×3 camera array which will allow further investigation on terahertz light fields and will push the state-of-the-art.

Publications

• “Terahertz light-field imaging”. In: IEEE Trans. THz Sci. Technol. 6.5 (2016), pp. 649–657
  R. Jain, J. Grzyb, and U. R. Pfeiffer
  
• “Investigations on the plenoptics based image generation for THz reflection imaging”. In: Int. Conf. on Infrared, Millimeter, and Terahertz Waves. 2017, pp. 1–2
  R. Jain et al.
  
• “Object feature extraction with focused terahertz plenoptic imaging”. In: Int. Conf. on Infrared, Millimeter, and Terahertz Waves. IEEE. 2018, pp. 1–2
  R. Jain et al.
  
• “34.3 A 32×32 pixel 0.46-to-0.75 THz light-field camera SoC in 0.13µm CMOS”. In: IEEE Int. Solid-State Circuits Conf. IEEE, Feb. 2021
  R. Jain et al.