Imaging Arrays for Terahertz Frequencies
Terahertz (electromagnetic) waves (or Far Infrared) span over 300GHz to 10THz. Previously used for radioastronomy, THz waves have been shown to be of great importance for many other applications: non-destructive inspection, remote sensing of chemicals, medicine, biology, just to name a few. Terahertz Imaging is capable of detection of hidden weapons on a large distance. It can also discover cancer on much earlier stage than visual inspection, and does not damage the tissue. In order to bring THz imaging from research labs to airports, hospitals, etc. , compact, lightweight, user friendly, low cost systems are required. Currently, THz imaging is accomplished via scanning of the object under test in the field of view of a single THz detector (or scanning the THz detector itself). It limits the frame rate of the image acquisition, and reduces the detection sensitivity. Next generation THz imagers ought to the based on large size arrays of THz detectors (similar to the once used in visual and IR cameras). In our laboratory we develop two types of THz detectors, which could be used in THz imagers: Schottky diodes and bolometers. Those have been used e.g. for space based radio astronomy and aeronomy. Our research includes device physics, RF circuits, THz antennas and optics, electronics. We have participated in development of one of the first THz radar for security imaging. Many our diploma students finish with publication of their results in prestigious scientific journals, with presentations at international conferences. The goal of the project is to investigate design options of large detector arrays for Terahertz Imaging. Two possible optical coupling approaches will have to be analyzed in terms of the optical coupling efficiency, the readout, and the complexity: planar antennas on the lens, and mini-mirrors (see the pictures). Optimization parameters are: pixel density, optical/electrical crosstalk, possibilities for multi-wavelength (multi-color) functionality. RF and optical simulation will be done using software CST-Microwave Studio and Zemax. Specifics of the existing THz detectors have to be considered. Project description: Theoretical: Fundamentals of THz antennas and optics, THz detectors; existing IR arrays. Methods: Electromagnetic simulation with CST-Microwave Studio. Optical simulations with Zemax. Goals: Using one/two of our THz antenna designs, investigate the beam properties with two proposed array layouts. Influence of the readout circuits on the optical performance have to be analyzed for different pixel densities.
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Last modified: June 21, 2011