THz Imaging Compressive sensing Hadamard spectroscopy THz Laser DMD Hadamard matrices Experimental model v1.0 Experimental model v2.0 Experimental model v3.0
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THz domain spectroscopy probes the characteristic vibrational and rotational modes of molecules. Due to this property, the molecular structure of the analyzed samples can be determined from the emitted or absorbed THz radiation. Additionally, given the weak energy of far-infrared quanta, these radiations are not harmful to the living world.
Experimental Setup
From these two reasons alone, the THz range of electromagnetic spectrum is associated today with two major research directions:
  • Space, by observation of chemical composition of the atmosphere and surface of comets, planets, including the Earth, and satellites; probing the molecular chemistry of the universe
  • Defense, by identification of hazardous substances of interest, home defense and remote imaging of hidden dangerous objects
Experimental Setup_top view
The central objective of the project is to develop a THz range Hadamard Transform Image Spectrometer, incorporating, among other components, a digital micromirror device (DMD) hardware and compressive imaging (CI) or compressive sensing/sampling (CS) software technique.
Therefore, the project aims to perform research related to:
  • spectroscopy of space interest sources in the THz domain (and FIR)
  • acquisition and reconstruction of images in the THz domain by CS technique
For this purpose, the following latest methods will be applied during the project:
  • Hadamard spectroscopy
  • Numerical imaging with spatial multiplexing
  • DMD for spatial modulation and software for digital optics
  • CS for image recording and compression
Due to technological advance, it becomes feasible to build, for space applications, a spectrometer with optimized data acquisition, small mass and dimensions, and no moving parts.
Our project research will proceed with this trend and will materialize into an experimental model for a Hadamard image spectrometer for THz domain. The principle of the instrument (click the image to enlarge) is as follows: a THz source (which may be collimated or focused, with special THz optics) is incident upon specially designed Hadamard masks. Technically, the masks may be mechanical, DMD or even a Liquid Crystal on Silicon (LCOS). The interaction with the masks (which can be obtained either by transmission or reflection) followed by radiation collimation or focusing (depending on experimental needs), results in the optical computation of multiplexed image projections.
The projections are sensed by a THz detector, which converts them into an electrical signal, and finally transmitted to a computer for processing. The masks sequencing is controlled by a Modulator and the projections are acquired by a Data Acquisition module, both controlled by the computer.
∴ Facts
Title: Compressive THz Imaging and Hadamard Spectroscopy for Space Applications
Project No: 17/19.11.2012
Project type: CDI STAR Project
Starting date: Nov 2012
Duration: 36 months
Partners: 2
INFLPR - Coordinator
CEO Space Tech - Partner
⇒ Latest News
[July 23rd-24th, 2013]
Installation of the THz laser
[Jan 20th, 2013]
THz Imaging website online
[Nov 19th, 2012]
Project start