Coded-aperture imaging using photo-induced reconfigurable aperture arrays for mapping terahertz beams

TL;DR

This paper introduces a reconfigurable terahertz imaging technique using photo-induced aperture arrays on silicon, enabling real-time, low-cost beam mapping with programmable illumination and demonstrated effective imaging at 590 GHz.

Contribution

It presents a novel method of terahertz imaging with reconfigurable apertures controlled by digital light projection, achieving high modulation depth and rate for beam mapping.

Findings

Successful 4x4 coded-aperture imaging with Hadamard coding

Effective mapping of THz beams at 590 GHz

Imaging results closely match theoretical Gaussian beam models

Abstract

We report terahertz coded-aperture imaging using photo-induced reconfigurable aperture arrays on a silicon wafer. The coded aperture was implemented using programmable illumination from a commercially available digital light processing projector. At 590 GHz, each of the array element apertures can be optically turned on and off with a modulation depth of 20 dB and a modulation rate of ~1.3 KHz. Prototype demonstrations of 4 by 4 coded-aperture imaging using Hadamard coding have been performed and this technique has been successfully applied to mapping THz beams by using a 6 by 6 aperture array at 590 GHz. The imaging results agree closely with theoretical calculations based on Gaussian beam transformation, demonstrating that this technique is promising for realizing real-time and low-cost terahertz cameras for many applications. The reported approach provides a simple but powerful means to visualize THz beams, which is highly desired in quasi-optical system alignment, quantum-cascade laser design and characterization, and THz antenna characterization.