A microbolometer-based THz imager

Abstract

THz imaging is a very promising field rapidly growing in importance. This expanding field is at its early stage of development but already a large number of applications are foreseen. THz imaging promises to be a key technology in various fields, such as defense & security where it can be used to defeat camouflage. Based on its many years of experience in uncooled bolometers technology, INO has developed, assembled and characterized a prototype THz imager. The camera's 160 x 120 pixel array consists of pixels with a 52 µm pitch that have been optimized for the THz region. Custom camera electronics and an F/1 THz lens barrel complete the imager design. Real-time imaging at video rate of 30 frame/sec has been performed with a 3 THz quantum cascade laser set-up. THz images of numerous objectobscurant combinations are presented, proving the feasibility of video imaging in security screening applications.

MEMS-based uncooled THz detectors for staring imagers

“…Virtually all of the early thermal THz detectors were bolometers, as have been many of the current devices under development [2][3][4]12 . We have taken a different path in our approach in using a thermoelectric (TE) detector, and it is worthwhile to explain the rationale.…”

The Dawn of Ultrafast Nonlinear Optics in the Terahertz Regime

“…For higher sensitivity, a nonlinear detector such as a Schottky barrier diode or a hot electron bolometer can be used in a heterodyne configuration [27]. Recently, a bolometer-type uncooled THz camera became available [28,29] allowing direct visualization of the THz radiation beam intensity profile. For the case of coherent detection, the three primary methods are photoconductive sampling [5], electro-optic (EO) sampling [30], and more recently laser-plasma based detection [31].…”

Frequency Modulation and Absorption Improvement of THz Micro-bolometer with Micro-bridge Structure by Spiral-Type Antennas

“…Some improvements have been made for enhanced THz absorption of traditional micro-bolometer micro-bridge structure. Impedance matching metal thin film, proven to absorb THz wave due to resistive loss, is the first choice as an absorbing layer in micro-bridge structures for its low heat capacity, high thermal conductivity, and good compatibility with the fabrication process of THz micro-bolometers [ 18 , 19 ]. The absorption of metal thin film can be further improved by preparation process control and surface modification [ 20 ].…”