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Context. Integrated superconducting spectrometers (ISSs) for wide-band submillimeter (submm) astronomy use quasi-optical systems for coupling radiation from the telescope to the instrument. Misalignment in these systems is detrimental to the system performance. The common method of using an optical laser to align the quasi-optical components requires an accurate alignment of the laser to the submm beam from the instrument, which is not always guaranteed to a sufficient accuracy. Aims. We develop an alignment strategy for wide-band ISSs that directly uses the submm beam of the wide-band ISS. The strategy should be applicable in both telescope and laboratory environments. Moreover, the strategy should deliver similar quality of the alignment across the spectral range of the wide-band ISS. Methods. We measured the misalignment in a quasi-optical system operating at submm wavelengths using a novel phase and amplitude measurement scheme that is capable of simultaneously measuring the complex beam patterns of a direct-detecting ISS across a harmonic range of frequencies. The direct detection nature of the microwave kinetic inductance detectors in our device-under-test, DESHIMA 2.0, necessitates the use of this measurement scheme. Using geometrical optics, the measured misalignment, a mechanical hexapod, and an optimisation algorithm, we followed a numerical approach to optimise the positioning of corrective optics with respect to a given cost function. Laboratory measurements of the complex beam patterns were taken across a harmonic range between 205 and 391 GHz and were simulated through a model of the ASTE telescope in order to assess the performance of the optimisation at the ASTE telescope. Results. Laboratory measurements show that the optimised optical setup corrects for tilts and offsets of the submm beam. Moreover, we find that the simulated telescope aperture efficiency is increased across the frequency range of the ISS after the optimisation., ImPhys/Practicum support, Tera-Hertz Sensing, EMSD EEMCS Project technicians 1, Planetary Exploration

Lens based focal plane arrays (FPAs) with thousand elements are promising candidates for wide scanning sub-millimeter security imaging systems. To analyze such arrays, a field correlation approach is employed to design an FPA of quartz lenses coupled to a reflector. We consider quartz as the lens material due to its lower cost compared to silicon lenses. Here we focus on the design of the lens element at the edge of the FPA. The reflector’s scanning angle at the edge of its FPA is 20.3°, and the lens surface is shaped to couple better to the reflector. The far-field performance of the optimized shaped lens is validated by full-wave simulations with excellent agreement. The simulated scan loss of the system is 2.6 dB. A prototype was fabricated and will be measured to validate the simulation., Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public., Tera-Hertz Sensing

Terahertz Integral Field Unit with Universal Nanotechnology (TIFUUN) is a wideband spectral mapper operating at (sub)-millimeter wavelengths. The instrument is under development for ground-based astronomy and will be deployed to the ASTE telescope in Chile. In this work, the building blocks for TIFUUN’s wideband (2:1) mappers are discussed. These components are based on multi-lens focal plane arrays of leaky lens antennas coupled to filter banks based on Microwave Kinetic Inductance Detectors., Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public., Tera-Hertz Sensing

Future generation of astronomical imaging spectrometers are targeting the far infrared wavelengths to close the THz astronomy gap. Similar to lens antenna coupled Microwave Kinetic Inductance Detectors (MKIDs), lens absorber coupled MKIDs are a candidate for highly sensitive large format detector arrays. However, the latter is more robust to misalignment and assembly issues at THz frequencies due to its incoherent detection mechanism while requiring a less complex fabrication process. In this work, the performance of such detectors is investigated. The fabrication and sensitivity measurement of several lens absorber coupled MKID array prototypes operating at 7.8 and 12 THz central frequencies is ongoing., Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public., Tera-Hertz Sensing

A system concept for online alignment verification of millimeter-wave, corneal reflectometry is presented. The system utilizes beam scanning to generate magnitude-only reflectivity maps of the cornea at 650 GHz and compares these images to a precomputed/measured template map to confirm/reject sufficient alignment. A system utilizing five off-axis parabolic mirrors, a thin film beam splitter, and two-axis galvanometric mirror was designed, simulated, and evaluated with geometric and physical optics. Simulation results informed the construction of a demonstrator system which was tested with a reference reflector. Similarity metrics computed with the aligned template and 26 misaligned positions, distributed on a 0.5 mm x 0.5 mm x 0.5 mm mesh, demonstrated sufficient misalignment detection sensitivity in 23 out of 26 positions. The results show that positional accuracy on the order of 0.5 mm is possible using 0.462 mm wavelength radiation due to the perturbation of coupling efficiency via beam distortion and beam walk-off., Tera-Hertz Sensing

This paper presents a comparative study of different Multiple Input Multiple Output (MIMO) array architectures to realize high-capacity Point-to-Point (PtP) wireless links for potential use in future 6G backhauling applications. This study focuses on the 220-320 GHz band, defined by the new IEEE 802.15.3d standard. Both phased array and focal plane array architectures are studied, considering the link to operate in the radiative near-field. The theoretically achievable capacities are presented based on the channel matrix estimated in the radiative near-field and the application of Shannon’s capacity formula. It is found that capacities well above Tbps rates can theoretically be realized, even without the use of interference cancellation techniques., Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public., Tera-Hertz Sensing

This article presents a feasibility study of single feed per beam quasi-optical (QO) antennas for enabling incoherent multiple-input multiple-output (MIMO) array front-end architectures at 270 GHz. The objective is to reach ultrafast and radiated energy efficient point-to-point (PtP) wireless links by exploiting the multimode capacity of radiative (Fresnel region) near-field links. In this article, we present a feasibility study of the number of independent links achievable with QO MIMO incoherent arrays. For this purpose, we present theoretical curves of the level of EM co-coupling and interference between the multiple modes versus the link distance. The study focuses at the 252-325 GHz spectral bandwidth defined by the new IEEE 802.15.3d standard. A specific and new MIMO array architecture operating at 270 GHz based on a 2 × 2 array of parabolic reflectors is proposed for a link distance of 100 m. The proposed PtP MIMO system is capable of generating 16 dual-polarized modes in a 70 GHz bandwidth with signal-to-interference ratio >17 dB and a power co-coupling coefficient of -3 dB without the need for interference cancelation techniques. Combining this architecture with wideband front ends could potentially lead to an aggregated data rate in the order of terabit per second in a PtP wireless line-of-sight link, not previously achieved experimentally to the best of authors' knowledge., Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public., Tera-Hertz Sensing

Future applications in sensing and communications at (sub)-millimetre wavelengths will benefit from having large integrated coherent arrays. The use of lens arrays will enable the fabrication of integrated antenna front-ends with many potential independent beams as well as dynamic scanning capabilities. For applications such as MIMO communications, interferometric arrays and Tx/Rx duplexing capabilities, a key design parameter can be the mutual coupling between the integrated antenna front-ends. In this contribution we model such mutual coupling for lens antenna arrays using Geometrical Optics technique combined with a bidirectional forward ray-tracing. The validation of the methodology against full wave simulations is also presented here., Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public., Tera-Hertz Sensing

A focal plane array of extended-hemispherical silicon lenses coupled to aluminum coplanar-waveguide (CPW) Microwave Kinetic Inductance Detectors (MKIDs) has been designed to operate at 7.8 THz. Low-dispersive leaky-wave radiation has been used to efficiently illuminate the antireflection-coated lenses. To minimize the radiation loss from the antenna feeding lines at these high frequencies, the CPWs have been miniaturized and placed on a dielectric membrane. A test device has been fabricated and its experimental characterization in terms of sensitivity, optical coupling, and beam patterns is ongoing., Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public., Tera-Hertz Sensing, Electronics

A system concept for online alignment verification of millimeter-wave, corneal reflectometry is presented. The system utilizes beam scanning to generate magnitude-only reflectivity maps of the cornea at 650 GHz and compares these images to a precomputed/measured template map to confirm/reject sufficient alignment. A system utilizing five off-axis parabolic mirrors, a thin film beam splitter, and two-axis galvanometric mirror was designed, simulated, and evaluated with geometric and physical optics. Simulation results informed the construction of a demonstrator system which was tested with a reference reflector. Similarity metrics computed with the aligned template and 26 misaligned positions, distributed on a 0.5 mm x 0.5 mm x 0.5 mm mesh, demonstrated sufficient misalignment detection sensitivity in 23 out of 26 positions. The results show that positional accuracy on the order of 0.5 mm is possible using 0.462 mm wavelength radiation due to the perturbation of coupling efficiency via beam distortion and beam walk-off., Tera-Hertz Sensing

We present a freely accessible graphical user interface (GUI) for analyzing antenna-fed quasi-optical (QO) systems in reception (Rx). This analysis is presented here for four widely used canonical QO components: parabolic reflectors and elliptical, extended hemispherical, and hyperbolic lenses. The employed methods are geometrical optics (GO) and Fourier optics (FO). Specifically, QO components are illuminated by incident plane waves. By using a GO-based propagation code, the scattered fields are evaluated at an equivalent sphere centered on the primary focus of the component. The FO methodology is then used to represent the scattered fields over the focal plane as plane wave spectrum. A field correlation between this spectrum and the antenna feed radiating without the QO component is implemented to evaluate the induced open-circuit voltage on the feed in Rx. By performing a field matching between these two spectral fields, feed designers can optimize the broadside and/or steering aperture efficiencies of QO systems in a fast manner. The tool is packaged into a MATLAB GUI, which reports the efficiency terms, directivity, and gain patterns of antenna-coupled QO systems. The described tool is validated via full-wave simulations with excellent agreement., Tera-Hertz Sensing

We present a freely accessible graphical user interface (GUI) for analyzing antenna-fed quasi-optical (QO) systems in reception (Rx). This analysis is presented here for four widely used canonical QO components: parabolic reflectors and elliptical, extended hemispherical, and hyperbolic lenses. The employed methods are geometrical optics (GO) and Fourier optics (FO). Specifically, QO components are illuminated by incident plane waves. By using a GO-based propagation code, the scattered fields are evaluated at an equivalent sphere centered on the primary focus of the component. The FO methodology is then used to represent the scattered fields over the focal plane as plane wave spectrum. A field correlation between this spectrum and the antenna feed radiating without the QO component is implemented to evaluate the induced open-circuit voltage on the feed in Rx. By performing a field matching between these two spectral fields, feed designers can optimize the broadside and/or steering aperture efficiencies of QO systems in a fast manner. The tool is packaged into a MATLAB GUI, which reports the efficiency terms, directivity, and gain patterns of antenna-coupled QO systems. The described tool is validated via full-wave simulations with excellent agreement., Tera-Hertz Sensing

Future sub millimeter imagers are being developed with large focal plane arrays (FPAs) of lenses to increase the field of view (FoV) and the imaging speed. A full-wave electromagnetic analysis of such arrays is numerically cumbersome and time-consuming. This article presents a spectral technique based on Fourier optics combined with geometrical optics for analyzing, in reception, lens-based FPAs with wide FoVs. The technique provides a numerically efficient methodology to derive the plane wave spectrum (PWS) of a secondary quasi-optical component. This PWS is used to calculate the power received by an antenna or absorber placed at the focal region of a lens. The method is applied to maximize the scanning performance of imagers with monolithically integrated lens feeds without employing an optimization algorithm. The derived PWS can be directly used to define the lens and feed properties. The synthesized FPA achieved scan losses much lower than the ones predicted by standard formulas for horn-based FPAs. In particular, an FPA with scan loss below 1 dB while scanning up to ±17.5° (±44 beam-widths) is presented with directivity of 52 dBi complying with the needs for future sub millimeter imagers. The technique is validated via a physical optics code with excellent agreement., Accepted Author Manuscript, Tera-Hertz Sensing

Tera-Hertz Sensing

Tera-Hertz Sensing

Future sub millimeter imagers are being developed with large focal plane arrays (FPAs) of lenses to increase the field of view (FoV) and the imaging speed. A full-wave electromagnetic analysis of such arrays is numerically cumbersome and time-consuming. This article presents a spectral technique based on Fourier optics combined with geometrical optics for analyzing, in reception, lens-based FPAs with wide FoVs. The technique provides a numerically efficient methodology to derive the plane wave spectrum (PWS) of a secondary quasi-optical component. This PWS is used to calculate the power received by an antenna or absorber placed at the focal region of a lens. The method is applied to maximize the scanning performance of imagers with monolithically integrated lens feeds without employing an optimization algorithm. The derived PWS can be directly used to define the lens and feed properties. The synthesized FPA achieved scan losses much lower than the ones predicted by standard formulas for horn-based FPAs. In particular, an FPA with scan loss below 1 dB while scanning up to ±17.5° (±44 beam-widths) is presented with directivity of 52 dBi complying with the needs for future sub millimeter imagers. The technique is validated via a physical optics code with excellent agreement., Accepted Author Manuscript, Tera-Hertz Sensing

DESHIMA is a spectrometer for astronomical applications targeting sources at sub-mm wavelengths from 240GHz to 720GHz that will operate in the ASTE telescope in Atacama Desert, Chile. In this work, a quasi-optical system based on a hyper-hemispherical leaky lens antenna and a series of Dragonian reflectors is presented as the coupling chain for the EM radiation captured by the telescope into the detector. The design procedure is based on a field matching technique in reception. The achieved average illumination efficiency over the band is approximately 70%. The directivity patterns in the sky are also estimated. The side lobe, and cross-polarization levels, over the whole frequency band, are below-16dB, and-18dB, respectively. The measurement of the system is on-going, and will be presented at the conference., Tera-Hertz Sensing

In this work, a free accessible MATLAB interface is presented to analyze antenna-coupled Quasi-Optical (QO) systems in reception. This goal is achieved by using Fourier Optics (FO) and Geometrical Optics (GO) based methods. Specifically, the FO method represents the field focalized by a QO component on its focal plane as a plane wave spectrum when the component is illuminated by an incident field. This spectrum is related to the field scattered by the QO component which is calculated here using a GO method. By using this spectrum, the tool estimates the power received by an antenna placed at the focal plane of the QO component. Moreover, the performance in reception is evaluated., Tera-Hertz Sensing

DESHIMA is a spectrometer for astronomical applications targeting sources at sub-mm wavelengths from 240GHz to 720GHz that will operate in the ASTE telescope in Atacama Desert, Chile. In this work, a quasi-optical system based on a hyper-hemispherical leaky lens antenna and a series of Dragonian reflectors is presented as the coupling chain for the EM radiation captured by the telescope into the detector. The design procedure is based on a field matching technique in reception. The achieved average illumination efficiency over the band is approximately 70%. The directivity patterns in the sky are also estimated. The side lobe, and cross-polarization levels, over the whole frequency band, are below-16dB, and-18dB, respectively. The measurement of the system is on-going, and will be presented at the conference., Tera-Hertz Sensing

In this work, a free accessible MATLAB interface is presented to analyze antenna-coupled Quasi-Optical (QO) systems in reception. This goal is achieved by using Fourier Optics (FO) and Geometrical Optics (GO) based methods. Specifically, the FO method represents the field focalized by a QO component on its focal plane as a plane wave spectrum when the component is illuminated by an incident field. This spectrum is related to the field scattered by the QO component which is calculated here using a GO method. By using this spectrum, the tool estimates the power received by an antenna placed at the focal plane of the QO component. Moreover, the performance in reception is evaluated., Tera-Hertz Sensing

In this contribution, a focal plane array (FPA) at submillimeter wavelengths is presented for security applications. The detectors are based on kinetic inductance bolometers. Two frequency selective absorber (FSA) sets were designed to implement a security imager. The effective pattern of the imager coupled to a black body point source over a wide frequency band (1:6) was demonstrated experimentally with excellent agreement to the one estimated by using a Fourier optics based technique., Tera-Hertz Sensing

Reflection-mode terahertz (THz) imaging of corneal tissue water content (CTWC) is a proposed method for early accurate detection and study of corneal diseases. Despite promising results from ex vivo and in vivo cornea studies, interpretation of the reflectivity data is confounded by the contact between corneal tissue and dielectric windows used to flatten the imaging field. Herein, we present an optical design for noncontact THz imaging of cornea. A beam-scanning methodology performs angular normal incidence sweeps of a focused beam over the corneal surface while keeping the source, detector, and patient stationary. A quasi-optical analysis method is developed to analyze the theoretical resolution and imaging field intensity profile. These results are compared to the electric field distribution computed with a physical optics analysis code. Imaging experiments validate the optical theories behind the design and suggest that quasi-optical methods are sufficient for designing of THz corneal imaging systems. Successful imaging operations support the feasibility of noncontact in vivo imaging. We believe that this optical system design will enable the first, clinically relevant, in vivo exploration of CTWC using THz technology., Tera-Hertz Sensing, OLD Complex Projects

Passive imaging cameras at millimeter and submillimeter wavelengths are currently entering a new era with the development of large format arrays of direct detectors. Several of these arrays are being developed with bare absorbing meshes without any antenna coupling (lens or horn) structures. The design of such arrays is typically done resorting to geometrical considerations or basic broadside plane wave incidence analysis. This paper presents a spectral technique for the analysis of such focal plane arrays in reception using Fourier Optics, which is valid also for moderately skewed incident angles. The analysis constitutes a step improvement with respect to previously used methods by providing an accurate and efficient way to estimate the point-source angular response and the throughput from a distributed incoherent source of an absorbing mesh in the focal plane of a quasi-optical component (e.g. a parabolic reflector or lens). The proposed technique is validated with full-wave simulations. After presenting the analysis, the paper compares the performance of arrays of bare absorber in the focal plane of a quasi-optical component to those of corresponding antenna based arrays. It is found that absorbers lead to a comparable trade-off, in terms of spill-over and focusing efficiency, only for very tight samplings. For larger samplings, the focusing efficiency of absorbers is significantly lower than the one for antennas., Accepted Author Manuscript, Tera-Hertz Sensing

Passive imaging cameras at sub-millimeter wavelengths with large format focal plane arrays are being developed as the next generation of security screening systems. In this contribution, a dual-band focal plane array (FPA) for security imagers at submillimeter wave frequencies is presented. The detectors are based on bolometric superconducting kinetic inductance resonators, which allows the development of large FPAs at medium cooled temperatures. Two frequency selective absorber (FSA) sets coupled to superconductive resonator lines are designed to implement a dual color security imager. The performance of the dual band imager is evaluated using spectral analysis approach that combines Fourier optics with a Floquet mode field representation. The geometry of the unit cells is based on a Jerusalem cross configuration and the designed FSAs show a stable angular response and a rejection 1 to 3 of the undesired bandwidth. The detectors in the dual band FPA are distributed over a hexagonal grid to maximize their physical size and then improve their sensitivity. The effective point spread function of the imager coupled to a black body point source over a wide frequency band (1:6) was demonstrated experimentally with excellent agreement to the one estimated by using the proposed spectral technique., Accepted Author Manuscript, Tera-Hertz Sensing

In this contribution, a focal plane array (FPA) at submillimeter wavelengths is presented for security applications. The detectors are based on kinetic inductance bolometers. Two frequency selective absorber (FSA) sets were designed to implement a security imager. The effective pattern of the imager coupled to a black body point source over a wide frequency band (1:6) was demonstrated experimentally with excellent agreement to the one estimated by using a Fourier optics based technique., Tera-Hertz Sensing

Reflection-mode terahertz (THz) imaging of corneal tissue water content (CTWC) is a proposed method for early accurate detection and study of corneal diseases. Despite promising results from ex vivo and in vivo cornea studies, interpretation of the reflectivity data is confounded by the contact between corneal tissue and dielectric windows used to flatten the imaging field. Herein, we present an optical design for noncontact THz imaging of cornea. A beam-scanning methodology performs angular normal incidence sweeps of a focused beam over the corneal surface while keeping the source, detector, and patient stationary. A quasi-optical analysis method is developed to analyze the theoretical resolution and imaging field intensity profile. These results are compared to the electric field distribution computed with a physical optics analysis code. Imaging experiments validate the optical theories behind the design and suggest that quasi-optical methods are sufficient for designing of THz corneal imaging systems. Successful imaging operations support the feasibility of noncontact in vivo imaging. We believe that this optical system design will enable the first, clinically relevant, in vivo exploration of CTWC using THz technology., Tera-Hertz Sensing, OLD Complex Projects

Passive imaging cameras at millimeter and submillimeter wavelengths are currently entering a new era with the development of large format arrays of direct detectors. Several of these arrays are being developed with bare absorbing meshes without any antenna coupling (lens or horn) structures. The design of such arrays is typically done resorting to geometrical considerations or basic broadside plane wave incidence analysis. This paper presents a spectral technique for the analysis of such focal plane arrays in reception using Fourier Optics, which is valid also for moderately skewed incident angles. The analysis constitutes a step improvement with respect to previously used methods by providing an accurate and efficient way to estimate the point-source angular response and the throughput from a distributed incoherent source of an absorbing mesh in the focal plane of a quasi-optical component (e.g. a parabolic reflector or lens). The proposed technique is validated with full-wave simulations. After presenting the analysis, the paper compares the performance of arrays of bare absorber in the focal plane of a quasi-optical component to those of corresponding antenna based arrays. It is found that absorbers lead to a comparable trade-off, in terms of spill-over and focusing efficiency, only for very tight samplings. For larger samplings, the focusing efficiency of absorbers is significantly lower than the one for antennas., Accepted Author Manuscript, Tera-Hertz Sensing

Passive imaging cameras at sub-millimeter wavelengths with large format focal plane arrays are being developed as the next generation of security screening systems. In this contribution, a dual-band focal plane array (FPA) for security imagers at submillimeter wave frequencies is presented. The detectors are based on bolometric superconducting kinetic inductance resonators, which allows the development of large FPAs at medium cooled temperatures. Two frequency selective absorber (FSA) sets coupled to superconductive resonator lines are designed to implement a dual color security imager. The performance of the dual band imager is evaluated using spectral analysis approach that combines Fourier optics with a Floquet mode field representation. The geometry of the unit cells is based on a Jerusalem cross configuration and the designed FSAs show a stable angular response and a rejection 1 to 3 of the undesired bandwidth. The detectors in the dual band FPA are distributed over a hexagonal grid to maximize their physical size and then improve their sensitivity. The effective point spread function of the imager coupled to a black body point source over a wide frequency band (1:6) was demonstrated experimentally with excellent agreement to the one estimated by using the proposed spectral technique., Accepted Author Manuscript, Tera-Hertz Sensing

Passive imaging cameras at sub-millimeter wave-lengths are currently entering a new era with the development of large format arrays of direct detectors. Several of these arrays are being developed with bare absorbing meshes without any antenna coupling (lens or horn) structures. This paper uses a spectral electromagnetic model to analyze the performance of absorber based focal plane arrays in comparison to antenna based systems. The methodology is particularly suited to derive guidelines for optimizing the resolution and the sensitivity of thermal imaging cameras at sub-mm wavelengths. The proposed method is validated with full-wave simulations., Accepted Author Manuscript, Tera-Hertz Sensing

Passive imaging cameras at sub-millimeter wave-lengths are currently entering a new era with the development of large format arrays of direct detectors. Several of these arrays are being developed with bare absorbing meshes without any antenna coupling (lens or horn) structures. This paper uses a spectral electromagnetic model to analyze the performance of absorber based focal plane arrays in comparison to antenna based systems. The methodology is particularly suited to derive guidelines for optimizing the resolution and the sensitivity of thermal imaging cameras at sub-mm wavelengths. The proposed method is validated with full-wave simulations., Accepted Author Manuscript, Tera-Hertz Sensing