An efficient method for rapid, non-contact scanning of human cornea is presented. The optics utilize two, 101.6-mm diameter off-axis parabolic mirrors fed by a goniometrically scanned, planar mirror. An evaluation system at 650 GHz was built and demonstrated ~ 1.5 mm beam radius on target and ~ 30 ^o x 30 ^o field of view. The system was inspired by confocal laser scanning principles and represents a system design where image acquisition time is limited by SNR, not mechanical translation.

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.

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.

DESHIMA 2.0 is a spectrometer for astronomical applications targeting sources at sub-mm wavelengths from 240GHz to 720GHz. The design for its wide band Quasi-Optical system was presented in the previous works. In this work, the experimental validation of the beam pattern of the system at the lower end of its frequency band is presented. The measurement for the complete frequency band of the system is ongoing and will be presented at the conference.

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.

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.

Kinetic inductance bolometer (KIB) technology is a candidate for scalable submillimeter wave imaging systems, particularly suitable for person security screening applications. We have previously shown that the basic figures of merit are compatible with room-temperature radiometric imaging applications, and demonstrated the functionality of kilo-pixel detector arrays. In this article, we report on our imaging system based on 8208 KIBs organized on a 2D focal plane. We provide an overview on the basic components, including the detectors, optics, and cryogenics, and describe aspects relevant in system integration. Moreover, we demonstrate the capacity in actual concealed object detection by presenting datasets revealing metallic and dielectric objects hidden under the clothes of a test person.

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.