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Proceedings ArticleDOI

Optical Mode Characterization Using a VNA Phase and Amplitude Measurement Scheme at 104 GHz

TL;DR: In this article , the authors developed a modal framework, which uses the notion of optical modes, i.e. an unique set of individually coherent orthogonal field distributions, to propagate an incident electric field through an optical system.
Abstract: We have developed a modal framework [1], which uses the notion of optical modes, i.e. an unique set of individually coherent orthogonal field distributions, to propagate an incident electric field through an optical system. The framework relies on a transmission matrix and Singular Value Decomposition (SVD), to obtained the mode characteristics: their transmission efficiencies and spatial forms over the input and output surface of the optical system. Here, we present a VNA phase and amplitude measurement scheme used for determining the transmission matrix, and we compare the obtained mode characteristics to our model for a pair of limiting slits at 104 GHz, which show good agreement.
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Journal ArticleDOI
TL;DR: A series of observations and the analysis conducted to determine the wavelength dependence of the SPIRE spectrometer beam profile are described.
Abstract: One of the instruments on board the Herschel Space Observatory is the Spectral and Photometric Imaging Receiver (SPIRE). SPIRE employs a Fourier transform spectrometer with feed-horn-coupled bolometers to provide imaging spectroscopy. To interpret the resultant spectral images requires knowledge of the wavelength-dependent beam, which in the case of SPIRE is complicated by the use of multimoded feed horns. In this paper we describe a series of observations and the analysis conducted to determine the wavelength dependence of the SPIRE spectrometer beam profile.

54 citations

Journal ArticleDOI
TL;DR: In this article , a modal technique for modeling the behavior of spectrometers that allows for the propagation and detection of partially coherent fields, and the inclusion of straylight radiated by warm internal surfaces is presented.
Abstract: Modeling ultra-low-noise far-infrared grating spectrometers has become crucial for the next generation of far-infrared space observatories. Conventional techniques are awkward to apply because of the partially coherent form of the incident spectral field, and the few-mode response of the optics and detectors. We present a modal technique for modeling the behavior of spectrometers that allows for the propagation and detection of partially coherent fields, and the inclusion of straylight radiated by warm internal surfaces. We illustrate the technique by modeling the behavior of the long wavelength band of the proposed SAFARI instrument on the well-studied SPICA mission.

2 citations