Roser Juanola-Parramon

Demonstration of spectral and spatial interferometry at THz frequencies

A laboratory prototype spectral-spatial interferometer has been constructed to demonstrate the feasibility of the double-Fourier technique at far infrared (FIR) wavelengths (0.15-1 THz). It is planned to use this demonstrator to investigate and validate important design features and data-processing methods for future astronomical FIR interferometer instruments. In building this prototype, we have had to address several key technologies to provide an end-end system demonstration of this double-Fourier interferometer. We report on the first results taken when viewing single-slit and double-slit sources at the focus of a large collimator used to simulate real sources at infinity. The performance of the prototype instrument for these specific field geometries is analyzed to compare with the observed interferometric fringes and to demonstrate image reconstruction capabilities.

Progress in the critical assessment for a far-infrared space interferometer with double fourier modulation (FP7-FISICA)

The progress and results of the ongoing FP7-FISICA programme to re-asses the scientific goals of a Far-Infrared Space Interfereometer and push the development of some of its key technology elements are reported.

The balloon experimental twin telescope for infrared interferometry (BETTII): An experiment for high angular resolution in the far-infrared

The Balloon Experimental Twin Telescope for Infrared Interferometry (BETTII) is a new balloon-borne far-infrared interferometer, being designed to provide spatially-resolved spectroscopy in the far infrared (30–90 μm). The combination of an 8-meter baseline with a double-Fourier Michelson interferometer allows the identification and separation of closely-spaced astronomical sources, while also providing a low-resolution spectrum for each source. In this wavelength range, BETTII will provide subarcsecond angular resolution, a capability unmatched by other far-infrared facilities. This paper provides an overview of the entire design of the BETTII experiment, with a short discussion of the predicted performance on flight.

FIInS - A Python Simulator for a Far-infrared Double Fourier Interferometer in Space

FIInS is a Python software package developed to simulate the performance of a Double Fourier Interferometer in space. FIInS will ‘observe’ a model sky and incorporate the physics and errors expected from a real system.

Optical and quasi-optical analysis of system components for a far-infrared space interferometer

Many important astrophysical processes occur at wavelengths that fall within the far-infrared band of the EM spectrum, and over distance scales that require sub-arc second spatial resolution. It is clear that in order to achieve sub-arc second resolution at these relatively long wavelengths (compared to optical/near-IR), which are strongly absorbed by the atmosphere, a space-based far-IR interferometer will be required. We present analysis of the optical system for a proposed spatial-spectral interferometer, discussing the challenges that arise when designing such a system and the simulation techniques employed that aim to resolve these issues. Many of these specific challenges relate to combining the beams from multiple telescopes where the wavelengths involved are relatively short (compared to radio interferometry), meaning that care must be taken with mirror surface quality, where surface form errors not only present potential degradation of the single system beams, but also serve to reduce fringe visibility when multiple telescope beams are combined. Also, the long baselines required for sub-arc second resolution present challenges when considering propagation of the relatively long wavelengths of the signal beam, where beam divergence becomes significant if the beam demagnification of the telescopes is not carefully considered. Furthermore, detection of the extremely weak far-IR signals demands ultra-sensitive detectors and instruments capable of operating at maximum efficiency. Thus, as will be shown, care must be taken when designing each component of such a complex quasioptical system.

Demonstrating Spectro-Spatial Interferometry in the Thermal Infrared: Recent progress

The recent developments of the Thermal Spectro-Spatial Interferometric Testbed (SSIT), a Double Fourier Modulation (DFM) interferometer operating in the thermal infrared wavelength range are presented. The optical design is described and the technical challenges discussed.

The balloon experimental twin telescope for infrared interferometry (BETTII): interferometry at the edge of the atmosphere

The Balloon Experimental Twin Telescope for Infrared Interferometry (BETTII) is an 8-meter baseline far-infrared interferometer designed to fly on a high altitude balloon. BETTII uses a double-Fourier Michelson interferometer to simultaneously obtain spatial and spectral information on science targets; the long baseline permits subarcsecond angular resolution, a capability unmatched by other far-infrared facilities. This program started in 2011, and is now in the process of building and testing components of the mission, aiming for first flight in fall of 2015. This paper will provide an overview of the BETTII experiment, with a discussion of current progress and of future plans.

Laboratory Development of Spatial/Spectral Interferometry for Far-IR Space Applications

The laboratory development of spatial/spectral interferometry for use in Far-IR space-based applications is discussed. These techniques will provide the combined spatial and spectral resolution required by the next generation of astronomical Far-IR instruments.

The Balloon Experimental Twin Telescope for infrared interferometry (BETTII): first flight

The Balloon Experimental Twin Telescope for Infrared Interferometry (BETTII) is an 8-meter far-infrared (30-100 μm) double-Fourier Michelson interferometer designed to fly on a high altitude scientific balloon. The project began in 2011, and the payload was declared ready for flight in September 2016. Due to bad weather, the first flight was postponed until June 2017; BETTII was successfully launched on June 8, 2017 for an engineering flight. Over the course of the one night flight, BETTII acquired a large amount of technical data that we are using to characterize the payload. Unfortunately, the flight ended with an anomaly that resulted in destruction of the payload. In this paper, we will discuss the path to BETTII flight, the results of the first flight, and some of the plans for the future.

Progress in spectral-spatial interferometry at multi-THz frequencies — Potential applications

Spectral-spatial interferometry pioneered in a narrow band in the near infrared has not enjoyed much exploitation as a technique. Proposed as a promising modulation method for a potential Far-infrared future satellite, a period of study was performed on two testbeds to improve and evolve this technique in the laboratory in order to simplify some of the technical aspects and the data analysis involved. Here we will present an update on the successful upgrade of a previous wideband millimetric (0.3-1.0 THz) testbed to a far-IR (11-14THz) one, as well as the ongoing progress on a broadband setup for an imaging system with a commercial thermal-or mid-IR (8 to 12 micron or 25-35 THz) camera currently working as imaging FTS. Source size, coherence and technical issues are discussed.