We present the B-BOP instrument, a polarimetric camera on board the future ESA-JAXA SPICA far-infrared space observatory. B-BOP will allow the study of the magnetic field in various astrophysical environments thanks to its unprecedented ability to measure the linear polarization of the submillimeter light. The maps produced by B-BOP will contain not only information on total power, but also on the degree and the angle of polarization, simultaneously in three spectral bands (70, 200 and 350 microns). The B-BOP detectors are ultra-sensitive silicon bolometers that are intrinsically sensitive to polarization. Their NEP is close to 10E-18 W/sqrt(Hz). We will present the optical and thermal architectures of the instrument, we will detail the bolometer design and we will show the expected performances of the instrument based on preliminary lab work.
The Infra-Red Telescope (IRT) is part of the payload of the THESEUS mission, which is one of the two ESA M5 candidates within the Cosmic Vision program, planned for launch in 2032. The THESEUS payload, composed by two high energy wide field monitors (SXI and XGIS) and a near infra-red telescope (IRT), is optimized to detect, localize and characterize Gamma-Ray Bursts and other high-energy transients. The main goal of the IRT is to identify and precisely localize the NIR counterparts of the high-energy sources and to measure their distance. Here we present the design of the IRT and its expected performance.
Structured Light Systems (SLS) give access, without contact, to a rich measurement of a cloud of points belonging to a same object surface. SLS received much interest in the past years and became a standard technique. The aim of this talk is to present the design of such a means, working in the visible spectrum, dedicated to shock physics (implying velocities up to several km/s) and to provide an example of measurements with a 3D reconstruction. A dedicated development is necessary (laser lighting, speckle smoothing, ambient light canceling, depth of field improvement), since commonly developed SLS don’t suit this field of study, mainly for three reasons: phenomena of interest (usually lasting a few microseconds) require extremely short exposure durations (few nanoseconds to few hundreds of picoseconds); the field of view ranges from millimeter for samples shocked by high power lasers to decimeter for high-explosive setups ; and finally, experimentations have single-shot acquisitions. The main domains of study are fragmentations, surface deformations and associated damages, like micro-spalling or ejected particle clouds.
Heterodyne Velocimetry (or Photonic Doppler Velocimetry) has been used in detonics experiments for a few years
now, mainly thanks to the recent evolution of telecom components.
In its principle it is nothing else but a displacement interferometer, delivering beats versus time. A sliding Fourier
transform processing on the raw signal thus allows to derive velocity versus time. The device is made up of a 1.55 μm
Erbium laser delivering 2 W (split into 4 channels), single-mode optical fibers, fast photodetectors and digitizers (8 GHz
bandwidth, 20 GS/s sampling).
To begin with, we present a new heterodyne velocimeter setup embedding a second low-power frequency-tunable
laser (50 mW) acting as a local oscillator. Its frequency can be shifted, to make it higher than the main laser, up to the
bandwidth of the digitizer (13 GHz soon). The Doppler wave coming from the first laser and reflected by the moving
target interferes with this shifted reference, therefore doubling the overall bandwidth of the system.
On top of enhancing the measurable velocity range, the existence of beats at static gives a convenient means to tune
the power levels of the laser and match the electric signal to the dynamics of the detector.
Finally, three applications are presented: the first one deals with the classical measurement of free surface velocity
on metallic shock loaded plates, in the second part we present the velocity distribution of tin particles ejected under
shock. The third application relates to direct measurement of the velocity of detonation wave into nitromethane, by using
immersed optical fibers.
The James Webb Space Telescope (JWST) Observatory is the successor mission to the Hubble Space Telescope and will
lead to great scientific advancements in near- and mid-infrared astronomy. One of the four science instruments on board
the spacecraft is NIRSpec, which is being developed by the European Space Agency (ESA) with EADS Astrium
Germany GmbH as the prime contractor. This multi-object spectrograph will be able to measure the spectra of at least
100 objects simultaneously in the near infrared wavelength range from 0.6µm to 5.0µm and at various spectral
In order to assess the performance of the instrument, a simulator has been developed to calculate key characteristics of
the optical design and the final instrument output. It uses Fourier Optics with wavefront error maps to predict the point
spread function on the Micro Shutter Assembly (MSA) and the detector and can include real, as measured, spectral data
of filters and dispersive elements. With the implementation of parameterized image distortion and detector features, it is
possible to obtain full realistic detector frames for any optical input. Still the computation time is comparably short. The
program will be of great use to predict and verify response of NIRSpec during the test and calibration campaigns.
The James Webb Space Telescope (JWST) Observatory, the follow-on mission to the Hubble Space
Telescope, will yield astonishing breakthroughs in infrared space science. One of the four
instruments on that mission, the NIRSpec instrument, is being developed by the European Space
Agency with EADS Astrium Germany GmbH as the prime contractor. This multi-object
spectrograph is capable of measuring the near infrared spectrum of at least 100 objects
simultaneously at various spectral resolutions in the 0.6 μm to 5.0 μm wavelength range.
A physical optical model, based on Fourier Optics, was developed in order to simulate some of the
key optical performances of NIRSpec. Realistic WFE maps were established for both the JWST
optical telescope as well as for the various NIRSpec optical stages. The model simulates the optical
performance of NIRSpec at the key optical pupil and image planes. Using this core optical
simulation module, the model was expanded to a full instrument performance simulator that can be
used to simulate the response of NIRSpec to any given optical input. The program will be of great
use during the planning and evaluation of performance testing and calibration measurements.