SPICE is a high resolution imaging spectrometer operating at extreme ultraviolet wavelengths, 70.4 – 79.0 nm and 97.3 -
104.9 nm. It is a facility instrument on the Solar Orbiter mission. SPICE will address the key science goals of Solar
Orbiter by providing the quantitative knowledge of the physical state and composition of the plasmas in the solar
atmosphere, in particular investigating the source regions of outflows and ejection processes which link the solar surface
and corona to the heliosphere. By observing the intensities of selected spectral lines and line profiles, SPICE will derive
temperature, density, flow and composition information for the plasmas in the temperature range from 10,000 K to
10MK. The instrument optics consists of a single-mirror telescope (off-axis paraboloid operating at near-normal
incidence), feeding an imaging spectrometer. The spectrometer is also using just one optical element, a Toroidal Variable
Line Space grating, which images the entrance slit from the telescope focal plane onto a pair of detector arrays, with a
magnification of approximately x5. Each detector consists of a photocathode coated microchannel plate image
intensifier, coupled to active-pixel-sensor (APS). Particular features of the instrument needed due to proximity to the Sun
include: use of dichroic coating on the mirror to transmit and reject the majority of the solar spectrum, particle-deflector
to protect the optics from the solar wind, and use of data compression due to telemetry limitations.
Discrepancies between recent global earth albedo anomaly data obtained from the climate models, space and ground
observations call for a new and better earth reflectance measurement technique. The SALEX (Space Ashen Light Explorer)
instrument is a space-based visible and IR instrument for precise estimation of the global earth albedo by measuring the
ashen light reflected off the shadowy side of the Moon from the low earth orbit. The instrument consists of a conventional
2-mirror telescope, a pair of a 3-mirror visible imager and an IR bolometer. The performance of this unique multi-channel
optical system is sensitive to the stray light contamination due to the complex optical train incorporating several reflecting
and refracting elements, associated mounts and the payload mechanical enclosure. This could be further aggravated by the
very bright and extended observation target (i.e. the Moon). In this paper, we report the details of extensive stray light
analysis including ghosts and cross-talks, leading to the optimum set of stray light precautions for the highest
signal-to-noise ratio attainable.
The Amon-Ra instrument is the main optical payload of the EARTHSHINE satellite and a unique Earth reflectance monitor. It consists of two separate optical systems, one imaging photon fluxes over the visible waveband and the other bolometrically measuring global emissions while the satellite orbits about the L1-Lagrange point. Two optical systems were designed to share the same apertures to the Sun and Earth and view the same target along the same direction as the spacecraft rotates. This design approach is advantageous in minimising the optics alignment problem as well as the differential degradation of front-end optics and detectors between the two systems. Nevertheless, such an approach makes it diffcult to control stray-light separately in each system and the signal of one source may be corrupted due to the other. In this paper, we discuss the stray-light performance of the Amon-Ra instrument and report the analysis results.
The VISTA IR Camera has now completed its detailed design phase and is on schedule for delivery to ESO’s Cerro Paranal Observatory in 2006. The camera consists of 16 Raytheon VIRGO 2048x2048 HgCdTe arrays in a sparse focal plane sampling a 1.65 degree field of view. A 1.4m diameter filter wheel provides slots for 7 distinct science filters, each comprising 16 individual filter panes. The camera also provides autoguiding and curvature sensing information for the VISTA telescope, and relies on tight tolerancing to meet the demanding requirements of the f/1 telescope design. The VISTA IR camera is unusual in that it contains no cold pupil-stop, but rather relies on a series of nested cold baffles to constrain the light reaching the focal plane to the science beam. In this paper we present a complete overview of the status of the final IR Camera design, its interaction with the VISTA telescope, and a summary of the predicted performance of the system.
As detailed instrument design progresses, judgements have to be made as to what changes to allow and when models such as thermal, stray-light and mechanical structure analysis have to be re-run. Starting from a well-founded preliminary design, and using good engineering design when incorporating changes, the design detailing and re-run of the models should bring no surprises. Nevertheless there are issues for maintaining the design and model configuration to a reasonably concurrent level. Using modern modeling software packages and foresight in setting up the models the process is made efficient, but at the same time the level of detail and number of cases now needed for instrument reviews is also large in order to minimise risks.
We describe examples from the detailed instrument design of the VISTA IR Camera to illustrate these aspects and outline the design and analysis methods used.
The SPIRE instrument for the FIRST mission will consist of a three band imaging submillimeter photometer and a two band imaging Fourier Transform Spectrometer (FTS) optimized for the 200 - 400 micrometers range, and with extended coverage out to 670 micrometers . The FTS will be used for follow-up spectroscopic studies of objects detected in photometric surveys by SPIRE and other facilities, and to perform medium resolving power (R approximately 500 at 250 micrometers ) imaging spectroscopy on galactic and nearby extra-galactic sources.
HIRDLS is a space-borne instrument that will measure the concentration of certain trace gases in the Earth's atmosphere. This requires accurate spectro-radiometric infra red measurements of weak sources of small angular size in the presence of strong adjacent sources of unwanted radiation. The design of the principal optical system is described and the constraints are explained. In particular, the important stray- light problems will be described, including incoherent scatter, ghost reflections and diffraction effects.
The coronal diagnostic spectrometer is designed to probe the solar atmosphere through the detection of spectral emission lines in the extreme ultraviolet wavelength range 15.0 - 80.0 nm. By observing the intensities of selected lines and line profiles, it is possible to derive temperature, density, flow, and abundance information for the plasmas in the solar atmosphere. Spatial resolution down to a few arcseconds and temporal resolution of seconds, allows such studies to be made within the fine-scale structure of the solar corona. Furthermore, coverage of a large wavelength band provides the capability for simultaneously observing the properties of plasma across the wide temperature ranges of the solar atmosphere. The CDS design makes use of a Wolter-Schwarzschild II telescope which simultaneously illuminates two spectrometer systems, one operating in normal incidence the other in grazing incidence. In this paper we describe the salient features of the design of the CDS instrument and discuss the performance characteristics of CDS as established through pre-delivery test and calibration activities.
The straylight analysis program GUERAP III requires a complicated. input dataset
Which discourages its use. The GUFDIPP program package provides an environment for
swiftly generating, cliecking and maintaining GUERAP datasets, so making GUERAP more
The main design features and the early findings of the Rosat XUV wide field camera (WFC) are discussed. The most important data on the WFC telescope and detectors are presented. The WFC operational features, observing efficiency, filter performance, thermal performance star tracker performance, and single-event upsets are discussed. The first WFC images are compared with preflight calibration data.
The ROSAT project is an international collaboration between the Federal Republic of Germany, the United Kingdom, and the United States. The satellite, due to be launched in June 1990, carries a payload of two coaligned imaging telescopes: the German X-Ray Telescope (XRT), which operates in the soft x-ray band (0.1 to 2 keV or 6 to 100 A), and the UK Wide Field Camera (WFC), which operates in the XUV band (0.02 to 0.2 keV or 60 to 600 A). ROSAT will perform two main tasks in its anticipated two to four year lifetime: a six-month all-sky survey in the soft x ray and XUV bands followed by a program of pointed observations for detailed studies of thousands of individual targets. In this paper we review the
design and performance of the WFC. The instrument is a grazing incidence telescope comprising a set of three nested, Wolter-Schwarzschild Type I, gold-coated aluminum mirrors with a microchannel plate detector at their common focus. Thin plastic and metal film filters define the wavelength passbands.