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We describe the conceptual design of the instrument. In particular, we explain the design and analysis of the straylight rejection baffles and occulter needed to block the image of the solar disc, in order to render the much fainter corona visible. We discuss the development of in-house analysis code to predict the straylight diffraction effects that limit the instrument’s performance, and present results, which we compare against commercially available analysis tools and the results from breadboard testing. In particular, we discuss some of the challenges of predicting straylight effects in this type of instrument and the methods we have developed for overcoming them.
We present the test results from an optical breadboard, designed to verify the end-to-end straylight rejection of the instrument. The design and development of both the breadboard and the test facility is presented. We discuss some of the challenges of measuring very low levels of straylight and how these drive the breadboard and test facility design. We discuss the test and analysis procedures developed to ensure a representative, complete characterisation of the instrument’s straylight response.
In this paper we describe our innovative systems approach to the design of the CCD cameras for two of SDO’s remote sensing instruments, the Atmospheric Imaging Assembly (AIA) and the Helioseismic and Magnetic Imager (HMI). Both instruments share use of a custom-designed 16 million pixel science-grade CCD and common camera readout electronics. A prime requirement was for the CCD to operate with significantly lower drive voltages than before, motivated by our wish to simplify the design of the camera readout electronics. Here, the challenge lies in the design of circuitry to drive the CCD's highly capacitive electrodes and to digitize its analogue video output signal with low noise and to high precision. The challenge is greatly exacerbated when forced to work with only fully space-qualified, radiation-tolerant components. We describe our systems approach to the design of the AIA and HMI CCD and camera electronics, and the engineering solutions that enabled us to comply with both mission and instrument science requirements.
RAL Space is contracted by e2v technologies Ltd to provide the CCD readout electronics for each of the three WUVS channels. The programme involves the design, manufacturing, assembly and testing of each Camera Electronics Box (CEB), its associated Interconnection Module (ICM), Electrical Ground Support Equipment (EGSE) and harness.
An overview of the programme will be presented, from the initial design phase culminating in the development of an Engineering Model (EM) through qualification whereby an Engineering Qualification Model (EQM) will undergo environmental testing to characterize the performance of the CEB against the space environment, to the delivery of the Flight Models (FMs). The paper will discuss the challenges faced managing a large, dynamic project. This includes managing significant changes in fundamental requirements mid-programme as a result of external political issues which forced a complete re-design of an existing CEB with extensive space heritage but containing many ITAR controlled electronic components to a new, more efficient solution, free of ITAR controlled parts. The methodology and processes used to ensure the demanding schedule is maintained through each stage of the project will be presented including an insight into planning, decision-making, communication, risk management, and resource management; all essential to the continued success of the programme.
This paper presents the results of the detailed characterisation of the WUVS CCD drive electronics. The electronics include a novel high-performance video channel design that utilises Digital Correlated Double Sampling (DCDS) to enable low-noise readout of the CCD at a range of pixel frequencies, including a baseline requirement of less than 3 electrons rms readout noise for the combined CCD and electronics system at a readout rate of 50 kpixels/s. These results illustrate the performance of this new video architecture as part of a wider electronics sub-system that is designed for use in the space environment. In addition to the DCDS video channels, the CEB provides all the bias voltages and clocking waveforms required to operate the CCD and the system is fully programmable via a primary and redundant SpaceWire interface. The development of the CEB electronics design has undergone critical design review and the results presented were obtained using the engineering-grade electronics box. A variety of parameters and tests are included ranging from general system metrics, such as the power and mass, to more detailed analysis of the video performance including noise, linearity, crosstalk, gain stability and transient response.
In-orbit verification, calibration, and performance of the Heliospheric Imager on the STEREO mission
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