EIS CCD camera - System Requirements Document

EIS CCD camera - System Requirements Document
Solar-B
EIS
*
EIS CCD camera - System Requirements
Document
EUV
Imaging
Spectrometer
Title
Doc ID
ver
Author
Date
EIS CCD camera - Systems
Requirement Document
MSSL/SLB-EIS/SP01
1.0
Chris McFee
3 November 1999
Page 1 of 7
Contents
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2 Scientific Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3 Technical Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
4 Operational requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
5 Notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
5.1 Temporal resolution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
5.2 Calibration facilities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Page 2 of 7
Change Record
Date
3/11/1999
16/3/2000
Issue
1.0
1.1
Section
5.2
Description of change
First Issue
Updated to include reduction of windows to two
per CCD
Page 3 of 7
1
Introduction
1.1
The purpose of this document is to establish the requirements for the EIS CCD camera. The
user requirements for the camera have been derived from EIS-sysreg-eng-userneed, which
establishes the science requirements for EIS, and EIS-sys-eng-sysreq which describes the
system level requirements for EIS.
1.2
The system requirements for the camera can come from three different areas:
• directly from the science requirements - e.g the need to achieve a particular cadence rate
or dynamic range;
• as technical requirements from the EIS system design, which themselves have been
derived from the science requirements;
• requirements which are not specficied by the telescope design or science requirements but
which can be thought of as being implicit, e.g sufficient calibration facilities must be
provided
1.3
The EIS design will consist of a mirror, a slit, a grating, and a detector (the exact
specifications of the EIS are still TBD). An area of the sun (selected via uplinked command)
is focused onto the slit. In turn, this image is dispersed by the reflection grating into two
seperate spectral regions, a low wavelength regions (170-210°), and a high wavelength region
(250-290°), and these regions are then focused by the grating onto two CCDs mounted in the
camera head.
2
Scientific Requirements
The following table describes the relevant Scientific Requirements, as laid out in the Systems
Requirements document, and their implications for the CCD camera head design.
1
Requirement
Wavelength
range
Value
low - 180-204Å
high - 250-290Å
2
Temporal
resolution
commensurate with
evolution of features
3
Spatial resolution
< 2"
Implications for CCD specification
Two CCD detectors will be required
The CCDs should be backthinned to
maximise the Quantum Efficiency at
these wavelengths
The CCD must support a number of
imaging modes
Separate amplifier paths may be
provided to maximise the cadence
The design of the spectrometer
assumes a CCD pixel size of 13.5µm
Page 4 of 7
4
<20km/s/pixel
5
Spectral
Resolution
Field of View
6
Sensitivity
must be as high as
possible
3
7
1000" (spatial direction)
x2000" (spectral
direction)
The camera head must be located
within the Rowland circle associated
with the spectrometer sufficiently
accurately to enable a good focus to
be achieved and maintained
throughout the working life of SolarB
The design of the spectrometer
assumes a CCD pixel size of 13.5um
Size of CCD must be sufficient to
cover entire FOV, this requires a
CCD size of 2048 x 1024 pixels to
allow for alignment issues
The CCD must have a high QE at the
required wavelengths, and the
dynamic range of the CCD should be
as high as possible
A low on chip read out noise must be
available. This will require the use of
correlated double sampling (cds).
Variable cds times will enable the
operator to trade off read out noise
with cadence rate
The CCD must minimise both dark
noise and CTI as much as possible.
This requires an appropriate trade off
between temperature (via a cold
finger) and dither clocking to
minimise the dark noise; and
temperature, shielding, and operating
parameters to minimise the effect of
radiation on the device
The device will be backthinned to
maximise QE. Precautions must be
taken to reduce the effect of
contamination on the CCD backface
Technical Requirements
Requirement
CCD mounting
Implications for CCD specification
The two active
wavelength areas will be
separated by 27.8mm ±
TBD
The depth of focus is
TBD
A self contained housing is required
for the CCD and Read Out
Electronics which must be capable of
mounting accurately onto the
appropriate position on EIS
Page 5 of 7
8
4
9
10
CCD power
consumption
The camera head will
need to be mated with the
EIS structure, and tests
established to show that a
correct alignment has
been achieved
The power consumption
should be within the
values established for
EIS (TBD)
The mounting must be capable of
alignment in all three axes
The CCD will be operated at room
temperature to allow the tests to be
conducted efficiently. The device
may have to be operated with dither
clocking, or an MPP CCD may need
to be selected
Operational requirements
Requirement
The nominal
mission lifetime
of Solar-B is 3
years
The radiation
environment over
the mission
lifetime should
not cause a
degradation of
the CCD
Sufficient calibration
functionality should be
provided to allow the
CCD to operate within its
required performance
limits for this time
Implications for CCD specification
The camera head must be able to
send CCD images to ground based
users
The camera head must be
configurable by ground-based
users
Sufficient test functionality should
be available to allow the CCD
detector to provide calibration data
to ground based users. This may
include provision of a suitable flat
field at the detector face and an
Fe55 source, suitably housed in the
camera head
An appropriate choice of
temperature, shielding and device
operating parameters will be
necessary to minimise radiation
damage and its effects
Heaters must be provided to
maintain the optimum operating
temperature, and to allow removal
of contaminants, and "annealing"
of ionisation induced dark noise
Page 6 of 7
5
Notes
5.1
Temporal resolution
A number of measurement modes must be provided. In particular:
•
readout window:
a known area of the image can be selected. Charge from pixels prior to the read out
window do not need to be read and can be quickly dumped.
The window will be specified in terms of two co-ordinates (xstart,ystart) and (xend,
yend) - where x refers to the pixel number (i.e the spectral direction) and y refers to
the line number (i.e the spatial direction).
•
binning in the serial and parallel registers:
It should be possible to bin pixels in both the parallel and serial directions
The binning ratio can be specified in terms of m x n where m refers to the binning
ratio in the spectral direction, and n refers to the binning ratio in the spatial direction.
Note - due to saturation of charge in the summing registers, there will be a physical
limit to the amount of charge that can be binned in either direction.
5.2
•
specification of windows:
up to two windows will be available per CCD. One window can be readout to the
right hand amplifier, the other to the left hand amplifier. Both windows must be the
same row height.
•
integration time:
as well as a range of integration times, it should be possible to specify a zero
integration time as an additional calibration mode.
•
flush the CCD:
i.e dump all the charge from the CCD before taking an image.
Calibration facilities
The camera head design will need to support the following specialised measurement modes:
1 Dark Current
2 Flat fielding
3 Overscan
4 CTI
5 Read out noise
6 Bias value
Page 7 of 7
Was this manual useful for you? yes no
Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Download PDF

advertisement