Detector Testing Methodologies For Large Focal Planes

1
THE WEEKLY
This Weeks Forecast Clear Skies Seeing 0.4 Some
Ash Warm Seas
DETECTOR
The Nerds are Back In Town !!
19 - 25 June, 2005 0.00
Taormina, Italia
Detector Testing Methodologies For Large Focal
Planes
P. C. Moore and G. Rahmer
Subtle change of paradigm
Focal planes
Linking detector performance to science objectives
It is a familiar saying that in science, asking a
question usually provides more questions than
answers. In this way, the questions we asked
yesterday have led us to ask new questions today
that require ever increasing contributions of
social, political, and capital investment to
answer. To this end, a subtle change of paradigm
is in process with regard to the methodology of
developing astronomical instrumentation.
Historically instrumentation was designed
specifically for an institutional telescope, or a
small group of telescopes, and with a relatively
wide range of application for general application
to astronomy. With relevance to this paper, this
often meant designing an instrument to
accommodate the convolution of a new or enhanced
detector technology with the current demands of a
national group of scientists. Today we see a
trend towards large collaborations to supply the
scientific, engineering, and capital investment
required to provide the instrumentation needed to
supply an answer to perhaps just one or two
specific questions. In this new paradigm, the
science objectives have clear priority the
instrument being designed specifically for these
requirements, and often, a telescope being built
to accommodate the instrument.
The use of large detector mosaics to support
future instrumentation poses new demands on the
timeliness and rigor of detector testing
procedures. Ideally, the characterization and
selection of detectors for any particular new
instrument should not appear as a critical path
in the project. Committing to a large lot run of
devices is expensive and deserves deep analysis
of the factors that affect scientific tradeoff,
developmental risk, and delivery schedules. We
propose a methodology that involves incorporation
of the elements of detector testing at the very
beginning of the instrument requirement
definition process In this way the selection of
detectors to provide the maximum science
potential can be assured and audited.
By analyzing the science tradeoffs that will
occur when detector performance is less than (or
better than) the instrument specification, a
figure of merit can be established for each
tested detector. This will allow an unambiguous
comparison of different detectors and detector
technologies to be made and reflect the degree of
suitability of any particular detector to the
instrument science objectives. To derive the
figure of merit for each detector, metrics are
obtained from direct measurements of a detectors
performance, which are then normalized to a
typical operational model of an instrument
observational unit. Five metrics are considered
in the figure of merit. These are cadence (i.e.
Observed sky / time), observed optical quality,
observational depth, photometric accuracy, and
observatory efficiency. Each metric for a
particular detector is calculated using measured
detector parameters.
2
THE WEEKLY
This Weeks Forecast Clear Skies Seeing 0.4 Some
Ash Warm Seas
DETECTOR
The Nerds are Back In Town !!
19 - 25 June, 2005 0.00
Taormina, Italia
Detector Testing Methodologies For Large Focal
Planes
P. C. Moore and G. Rahmer
Time / Resource Availability
Budget Requirements
Science Requirements
Detector Availability
Whats For Lunch
Well Depth
3
THE WEEKLY
This Weeks Forecast Clear Skies Seeing 0.4 Some
Ash Warm Seas
DETECTOR
The Nerds are Back In Town !!
19 - 25 June, 2005 0.00
Taormina, Italia
Detector Testing Methodologies For Large Focal
Planes
P. C. Moore and G. Rahmer
New Detector
New Instrument
New Question
Science
Engineering
Subtle change of paradigm
New Question
New Instrument
New Question
Science
Engineering
4
THE WEEKLY
This Weeks Forecast Clear Skies Seeing 0.4 Some
Ash Warm Seas
DETECTOR
The Nerds are Back In Town !!
19 - 25 June, 2005 0.00
Taormina, Italia
Detector Testing Methodologies For Large Focal
Planes
P. C. Moore and G. Rahmer
Subtle change of paradigm
Focal planes
Some Current Questions
Require
5
THE WEEKLY
This Weeks Forecast Clear Skies Seeing 0.4 Some
Ash Warm Seas
DETECTOR
The Nerds are Back In Town !!
19 - 25 June, 2005 0.00
Taormina, Italia
Detector Testing Methodologies For Large Focal
Planes
P. C. Moore and G. Rahmer
Subtle change of paradigm
Focal planes
Linking detector performance to science objectives
Measured Detector Characteristics
QE_at_ ?
Cosmetics
Hard Metrics
.
Fill Factor
Science Requirements
6
THE WEEKLY
This Weeks Forecast Clear Skies Seeing 0.4 Some
Ash Warm Seas
DETECTOR
The Nerds are Back In Town !!
19 - 25 June, 2005 0.00
Taormina, Italia
Detector Testing Methodologies For Large Focal
Planes
P. C. Moore and G. Rahmer
Characterization Lab established to prove concept
New dewar design and serialization key to
reduction in characterization time.
North Detector Lab begins to take shape, South to
follow soon.
7
THE WEEKLY
This Weeks Forecast Clear Skies Seeing 0.4 Some
Ash Warm Seas
DETECTOR
The Nerds are Back In Town !!
http//www.noao.edu
19 - 25 June, 2005 0.00
Taormina, Italia
Detector Testing Methodologies For Large Focal
Planes
P. C. Moore and G. Rahmer
Subtle change of paradigm
Focal planes
Linking detector performance to science objectives
It is a familiar saying that in science, asking a
question usually provides more questions than
answers. In this way, the questions we asked
yesterday have led us to ask new questions today
that require ever increasing contributions of
social, political, and capital investment to
answer. To this end, a subtle change of paradigm
is in process with regard to the methodology of
developing astronomical instrumentation.
Historically instrumentation was designed
specifically for an institutional telescope, or a
small group of telescopes, and with a relatively
wide range of application for general application
to astronomy. With relevance to this paper, this
often meant designing an instrument to
accommodate the convolution of a new or enhanced
detector technology with the current demands of a
national group of scientists. Today we see a
trend towards large collaborations to supply the
scientific, engineering, and capital investment
required to provide the instrumentation needed to
supply an answer to perhaps just one or two
specific questions. In this new paradigm, the
science objectives have clear priority the
instrument being designed specifically for these
requirements, and often, a telescope being built
to accommodate the instrument.
The use of large detector mosaics to support
future instrumentation poses new demands on the
timeliness and rigor of detector testing
procedures. Ideally, the characterization and
selection of detectors for any particular new
instrument should not appear as a critical path
in the project. Committing to a large lot run of
devices is expensive and deserves deep analysis
of the factors that affect scientific tradeoff,
developmental risk, and delivery schedules. We
propose a methodology that involves incorporation
of the elements of detector testing at the very
beginning of the instrument requirement
definition process In this way the selection of
detectors to provide the maximum science
potential can be assured and audited.
By analyzing the science tradeoffs that will
occur when detector performance is less than (or
better than) the instrument specification, a
figure of merit can be established for each
tested detector. This will allow an unambiguous
comparison of different detectors and detector
technologies to be made and reflect the degree of
suitability of any particular detector to the
instrument science objectives. To derive the
figure of merit for each detector, metrics are
obtained from direct measurements of a detectors
performance, which are then normalized to a
typical operational model of an instrument
observational unit. Five metrics are considered
in the figure of merit. These are cadence (i.e.
Observed sky / time), observed optical quality,
observational depth, photometric accuracy, and
observatory efficiency. Each metric for a
particular detector is calculated using measured
detector parameters.