Even as remote sensing technology has advanced in leaps and bounds over the past decade, the remote sensing community lacks interfaces and interaction models that facilitate effective human operation of our sensor platforms. Interfaces that make great sense to electrical engineers and flight test crews can be anxiety-inducing to operational users who lack professional experience in the design and testing of sophisticated remote sensing platforms. In this paper, we reflect on an 18-month collaboration which our Sandia National Laboratory research team partnered with an industry software team to identify and fix critical issues in a widely-used sensor interface. Drawing on basic principles from cognitive and perceptual psychology and interaction design, we provide simple, easily learned guidance for minimizing common barriers to system learnability, memorability, and user engagement.
In this paper, we address the needed components to create usable engineering and operational user interfaces (UIs) for airborne Synthetic Aperture Radar (SAR) systems. As airborne SAR technology gains wider acceptance in the remote sensing and Intelligence, Surveillance, and Reconnaissance (ISR) communities, the need for effective and appropriate UIs to command and control these sensors has also increased. However, despite the growing demand for SAR in operational environments, the technology still faces an adoption roadblock, in large part due to the lack of effective UIs. It is common to find operational interfaces that have barely grown beyond the disparate tools engineers and technologists developed to demonstrate an initial concept or system. While sensor usability and utility are common requirements to engineers and operators, their objectives for interacting with the sensor are different. As such, the amount and type of information presented ought to be tailored to the specific application.
The evolution of exquisitely sensitive Synthetic Aperture Radar (SAR) systems is positioning this technology for use in time-critical environments, such as search-and-rescue missions and improvised explosive device (IED) detection. SAR systems should be playing a keystone role in the United States’ Intelligence, Surveillance, and Reconnaissance activities. Yet many in the SAR community see missed opportunities for incorporating SAR into existing remote sensing data collection and analysis challenges. Drawing on several years' of field research with SAR engineering and operational teams, this paper examines the human and organizational factors that mitigate against the adoption and use of SAR for tactical ISR and operational support. We suggest that SAR has a design problem, and that context-sensitive, human and organizational design frameworks are required if the community is to realize SAR's tactical potential.
The self-referencing interferometer (SRI) wavefront sensor (WFS) is being developed for applications requiring laser
propagation in strong scintillation. Because it directly measures the optical field of the wavefront, the SRI WFS is less
effected by scintillation than conventional WFSs. This feature also means the phase determined from the WFS
measurements is limited to the range -π to π, due to the use of the arctangent function. If a segmented wavefront
corrector is used, this constraint is not a problem. However, if a continuous facesheet deformable mirror is used, the
resulting phase should be unwrapped in order to minimize fitting error. There are a couple of places in the adaptiveoptical
(AO) closed-loop control process where an unwrapping algorithm can be inserted. Simulations of these
configurations have shown that how and where the unwrapping is carried out affects overall AO performance and loop
stability. This paper presents an overview of the unwrapping options and the associated issues. A laboratory
demonstration of two control loop configurations was carried out to test the validity of the simulation results. These
experiments and their outcome are discussed.
Over the last few years the Starfire Optical Range, Air Force Research Laboratory, Kirtland AFB, has been
developing the self-referencing interferometer (SRI) wave front sensor (WFS). The objective of this project
has been to demonstrate and evaluate the performance advantages the SRI WFS provides over conventional
WFSs, particularly in applications requiring laser propagation in strong scintillation. The initial SRI prototypes
relied on a temporal phase shifting approach to produce and capture the required interference images for wave
front reconstruction. This approach simplified the initial development by minimizing issues related to detector
calibration and the co-alignment of beams. In this paper we discuss the next step in our SRI development efforts
and present the design of a spatial phase shifting SRI WFS. The design allows all four interference images-
with respective phase shifts of 0, π/2, π, and 3π/2 between the reference and signal beams- to be captured
simultaneously on a single camera. Initial results from a laboratory demonstration of the design are shown.
Multi-Conjugate Adaptive-Optical (MCAO) systems have been proposed as a means of compensating both intensity and phase aberrations in a beam propagating through strong-scintillation environments. Progress made on implementing a MCAO system at the Starfire Optical Range (SOR), Air Force Research Laboratory, Kirtland AFB, is discussed. As a preliminary step toward controlling a two deformable mirror (DM) system, the First-stage Intensity Redistribution Experiment (FIRE) examines one aspect of an MCAO system-control and compensation of wavefront intensity. Two wavefront sensors (WFS) and a single DM are employed for this experiment. One WFS is placed conjugate to the DM while the second WFS is located at a distance which produces a desired Fresnel number for the propagation between the WFSs. The WFS measurements are input to a Gerchberg-Saxton based control algorithm in order to determine the DM commands. The phase pattern introduced by the DM is chosen so propagation along the path between the two WFSs produces a desired intensity profile at the second WFS. The second WFS is also used to determine the accuracy of the intensity redistribution and measure its effects on the wavefront phase. In the next phase of MCAO development, a second DM will be added conjugate to the second WFS in order to correct the remaining phase aberrations. This paper presents the setup and operation for FIRE along with initial laboratory results.
This paper discusses the application of adaptive control methods in the Atmospheric Simulation and Adaptiveoptics
Laboratory Testbed at the Starfire Optical Range at the Air Force Research Laboratory, Kirtland AFB.
Adaptive compensation is useful in adaptive optics applications where the wavefronts vary significantly from one
frame to the next or where wind velocities and the strength of atmospheric turbulence change rapidly, rendering
classical fixed-gain reconstruction algorithms far from optimal. The experimental results illustrate the capability
of the adaptive control scheme to increase Strehl ratios and reduce jitter.
The Self-Referencing Interferometer Wavefront Sensor (SRI WFS) has been shown to outperform conventional wavefront sensors in strong scintillation environments. Recently, the Starfire Optical Range has developed a prototype SRI to evaluate its performance. This paper discusses the purposes of optically amplifying the reference beam. Specifically, it addresses regions of operation where gain improves signal-to-noise ratio (SNR) values, and thus the SRI WFS performance. Conditions are also addressed when Amplified Spontaneous Emission (ASE) from the optical amplifier degrades the overall signal, resulting in less than acceptable SNR ratios. Laboratory measurements of SRI WFS performance with an optical amplifier are presented.
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