Over the last few years, Boulder Nonlinear Systems (BNS) and North Carolina State University (NCSU) have developed
a new beam steering technique that uses a stack of thin liquid crystal polarization gratings (LCPGs) to efficiently and
non-mechanically steer a beam over a large field-of-regard (FOR) in discrete steps. This technology has been
successfully transferred to BNS through an exclusive license agreement, and a facility has been completed to enable
commercial production of these devices. This paper describes the capabilities enabled by both the LCPGs and the
successful transfer of this technology.
Liquid Crystal on Silicon micro-displays are the enabling components on a variety of commercial consumer products
including high-definition projection televisions, office projectors, camera view-finders, head-mounted displays and picoprojectors.
The use and potential application of LCOS technology in calibrated scene projectors is just beginning to be
explored. Calibrated LCOS displays and projectors have been built and demonstrated not only in the visible regime, but
also in the SWIR, MWIR and LWIR. However, LCOS devices are not only capable of modulating the intensity of a
broadband illumination source, but can also manipulate the polarization and/or phase of a laser source. This opens the
possibility of both calibrated polarization displays and holographic projection displays.
Boulder Nonlinear Systems (BNS) has demonstrated a MWIR step and stare imaging system for AFRL that eliminates
the need for turrets and multiple cameras to scale the performance of available thermal imagers. The demonstration
system non-mechanically switches between fields-of-regard in a Hex-7 pattern to achieve 0.1 milliradian resolution
within a 17.5x17.5 degree field-of-regard. The sub-millisecond shutter switching time and polarization independence
maximizes the imaging integration time and sensitivity. The system uses a 1024x1024 (19.5 micron square pixels) InSb
camera with a 4.5 to 5 micron passband filter. Larger area detectors could be used to obtain larger fields-of-view, or the
system could be scaled to a larger pattern of shutter arrays. The system was developed to provide a cost-effective
method of providing night-vision and thermal imaging capabilities for persistent, high-resolution surveillance
applications with sufficient resolution to track mounted and un-mounted threats. The demo hardware was engineered to
enable near-term field and flight testing.
The Super-resolution Sensor System (S3) program is an ambitious effort to exploit the maximum information a laser-based
sensor can obtain. At Lockheed Martin Coherent Technologies (LMCT), we are developing methods of
incorporating multi-function operation (3D imaging, vibrometry, polarimetry, aperture synthesis, etc.) into a single
device. The waveforms are matched to the requirements of both hardware (e.g., optical amplifiers, modulators) and the
targets being imaged. The first successful demonstrations of this program have produced high-resolution, three-dimensional
images at intermediate stand-off ranges. In addition, heavy camouflage penetration has been successfully
demonstrated. The resolution of a ladar sensor scales with the bandwidth as dR = c/(2B), with a corresponding scaling of
the range precision. Therefore, the ability to achieve large bandwidths is crucial to developing a high-resolution sensor.
While there are many methods of achieving the benefit of large bandwidths while using lower bandwidth electronics
(e.g., an FMCW implementation), the S3 system produces and detects the full waveform bandwidth, enabling a large set
of adaptive waveforms for applications requiring large range search intervals (RSI) and short duration waveforms. This
paper highlights the combined three-dimensional imaging and vibrometry demos.
The Super-resolution Sensor System (S3) program is an ambitious effort to exploit the maximum information a laser-based sensor can obtain. At Lockheed Martin Coherent Technologies (LMCT), we are developing methods of incorporating multi-function operation (3D imaging, vibrometry, polarimetry, aperture synthesis, etc.) into a single device. The waveforms will be matched to the requirements of both hardware (e.g., optical amplifiers, modulators) and the targets being imaged. The first successful demonstrations of this program have produced high-resolution, three-dimensional images at intermediate stand-off ranges. In addition, heavy camouflage penetration has been successfully demonstrated. The resolution of a ladar sensor scales with the bandwidth as dR = c/(2B), with a corresponding scaling of the range precision. Therefore, the ability to achieve large bandwidths is crucial to developing a high-resolution sensor. While there are many methods of achieving the benefit of large bandwidths while using lower bandwidth electronics (e.g., an FMCW implementation), the S3 system produces and detects the full waveform bandwidth, enabling a large set of adaptive waveforms for applications requiring large range search intervals (RSI) and short duration waveforms. This paper highlights the three-dimensional imaging and camo penetration.
High range-resolution active imaging requires high-bandwidth transmitters and receivers. At Lockheed Martin Coherent
Technologies (LMCT), we are developing both linear Frequency Modulated Continuous Wave (FMCW) and short pulse
laser radar sensors to supply the needed bandwidth. FMCW waveforms are advantageous in many applications, since
target returns can be optically demodulated, mitigating the need for high-speed detectors and receiver electronics,
enabling the use of much lower bandwidth cameras. However, some of the penalties paid for these transceivers include
a finite range search interval (RSI) and the requirement for slow chirp or long-duration waveforms, owing to the
relatively slow sample frequency of the cameras used in the receiver. For applications requiring larger RSI's and short
duration waveforms, LMCT is also developing high bandwidth pulsed ladar waveforms and receivers. This paper will
include discussion of these two methods, their tradeoffs and sample imagery collected at LMCT.
The spatial resolution of a conventional imaging LADAR system is constrained by the diffraction limit of the telescope aperture. The purpose of this work is to investigate Synthetic Aperture Imaging LADAR (SAIL), which employs aperture synthesis with coherent laser radar to overcome the diffraction limit and achieve fine-resolution, long range, two-dimensional imaging with modest aperture diameters. This paper details our laboratory-scale SAIL testbed, digital signal processing techniques, and image results. A number of fine-resolution, well-focused SAIL images are shown including both retro-reflecting and diffuse scattering targets. A general digital signal processing solution to the laser waveform instability problem is described and demonstrated, involving both new algorithms and hardware elements. These algorithms are primarily data-driven, without a priori knowledge of waveform and sensor position, representing a crucial step in developing a robust imaging system. These techniques perform well on waveform errors, but not on external phase errors such as turbulence or vibration. As a first step towards mitigating phase errors of this type, we have developed a balanced, quadrature phase, laser vibrometer to work in conjunction with our SAIL system to measure and compensate for relative line of sight motion between the target and transceiver. We describe this system and present a comparison of the vibrometer-measured phase error with the phase error inferred from the SAIL data.
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