Jigsaw three-dimensional (3D) imaging laser radar is a compact, light-weight system for imaging
highly obscured targets through dense foliage semi-autonomously from an unmanned aircraft. The
Jigsaw system uses a gimbaled sensor operating in a spot light mode to laser illuminate a cued
target, and autonomously capture and produce the 3D image of hidden targets under trees at high 3D
voxel resolution. With our MIT Lincoln Laboratory team members, the sensor system has been
integrated into a geo-referenced 12-inch gimbal, and used in airborne data collections from a UH-1
manned helicopter, which served as a surrogate platform for the purpose of data collection and
system validation. In this paper, we discuss the results from the ground integration and testing of the
system, and the results from UH-1 flight data collections. We also discuss the performance results
of the system obtained using ladar calibration targets.
We have developed a three-dimensional (3D) imaging ladar focal plane array (FPA) for military and commercial applications. The FPA provides snap-shot, direct detection, high-resolution range and range-sampled intensity imaging capability on a single chip. The FPA is made of a 64x64 element, 100-μm pixel pitch detector array that is directly bump bonded to a matched CMOS based silicon readout integrated circuit (ROIC) with parallel ladar signal processing at each pixel. A room temperature, SWIR InGaAs detector variant for imaging near 1.5-μm wavelengths and a cooled MWIR HgCdTe detector variant for imaging near 3-μm to 5-μm wavelengths have been fabricated. We have built a prototype SWIR FPA, integrated it to a compact, transportable SWIR flash ladar transceiver, and collected initial range images outdoors. We present the measured performances of the detector, the readout, and the image data collected with the focal plane array.
We are developing a novel 2D focal plane array (FPA) with read-out integrated circuit (ROIC) on a single chip for 3D laser radar imaging. The ladar will provide high-resolution range and range-resolved intensity images for detection and identification of difficult targets. The initial full imaging-camera-on-a-chip system will be a 64 by 64 element, 100-micrometers pixel-size detector array that is directly bump bonded to a low-noise 64 by 64 array silicon CMOS-based ROIC. The architecture is scalable to 256 by 256 or higher arrays depending on the system application. The system will provide all the required electronic processing at pixel level and the smart FPA enables directly producing the 3D or 4D format data to be captured with a single laser pulse. The detector arrays are made of uncooled InGaAs PIN device for SWIR imaging at 1.5 micrometers wavelength and cooled HgCdTe PIN device for MWIR imaging at 3.8 micrometers wavelength. We are also investigating concepts using multi-color detector arrays for simultaneous imaging at multiple wavelengths that would provide additional spectral dimension capability for enhanced detection and identification of deep-hide targets. The system is suited for flash ladar imaging, for combat identification of ground targets from airborne platforms, flash-ladar imaging seekers, and autonomous robotic/automotive vehicle navigation and collision avoidance applications.
We describe a tunable, 1.3 to 5 micrometers wavelength reflectance measurement system using an optical parametric oscillator (OPO) as the light source. The OPO source consists of a 1 micrometers Nd:YAG laser which is frequently shifted to 1.3-5 micrometers wavelengths using a periodically poled lithium niobate nonlinear optical crystal. The system design, calibration, and measurement of the directional-hemispherical reflectance factor and the bi-directional reflectance distribution function of different target materials are presented.
We investigate the phenomenology and modeling for the development of an active multispectral laser radar (LADAR) sensor to image and identify ground targets in the 1 to 5 micrometers wavelength region. This sensor will be especially useful in high clutter situations or situations where the target is partially concealed. A continuously tunable optical parametric oscillator using a periodically poled lithium niobate (PPLN) nonlinear optical crystal is investigated as a candidate light source for the sensor. A 1 micrometers Nd:YAG laser was frequency shifted in PPLN to produce continuously tunable output between 1.35 to 5 micrometers wavelengths and signal output energy of up to 3.3 mJ in a 3 ns pulse. A tunable monostatic reflectometer system is fabricate for the measurement of the bidirectional reflectance distribution function of the LADAR target materials A method or band selection is formulated and tested using library reflectance spectra. Results of this work will be used for tower based imaging of different targets in cluttered backgrounds at ranges out to 3 km.