This paper will discuss applications of angle resolved amplitude modulated laser radar to a variety of industrial and manufacturing environments. This paper will also compare laser radar to existing vision technologies and show how laser radar improves manufacturing processes.

This paper describes the depth surrounding activities in Sweden. These include the development of a helicopter borne lidar called FLASH as well as instrumentation for in situ measurement of the optical water parameters. The FLASH system has been further developed into two operational systems called Hawk Eye with Saab Dynamics as the main contractor and Optech Inc. as the main subcontractor. Data collection and evaluation from Hawk Eye will be discussed. The Swedish Defence Research Establishment (FOA) is member of the Hawk Eye project team together with the National Maritime Administration, the Royal Swedish Navy and the Defence Material Administration. Together with the Swedish Maritime Administration, FOA has been engaged in analysis of lidar data to determine system performance and possible ways to optimize that in relation to lidar parameters and anticipated bottom depth and topography. Examples from that analysis will be presented. The test analysis so far strongly supports the depth sounding lidar technology as being a rapid and accurate sounder fulfilling the requirement by International Hydrographic Office on depth accuracy.

In 1995, under a USAF SBIR Phase I program, Burns Engineering Corporation investigated the application of new integrated photonics technologies and hybrid manufacturing processes to the miniaturization of an imaging laser radar receiver which has complete receiving and range counting circuitry for each pixel in a 25-by-25 element avalanche photodiode array. The `parallel multichannel' receiver (PMR) is a compact, robust, and modular laser radar subsystem which can produce high resolution 3D range imagery at 1 kHz frame rates without the use of a scanner. The modular PMR is attractive as a common module solution for a wide variety of high performance, low cost, autonomous laser-guided seeker applications. The system described illustrates one approach to integrating and packaging high-density photonic arrays and associated signal processing electronics to yield a high-performance imaging laser radar receiver using existing technology. Burns Engineering has been selected by the USAF to build a benchtop prototype, proof-of-concept demonstrator in a follow-on, SBIR Phase II program.

Sandia National Laboratories is nearing the completion of the initial development of a unique type of range imaging sensor. This innovative imaging optical radar is based on an active flood-light scene illuminator and an image intensified CCD camera receiver. It is an all solid-state device (no moving parts) and offers significant size, performance, reliability, simplicity, and affordability advantages over other types of 3D sensor technologies, including: scanned laser radar, stereo vision, and structured lighting. The sensor is based on low cost, commercially available hardware, and is very well suited for affordable application to a wide variety of military and commercial uses, including: munition guidance, target recognition, robotic vision, automated inspection, driver enhanced vision, collision avoidance, site security and monitoring, terrain mapping, and facility surveying. This paper reviews the sensor technology and its development for the advanced conventional munition guidance application, and discusses a few of the many other emerging applications for this new innovative sensor technology.

Previous efforts to develop 3D laser radar (ladar) imagers have required multiple laser pulses and complex stable scanning and timing systems in order to generate images. This paper describes an approach that will enable a complete 3D ladar image (angle-angle-range) to be captured with a single pulse. Using a unique processor chip that is bump bonded directly behind the detector array, the sensor provides separate independent range finder circuitry for each pixel. The time-of-flight for each pixel is recorded on the chip and the values are then read out serially. This approach allows the range resolution to be determined by the laser pulse width and electronics bandwidth and to be independent of image framing rates. This paper will discuss the design, laboratory tests and present the status of the imager that will be assembled for field demonstrations. The specifications of the demonstration unit are for a 64 X 64 pixel imager with a resolution of .3 X .3 X .3 meters (1 X 1 X 1 feet). The system is expected to operate at approximately video framing rates (30 frames per second) and the resulting image will be displayed in a false color picture on the processor monitor.

High-quality eye treatment needs sophisticated and accurate instrumentation for cornea profile measurement before and after laser ablation. Plastic PMMA specimens are in ordinary use for pre-operational adjustment of laser intensity distribution, supposed that the results of the cornea surface ablation and the ablation of the plastic surface are identical. We investigated dual-beam technique for path- difference measurement of two laser beams, reflected from two neighboring points of the surface to be measured. The beams are frequency shifted relative to each other. Interference in the plane of receiver gives differential frequency, its phase being dependent on path difference. Acousto-optical scanning results in 2D distribution of path difference. To get surface profiles, along-line videosignals undergo the mathematical operation of integration. The sensitivity of several nanometers was got to flat specimens. For convenience of image processing and visualization, TV type scanning is applied to laser beams.

More than 10 years of operation of a cw-Doppler lidar for boundary layer winds together with the hardware development of a compact laser Doppler anemometer for ballistic wind measurements and the development of an airborne sensor, concluded in the proposed design of an operational system. The different problems with lasers (10 micron systems vs. 2 micron systems, pulsed or cw), detectors and atmospheric stability conditions will be presented. The hardware of the compact laser Doppler anemometer and the airborne sensor ADOLAR will be analyzed with respect of a proposed automatic operational system. Criteria of the proposed system are the laser, the detection and signal processing algorithm and the reliability of the system in a harsh environment like a battlefield. For the laser the first criteria is the all- weather capability. A cw laser system is affected by a low overcast. Without additional information on the cloud base height the results may be misinterpreted. A pulsed system gives both, wind profile and cloud base height. All other criteria for the selection of an optimal sensor will be presented.

The NASA Langley Research Center's 14-inch airborne aerosol lidar system, which is routinely flown on several NASA aircraft including the DC-8 and the P-3, has been upgraded with several modifications to enhance its measurement capabilities. A new 900 mJ, 10 pps Nd:YAG laser was added with the capability of producing 5 watts of power at 1064 nm, 2.5 watts at 532 nm and 1.5 watts at 355 nm. The existing detector package has been modified to accommodate the three wavelengths and to permit cross-polarization measurements at 532 nm. New software was developed for on- line data visualization and analysis, and computer- controlled laser alignment is being incorporated. The system is now capable of producing real-time color modulated backscatter plots. Other additions include a Pentium/90 processor, GPS (Global Positioning System) and ARINC (Aeronautical Radio Inc.) receivers for acquiring accurate aircraft position data. In 1992 and 1993 this system was flown on several airborne missions to map and characterize the stratospheric aerosol cloud produced by the 1991 eruption of the Mount Pinatubo volcano. Efforts to map the global distribution of Pinatubo were made on both daytime as well as nighttime flights from Moffett Field in California to the South Pacific, to Central and South America, to Australia and to Alaska. In September 1994, the system (aboard NASA's P-3) made correlative measurements along shuttle orbit ground tracks in support of the Lidar In-space Technology Experiment flown on the Space Shuttle. In this paper the system upgrades will be discussed and selected data obtained during these recent airborne campaigns will be presented.

One of the primary difficulties with high altitude airdrop missions is the effect of the wind field on the objects dropped. Aircraft crews currently obtain wind fields using a combination of measuring winds at altitude during flight, data from local weather stations and data from balloon launches (radiosondes). This data is used to adjust the cargo release point to compensate for the intervening winds. Since these methods have limited utility, a desired alternative would be a sensor placed on board the aircraft able to accurately measure real time wind fields at any location. The purpose of the project presented is to demonstrate a flightworthy eye-safe solid state laser radar system meeting these criteria. The system, which was assembled from available subsystems not designed nor engineered for this particular application, was named `Interim Operational Capability'. These subsystems were hardened and integrated together in such a way as to be installed on an operational Air Force aircraft in a short time-frame, thereby providing a near term wind field measuring capability for airdrop missions, should the need arise.

A CO₂-ladar system is used for measurements. The signal from the system is a sinusoidal FM-modulated multi-component signal. To extract the modulating frequencies time-frequency representations, e.g., the Wigner-Ville distribution and the Choi-Williams distribution are used. The estimation method is applied both to simulated and real data. Estimation of the vibration frequencies is shown to be feasible even for low SNR, e.g., -4 db.

A vast field of non-contact metrology, vibrometry, dynamics and microdynamics problems solved on the basis of laser Doppler method resulted in the development of great variety of laser Doppler radar (LDR). In coherent LDR few beams with various polarization are generally adopted, that are directed at the zone of measurement, through which the probing air stream moves. Studies of various coherent LDR demonstrated that polarization-phase effects of scattering can in some cases considerably effect on the signal-to-noise ratio of the Doppler signal. On the other side using phase effects can simultaneous measurement of size and velocity of spherical particles. New possibilities for improving the accuracy of measuring spherical particles' sizes come to light when application is made in coherent LDR of two waves- probing and one out of the types of symmetrical reception of scattered radiation, during which phase-conjugate signals are formed. The theoretical analysis on the basis of the scattering theory showed, that in symmetrical reception of scattered radiation with respect to the planes OXZ and OYZ output signal of the photoreceiver contains two high- frequency signal components, which in relation to parameters of the probing and size, can either be in phase or antiphase. Results of numerical modeling are presented: amplitude of high frequency signal, coefficient of phase and polarization matching of mixed waves, the depths of photocurrent modulation and also signal's phase in relation to the angle between the probing beams. Phase method of determining particle's sizes based on the use of two wavelengths probing and symmetrical reception of scattered radiation in which conditions for the formation of phase conjugated high-frequency signals are satisfied is presented.

In 1999 after a 3-year transit, the Near-Earth Asteroid Rendezvous (NEAR) spacecraft will enter a low-altitude (approximately 50 km) orbit about the asteroid, 433 Eros. Five instruments, including a laser radar, will operate continuously during the one-year orbit at Eros. The NEAR laser rangefinder (NLR), developed at the Applied Physics Laboratory (APL), is a robust rangefinder and the first spaceborne altimeter to have continuous inflight calibration capability. A bistatic configuration, the NLR uses a diode- pumped Cr:Nd:YAG transmitter and a leading-edge receiver with a 3.5-inch aperture Dall-Kirkham telescope. Detection is accomplished using an enhanced-silicon avalanche photodiode. From system tests, the NLR is capable of ranging in excess of 100 km to the asteroid's surface. Measurements of the time-of-flight between laser pulse firings and detection of surface backscatter are made using an APL- developed receiver having range resolution of 31.48 cm and accuracy of 2 m. Total mass of the NLR is 4.9 kg and its average power consumption is <EQ 15.1 W. This paper reviews specifications for the NLR instrument, provides overall design details, and presents system performance using prelaunch test results.

The Near Earth Asteroid Rendezvous (NEAR) mission is the first mission of the NASA Discovery Program. The NEAR spacecraft, developed and tested by the Johns Hopkins University Applied Physics Laboratory (JHU/APL), embarked on a four year mission on February 17, 1996. During the three- year cruise phase, the satellite will fly near the asteroid Mathilde and will receive an energy boost during an Earth swing-by in 1998. In 1999 NEAR will begin its year long orbit around the asteroid 433 Eros to collect scientific data using several instruments including an imager, a magnetometer, an X-ray/Gamma-ray detector, and a laser altimeter. The NEAR Laser Rangefinder (NLR) will provide altimetry data for characterizing the topography of Eros from a distance of 42 km. The instrument was designed and tested to meet the requirements of the NEAR space environment. In this paper we review the NLR design, present the test philosophy, highlight the tests, and present test results.

The Near Earth Asteroid Rendezvous (NEAR) Laser Rangefinder (NLR) is a bistatic system using a diode pumped Nd:YAG laser and a Dall-Kirkham telescope for a receiver. The NLR is one of a suite of five scientific data gathering instruments on the NEAR spacecraft. The NLR receiver is sensitive to incident IR radiation (1064 nm) and can detect return signals from the asteroid as low as 0.1 fJ per pulse, which corresponds to an average power of 9 nW (10 ns pulse). The design, development,a nd testing of the receiver will be discussed in this paper. Technological legacies from other space based programs were significant in meeting the schedule and cost requirements of a Discovery series program and will be discussed herein. Finally, the development of a cost effective, low impact, Level 50 clean area (pivotal in achieving the required environment for integration and test) will be presented.

This paper discuses the development of a short wavelength infrared laser ranging scanner system at the Canadian Space Agency in cooperation with the National Research Council Canada. A laser source at 1.54 micrometers wavelength is chosen for its relatively eye-safe property. The scanner system is to be considered for use as a space vision system for applications such as robot vision, satellite acquisition and tracking and high resolution 3D imaging for inspection. As an active system, this laser scanner offers an important advantage over conventional vision systems by providing its own illumination and having no dependence on ambient lighting. While providing relatively eye-safe operation, the choice of IR wavelength also improves the background rejection of solar radiation, the latter being about 5.8 times lower than in the visible. The system possesses two modes of operation for making range measurements: triangulation for short distances (0.5 m to 20 m) and time- of-flight for greater range (10 m to beyond 1 km). A short pulse high repetition rate laser is required for time-of- flight measurements. For space applications, the laser must be compact, rugged and efficient while operating in the eye- safe spectrum (1.5 to 1.8 micrometers ). Currently, a YAG laser with an OPO is used to demonstrate the system's operation at 1.54 micrometers , but is too bulky for a space environment. Eventually it will be replaced with a more compact and efficient fiber laser currently being developed. This paper presents the results of the capabilities and performance of the scanner.

A multi-joule, wavelength agile, CO₂ transceiver is being assembled in support of a two phase, airborne chemical sensing demonstration employing both direct (Phase I) and coherent (Phase II) detection methods. The Phase II, coherent detection transceiver concept design, and performance are described below.

A new technique for realistic synthesis of ladar imagery has been developed for the Irma scene generation code, version 4.0. A wide range of phenomenological effects as well as internal sensor effects can be modeled in detail. Both solid state and CO₂ time-of-flight measurement pulsed laser radars are supported for the monostatic case. Since the active range gate signal is computed, effects of multiple objects within the beam can be studied. User-definable processing operations allow evaluation of signal processing algorithms for design studies.

This paper presents the construction of a 2D multiple aperture coherent laser radar simulation that is capable of including the effects of the time evolution of speckle on the laser radar output. Every portion of a laser radar system is modeled in software, including quarter and half wave plates, beamsplitters (polarizing and non-polarizing), the detector, the laser source, and all necessary lenses. Free space propagation is implemented using the Rayleigh- Sommerfeld integral for both orthogonal polarizations. Atmospheric turbulence is also included in the simulation and is modeled using time correlated Kolmogorov phase screens. The simulation itself can be configured to simulate both monostatic and bistatic systems. The simulation allows the user to specify component level parameters such as extinction ratios for polarizing beam splitters, detector sizes and shapes. orientation of the slow axis for quarter/half wave plates and other components used in the system. This is useful from a standpoint of being a tool in the design of a multiple aperture laser radar system.

A user friendly modular computer code is described for CW coherent laser radar which includes all relevant physical effects needed to evaluate the probability of detection versus time after launch for ballistic missiles or other targets of interest. The beginning point of the code is the conventional laser radar range equation. Atmospheric attenuation is determined from an integral FASCODE calculation, and the laser radar range equation is solved for a curved-earth geometry including free air turbulence induced beam spreading. Several different atmospheric turbulence models are selectable. Target cross-sections can be input into the code as a function of aspect angle Coherence time and transverse coherence length limits are included in the code. Beam jitter effects are also calculated. The carrier-to-noise ratio is calculated including all of these (complicated) variables and degradations. The code then calculates the probability of detection of the target as a function of time using incoherent integration of coherent sub-pulses. The governing equations and practical results are presented for detection and tracking of long range theater ballistic missiles from airborne surveillance platforms. The use of CW lasers requires increased measurement times compared to pulsed lasers and results in an averaging of the target fading statistics.

We have recently been examining the performance of coherent laser radar systems for theater missile defense missions from an airborne platform. The application requires long range performance from a light weight, small volume system using existing technology. Specialized signal processing is required to efficiently extract the maximum information from the available laser output power. In this paper we consider methods to improve system performance by combining several laser radar pulses, showing that, in the presence of target fading, incoherent pulse averaging is superior. We describe a straightforward calculation method for incoherent pulse averaging. Steady and unsteady pointing errors degrade the performance of a coherent laser radar system in an airborne application. We present a calculation method and predictions of the performance penalties associated with jitter and boresight error for fading targets.

Two methods for restoration of images of coherently illuminated objects or coherent sources using multiple short-exposure images are proposed. The first method is based on the same concepts as the Knox-Thompson technique used for incoherent imaging. Sampling resolution requirements are calculated as a function of turbulence strength and lens size. The second method uses a probability maximization technique to form an estimate of the object based on the images taken and knowledge of the statistical nature of atmospheric turbulence. Both techniques require phase information of the electric field in the image plane. Methods of obtaining this information are also discussed.

Use of ladar seekers for autonomous vehicle identification and targeting from short range, expendable munitions is increasingly of interest due to the inherently high resolution shape data and the relatively low unit cost of the sensor. In addition, low-cost digital signal processors are now available that can manage the computational workload required for autonomous operation in a wide variety of tactical scenarios. A set of detection, segmentation, and vehicle identification algorithms have been developed which have been demonstrated on real and synthetic seeker data and have been targeted for the architecture and resources available on a tactically realistic processor. Results of preliminary algorithm testing are presented.

The development of a capability to infer wind velocities simultaneously at a number of ranges along one direction in real time is described. The elastic backscatter lidar data used was obtained using the XM94 lidar, developed by Los Alamos National Laboratory for the US Army Chemical and Biological Detection Command. In some respects this problem is simpler than measuring wind velocities on meso- meteorological scales. Other requirements, particularly high temporal fidelity, have driven the development of faster software algorithms and suggested opportunities for the evolution of the hardware.

The possibility of increasing the contrast of emission lines of certain elements in the laser spark spectroscopy method by initiating plasma plums by a laser wavelength which coincides with resonance transition of these elements was investigated. The results show that the resonance excitation of plasma by tunable lasers is one of the most promising ways for the increasing sensitivity of the remote spectrochemical analysis.

The paper reviews the basic capabilities and utility of the FLD laser radar system and highlights key features which lead to a combined LADAR/LIDAR capability.

The High Performance CO₂ Ladar Surveillance Sensor system (HI-CLASS) is a state-of-the-art coherent ladar system which will provide precision tracking and high resolution imaging at the Air Force Maui Optical Station (AMOS). System development is occurring in 3 phases representing increasing hardware/software complexity and system capability. The recently-completed Phase I HI-CLASS system employs a compact, pulsed, coherent CO₂ oscillator, a heterodyne receiver, and signal recorder coupled to the AMOS 0.6 m Laser Beam Director to demonstrate target (satellite) acquisition and tracking, illumination, return signal detection, signal recording, and off-line processing for range and range rate extraction and range- amplitude imaging. A description of the Phase I satellite ranging and ground-based remote sensing tests verifying the FLD system operating concept will be presented. The cooperative target range and range rate measurements, as well as imaging precursor demonstration, will be discussed. The talk will include a discussion of the 21 km demonstration of remote sensing using natural terrain returns. Results generated on phase I data with the phase II algorithm will also be described.

We present a summary of recent imagery and tracking measurements made with the ROBS laser radar system operating at White Sands Missile Range. The ROBS instrument utilizes a 0.5 meter aperture optical system, 3 - 5 micron imaging cameras, and a coherent CO₂ laser radar for range and Doppler measurements. The optical system is based on a roving fovea design, which enables signal target tracking over large angles at high track update rate, and rapid retargeting between multiple targets. Results of several field measurements are presented.

Novel 3D multichannel optical control systems are introduced for large coherent optical, array applications such as coherent laser radar and steered coherent optical communication links. Three optical control systems are introduced using a wide variety of photonic technologies such as acousto-optics, liquid crystals, bulk birefringent crystals, and polarization optics. System control speeds vary from a slow milli-second range to a fast sub- microsecond range. Each proposed system is appropriate for a particular application.

Lidar measurements, conducted at Hampton, Virginia, over the past 4 years, have provided data to characterize the mid- latitude stratospheric aerosol cloud produced by the Mount Pinatubo volcano in June 1991. These data also extend a long-term record on the stratospheric aerosol backscatter over the Hampton area dating back to 1974. Since shortly after the Pinatubo eruption, frequent measurements of aerosol backscatter have been taken using a 48-inch ground- based lidar facility at the NASA Langley Research Center in Hampton, Virginia. Aerosol backscatter ratios at 649 nm were measured throughout the 4-year period. In November 1992, a 532 channel was added to the 48-inch lidar, and backscatter ratio measurements were started for that wavelength as well as for 694 nm. Results show that integrated backscatter values increased to more than two orders of magnitude above background levels within about eight months after the Pinatubo eruption. These levels have gradually decreased since then, but some variations caused by seasonal influences have been observed. Recent measurements (December 1995) indicate that the aerosol loading has returned to approximately pre-Pinatubo levels. Over the time period that these measurements were conducted, a number of hardware modifications were made to enhance measurement capability of the Langley 48-inch lidar system, including the addition of a Nd:YAG laser, a more versatile detector package, and a Sun Sparcstation for automation and data analysis.

Here we report the characterization of the temporal jitter of a passively Q-switched Nd:YAG microchip laser. We experiment with different control schemes to reduce the observed jitter. Measurements were made for microchip laser temperatures from 10 degree(s) to 50 degree(s)C. The microchip laser was operated at various pulse rates from 500 Hz to 26 kHz.

Recently, lasing action and subsequent optical parametric oscillation has been demonstrated inside a single crystal of Nd:MgO:LiNbO₃ that is pumped by semiconductor diodes. This device, known as OPOL (Optical Parametric Oscillator/Laser), is a highly efficient, continuously tunable coherent optical source that can generate near and mid-IR wavelengths in a compact unit. An OPAL (Optical Parametric Amplifier/Laser) is a similar device that can amplify weak signals. AN OPOL can be used to generate eyesafe wavelengths whereas an OPAL can be used to amplify weak return signals, and in combination can provide eye-safe operation, effective range enhancement and wavelength agility in a range finder. The AN/GVS-5 is a hand-held range finder that is powered by a 24 V dc battery, and uses a flash lamp pumped Nd:YAG laser operating at 1064 nm for its operation to provide a maximum range of 10 km. In this paper, the design of a battery operated OPOL and OPAL is presented, and their application in retrofitting the AN/GVS5 unit to provide eyesafe and wavelength agile operation is discussed.

The basic research and engineering work for developments of eyesafe radar transmitter are reviewed. The characteristics of two model transmitters are introduced. Laser output at 1.54 micrometers with 5 mJ of energy and a 60 ns pulse width was demonstrated at 15 Hz using a rotating prism Q-switch. The laser media is an experimental Er:Glass, designated QX/ER.

Based on the size distribution function and concentrations of aerosol particles which were determined in the coastal zones of the southern Baltic Sea by means of the lidar method the thickness of the mixed atmosphere layer above the sea surface was derived. The thickness was determined taking into consideration such factors as wind direction and velocity and different types of sea bottoms. In the range of wind velocities from u equals 1 m/s to u equals 11 m/s the thickness of the mixed atmosphere layer varied from several meters to 1,000 meters. It was also confirmed that wind direction as well as different sea bottoms influence the thickness of the mixed layer significantly.

The DO-SAR system consists of an airborne SAR sensor unit and ground-based image processing equipment. It has been built in the late eighties. In order to study algorithms, there was the need to generate dual frequency multipolarization data simultaneously. The DO-SAR images allow a comparison on a pixel by pixel basis. The system has been enhanced to along track and across track interferometry. The across track modes are used to generate height profiles with high accuracy. The along track interferometry can be used to estimate the velocity of targets on ground and the velocity of the aircraft. The system has been operating since 1989. It has been used overall in Europe for maritime and oceanic missions. It was used to fly over flooded areas and it provides simultaneous images together with SIRC, in Denmark and Germany. Presently, it is used to generate interferometric single path images in tropic areas in order to classify the tropical forests.