Vincent M. Contarino

Nanosecond gated optical sensors for ocean optic applications

Nanosecond gated photosensitive modules with wide dynamic range has been design for ocean optic applications (1) on base R7400U Hamamatsu (5mm. active area) photomultiplier tube. The photomultiplier tubes R7400U series have two kinds of photocathode: low resistance semitransparent multialkali photocathodes that can be gated with nanosecond response and semitransparent bialkali photocathodes with large resistance and slow gate response time (2). Different kinds of photocathodes require different approach to gating circuits design. High-speed pulse gating (gating rise time 10 nsec, setting time 40 nsec for 99%) has been used for enhancing of target contrast at ocean optic application for both kinds: semitransparent bialkali and semitransparent multialkali photocathodes. Wide dynamic range (50 dB of optical power) has been achieved by optimizing of applied to dynodes voltages. Compression up to 30 dB has been used for following output signal digital processing.

Nanosecond gated PMT for LIDAR-RADAR applications

Wide dynamic range gating photosensor modules has been design for LIDAR-RADAR applications on base R7400U (active area 8 mm. diameter) R7600U (active area 18x18 mm.) Hamamatsu photomultiplier tubes. The photomultiplier tubes R7400U, series have two kinds of photocathode: low resistance semitransparent multialkali photocathodes and semitransparent bialkali photocathodes with large resistance. Different kinds of photocathodes require different approach to gating circuits design. High-speed pulse gating (gating rise time 10 nsec, setting time 40 nsec for 99%) has been used for enhancing of target contrast at ocean optic application for both kinds: semitransparent bialkali and semitransparent multialkali photocathodes. Wide dynamic range (50 dB of optical power) has been achieved by optimizing of applied to dynodes voltages. Compression up to 30 dB has been used for following output signal digital processing. Hamamatsu photosensitive modules were used in the two system receivers in pulsed LIDAR system. The system was mounted on the bow of the R/V New Horizon and collected data from August 25 thru September 8, 2005 as part of the LOCO field test in Monterey Bay. Approximately 4 million LIDAR profiles were collected during this period. During the field test the profiles were processed to show relative changes in water optical properties and to reveal water column structure in real time.

New distributed radar technology based on UAV or UGV application

Regular micro and nano radars cannot provide reliable tracking of low altitude low profile aerial targets in urban and mountain areas because of reflection and re-reflections from buildings and terrain. They become visible and vulnerable to guided missiles if positioned on a tower or blimp. Doppler radar cannot distinguish moving cars and small low altitude aerial targets in an urban area. A new concept of pocket size distributed radar technology based on the application of UAV (Unmanned Air Vehicles), UGV (Unmanned Ground Vehicles) is proposed for tracking of low altitude low profile aerial targets at short and medium distances for protection of stadium, camp, military facility in urban or mountain areas.

Directional antenna array (DAA) for communications, control, and data link protection

A next generation of Smart antennas with point-to-point communication and jam, spoof protection capability by verification of spatial position is offered. A directional antenna array (DAA) with narrow irradiation beam provides counter terrorism protection for communications, data link, control and GPS. Communications are “invisible” to guided missiles because of 20 dB smaller irradiation outside the beam and spatial separation. This solution can be implemented with current technology. Directional antennas have higher gain and can be multi-frequency or have wide frequency band in contrast to phase antenna arrays. This multi-directional antenna array provides a multi-functional communication network and simultaneously can be used for command control, data link and GPS.

Neuro-Fuzzy Logic Application for Hyperspectral Remote Sensing

This paper reports on a novel approach to the optical information processing for the hyperspectral remote sensing systems by means of developed unification algorithm of the two mathematical tools: the fuzzy logic and the neural network. New neuro - fuzzy classification algorithm for hyperspectral remote sensed images has been proposed. It is able to replace complicated empirical formulae, which require the knowledge of dependences of many input parameters that rapidly cha nge during of range time and difficult for crisp determination.

Large-area intensified photodiodes for ocean optics applications

Subject: INTEVAC hybrid photomultiplier vacuum tube IPD-280 with 18 mm GaAsP photocathode, imaging electron optics, ion trap and 0.5, 1.0 diameter Schottky barrier anode. Problem: Large area intensified photodiodes (IPDs) have parameters (high sensitivity, gain, speed of operation, bandwidth, low noises), which are ideal for Ocean optic applications. However, these IPDs have not enough dynamic range and lifetime. Target of objective investigation: Identify the cause for small dynamic range and short lifetime of IPDs and optimize them for Ocean Optic applications. The voltages applied to photocathode and focusing electrodes have been experimentally optimized for maximal IPD sensitivity,dynamic range, pulse rise, and transit time. The photoelectrons trajectories and ions have been simulated using SIMION 3D 7,0 software for various voltages applied to the focusing electrodes. The uniformity of the photocathode has been tested to determine the impact of ions on the photocathode. Electron and ion currents investigations have been made for both negative and positive voltages applied to the ion trap electrode. Optimizing the regime for electron focusing and minimizing the ion current impact to photocathode was determines as result of the investigation. Reducing the voltages applied to photocathode and focusing the electrodes from 8 KV to 4-6 KV decreased the ion current. In this regime, the gain of IPD does not decrease significantly and the rise time and transit time of IPD remined practically the same.

Techniques for determining marine mammal densities

Determining marine mammal densities is a complex problem that has been ongoing for many decades. Modern approaches use a combination of sophisticated acoustic monitoring and highly trained visual observers from both ships and aircraft. New camera systems with automatic detection algorithms offer the option to do quantitative airborne surveys safely and quickly. This paper presents a discussion on the various methods of calculating marine mammal densities and demonstrates how all these methods can work together to present quantitative density measurements.

Remote polarization measurements of the air-sea interface

Narrow band polarization measurements were taken from a bridge in San Diego Harbor using the Advanced Coherent Technologies Multi-mission Adaptable Narrowband Imaging Spectrometer (MANTIS) multichannel imaging system. MANTIS was capable of simultaneously collecting four channels of imagery through a narrowband green (532 nm) filter together with linear polarizers oriented at 0, 45, 90, and 135 degrees. This configuration enabled the collection of the first three Stokes Vector elements. The data is being gathered to explore methods of calculating the sea surface Mueller Matrix. Models, methods, and measurements are presented. Of specific interest is the deviation of the modeled data from the measured data and its causes. The data and a model are used to estimate the contribution of upwelled polarized light.

Affordable spectro-polarimetry using MANTIS-3T

PAR Government Systems Corporation (PAR) with Advanced Coherent Technologies, LLC (ACT) has developed affordable, narrow-band polarimetry sensor hardware and software based upon the PAR Mission Adaptable Narrowband Tunable Imaging Sensor (MANTIS). The sensor has been deployed in multiple environments. Polarimetric imagery of the clear blue sky and the sea surface has been collected. In addition, a significant amount of calibration data has been collected to correctly calibrate the sensor for real-time Stokes Vector imaging. Data collected with the MANTIS polarization sensor has been compared to modeled data. The sensor hardware and software is described and some representative collected calibration data are presented and compared to a developing model.

Neuro-fuzzy model for multi-channel underwater imaging

Multispectral imaging system usually consist 2-15 different color channels, hyperspectral system - 100-200 channels. The image processing in each channel includes the complicated calculations and the final results have quite a large error. As is well known that there are large number of input parameters and some their uncertainty in the case of airborne and underwater LIDAR systems modeling. The using of statistical and determined models give the result having quite a large error of optical information processing and the given calculations take a lot of time to compute. The fundamentally different mathematical algorithms - the neural networks and the fuzzy logic is offered to use. It is realized with specially developed algorithms for multi-channel image processing. The new neuro-fuzzy model of foam coverage for four color channels has been developed to determine the interval of the minimal reflections and to obtain the images of non-foam covered areas.