Target range of Infra-Red (IR) point target warning systems, is determined by the effective entrance pupil diameter of
the system's optics. In addition, the system's F/# is usually set by the detector (as in cryogenically cooled detectors).
Moreover, the detector's aspect-ratio usually set the field proportions (5:4, 4:3, etc.).Thus for example, for wide angle
systems, the horizontal coverage angle is usually determining the vertical one.
We propose a system including anamorphic optics that changes the effective focal length of each axis independently,
keeping the detector's given F/#, thus changing the effective aperture. Since the range is approximately proportional to
the effective aperture, we achieve a range improvement of the square-root of the vertical and horizontal focal length
ratio, reducing the vertical coverage accordingly. In this way, we make the field proportions less dependent of the
Using this method, it is made possible for wide angle systems to improve target detection range on the expense of the
vertical coverage, without changing the horizontal coverage or increasing the amount of detection units (e.g. FLIRs).
Infrared sensor technology, high performance computing hardware and advanced detection and tracking algorithms have enabled a new generation of infrared warning systems for navy surface vessels. In this paper we describe Sea Spotter - a new third-generation naval IRST system, which is unique in offering a fully staring electro-optical imaging unit. Starting from naval IRST operational requirements, we describe the considerations and constraints that led us to the configuration of the sensor head and the supporting hardware. The second part of the paper is dedicated to the target acquisition methodology, including the use of originally developed machine learning technology for target acquisition and tracking.
The potential for using fiber Bragg grating rosettes for the location of ultrasound sources in anisotropic structures is
discussed. Anisotropic propagation of Lamb waves in a carbon fiber composite plate has been investigated using two
approaches. Firstly, a finite element model of the displacements/strains produced by the wave was developed and,
secondly, in-plane ultrasonic strain mapping was carried out, utilizing the directional properties of FBG sensors. The
possibility of designing FBG rosette configurations for use on anisotropic structures is discussed in light of these results.
In previous work we have described the detection and location of damage in isotropic materials using fibre Bragg
gratings rosettes to directionally detect Lamb waves. To extend this technique to composite materials it is necessary to
understand the propagation characteristics of ultrasound in these materials as a function of their orientation with respect
to the ply, and also the directional response of fibre Bragg gratings to them. Finite element modeling of Lamb wave
propagation in a 0°, 90° carbon fibre plate is described, as are experiments to detect these waves for various orientations
of the source and alignments of the FBG transducers. Results of the experiments are interpreted with respect to
predictions from the FE modeling and are shown to give good qualitative agreement.
An array of piezoelectric ultrasonic exciters/sensors and fiber Bragg grating sensors is embedded between an Aluminum
plate and a composite patch. Using Lamb waves, the array is shown to be capable of detecting a developing damage in
the aluminum plate, as well as locating it.