Solar Blind UV Sensor for the Missile Warning System

(SBUV-MWS) R&D proposal

1.         Preface

The anti-missile defensive aids suite (DAS) for passenger air jets is composed of several elements:

1.1.          A Missile Warning Sensor which detects the solar blind UV (SBUV) radiation and hands over coordinates of the threatening missile

1.2.          A fine-track system that tracks the missile either via its plume or its kinetic heating signature

1.3.          A jammer to dazzle or damage the seeker of the missile - thus preventing a successful engagement

1.4.          A central processor system that controls the above sequence and also filters out known false alarm signals by the use of threat signature algorithms

1.5.          A missile direction indicator for the location of the missile launch and the engagement of the Counter Measure system

Ofil is aiming to provide the Missile Warning Sensor for the anti-missile defensive aids suite.

2.         Ofil’s added value

Ofil Ltd. is an Israeli company specializing in detection in the Solar Blind UV (SBUV) spectral band (240-280 nm). The company has developed a proprietary filtering technology for the SBUV band. In this spectral band, solar radiation is completely absorbed by the ozone layer of the earth atmosphere, and the background of solar radiation at the earth surface is zero. This filtering technology enables detection of the emission of weak UV emitters in full daylight with no interference from solar radiation.  As most SBUV emitters are man made and with characteristic UV signatures, the detection of UV emission from exhaust plumes of Shoulder Launched Surface to Air Missiles (SLSAM) will occur at low false alarm rate.

Ofil has gained ten-years of experience in the development of solar blind UV (SBUV) filters, optics, sensors and integrated imaging systems. The flagship product of Ofil, the DayCor®II imager is currently the most sensitive SBUV imaging system available in the commercial market. Evidence of this is the rapidly growing DayCor®II users community among the leading electrical utilities that use this imager for detection of corona discharge which is a very weak UV emitter. Ofil developed special solar blind UV optics for the DayCor II imager. The DayCor imager is also suitable for fire detection and tracking of UV marked targets.

3.         R&D proposal description

Every airborne DAS is equipped with four to five Missile Warning Sensors. Each sensor is providing a conical coverage of about 90°. The sensors are pointed all around and below the aircraft.

Ofil offers the advantage of its unique technological capabilities to develop the Missile Warning Sensors. This sensor can be supplied to major DAS contractors on an OEM basis and can serve several DAS contractors.

The sensor should provide enough sensitivity to enable the jammer system to engage the approaching missile in time and to deal with multi threat situations (few missiles that are launched simultaneously).

Preliminary evaluation of the sensor to be developed, using Ofil’s proprietary technology, points to a detection capability of UV emitting threats from a distance of 4-5 km. The sensor should be totally solar blind (not affected by solar radiation) and with minimum internal noise.

The sensor will consist of the following components:

3.1.          Solar blind intensified imaging device that turns a single photon that activates the sensor into a countable event. The most sensitive intensified spatial detector will be chosen after evaluation of the various options available.

3.2.          Special wide angle SBUV optics designed to get the desired field of view coverage (about 90°). The design will seek the largest practical photon collecting area for this field of view. Ofil had already gained experience in developing and manufacturing UV optics with maximum photon collecting area.

3.3.          Solar Blind UV (SBUV) filter

The filter is Ofil's core technology (patent pending: USA patent pending 08/761,778 Solar Blind Filter). This filter is unique in its ability to absorb all solar radiation while transmitting with high efficiency in a narrow band in the UV Solar Blind (peak at 260 nm and more than 12% transmittance).  The absorption of the solar radiation reduces all solar background signals to the sensor’s noise level (i.e. negligible level). By fitting the filter transmission to the spectral response of the proper detector, the SBUV signature of the SLSAM can be detected in full sun light with an excellent signal to background ratio.

3.4.          A Digital Signal Processor (DSP) removing random noise signals from the   information supplied to the central processing unit. The DSP will then supply to the Central Processor dynamic and spatial information about the approaching missile. 

3.5.          The system design will be optimized in with respect to sensitivity, background rejection, dynamic range and spatial resolution.

4.         R&D process description

4.1.          System concept design according to operational requirements set by the appropriate authorities, Ofil personnel will perform detailed concept design for the Missile Warning Sensor.

4.2.          Identify the potential strategic partners (business and technical) among the DAS contractors with whom the interface to the central processor will be designed and operational testing will be performed.

4.3.          In the System technical design stage the sensor operational requirements will be translated into technical specification with assistance of professional consultants in electro optics.

4.4.          Preliminary design of system components (optics, filter, intensified spatial detector and DSP)

4.5.          Production of prototype unit

4.6.          Prototype assembly and preliminary technical and operational testing of the sensor

4.7.          Final beta design according to prototype testing, production, assembly and testing      

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