Textron Systems Corporation

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Textron Corporation

Victor H Hasson

Hsian P Chou

Robert J Kraft

Mark A Kovacs

Gerald A Nordstrom

A laser source provides a pulse that is subdivided and replicated into subpulses by a delay structure having a plurality of steps. Each of the subpulses is delayed by one of the plurality of steps and the amount that each subpulse is delayed is different than the others with respect to the pulse. The amount of each delay, and the consequent time delay produced, is greater than the duration of the pulse, which minimizes overlap between adjacent subpulses. The pulse may be transmitted through the delay structure or it may be reflected from the delay structure. Repetition rates of up to hundreds of THz or greater are achieved, and the system and method may be used in Time Division Multiplexing Systems. Information may be transmitted and carried by the subpulses by appropriate modulation techniques.

Optical pulse train generator

A method and apparatus for cooling a high power laser oscillator or amplifier is disclosed in which a plurality of laser gain media that are configured such that the width of the media is greater than the thickness of the media, are sandwiched between pairs of optically transparent materials having high thermal conductivity. In this way, a shortened thermal path is created from the face surface of the laser gain media axially via the optically transparent heat conductor to an external heat exchange system. This provides an increased level of cooling of the interior of the laser gain media and avoids the deleterious effects caused by over heating of the laser gain media particularly with large effective cross sections desired for high power and/or high pulse repetition and high pulse energy operation.

Cooling of high power laser systems

An active optical amplifier in which a unitary optical amplifier constructed from a unitary optically transparent chip that has been doped so as to be optically active, amplifies incoming signal photons when excited by a pump laser of sufficient energy. The unitary optical amplifier receives input photons and pump laser energy and provides output photons that have the same spatial orientation and phase as the corresponding input photons. A laser direction and ranging (LADAR) may be constructed from the active optical amplifier by further including first imaging optics to focus the input photons onto the surface of the unitary optical amplifier and second imaging optics to focus the output photons from the active unitary optical amplifier onto a focal plane image sensor array. The electronic signals from the focal plane image sensor array may then be displayed on a conventional display. A plurality of unitary optically transparent amplifier chips are configured in a stacked arrangement, each receiving a pump signal, and the stacked arrangement provides for the amplification of input photons.

Optical amplifier employing an active doped unitary amplifier

An optical correlator is used to detect the presence of a target in a laser detection and ranging (LADAR) system by analyzing the return signal, and to provide initial estimates of the targets range and velocity to the LADAR receiver. The optical correlator includes an acoustic optical Bragg cell that deflects an input laser signal using the received and down-converted LADAR signal. An integrating optical detector is disposed to receive the optical outputs of the acoustic optical Bragg cell and an optical processor analyzes and processes the integrating optical detector data. The integrating optical detector integrates the optical outputs of the Bragg cell over time and the integrating optical detector output is sampled over a sampling period so that target detection is uncorrelated to noise. An integrating optical detector data point that exceeds a predetermined threshold is considered to be a valid detected target and the location of the output of the optical correlator on the integrating optical detector is indicative of the Doppler shift and hence the velocity of the detected target. The time of detection of the target is indicative of the range to the target. This allows the range-Doppler-amplitude of the target to be estimated and provided to the receiver to allow for more accurate processing of the receiver data. In addition, the optical correlator can be used to provide whole body Doppler and range estimates of the target and can also inherently averages the speckle data.

Hybrid optical correlator/digital processor for target detection and discrimination

A passive ranging system measured spectra of solar radiation off an adjacent spot and a distal target. Reflected solar radiation and differential attenuation are used to estimate target range. A comparison of absorption spectra from the solar illuminated distal target compared to the adjacent location is performed. Since the sun's position is always known, the increased absorption due to a distant target is derived from the differential between the adjacent spot and the distal target.

Passive ranging to a target reflecting solar radiation

A passive ranging optical system is coupled to an active radar system. The passive ranging optical system provides range and rate information to the active radar system. After receiving the range and rate information, the active radar system uses fewer transmission pulses but achieves higher resolution of the range of the target because of improved range gate information.

Passive ranging to source of known spectral emission to cue active radar system

A system and method of passive ranging for a luminous target which employs a prior knowledge of atmospheric attenuation of spectral frequencies to determine range by comparing the intensities of a frequency component, that is attenuated by propagation through the atmosphere, with a frequency component that is not.

Passive ranging to source of known spectral emission

Multiple independent spectral measurements of light reflected from a target are produced concurrently by illuminating the target with a train of laser pulses wherein the train of pulses produces a line spectrum within the illuminating signal. A characteristic dimension of the receiving aperture is established based on illuminating wavelength, a cross-sectional dimension of illuminated region of a target, and the range between a target and the receiving aperture or image plane. The characteristic dimension corresponds to the spacing of peaks in a speckle pattern of an image plane. The use of multiple receiving telescopes having the characteristic dimension allows for independent measurements concurrently by each of the receiving telescopes. The train of illuminating pulses is generated by mode-locked operation of the laser for synchronization of sinusoidal components at line frequencies of the pulse train spectrum, and wherein the spacing of the spectral lines is at least a decorrelation frequency. The number of spectral lines preferably equals the number of independent measurements concurrently attainable during reception of the reflected pulse train. Alternatively, the laser frequency may be linearly swept such that the overall bandwidth is equal to the bandwidth encompassed by the line spectrum of the generated pulse.

Speckle mitigation for coherent detection employing a wide band signal

A system and method of passive ranging for a luminous target employs a prior knowledge and a present measurement of its electromagnetic spectrum during a target acquisition procedure and, subsequently, during analysis of the spectrum to determine the effects of atmospheric attenuation on various parts of the spectrum. Relative attenuation of various spectral components by the atmosphere is indicative of target range.

A system and method of passive detection of a luminous target employs a prior knowledge and a present measurement of its electromagnetic spectrum during a target acquisition procedure and, subsequently, during analysis of the spectrum to determine the presence of Doppler shift and broadening of lines of the spectrum. The prior known reference spectrum is adjusted for the Doppler shift so as to enable identification of the corresponding spectral lines of the received target spectrum. A history of the spectral data enables an identification of the type of target, as in the case of a rocket, and a determination of characteristics of a flight of the rocket.

Passive detection of source of known spectral emission

A high pressure self-sustained gas laser operating at a high specific energy loading and long pulselength. The laser comprises an endless duct for circulating a laser generating gaseous medium and two discharge electrodes for exciting the molecules of the gaseous medium. Behind the discharge cathode electrode is an electron-beam transmitter for transmitting a beam of preionizing electrons into the gaseous medium to preionize the region near the cathode discharge electrode. The region unpreionized by the electron beam is ionized by drifting electrons from the cathode region and avalanche ionization. The applied discharge voltage never exceeds the glow voltage allowing low discharge flush factors under repetitive operation with flowing laser gas.

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Winchester, MA, United States of America

Victor H Hasson