A null command generator test apparatus capable of operating in either the open or closed loop configuration for testing the Sarcalm system. When operating in an open loop configuration the null command generator test apparatus utilizes the normalized voltage output of the null command generator as the estimator for the beam pointing error. When operating in the closed loop configuration, the test apparatus utilizes either the voltage output of the null command generator or the angle difference ...

A phase/phase/frequency-scan radar apparatus having multiple-beam search and single-beam track capabilities, using a single array antenna employing a novel combination of phase/phase scan in two dimensions together with frequency-scan. Generally, the additional frequency scan capability need be used in one dimension only, preferably azimuth, but the concept could readily be extended to two-dimensional add-on frequency scan if desired.

A multilayer stack of alternating low index and high index of refraction low loss dielectric mirror layers are formed on top of a metallic mirror surface, the thicknesses of the mirror layers being chosen to satisfy the Bragg condition at a selected incident angle of polarized light. The dielectric layer adjacent the metallic reflective mirror substrate can have a thickness which produces circularly polarized light exiting the apparatus. An electro-optical layer of EO material can be substituted...

Seismic detection of a target is obtained with a geophone detecting earth vibrations caused by the actions of the target. The vibrations are wide band amplified and band-passed filtered with the pass bands being fed to the threshold detectors. The outputs of the threshold detectors are fed to a diode AND logic circuit, the output thereof indicating the presence of a target.

This invention comprises a new group of fiber optic switching devices that use layers of surface-established ferroelectric liquid crystals (FLCs) as the switching media. In each of the devices light impinges upon the ferroelectric liquid crystal at an angle of 90.degree. (normal incidence) with the surface plane. Each FLC gives 0.degree. or .pi..degree. optical rotation, depending upon the polarity of the electric voltage applied. A series of polarizing beam splitters are used to separate unpola...

A method for eliminating self-screening noise jamming from the main beam of a radar in order to reveal the skin echoes of aircraft at the same angle, including the aircraft carrying the jammer by using a main antenna and an auxiliary antenna located a short distance apart, delaying the signal from the auxiliary antenna, decorrelating the signals and cancelling the jamming signals.

A degenerate four-wave mixing arrangement employs a photorefractive crystal as a real time holographic recording medium to record a hologram of the noisy optical signal. The signal passes through the crystal and is phase conjugated by a self pumped barium titanate phase conjugator, and the resulting phase conjugate beam reads out the hologram and multiplicative noise is substantially reduced in the optical output signal.

The unauthorized separation of a second member such as a door with respect to a first member affixed to a computer frame and the subsequent replacement of the initial position of the door creates a change of state of a square loop magnetic member integral with the computer frame. This change of state can be monitored from time to time to indicate an unauthorized opening of the door.

Spatially variable nonlinear optical thresholding in the Fourier plane reduces signal-dependent noise, such as scalar multiplicative noise. Coherent artifact noise reduction by a factor of four is attained using deamplifying photorefractive two-beam coupling. A variable light transmittance threshold across a spatially thresholded light modulating element such as a photorefractive crystal is utilized for this purpose.

An airborne radar warning receiver for track-while-scan radar including a first radar frequency receiver and logic circuitry for determining an increase in pulse rate frequency, second radar frequency receiver connected to a signal filter and an automatic gain control amplifier connected to the receiver and a logic circuitry connected to the amplifier and to the pulse rate frequency logic whereby the ratio is determined between the time from the start of scan until the radar beam illuminates the...