Abstract: An optical relay comprises a light-transmissive substrate having a plurality of diffractive optical elements, where at least one diffractive optical element is characterized by nonuniform diffraction efficiency. The substrate and diffractive optical elements are designed and constructed to relay at least a portion of a light beam emanating from an object to at least one predetermined eye-box in a manner such that for each point of the object, there is a set of parallel outgoing light rays originating from the point and arriving to the eye-box. The color difference between any two parallel light rays of the set is less than 50 ?E* units.

Abstract: A diffractive optical element is disclosed. The optical element comprises a grating having a periodic linear structure in at least one direction. The linear structure is characterized by non-uniform duty cycle selected to ensure non-uniform diffraction efficiency.

Abstract: An optical relay device, comprising a substrate, and at least one diffractive optical element is disclosed. The substrate is made, at least in part, of a light transmissive polymeric material characterized by a birefringence, ?n, satisfying the inequality |?n|<?, where ? is lower than the birefringence of polycarbonate. In a preferred embodiment, the light transmissive polymeric material comprises a cycloolefin polymer or a cycloolefin copolymer.

Abstract: A method for coherent detection and demodulation of a FDMA signal, that is a superposition of amplitude modulated carriers, is provided. An array of special digital phase-locked loops (PLLs) is implemented in a digital signal processor (DSP) for processing the received signal after it is digitized, and for extracting the envelopes corresponding to each carrier. Each PLL is deliberately made to slowly respond to error signals in order to allow the loop to preserve its phase while the amplitude value of the envelope flips sign. A down-decimation technique is employed in order to reduce the computational load. This is achieved by applying a finite impulse-response filter (FIR) only once per each frame, thereby only a single multiplication of the frame by the vector of filter's taps is employed. A digital generation of sine and cosine sampled waveforms is employed inside a PLL by using a real-time solution of a difference equation.

Abstract: A method for reducing a current crosstalk interference component from an oscillating multiplex electric current flowing through a magnetic coil of a given electrical circuit originated from an electromagnetic flux emanating from a magnetic coil of a certain neighboring electrical circuit and intercepted by the magnetic coil of the given electrical circuit. The oscillating multiplex electric current has a main current component, related to the given electrical circuit, which is superposed with the current crosstalk interference component. The reduction of the crosstalk interference is achieved by estimating the current crosstalk interference component induced by the certain neighboring electrical circuit, and subtracting this current crosstalk interference component from a multiplex electric current flowing through the magnetic coil of the given electrical circuit by using earlier obtained crosstalk interference estimates.