Other

US Government As Represented by the Secretary of the Army

Ming-Chiang Li

Weimin Zhou

An apparatus comprising a fiber optical loop for conducting a first and a second pulse having a corresponding first and second wavelength, a first splitter for separating the first and second light pulses in the optical loop into a first and second light path to introduce a predetermined time delay between the first and second light pulses, a coupler for tapping a replica of the pair of light pulses from the loop, an auto-correlation module, coupled to the coupler, for correlating the replica of the pair of light pulses with each other to produce a set of data points comprising a plurality of multiplied and correlated pair of pulses and a transform module, coupled to the auto-correlation module, for transforming the data points into a channelized frequency spectrum.

Method and apparatus for analyzing the spectrum of radio-frequency signals using a fiber optic recirculation loop

Embodiments of the present invention are low cost, robust, broadband, optimum, high precision methods and apparatus of processing pulsed, transient, non-cooperative, non-reproducible, complex, or simultaneous signals based on correlation measurements utilizing optical RF signal train generators. An embodiment of the inventive apparatus comprises: (a) a signal receiving apparatus which receives one or more signals, and outputs the signals; (b) a replica generation apparatus, which comprises one or more RF signal train generators, accepts signals from the receiving apparatus as inputs, and outputs trains of replica pairs, where relative separations between two members in the replica pairs are same or different; and (c) an integration apparatus which performs Doppler, self, or mutual (cross) correlation operations on the replica pairs at RF or optical level. The apparatus of present invention advance interferoceivers of prior art, and overcome deficiencies of radar receivers, channelized receivers, electronic warfare receivers, spectrum analyzers, sampling oscilloscopes, and many others.

Robust and broadband signal processing using replica generation apparatus

An apparatus and method for receiving electromagnetic waves using photonics includes a transmission unit transmitting electromagnetic waves in intervals; a time delay unit coupled to the transmission unit and controlling the transmission unit to transmit the electromagnetic waves in the intervals; an antenna receiving the electromagnetic waves reflected from the target; an interferoceiver coupled to the antenna and receiving the electromagnetic waves from the antenna, the interferoceiver comprising an optical recirculation loop to produce replica electromagnetic waves; and a computer identifying the target from the reflected electromagnetic waves.

Apparatus and method for receiving electromagnetic waves using photonics

The invention presents a design of optimum edges for antennas of loudspeakers, microphones, hydro-speakers, hydro-phones, brass and wind instruments, and ultrasonic transducers. These edges have a serrated-roll shape, and enhance the acoustical field strength uniformity. Loudspeakers, hydro-speakers, and ultrasonic transducers will become more effective in radiating acoustical power. The quality of these apparatuses are enriched. The musical tone emitted by loudspeakers, brass and wind instruments becomes more smooth, mellow, rich, clean, and elegant.

Optimum edges for speakers and musical instruments

This invention relates to advanced RF support systems which utilize optical fibers or direct lasers to achieve RF transmission and reception of navigation signals from widely separated supporting sites. The functional goals of these systems are to support navigation, guidance, control, and survey systems. A RF supporting network according to the present invention comprises a master supporting site; a number of secondary supporting sites; and a network of optical RF link systems which links secondary supporting sites with the master supporting site. The stable clock, GPS signal generators, and receivers are located only at the master site, which is also the processing, command, and control center. A network architecture of the present invention will provide a low cost mean to users in need of precision navigation and time information. Furthermore, the present invention furnishes an advance means in determining the instantaneous velocity of GPS satellites with high accuracy. The present invention drastically increases our navigation and survey capabilities as well as other applications.

Optical RF support network

Embodiments of the present invention are inspection methods and inspection apparatus for high speed, high precision inspection using parallel processing. In particular, an embodiment of a first aspect of the present invention is an inspection apparatus for inspecting a sample that uses parallel processing and which comprises: (a) a source of radiation which outputs superbroad inspection radiation having a frequency spectrum with an inspection width and reference radiation; (b) an inspection applicator apparatus which applies the inspection radiation as input to the sample; (c) an inspection collector apparatus which collects at least a portion of the inspection radiation that is scattered by the sample and applies at least a portion of the scattered inspection radiation as input to a dispersal apparatus; (d) wherein the dispersal apparatus applies radiation from the scattered inspection radiation as input to a plurality of coherence processors and applies radiation from the reference radiation as input to the plurality of coherence processors; and (e) a processor that fourier analyzes outputs from the coherence processors.

High speed inspection of a sample using coherence processing of

Interferoceivers are apparatus which use optical fiber loop based radio frequency (RF) signal train generators to store transient pulses and regenerate their identical replicas for analysis. The present invention further advances the art of RF signal train generators and interferoceivers in investigating acoustical, electromagnetic, and optical transient phenomena. The disclosure includes mechanisms for tuning the interferoceivers, and means for forming synthetic images with chaotic pulses or pulses of opportunity.

Different models for RF signal train generators and interferoceivers

A radar system comprises an optical fiber RF storage subsystem for storing a portion of RF signals before the transmission. The radar system further comprises a coherent RF receiver to process reflected RF signals using stored RF signals as a reference. Furthermore, the optical fiber RF storage system is used to store initially received RF signals for comparison with sequentially received RF signals.

Optical fiber based radars

A descriptor has the capabilities of providing state vectors to describe movable platforms, extended objects, information collecting and surveillance systems. An aggregator furnishes the descriptor with abilities to deliver the state vectors in dynamical situations of instabilities and chaos. The former comprises navigation antennas, optical RF link systems, and processing center for delivering the state vectors from received navigation RF signals. The latter comprises an RF delay loop for aggregating a train of RF signals into a single RF pulsed signal and means for outputting the pulsed signal for analysis. The aggregator has many applications. For instance, an aggregator is able to unscramble pseudo random signals with partial codes and to enhance the statistics of weak transient signals.

Embodiments of the present invention are inspection methods and inspection apparatus for use in inspecting a sample such a wafer, photomask, and the like used in the semiconductor industry to fabricate circuits, memory, and the like. An embodiment of the inventive inspection apparatus comprises: (a) a source of radiation which outputs superbroad inspection radiation and superbroad reference radiation; (b) a radiation applicator apparatus which applies the inspection radiation as input to a portion of the sample and which applies the reference radiation as input to a reference; and (c) a radiation collection apparatus which applies at least a portion of the inspection radiation scattered by the portion of the sample as input to a defect processor and which applies at least a portion of the reference radiation scattered by the reference as input to the defect processor; wherein the defect processor measures differences between the radiation scattered by the reference and the radiation scattered from the portion of the sample.

Sample inspection using interference and/or correlation of scattered

Embodiments of the present invention are inspection methods and inspection apparatus using superbroad radiation. In particular, an embodiment of the present invention is an inspection apparatus which comprises: (a) a source of radiation which outputs superbroad inspection radiation and superbroad reference radiation; (b) an inspection applicator apparatus which applies the inspection radiation as input to the sample; (c) an inspection collection apparatus which collects at least a portion of the inspection radiation that is scattered by the sample and applies at least a portion of the scattered inspection radiation as input to a dispersal apparatus; and (d) a reference collection and delay apparatus which produces a predetermined number of reference radiation outputs having predetermined delays with respect to one another and applies the reference radiation outputs as inputs to the dispersal apparatus; wherein the dispersal apparatus applies radiation from the scattered inspection radiation as input to a coherence processor and applies radiation from the reference radiation outputs as input to the coherence processor.

High speed inspection of a sample using superbroad radiation coherent

New apparatus comprise a optical fiber based RF signal train generator for storing transient RF pulses and regenerating the identical replicas for analysis. The apparatus further comprise RF receivers to process one stored pulse with a reference to other stored pulse. The present invention drastically increases our abilities to investigate acoustical, electromagnetic, and optical transient phenomena.

RF signal train generator and interferoceivers

A bistatic radar system includes a transmitting radar site; a receiving radar site; and an optical fiber RF link system for transmitting RF signals from the receiving site to the transmitting site and for transmitting command and control signals from the transmitting site to the receiving site.

Optical fiber based bistatic radar

An optical RF stereo systems includes multiple remote vehicles, a processing center, and optical RF link systems for transmitting RF signals from remote vehicles to the processing center and for transmitting command and control signals from the processing center to remote vehicles.

Growing community of inventors

Mitchellville, MD, United States of America

Ming-Chiang Li