Time delay beam formation
First Claim
1. A system for generating at least one time delay signal from an input signal, comprising the elements A-H:
- A) a source of coherent light,B) divider means for dividing the light into at least a first leg and a second leg,C) modulation means for modulating light in the first leg by a signal,D) optical isolator means for preventing light in the first leg from being reflected back towards the source of coherent light,E) signal channelizer means for dividing modulated light in the first leg into a plurality of spectral components,F) signal control means for dividing light in the second leg into a plurality of paths and for shifting the phase of light in each of the plurality of paths to thereby generate a plurality of phase-shifted optical reference signals, each one of the plurality of phase-shifted optical reference signals corresponding to one of the plurality of spectral components,G) detection means for detecting each one of the plurality of phase-shifted optical reference signals together with a corresponding one of the spectral components and for generating an output signal, andH) summation means for summing output signals generated by the detection means.
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Abstract
Optical systems are disclosed which are capable of generating and rapidly changing time delays of electrical signals for true time delay beam formation and beam steering and for signal processing applications. The systems utilize an interferometer configuration. A first optical modulator in a first leg of the interferometer is used to modulate coherent light with the signal to be delayed. In a second leg of the interferometer, a second optical modulator provides beam steering to a prism stack, which produces a set of plane reference waves having a range of orientations required to generate a desired range of time delays. Preferably the optical modulators are acousto optic Bragg cells. Alternatively, a stack of lens pairs or diffractive optical elements or a holographic optic element may be used in place of the prism stack. The modulated optical signal from the first leg interferes on an array of photodiodes with the reference waves from the second leg. The resulting electrical signals out of the photodiodes are delayed replicas of the signals driving the optical modulator in the first leg.
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Citations
17 Claims
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1. A system for generating at least one time delay signal from an input signal, comprising the elements A-H:
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A) a source of coherent light, B) divider means for dividing the light into at least a first leg and a second leg, C) modulation means for modulating light in the first leg by a signal, D) optical isolator means for preventing light in the first leg from being reflected back towards the source of coherent light, E) signal channelizer means for dividing modulated light in the first leg into a plurality of spectral components, F) signal control means for dividing light in the second leg into a plurality of paths and for shifting the phase of light in each of the plurality of paths to thereby generate a plurality of phase-shifted optical reference signals, each one of the plurality of phase-shifted optical reference signals corresponding to one of the plurality of spectral components, G) detection means for detecting each one of the plurality of phase-shifted optical reference signals together with a corresponding one of the spectral components and for generating an output signal, and H) summation means for summing output signals generated by the detection means. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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Specification