Recursive optical filter system
First Claim
1. A recursive optical filter system comprising:
- a source which produces a substantially coherent, collimated beam of optical radiation;
optical filtering means including means for producing an optical Fourier transform, an optical filter, and means for producing an optical inverse Fourier transform;
recursive means for directing said beam in a manner to traverse said optical filtering means a plurality of times, and means for extracting said beam for utilization, the recursive passage of said beam through said filtering means resulting in an efficient attenuation of unwanted spectral components of said beam.
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Abstract
An optical notching or filtering system in which a beam of optical radiation is passed through the optical filtering means a multiplicity of times. The optical filtering means has an optical Fourier transform means, a spatial filter, optical inverse Fourier transform means, and a reflector array. After an input optical signal beam undergoes a filtering pass by being directed through the transform means, the filter, and the inverse transform means, the reflector array re-introduces the beam for a multiplicity of subsequent filtering passes. Four embodiments of the system of the invention having various configurations of the reflector arrays for use with one- and two-dimensional spatial filters are disclosed. The various embodiments are set forth as being used in a heterodyning optical notching filter system.
36 Citations
27 Claims
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1. A recursive optical filter system comprising:
- a source which produces a substantially coherent, collimated beam of optical radiation;
optical filtering means including means for producing an optical Fourier transform, an optical filter, and means for producing an optical inverse Fourier transform;
recursive means for directing said beam in a manner to traverse said optical filtering means a plurality of times, and means for extracting said beam for utilization, the recursive passage of said beam through said filtering means resulting in an efficient attenuation of unwanted spectral components of said beam. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 22, 23, 24, 25, 26, 27)
- a source which produces a substantially coherent, collimated beam of optical radiation;
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20. A recursive optical filter for RF signals comprising:
- an RF signal source;
a source which produces a substantially coherent, collimated beam of optical radiation;
an acousto-optic modulator excited by a transducer driven by RF signals from said RF source;
an optical filtering means including means for producing an optical Fourier transform, an optical filter, and means for producing an inverse optical Fourier transform;
optical recursive directing means associated with said optical filtering means, whereby RF signals from said RF signal source drive said acousto-optic modulator to impress the RF spectra on an optical radiation beam directed therethrough from said radiation source, the modulated beam from said modulator being re-directed through said optical filtering means a plural number of times by said recursive directing means such that the optical beam exiting from said optical filtering means carries a spatially filtered RF modulation. - View Dependent Claims (21)
- an RF signal source;
Specification