Optical digital to analog converter
First Claim
1. An optical digital to analog conversion apparatus comprising:
- controllable density optical transmission device having multiple defined density states for transmission of coherent optical radiation therethrough as a plurality of optical signals having particular numerical values inputted thereto;
optical weighting means, positioned for receiving the plurality of optical signals from said optical transmission device, for providing different optical weights to each of said plurality of signals;
optical summing means, positioned for summing the plurality of weighted optical signals, for producing an output optical signal having an amplitude representing a combination of said plurality of particular numerical values;
masking means providing an aperture for defining an output location for said output optical signal; and
a lens positioned with respect to said masking means and said summing means so that a fourier transform relationship exists therebetween.
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Accused Products
Abstract
Method and apparatus for conversion of digital multistate signals, represing a numerical value, to an optical output signal having an amplitude analogous to the numerical value. A controllable density optical transmission device provides plural optical signals representative of the digital states of components of the input signal. The plural optical signals are weighted and summed by optical filters to provide the desired analogous optical output representing the input numerical value. The use of phase shifting filters enables the conversion of negative and complex numbers. A two dimensional liquid crystal array may be used as the controllable optical transmission device to enable conversion of a plurality of numerical values simultaneously.
15 Citations
17 Claims
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1. An optical digital to analog conversion apparatus comprising:
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controllable density optical transmission device having multiple defined density states for transmission of coherent optical radiation therethrough as a plurality of optical signals having particular numerical values inputted thereto; optical weighting means, positioned for receiving the plurality of optical signals from said optical transmission device, for providing different optical weights to each of said plurality of signals; optical summing means, positioned for summing the plurality of weighted optical signals, for producing an output optical signal having an amplitude representing a combination of said plurality of particular numerical values; masking means providing an aperture for defining an output location for said output optical signal; and a lens positioned with respect to said masking means and said summing means so that a fourier transform relationship exists therebetween. - View Dependent Claims (4, 5, 6)
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2. A method for converting binary electrical signals to analog optical signals comprising the steps of:
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controlling a controllable density optical transmission device with said electrical signals for producing a plurality of optical signals; passing coherent optical radiation through said optical transmission device to produce said plurality of optical signals; optically weighting and adding predetermined amounts of phase shift to said optical signals produced by said optical transmission device for representing different forms of analog numerical quantities; and summing the plurality of weighted and phase shifted optical signals at an output location defined by an optical masking means.
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3. Optical digital-to-analog conversion apparatus comprising:
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controllable density optical transmission device having multiple defined density states for transmission of coherent optical radiation therethrough as a plurality of optical signals having particular intensities for representing a plurality of particular numerical values inputted thereto; optical weighting means, positioned for receiving the plurality of optical signals from said optical transmission device, for providing different optical weights to each of said plurality of signals; optical summing means, positioned for summing the plurality of weighted optical signals, for producing an output optical signal having an amplitude representing a combination of said plurality of particular numerical values; and a pluality of lenses, wherein said optical transmission device, said weighting means and said summing means are positioned with respect to said lenses so as to have a fourier transform relationship between the front and back focal planes of the lenses.
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7. An optical digital to analog conversion apparatus comprising:
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controllable density optical transmission device having multiple defined density states for transmission of coherent optical radiation therethrough as a plurality of optical signals having particular intensities for representing a plurality of particular numerical values inputted thereto; optical weighting means, positioned for receiving the plurality of optical signals from said optical transmission device, for providing different optical weights to each of said plurality of signals; optical summing means, positioned for summing the plurality of weighted optical signals, for producing an output optical signals having an amplitude representing a combination of said plurality of particular numerical values; and phase shifting means positioned adjacent said optical transmission device for providing different phases to different ones of said plurality of optical signals. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14, 15)
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16. Optical digital-to-analog conversion apparatus comprising:
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controllable density optical transmission device having multiple defined density states for transmission of coherent optical radiation therethrough as a plurality of optical signals having particular intensities for representing a plurality of particular numerical values inputted thereto; optical weighting means, positioned for receiving the plurality of optical signals from said optical transmission device, for providing different optical weights to each of said plurality of signals; optical summing means, positioned for replicating and superimposing the plurality of weighted optical signals at an output plane of the apparatus, for producing at said output plane an output optical signal having an amplitude representing a combination of said plurality of particular numerical values, wherein said optical weighting means and said summing means are combined in a filter means having a predetermined density variation; a first lens means which is disposed between said optical transmission device and said filter means so as to provide a Fourier transform relationship between said optical transmission device and said filter means; and a second lens means which is disposed between said filter means and said output plane so as to provide a Fourier transform relationship between said filter means and said output plane.
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17. Optical digital-to-analog conversion apparatus comprising:
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controllable density optical transmission device having multiple defined density states for transmission of coherent optical radiation therethrough as a plurality of optical signals having particular intensities for representing a plurality of particular numerical values inputted thereto; optical weighting means, positioned adjacent said optical transmission device, for providing different optical weights to each of said plurality of signals; optical summing means, including a diffraction grating for replicating and superimposing the plurality of weighted optical signals at an output plane of the apparatus, for producing at said output plane an output optical signal having an amplitude representing a combination of said plurality of particular numerical values; a first lens means which is disposed between said optical transmission device and said diffraction grating so as to provide a Fourier transform relationship between said optical transmission device and said diffraction grating; and a second lens means which is disposed between said diffraction grating and said output plane so as to provide a Fourier transform relationship between said diffraction grating and said output plane.
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Specification