Micrometer wave imaging device
First Claim
1. A device for providing signals responsive to millimeter wave radiation detected from a field of view, comprising:
- an array of millimeter wave mixer/detector elements, optically aligned with the field of view;
a multiple element array of sources of millimeter wave energy located at an angle to the axis of optical alignment of said array of mixer/detector elements and field of view;
means for separating said energy into an illumination beam and a local oscillator beam;
means for directing the illumination beam onto the field of view;
means for directing the local oscillator beam onto the mixer/detector array so as to uniformly illuminate the mixer/detector array; and
means for focusing milli field of view onto said mixer/detector
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Accused Products
Abstract
A millimeter wave sensing device is disclosed comprising a local oscillator source generating a millimeter wave signal which is mixed with millimeter wave radiation reflected from or emitted by objects in a field of view. The mixing is performed in a staring array of mixer/detector elements which need not be mechanically or electronically scanned to generate signals responsive to the entire field of view. In a first embodiment of the invention, the device detects millimeter wave radiation emitted by or reflected from the object to be imaged. In a second embodiment of the invention, the oscillator used to provide the local oscillator signal is also used to illuminate the field of view. In the second embodiment of the invention, the oscillator signal is preferably linearly polarized, and a polarizing grid is used to separate the local oscillator signal and illumination beam and direct them in a simple and efficient manner. A twist reflector may also be used to rotate the polarization of a portion of the beam to direct it onto the mixer/detector array for mixing with the received signal from the field of view.
Improved constructions of millimeter wave source and mixer/detector elements are also disclosed, which greatly simplify construction of the device.
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Citations
68 Claims
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1. A device for providing signals responsive to millimeter wave radiation detected from a field of view, comprising:
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an array of millimeter wave mixer/detector elements, optically aligned with the field of view; a multiple element array of sources of millimeter wave energy located at an angle to the axis of optical alignment of said array of mixer/detector elements and field of view; means for separating said energy into an illumination beam and a local oscillator beam; means for directing the illumination beam onto the field of view; means for directing the local oscillator beam onto the mixer/detector array so as to uniformly illuminate the mixer/detector array; and means for focusing milli field of view onto said mixer/detector - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28)
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29. A millimeter wave detecting device, comprising:
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an array of millimeter wave mixer/detector elements, aligned along an optical path with respect to a field of view; means for focusing millimeter wave radiation emitted by or reflected from objects in the field of view onto said mixer/detector array; an array of sources of millimeter wave energy located out of said optical path for generating a highly uniform millimeter wave local oscillator signal; and means disposed in said optical path for directing said millimeter wave local oscillator signal onto said mixer/detector array to uniformly illuminate said mixer/detector array, while permitting focused radiation to traverse said optical path to be incident onto the mixer/detector array; wherein each of the mixer/detector elements of the array detect and mix the local oscillator signal and focussed radiation from a particular portion of the field of view and provide an output signal responsive to said portion of the field of view. - View Dependent Claims (30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46)
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47. Method for generating an image of a field of view, comprising the steps of:
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focusing millimeter wave energy emitted by or reflected from objects in a field of view onto an array of mixer/detector elements sensitive to millimeter-wave energy, thereby defining an optical path extending between said field of view and said array; employing a multiple-element array of sources to generate a highly uniform beam of millimeter-wave energy, employing division means disposed in said optical path to divide said beam of millimeter-wave energy into minor and major components, directing a first minor portion of said beam onto said array of mixer/detector elements to uniformly illuminate said array of mixer/detector elements, directing a second major portion of said beam into the field of view, mixing the focussed energy with the minor portion of the beam individually in the elements of said mixer/detector array, detecting difference-frequency signals resulting from said mixing step with respect to each of the elements of said mixer/detector array, and employing the detected signals to form an image, in which individual picture elements of the image correspond to the signals detected by the individual mixer/detector elements of said array. - View Dependent Claims (48, 49, 50, 51)
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52. Method for generating an image of a field of view, comprising the steps of:
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focusing energy reflected from or emitted by objects in the field of view onto an array of mixer/detector elements sensitive to millimeter-wave energy, thus defining an optical path extending between the field of view and the array; employing a multiple element array of millimeter wave sources to generate a highly uniform local oscillator signal of millimeter-wave energy; directing said local oscillator signal onto means disposed in said optical path for reflecting said local oscillator signal onto said array of mixer/detector elements, whereby said array of mixer/detector elements is uniformly illuminated by said local oscillator signal, individually mixing the focussed energy with the local oscillator signal in the elements of said mixer/detector array, detecting the signals resulting from said mixing step, and employing the detected signals to form an image in which individual picture elements of said image correspond to the signal detected by the individual mixer/detector elements of said array. - View Dependent Claims (53)
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54. A device for forming an image signal, said image signal comprising a number of pixels each corresponding to a predetermined portion of a field of view, said device comprising:
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an array of a number of mixer/detector elements, the number being equal to the number of pixels of the image signal, a multiple-element array of sources, each a multiple-element array of sources, each emitting a millimeter wave local oscillator signal; means for focusing radiation received from the field of view onto the mixer/detector array; and means disposed between the means for focusing and the mixer/detector array for reflecting the local oscillator signal onto the mixer/detector array, while permitting passage therethrough of the radiation received from the field of view; said elements of said mixer/detector array each being adapted to mix a local oscillator signal emitted by one of said sources with radiation emitted by or reflected from objects in a particular portion of the field of view, yielding sum and difference signals, and each comprising means for deriving a portion of the image signal from said difference signals corresponding to a single pixel of said image signal. - View Dependent Claims (55, 56, 57, 58, 65, 66, 67, 68)
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59. Method of forming an image of objects in a field of view, comprising the steps of:
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focusing radiation received from objects in the field of view onto a mixer/detector array comprising a number of mixer/detector elements equal to the number of pixels in the image, employing an array of millimeter wave sources to generate local oscillator signals, disposing means for reflecting said local oscillator signals between said field of view and said mixer/detector array, said means for reflecting passing said focussed radiation therethrough, mixing the local oscillator signal from one of said sources and radiation from a portion of the field of view to form sum and difference signals in each of said mixer/detector elements, and using the difference signals from each of the mixer/detector elements to form the corresponding pixels of the image. - View Dependent Claims (60, 61, 62, 63, 64)
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Specification