Micrometer wave imaging device

A millimeter wave detecting device, comprising:

• 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.

Method for generating an image of a field of view, comprising the steps of:

• 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.

Method for generating an image of a field of view, comprising the steps of:

• 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.

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:

• 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.

Method of forming an image of objects in a field of view, comprising the steps of:

• 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.