Method and apparatus for three dimensional range resolving imaging
First Claim
1. A method for detecting and imaging an object enveloped by a backscattering medium which is at least partially transmitting to light, the method comprising the steps of:
- generating a light pulse of a first wavelength;
splitting said light pulse into first and second light pulses;
homogenizing said first light pulse to provide a third light pulse having a uniformly illuminated field-of-view;
inducing a first angular deviation in said third light pulse and projecting said third light pulse having said first angular deviation toward the backscattering medium and at the object enveloped by the medium, wherein a fourth light pulse is generated by the reflection of said third light pulse having said first angular deviation back from the object;
inducing a second angular deviation in said fourth light pulse, wherein said second angular deviation is oriented in a direction generally opposite to said first angular deviation;
filtering said fourth light pulse having said second angular deviation to provide a fifth light pulse;
generating a pulse train from said second light pulse;
converting photon energy received at an array of detectors from said pulse train into at least one first electrical signal and converting photon energy received at said array of detectors from said fifth light pulse into at least one second electrical signal; and
processing said first electrical signal to determine compensating factors indicative of the differences in gain and offset between each of said array of detectors and processing said compensating factors and said second electrical signal to generate an imaging signal indicative of the object.
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Accused Products
Abstract
A three dimensional range resolving imaging sensor is presented. The sensor comprises a transmitter for generating a light pulse which passes through beam homogenizer and a pair of Fresnel-Risley prisms. This pulse is then directed through an environmental window towards an object enveloped in a backscattering medium. A portion of the light pulse is reflected back towards the sensor. However, prior to detecting the return light pulse, a detector array is internally calibrated by exposure to a calibration pulse. This detector array preferably comprises a two-dimensional photo multiplier tube (PMT) array. A corresponding array of light tapers is disposed before the PMT array to increase the fill factor of the PMTs. Gain and offset corrections are made for each PMT from this exposure. The return pulse passes through the environmental window and impinges a pair of Fresnel-Risley scanner plates. These plates introduce a fixed angular deviation which is dependent on the orientation of the plates. This pulse then passes through a spectral bandpass filter and onto a collection mirror. The collected return pulse is then directed to the PMT array. The output of the PMT array comprises a plurality of electrical signals. These signals are conditioned and then processed by an image processor. The image processor provides a visual display which is available to an operator. Also, the image processor may perform automated target recognition and alert the operator when a target is detected.
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Citations
28 Claims
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1. A method for detecting and imaging an object enveloped by a backscattering medium which is at least partially transmitting to light, the method comprising the steps of:
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generating a light pulse of a first wavelength; splitting said light pulse into first and second light pulses; homogenizing said first light pulse to provide a third light pulse having a uniformly illuminated field-of-view; inducing a first angular deviation in said third light pulse and projecting said third light pulse having said first angular deviation toward the backscattering medium and at the object enveloped by the medium, wherein a fourth light pulse is generated by the reflection of said third light pulse having said first angular deviation back from the object; inducing a second angular deviation in said fourth light pulse, wherein said second angular deviation is oriented in a direction generally opposite to said first angular deviation; filtering said fourth light pulse having said second angular deviation to provide a fifth light pulse; generating a pulse train from said second light pulse; converting photon energy received at an array of detectors from said pulse train into at least one first electrical signal and converting photon energy received at said array of detectors from said fifth light pulse into at least one second electrical signal; and processing said first electrical signal to determine compensating factors indicative of the differences in gain and offset between each of said array of detectors and processing said compensating factors and said second electrical signal to generate an imaging signal indicative of the object. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A three dimensional range resolving imaging sensor for detecting and imaging an object enveloped by a backscattering medium which is at least partially transmitting to light, comprising:
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means for generating a light pulse of a first wavelength; means for splitting said light pulse into first and second light pulses; beam homogenizer means receiving said first light pulse and providing a third light pulse having a uniformly illuminated field-of-view; first prism means receiving said third light pulse and inducing a first angular deviation therein, said first prism means projecting said third light pulse having said first angular deviation toward the backscattering medium and at the object enveloped by the medium, wherein a fourth light pulse is generated by the reflection of said third light pulse having said first angular deviation back from the object; second prism means receiving said fourth light pulse and inducing a second angular deviation therein, wherein said first angular deviation is oriented in a direction generally opposite to said second angular deviation; filter means for filtering said fourth light pulse having said second angular deviation to provide a fifth light pulse; means for generating a pulse train from said second light pulse; an array of detectors for converting photon energy received from said pulse train into at least one first electrical signal, said array of detectors for converting photon energy received from said fifth light pulse into at least one second electrical signal; and processor means for determining compensating factors indicative of the differences in gain and offset between each of said array of detectors in response to said first electrical signal, said processor means responsive to said compensating factors and said second electrical signal generating an imaging signal indicative of the object. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28)
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Specification