System and method for measuring distance
First Claim
1. A distance measuring system, comprising:
- means for generating a beam of electromagnetic energy of selected characteristics and illuminating a target therewith so that at least a fraction of said beam is reflected from said target thereby to form a reflected beam;
first detector means for detecting the intensity of said electromagnetic energy, said first detector means being positioned to receive said reflected beam and being responsive thereto to generate a first signal the magnitude of which is directly proportional to the intensity of said reflected beam at said first detector means;
second detector means for detecting the intensity of said electromagnetic energy, said second detector means being spaced apart in target range from said first detector means, said second detector means being positioned substantially in colinear alignment with the point on said target from which said beam is reflected and said first detector means to also receive said reflected beam, said second detector means being responsive to said reflected beam to generate a second signal the magnitude of which is proportional to the intensity of said reflected beam at said second detector means;
means connected to receive said first and second signals for generating a difference signal the magnitude of which is a function of the difference between the magnitudes of said first and second signals; and
means connected to receive said first signal and said difference signal for generating a quotient signal the magnitude of which is proportional to the magnitude of said first signal divided by the magnitude of said difference signal whereby the magnitude of said quotient signal is a known function and hence a measure of target range.
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Accused Products
Abstract
A pair of light intensity detectors are spaced apart in range and an arrangement is included for reflecting light from a target to the detectors. The system measures target range by dividing the output signal of one of the detectors by a signal which is a function of the difference between the output signals of the two detectors to produce a quotient signal. To avoid low signal instability problems, the difference signal is generated in one embodiment of the system by subtracting only a selected fraction of the output signal of the far detector from that of the near detector. A substantially linearized output signal representing target range is produced in this system embodiment by raising the quotient signal to a selected power. The light detectors are preferably incorporated in input circuits which are temperature compensated.
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Citations
25 Claims
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1. A distance measuring system, comprising:
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means for generating a beam of electromagnetic energy of selected characteristics and illuminating a target therewith so that at least a fraction of said beam is reflected from said target thereby to form a reflected beam; first detector means for detecting the intensity of said electromagnetic energy, said first detector means being positioned to receive said reflected beam and being responsive thereto to generate a first signal the magnitude of which is directly proportional to the intensity of said reflected beam at said first detector means; second detector means for detecting the intensity of said electromagnetic energy, said second detector means being spaced apart in target range from said first detector means, said second detector means being positioned substantially in colinear alignment with the point on said target from which said beam is reflected and said first detector means to also receive said reflected beam, said second detector means being responsive to said reflected beam to generate a second signal the magnitude of which is proportional to the intensity of said reflected beam at said second detector means; means connected to receive said first and second signals for generating a difference signal the magnitude of which is a function of the difference between the magnitudes of said first and second signals; and means connected to receive said first signal and said difference signal for generating a quotient signal the magnitude of which is proportional to the magnitude of said first signal divided by the magnitude of said difference signal whereby the magnitude of said quotient signal is a known function and hence a measure of target range. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A method of measuring range to a target, comprising:
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reflecting electromagnetic energy from the target; sensing the intensity of the target reflected electromagnetic energy at first and second locations spaced apart a predetermined distance in target range, said first and second locations being substantially in colinear alignment with the point on the target from which the energy is reflected; generating a difference signal the magnitude of which is a function of the difference between the magnitudes of the intensity of the target reflected energy at said first and second locations; and
,generating a quotient signal the magnitude of which is proportional to the magnitude of the intensity of the target reflected energy at said first location divided by the magnitude of said difference signal whereby said quotient signal is a known function and hence a measure of target range. - View Dependent Claims (18, 19, 20, 21, 22, 23)
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24. A method of measuring range to a target, comprising:
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reflecting electromagnetic energy from the target; sensing the intensity of the target reflected electromagnetic energy at first and second locations spaced apart a predetermined distance in target range, said first and second locations being substantially in colinear alignment with the point on the target from which the energy is reflected; generating a difference signal the magnitude of which is a function of the difference between the magnitudes of the intensity of the target reflected energy at said first and second locations, the magnitude of said difference signal being equal to the one of said sensed intensities at said first and second locations which has the largest magnitude less a predetermined percent of the magnitude of the smaller of said sensed intensities; generating a quotient signal the magnitude of which is linearly proportional to the magnitude of the intensity of the target reflected energy at said first location divided by the magnitude of said difference signal whereby said quotient signal is a known function and hence a measure of target range; and
,generating an output signal equal to the magnitude of said quotient signal raised to a selected power whereby the magnitude of said output signal is substantially linearly proportional to target range over a selected range of values of target range. - View Dependent Claims (25)
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Specification