Differential absorption ranging method and apparatus
First Claim
1. A method of determining distance between two objects, comprisingproviding one object with a source of frequency modulated laser light and another object with an optical receiver;
- emitting a laser light beam while modulating its frequency through a frequency range greater than a frequency range characteristic of atmospheric oxygen absorption;
receiving the frequency modulated laser light beam at the other object; and
analyzing the received frequency modulated laser light beam to determine from signal strengths in the frequency range of modulation the distance between the two objects.
2 Assignments
0 Petitions
Accused Products
Abstract
The distance between two objects, such as aircraft, helicopters and other vehicles, can be determined by transmitting from a first object through atmosphere a first frequency which is absorbed by atmosphere and a second frequency which is not absorbed by atmosphere, receiving at a second distant object the first and second frequencies, and determining from the received first and second frequencies the distance between the first and second objects. In preferred methods and apparatus, the first frequency is a frequency characteristic of atmospheric oxygen absorption (e.g., 760 nm wavelength), and the frequency transmission comprises emitting a laser light beam while modulating its frequency through a frequency range which is greater than a frequency range characteristic of atmospheric oxygen absorption (e.g., 750 nm-770 nm wavelength) and includes a second frequency which is not absorbed by atmosphere.
-
Citations
37 Claims
-
1. A method of determining distance between two objects, comprising
providing one object with a source of frequency modulated laser light and another object with an optical receiver; -
emitting a laser light beam while modulating its frequency through a frequency range greater than a frequency range characteristic of atmospheric oxygen absorption; receiving the frequency modulated laser light beam at the other object; and analyzing the received frequency modulated laser light beam to determine from signal strengths in the frequency range of modulation the distance between the two objects. - View Dependent Claims (2, 3, 4, 5)
-
-
6. Apparatus for determining the distance between two objects, comprising
first means for providing a beam of frequency modulated laser light, said first means being adapted for modulation of the emitted laser light beam through a frequency range greater than a frequency range characteristic of absorption by atmospheric oxygen; - and
second means for receiving said frequency modulated laser light beam, said second means being adapted for analyzing the received frequency modulated laser light beam to determine from signal strengths in the frequency range of modulation the distance between said first and second means. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13, 14)
- and
-
15. Apparatus for determining the distance between two objects, comprising
a first means comprising a first transmitter of a first signal with a predetermined power output at a frequency at which said first signal is absorbed by atmosphere, and a second transmitter of a second signal at said predetermined power output at a frequency at which said second signal is not absorbed by atmosphere; - and
a second means comprising a receiving means for said first signal and for said second signal, and a distance determination means for determining the distance of said second means from said first means from the received first and second signals. - View Dependent Claims (16)
- and
-
17. A method of determining distance between two objects, comprising the steps of
transmitting from a first object through atmosphere a first frequency which is absorbed by atmosphere and a second frequency which is not absorbed by atmosphere; -
receiving at a second distant object said first and second frequencies; providing a first output proportional to the strength of the received first frequency; providing a second output proportional to the strength of the received second frequency; and comparing the first and second outputs and determining from said first and second outputs the distance between the said first and second objects; and displaying the distance between the two objects. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25, 26, 27)
-
-
28. Apparatus for determining the distance between two objects, comprising
first means comprising frequency generating means for generating a first frequency which is absorbed by one or more atmospheric gasses and a second frequency which is not absorbed by atmospheric gasses and transmitter means for transmitting said first and second frequencies through atmosphere; - and
second means for receiving said first and second frequencies and for determining the distance from said first means. - View Dependent Claims (29, 30, 31, 32, 33, 34, 35, 36, 37)
- and
Specification