Accession Number : ADD008052

Title :   Imagery with Constant Range Lines.

Descriptive Note : Patent,

Corporate Author : DEPARTMENT OF THE AIR FORCE WASHINGTON DC

Personal Author(s) : Green,Leland D

Report Date : 02 Dec 1980

Pagination or Media Count : 8

Abstract : Method and apparatus for showing the relative range from an active line scan sensor to a target, the changes in range being shown on a recording medium as an alternate series of bright and dark lines. In particular, a modulated laser beam having high frequency components is utilized to illuminate the target, the reflected energy received at the sensor having the same modulation frequency but phase modified by the transit time required to make the roundtrip from the sensor to the target and return. The phase difference between the received energy and the transmitted, or reference, energy is shown on the recording medium by directing a portion of the reference energy to a detector which is also responsive to the received energy. Points in the image formed on the recording medium where the phase angles are the same can be made to appear white while the points where the phase angles differ by 180 deg can be made to appear black. The difference in the range between two black lines is equal to a specific sub-interval of the wavelength of the effective laser modulation frequency, the sub-interval being 1/n where n is the harmonic of the effective laser modulation frequency.

Descriptors :   *Patents, *Optical detection, *Range finding, *Laser beams, Phase shift, Laser modulators, Mode locked lasers, Line scanning, Flying spot scanners, Contours

Subject Categories : Lasers and Masers
      Optical Detection and Detectors

Distribution Statement : APPROVED FOR PUBLIC RELEASE