Accession Number:

ADA248938

Title:

Lidar Measurement of Optical Turbulence: Theory of the Crossed Path Technique

Descriptive Note:

Interim scientific rept.

Corporate Author:

PHILLIPS LAB HANSCOM AFB MA

Report Date:

1991-07-08

Pagination or Media Count:

44.0

Abstract:

The existing measurement capabilities of optical turbulence for IRoptical wavelengths are reviewed. It is shown that no capability exists for simultaneous high spatial and temporal resolution measurements of optical turbulence along an optical path. A general formulation of the remote sensing of optical turbulence is presented, emphasizing the importance of the altitude weighting function, dynamic range requirements and numerical issues. A new approach to lidar remote sensing of turbulence is presented that uses two lidar beams that are viewed by two receivers along a crossed path. The geometric aspects of this theory are discussed and followed by a quantitative formulation based on the Rytov approximation. The approach is similar to the binary star and crossed laser beam methods that have appeared in the literature. The method is based on the intensity covariance of two backscattered spots viewed along crossed paths. The effects of backscatter spot size and receiver averaging are presented. It is shown that the technique is sensitive to the inner scale and is insensitive to the presence of both backscattering spots in both receiver fields of view. The effects of diffraction, turbulence broadening and beam wander are discussed. Criteria are presented for all these effects in the design of a practical system.

Subject Categories:

  • Optical Detection and Detectors

Distribution Statement:

APPROVED FOR PUBLIC RELEASE