Laser heterodyne detection techniques

Menzies, Robert T.

doi:10.1007/3-540-07743-x_21

Cited by 20 publications

(7 citation statements)

References 69 publications

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“…Their theory is also a weakintegrated refractive-turbulence theory. Rye 8 used phenomenological arguments to include the effects of refractive turbulence. None of these theories has been shown to be valid for general path-integrated refractive turbulence.…”

Section: Effects Of Atmospheric Refractive Turbulencementioning

confidence: 99%

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Coherent laser radar performance for general atmospheric refractive turbulence

1991

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The signal-to-noise ratio (SNR) and heterodyne efficiency are investigated for coherent (heterodyne detection) laser radar under the Fresnel approximation and general conditions. This generality includes spatially random fields, refractive turbulence, monostatic and bistatic configurations, detector geometry, and targets. For the first time to our knowledge, the effects of atmospheric refractive turbulence are included by using the path-integral formulation. For general conditions the SNR can be expressed in terms of the direct detection power and a heterodyne efficiency that can be estimated from the laser radar signal. For weak refractive turbulence (small irradiance fluctuations at the target) and under the Markov approximation, it is shown that the assumption of statistically independent paths is valid, even for the monostatic configuration. In the limit of large path-integrated refractive turbulence the SNR can become twice the statistically independent-path result. The effects of the main components of a coherent laser radar are demonstrated by assuming untruncated Gaussians for the transmitter, receiver, and local oscillator. The physical mechanisms that reduce heterodyne efficiency are identified by performing the calculations in the receiver plane. The physical interpretations of these results are compared with those obtained from calculations performed in the target plane.

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Section: Effects Of Atmospheric Refractive Turbulencementioning

confidence: 99%

“…The zero-order fourth-moment expressions for the effects of refractive turbulence are given in terms of the second-moment Green's functions ((GG*)) for wave propagation in random media. 6 8 For narrow angular deviations caused by refractive turbulence and the Markov approximation, 8…”

Section: Zero-order Fourth-moment Solutionmentioning

confidence: 99%

Coherent laser radar performance for general atmospheric refractive turbulence

1991

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“…In the infrared wavelength region longer than 1.3 (im, however, solid state photoconductive and photovoltaic detectors are used, with extreme reduction in sensitivity in direct detection techniques. With the heterodyne detection technique, on the other hand, sensitivity can be greatly improved, since the thermal background noise component is restricted to a narrow bandwidth by the use of a local oscillator laser and a narrow bandwidth detection technique (Menzies, 1976). This detection scheme may provide not only signal intensity but also frequency, phase and polarization of the signal radiation, and is often referred to as a coherent detection.…”

Section: Coherent Lidarsmentioning

confidence: 98%

“…The transmitted light spectrum is heterodyne detected with extremely high resolution by mixing with a tunable-frequency local oscillator laser beam. The total path molecular absorption and sometimes its height information can be derived by assuming atmospheric pressure and temperature distribution (Menzies, 1976). …”

Section: Absorptionmentioning

confidence: 99%

Techniques for laser remote sensing of the environment

Kobayashi¹

1987

Remote Sensing Reviews

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“…30 (Otherwise, simple direct detection is used, as in the above mentioned examples.) In heterodyne detection, for each measurement wavelength, two wavelengths separated by a few MHz have to be mixed in a photodetector.…”

Section: Continuous (Cw) Co2 Laser Systemsmentioning

confidence: 99%