Biomedical subjects

Robert L Lucke

Publications and source records attributed to Robert L Lucke.

3 recordsLinked to original sources

PubMed2007

Theoretical wave structure function when the effect of the outer scale is significant.

The wave structure function (WSF) for a plane wave, calculated from the basic Rytov theory, is usually expressed as 6.88(r/r(0))(5/3), but this does not include the effect of a finite outer scale (or of a nonzero inner scale) of turbulence. When separation distance r is only 5% of the outer scale, this expression overpredicts the WSF by a factor of approximately 2. Accurate evaluations of the Rytov formulas are given for the WSFs of plane and spherical waves in Kolmogorov and von Karman turbulence and for the structure function of the atmosphere's index of refraction. Simple formulas make the results easy to use.

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PubMed2005

Fast computation of the narcissus reflection coefficient for the Herschel far-infrared/submillimeter-wave Cassegrain telescope.

Placement of a scatter cone at the center of the secondary of a Cassegrain telescope greatly reduces Nareissus reflection. To calculate the remaining Narcissus reflection, a time-consuming physical optics code/such as GRASP8 is often used to model the effects of reflection and diffraction. Fortunately, the Cassegrain geometry is sufficiently simple that a combination of theoretical analysis and Fourier propagation can yield rapid, accurate results at submillimeter wavelengths. We compare these results with those from GRASP8 for the heterodyne instrument for the far-infrared on the Herschel Space Observatory and confirm the effectiveness of the chosen scatter cone design.

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PubMed2002

Photon-limited synthetic-aperture imaging for planet surface studies.

The carrier-to-noise ratio that results from phase-sensitive heterodyne detection in a photon-limited synthetic-aperture ladar (SAL) is developed, propagated through synthetic-aperture signal processing, and combined with speckle to give the signal-to-noise ratio of the resultant image. Carrier- and signal-to-noise ratios are defined in such a way as to be familiar to the optical imaging community. Design equations are presented to show that a 10-microm SAL in orbit around Mars can give centimeter-class resolution with reasonable laser power. SAL is harder to implement in the short-wave infrared and is probably not practical at visible wavelengths unless many separate images can be averaged. Some tutorial information on phase-sensitive heterodyne detection and on synthetic-aperture signal processing and image formation is provided.

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