astroFns (version 4.0-0)

beamDiskOverlap: Gaussian beam and disk overlap with shift

Description

Calculate the overlap integral of a 2-D Gaussian beam and a uniform disk, including a shift between the centers of the beam and disk.

Usage

beamDiskOverlap(s = 0, r = 1, theta.fwhm = 1)

Arguments

s

Shift between centers

r

Disk radius

theta.fwhm

Gaussian beam FWHM

Value

• Value of the overlap integral, normalized to unity for a beam much smaller than the disk.

Details

Converts the 2-D integral to 1-D for speed. Use consistent units.

References

"Telescope illumination and beam measurements for submillimeter astrononomy," A.I. Harris, Internat. J. IR and mm Waves, 9, 231 (1988)

Examples

s <- seq(0, 10, 0.1)
plot(s, beamDiskOverlap(s, 4, 1), t='l', col=4)