Angular response of idealized entrance optics used in light measurements.
Usage
angular_response(
elevation.angle = 90,
geometry = "cosine",
zenith.angle = 90 - elevation.angle,
diameter = NULL
)Arguments
- elevation.angle, zenith.angle
numeric The elevation angle of a point light source such as the sun or its zenith angle [degrees].
- geometry
character The type of entrance optics, one of
"flat disk","cosine","dome","hemisphere","ball", or"sphere".- diameter
numeric The diameter of the entrance optics. If
NULL, the default, a relative value is returned.
Details
The maximum projected area (\(A_\mathrm{max}\)) is always computed for a circle of diameter \(d\) as \(A_\mathrm{max} = \pi \times d^2 / 4\) when computing actual projected areas, or set to \(A_\mathrm{max} = 1\) for computation of relative values.
The cosine response for a flat disk is computed as $$A_\mathrm{p} = A_\mathrm{max} \times \cos(z)$$
The hemispherical response for a dome is computed as $$A_\mathrm{p} = A_\mathrm{max} \times 0.5 \times (1 + \cos(z))$$
The spherical response for a "ball" is computed as $$A_\mathrm{p} = A_\mathrm{max} \times 1$$
See also
all_diffusers and diffusers.lst for
data for real sensors and entrance optics.
Examples
angular_response(45)
#> [1] 0.7071068
angular_response(45, "cosine")
#> [1] 0.7071068
angular_response(45, "dome")
#> [1] 0.8535534
angular_response(45, "sphere")
#> [1] 1
angular_response(c(0, 30, 60, 90))
#> [1] 0.0000000 0.5000000 0.8660254 1.0000000
angular_response(-c(0, 30, 60, 90))
#> [1] 0 0 0 0
angular_response(c(0, 30, 60, 90), "dome")
#> [1] 0.5000000 0.7500000 0.9330127 1.0000000
angular_response(c(0, 30, 60, 90), "sphere")
#> [1] 1 1 1 1