Vollwinkel

Vollwinkel, literally “full angle,” is a German technical term used especially in geometry, optics and lighting engineering. It denotes the complete opening angle of a cone or beam, defined as the angle between the two outer boundary rays. The Vollwinkel is twice the half-angle (Halbwinkel) of the same cone and represents the total angular extent that the system emits or accepts.

In photometry and lighting design, the Vollwinkel specifies the angular width of a light distribution. A smaller Vollwinkel corresponds to a narrow beam, while a larger Vollwinkel indicates a wider beam. For example, if a light source has a half-angle of 15 degrees, the Vollwinkel is 30 degrees. This measure is commonly used on datasheets and in optical design to characterize beam spread.

Geometrically, the term can also be used to refer to the total angular measure around a point, which is 360 degrees. In this sense, Vollwinkel contrasts with smaller, localized angle measures formed by pairs of lines, and it emphasizes the complete rotational extent at a vertex.

Etymology and usage notes: Vollwinkel combines Voll, meaning “full,” with Winkel, meaning “angle.” It is often contrasted with Halbwinkel, the half-angle, and with more general discussions of angle measures in planar geometry and three-dimensional optics. The precise meaning can depend on context, but in most technical documents the Vollwinkel represents the full opening angle of a beam or cone.

See also: Halbwinkel, Winkel, Beam divergence, Beam footprint, Light distribution.