Beam width divergence is the angular width of a beam, specifically defined as the angle subtended by the beam at its source.
Understanding Beam Divergence
Based on the provided reference, the term beam divergence is synonymous with the angular width of a beam. This angular width describes the spread of the beam as it propagates away from its source.
The reference states: "The angular width is also called the beam divergence. The angular width is the angle subtended by the beam at the source."
Angular Width Explained
The "angle subtended by the beam at the source" essentially quantifies how quickly the beam expands in cross-sectional area as it travels outwards. A beam with low divergence spreads very little over distance, while a beam with high divergence spreads rapidly.
Relation to Beam Width
While beam width can sometimes refer to the physical size (a length measurement, e.g., in millimeters) of the beam at a specific point along its path, beam divergence is inherently an angular measurement (e.g., in radians or degrees) that characterizes the beam's spreading behavior from its origin.
- Beam Width (Length): Size of the beam at a particular location.
- Beam Divergence (Angle): Rate at which the beam expands.
For instance, a laser beam typically has very low divergence, meaning it stays narrow over long distances. In contrast, the beam from a standard flashlight has much higher divergence, spreading out considerably over even short distances.
