the angle with which the beam from a lantern diverges. See also half angle.

Also called the beam spread; the angular dimension of the cone of light from reflectorized lamps encompassing the central part of the beam out ot the angle where the intensity is 50 percent of maximum.

The angle between the two directions for which the intensity is 50% of the maximum intensity as measured in a plane through the nominal beam centerline. For beams that do not possess rotational symmetry, the beam angle is generally given for two planes at 90°, typically the maximum and minimum angles. Typically reported in `Type B' photometry. Beam Spread (in any plane) The angle between the two directions in the plane in which the intensity is equal to a stated percentage of the maximum beam intensity. Applies to floodlights and the beam spread is given in vertical and horizontal planes. Note: The total luminaire coverage exceeds maximum intensity beam spread angles listed but is less bright for most luminaires. See Beam Angle.

The area of acoustic pulse transmission that spreads with distance over range.

The angle (in degrees) used to calculate the diameter of the spot for a given throw distance.

The angle between a transducer beamís main axis and the vertical axis of the ADCP or DVL (typically 20 or 30†).

is the angular beam width of a conical beam of light and is measured in degrees.

The angle at which light spreads from the front of the lantern. Sometimes shown as a minimum and maximum figures depending on the lanterns focussing capabilities.

The angular dimension of the cone of light from reflectorized lamps encompassing the central part of the beam out to the angle where the intensity is 50% of maximum. The beam angle sometimes called "beam spread", is often part of the ordering code for reflectorized lamps.

The included angle between those points on opposite sides of the beam axis where the intensity drops to 50% of maximum.

(Measurement and Inspection) Ultrasonic sensors emit a cone of sonic energy that diverges with distance. The angle of this beam is usually defined as the total (included) angle. Ultrasonic beams are not perfect cones. Most of the ultrasonic energy is in the center of the beam. The energy level decreases with distance away from the centerline. The beam angle is defined as the region where the energy is 50% of the energy measured on the centerline.