What is the calculation for angle of divergence?

The angle of divergence is typically calculated using the formula: ( \theta = \arctan\left(\frac{d}{L}\right) ), where ( d ) is the distance between two points (e.g., the width of a beam) and ( L ) is the distance over which the divergence occurs. This formula derives from basic trigonometry, where the tangent of the angle is the ratio of the opposite side (the distance) to the adjacent side (the length). The resulting angle ( \theta ) can then be expressed in degrees or radians, depending on the context.