What property of laser light allows for it to be focused into a tight beam?

The property of laser light that enables it to be focused into a tight beam is collimation. Collimated light consists of rays that are parallel to each other, which means that it does not spread out significantly as it travels. This characteristic allows the beam to maintain its intensity and direction over long distances, making it effective in various applications, including therapeutic and surgical treatments.

Monochromatic light refers to light of a single wavelength, which contributes to the purity of the color of the laser. While this is an important property, it does not inherently focus a beam; it primarily affects the quality and specificity of the beam's color.

Coherence is the property that describes the phase relationship between waves, often contributing to the uniformity of a laser light's wavefront. While coherence is vital for interference and imaging applications, it does not directly relate to how narrowly the beam can be focused.

Divergent light rays spread out as they move away from their source, which is contrary to the requirements for maintaining a tightly focused beam. Understanding these distinctions is crucial for effectively utilizing laser technology.