What does "coherent" refer to in the context of lasers?

• A. Single wavelength color
• B. Preparation of laser mirror
• C. Synchronized phase of light waves
• D. Focus of the laser beam

Answer: (C)

In the context of lasers, "coherent" refers to the synchronized phase of light waves. Coherence is a fundamental property of laser light that distinguishes it from ordinary light sources. It means that the light waves produced by the laser are in phase with one another, which contributes to the laser's ability to produce a narrow, focused beam of light.

This synchronized phase allows for constructive interference, where the peaks of the light waves align perfectly, resulting in a strong, uniform intensity of light. This is critical for applications that rely on precision and directionality, such as in telecommunications, medical procedures, and laser cutting.

The other options focus on different aspects related to lasers. For example, while a single wavelength color is a characteristic of a laser's light output, coherence specifically ties to the phase relationship of those wavelengths, which is key to its functionality. Preparation of laser mirrors involves the technical setup necessary for laser operation but does not define coherence. Lastly, while the focus of the laser beam is important for its applications, it does not capture the essence of what makes laser light coherent.