1. Fundamentals of Light and Laser Technology

A laser—Light Amplification by Stimulated Emission of Radiation—is a device that emits light through a process of optical amplification. Unlike ordinary light sources, which emit incoherent and broad-spectrum light, a laser produces a beam that is:

• Monochromatic: composed of a single wavelength or color,
• Coherent: the light waves are in phase, traveling in the same direction,
• Collimated: the beam stays narrow and focused over long distances.

These properties allow lasers to deliver concentrated energy with precision, making them particularly useful for both diagnostic and therapeutic medical applications. Laser light can be directed at specific tissues without affecting adjacent areas, enabling targeted interventions at the cellular or subcellular level (Akçayır & Akçayır, 2017; Albrecht et al., 2013).