ABSTRACT
The emitted laser light is a spatially coherent (waves of the same frequency and phase), narrow low-divergence beam. The laser’s beam of coherent light differentiates it from light sources such as lamps that emit incoherent light, of random phase varying with time and position. Although laser light is usually thought of as monochromatic, there are lasers that emit a broad spectrum of light (short pulses) or simultaneously at different wavelengths.
