What makes lasers dangerous compared to conventional light sources?
The main danger from hazardous exposure to laser light is due to their ‘spatial coherence.’ That refers to the fact that the wave traits of the laser beam have: • A fixed relation to time and space (coherent). • Are all of the same wavelength (monochromatic). • Can travel over great distances as a nearly parallel beam (collimated). All of this means that the power or energy that impacts an area such as the eye is independent of the distance to the radiation source. Imagine a laser pointer with a beam spot that remains about the same size over great distances. If you compare a thermal source of radiation like a light bulb, with a laser you will observe several differences. The light bulb emits light over a very broad spectrum of wavelengths with no specific direction of dispersion. A physicist would say that the bulb produces incoherent light. When comparing a light bulb with a laser, both emitting 1 W optical power, the power of the bulb that may reach the eye decreases with distance b
