How does one differentiate between an extended source and a point source of laser?

To differentiate between an extended source and a point source of laser, angular subtense is the most relevant factor. Angular subtense refers to the angle that an object subtends at a specific point, which helps in determining how the source appears from a certain distance. An extended source emits light over a larger area and creates a broader angle when viewed from a distance, unlike a point source, which appears as a singular, concentrated spot of light.

Understanding angular subtense is crucial in laser safety, as it affects how laser light can spread and impact various surfaces or individuals in its path. Proper identification of a laser's source type aids in implementing appropriate safety measures, as extended sources often pose different hazards compared to point sources due to their broader distribution of light.

While wavelength, safety standards, and energy output are important factors in laser safety and classification, they do not uniquely determine whether a laser is an extended or point source. Wavelength pertains to the color and characteristics of the laser light but does not define the spatial characteristics of the source. Safety standards relate to regulatory guidelines for operating lasers safely, while energy output measures the power of the laser but does not inform how the laser light is projected in terms of spatial characteristics.