Question

Explain the term coherence in respect to light. Given that ∆𝒍 = 𝝀/𝝀2 explain 

what each symbol represent.

Answer 1

Coherence, a fixed relationship between the phase of waves in a beam of radiation of a single frequency. Two beams of light are coherent when the phase difference between their waves is constant; they are noncoherent if there is a random or changing phase relationship.

∆𝒍 = 𝝀/𝝀2: ∆𝒍 is coherence length, 𝝀 is wavelength of a wave, 𝝀2 is is a wavelength of a second wave.