Formulas for numericals

(idk if these are correct, should verify them)

• Degree of coherence = $\frac{\Delta v}{v}=\frac{\lambda}{\Delta \lambda}$
  • Δλ: bandwidth
• Angular divergence θ=1.22λ/D=d/2l
  • d: spot size
  • l: distance of spot
  • D: diameter of beam/aperature size
  • λ: wavelength of light
• d=fθ
  • f:focal length
• Intensity I=Power/Area of spot
• θ=$\frac{d₂-d₁}{2(l₂-l₁)}$
  • θ: Angle of beam divergence
  • d₁, d₂ are diameters of laser at distances l₁, l₂
• Pulse or Coherence Time T=1/Δv
• Coherence length: l=c*coherence time = c/Δv = $\frac{\lambda ^2}{\Delta \lambda}$
• Line width: Δλ
• Quality factor Q=λ/Δλ
  • Coherent length l_c=Qλ₀
  • Coherent time T_c=Q/ν₀ or l_c/c