Lasers: principles, types, applications
Engineering Physics · Engineering
Study notes
A He-Ne laser (632.8 nm) emits 5 mW. How many photons per second? Photon energy: E = hc/λ = 1240/632.8 = 1.96 eV = 3.14×10⁻¹⁹ J. Rate = P/E = 5×10⁻³/3.14×10⁻¹⁹ ≈ 1.6×10¹⁶ photons/s.
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