Photon Flux Calculator
Calculate photon energy, flux, and irradiance from wavelength and power or pulse energy.
Photon energy depends on wavelength: E = hc/λ, so a 1 mW source at 532 nm delivers nearly twice as many photons per second as the same power at 266 nm. This converter computes per-photon energy in joules and eV, then divides optical power (CW) or pulse energy times repetition rate (pulsed) by that energy to give photon flux in photons per second. Wavelength entry accepts nanometers, micrometers, or wavenumbers (cm⁻¹). The optional beam diameter input — entered as the 1/e² Gaussian diameter — adds irradiance in W/m² and photon flux density in photons/s/cm², quantities used in rate-equation models, single-photon detection system design, and photodamage threshold comparisons.