Laser Brightness (Radiance) Calculator

Your details

Choose what to solve for. All other modes use the same physical inputs.
Total output power of the laser in watts.
W
Radius of the beam at its narrowest focus point (1/e2 intensity point).
mm
Total angular spread of the beam (full angle, not half angle) at the 1/e2 intensity level.
mrad
Central wavelength of the laser emission.
nm
Laser brightness (radiance)Poor beam quality
405,284.7346W/(mm²·sr)

Radiance: power per unit beam area per unit solid angle.

Beam area0.785398mm²
Solid angle0.000003sr
Etendue (geometric extent)0.000002mm²·sr
Diffraction-limited brightness14,133,077.0535W/(mm²·sr)
Beam quality M²5.905
5.905 M2
Diffraction-limited<1.1Near-ideal1.1-1.5Moderate quality1.5-3Poor quality3+

Radiance is 4.053e+5 W/(mm2 sr).

  • This beam is 2.87% of the diffraction-limited ideal (M2 = 5.91).
  • Etendue is 2.467e-6 mm2 sr. This is the phase-space volume conserved through any lossless optical system: you cannot reduce it.
  • Brightness is the fundamental figure of merit for focusing, fiber coupling, and material processing. A higher value means more power can be delivered to a smaller spot at a smaller solid angle.

Next stepYour beam quality (M2 = 5.91) indicates poor quality, likely a multimode or uncollimated source.

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