Abstract: To reduce the high dynamic range requirement on high speed amplifier, a probe for measuring the far field characteristics of narrow pulsed laser was designed based on using double detectors instead of the traditional single detector. From radiometric analysis on the probe’s optical structure, the illuminance transfer coefficient was deduced when the probe was irradiated evenly, and the model’s possible maximal error was also investigated when the probe was irradiated unevenly. From the aspect of minimizing the model’s error, both increasing the distance between translucent ceramic and detector and reducing the aperture are helpful, and reducing the two detectors’ abaxial distance can improve their measurement uniformity. The test result using 10 ns-width 1.064 μm laser shows that, the