Dual-wavelength transfer standard for laser peak-power measurement

The National Institute of Standards and Technology (NIST) and the Naval Surface Warfare Center - Corona Division (NSWC) have jointly developed a dual-wavelength extended-sensitivity radiometer (D-ESR) that functions as a portable transfer standard for measuring laser pulses at wavelengths of 1.06 μm and 1.55 μm. The peak-power irradiance range is from 500 pW/cm 2 to 50 μW/cm 2 within the wavelength range of 1.54 μm to 1.58 μm. A similar peak-power range is covered at a wavelength of 1.06 μm. The measurement range is covered by using smaller apertures or a neutral-density filter to reach the highest peak powers. The D-ESR radiometer is based on an InGaAs avalanche photodiode (APD) detector that is integrated with a transimpedance preamplifier module. The light-collecting optical system has a maximum aperture of approximately 125 cm 2 . The D-ESR is able to measure Gaussian pulse duration from 4 ns to 400 ns. The output is a negative-going pulse waveform that is measured with an oscilloscope. The total expanded uncertainty of a calibrated peak-power measurement with a D-ESR radiometer is approximately 9 % (k=2).