High-accuracy optical power measurements by using electrical-substitution cryogenic radiometer

Bazkir O., Ugur S., Samedov F., Esendemir A.

OPTICAL ENGINEERING, vol.44, no.1, 2005 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 44 Issue: 1
  • Publication Date: 2005
  • Doi Number: 10.1117/1.1829097
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Keywords: cryogenic radiometer, laser, stabilizer, optical power, STEFAN-BOLTZMANN CONSTANT, RESPONSE SELF-CALIBRATION, REALIZATION, SILICON, STANDARD, CANDELA
  • Middle East Technical University Affiliated: No


An optical power scale is established at Ulusal Metroloji Enstitusu (UME) using the helium-cooled primary-level electrical-substitution cryogenic radiometer. The scale is established at discrete laser wavelengths of vertically polarized tuneable Ar+, fixed He-Ne, and Nd:YAG (with second harmonic) laser sources. To increase measurement accuracy, laser intensities are stabilized to better than 0.009% using an electro-optical modulator. The spatial profiles of polarized laser beams are cleaned with a spatial filter. The optical power is measured using the static substitution method with an uncertainty of a few parts in 10-4. Repeatability of optical power measurements in the static substitution method, the measurement of window transmittance, and the measurement of power in a scattered beam are the most significant uncertainty components. (C) 2005 Society of Photo-Optical Instrumentation Engineers.