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Optical Metrology Laboratory

Photo of a laser and a spectral irradiance calibration system used to create lamp-detector alignment.

Researchers use a spectral irradiance calibration alignment jig and a laser beam to align a calibration source and test unit.

The NREL Optical Metrology Laboratory ensures that optical radiation resource measurement equipment is calibrated to national or international standards to ensure the quality and traceability of data. NREL considers optical radiation to range from 250 nm to 2,500 nm and to include the ultraviolet (250–400 nm), visible (400–750 nm), near-infrared (750–1,100 nm), and shortwave infrared (1,100–2,500 nm) ranges.


The Optical Metrology Laboratory provides National Institute of Standards and Technology-traceable measurements for:

  • Spectral irradiance and radiance (250–2,400 nm) scale realization
  • The calibration of user spectroradiometers
  • The measurement of natural sunlight and artificial source spectral distribution
  • Indoor and outdoor solar ultraviolet (250–400 nm), photosynthetically active radiation (400–700 nm), and photometric calibrations.
  • Spectral reflectance and transmission testing

In addition, the Optical Metrology Laboratory provides pulsed/continuous light source characterization that is traceable to National Institute of Standards and Technology standards.


The NREL Optical Metrology Laboratory offers a range of specialized equipment, such as:

  • An ASD, Inc., FieldSpec Pro fast (200–ms acquisition), wide-range (350–2,400 nm) spectroradiometer
  • An Optronic Laboratories OL-750 scanning spectroradiometer with a wide wavelength range (280–2,400 nm) and pulse integration capability
  • An Optronic Laboratories OL-756 ultraviolet double monochromator spectroradiometer with a 250–800 nm spectral range
  • NREL's Pulse Analysis Spectroradiometer System (PASS), which captures light pulse profiles and determines spectral irradiance at any position within a pulse profile
  • Portable, spectrally calibrated light sources that consist of constant-output incandescent lamps with measured spectral distribution (require AC power)
  • A 150-watt mercury/xenon solar simulator
  • Emission line sources for wavelength calibration, including mercury, xenon, neon, and argon penlights and wavelength emission documentation
  • National Institute of Standards and Technology-calibrated filter glasses (transmission and wavelength) and reflectance standards
  • Integrating spheres and fiber-optic probes for spectroradiometer systems
  • Filters, including glass and metal neutral density, wide and narrow passband, cut-on and cut-off glass, and interference types.

Learn More

For information about using the NREL Optical Metrology Laboratory, explore our Working with Us page.