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Spectral responsivity calibrations

These calibrations are based on the scale of spectral radiant power responsivity, which is maintained by NIST’s Primary Optical Watt Radiometer (POWR). Solid-state transfer standard detectors are used to transfer the optical power unit--the optical watt--from this cryogenic radiometer to the working standard detectors used in the SCFs. The visible to near-infrared (Vis/NIR) SCF typically measures the spectral responsivity of photodiodes in the 350 nm to 1800 nm spectral region. The ultraviolet (UV) SCF typically measures the spectral responsivity of photodiodes in the 200 nm to 500 nm spectral region.

The relative expanded uncertainties of these calibrations are plotted below. Tabulated values may be found in NIST Special Publication 250-41a (pdf available below).

relative expanded uncertainties of spectral responsivity

For technical information, see NIST Special Publication 250-41a (pdf).
For information about specific calibrations or to order a calibration, see Calibration Services’ Spectroradiometric detector measurements.

To see a list of frequently asked questions, see FAQs.

Major Accomplishments:

CCPR Key Comparisons

  • K2.a: Spectral responsivity, 900 nm – 1600 nm. Pilot by NIST. Draft A3 is in preparation.

  • K2.b: Spectral responsivity, 300 nm – 1000 nm. Approved for equivalence. Click here* to view the results on the BIPM website.

  • K2.c: Spectral responsivity, 200 nm – 400 nm. NIST participation complete. Other laboratories measurements in progress.

*By selecting this link, you will be leaving NIST webspace. NIST does not necessarily endorse the views or the facts presented on this site, nor does NIST endorse any commercial products that may be advertised or available on this site.

Selected Publications

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Spectral responsivity calibration photo


Spectral responsivity measurement:
Jeanne Houston, Project Leader
301-975-2327 Telephone
301-869-5700 Facsimile

100 Bureau Drive, M/S 8441
Gaithersburg, MD 20899-8441