Photodetector Measurements >

Photodetector Measurement Services and Uncertainties

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Current fees can be found in the NIST Calibration Services User Guide Fee Schedule. The uncertainties reported here follow, to the extent possible, the ISO Guide to the Expression of Uncertainty in Measurement (International Organization for Standardization, Geneva, Switzerland, 1993). Since 1994, the NIST policy has been to conform to the Guide in reporting its activities, using an expanded uncertainty coverage factor (as defined in the Guide) of k = 2. See Guidelines for Evaluating and Expressing the Uncertainty of NIST Measurement Results for a detailed explanation of the NIST policy. Unless otherwise noted all uncertainties will be stated as k = 2. Additional information on uncertainty, traceability, and other NIST Calibration Services can be found on the NIST Calibration Program web pages.

Service ID Number	Items of Test	Range	Relative expanded uncertainty (k = 2)
39071C	Ultraviolet Silicon Photodiodes (UDT UV100)	200 nm to 500 nm	0.4 % to 4 %
39072C	Retest of Ultraviolet Silicon Photodiodes (UDT UV100)	200 nm to 500 nm	0.4 % to 4 %
39073C	Visible to Near-Infrared Silicon Photodiodes (Hamamatsu S2281)	350 nm to 1100 nm	0.2 % to 4 %
39074C	Retest of Visible to Near-Infrared Silicon Photodiodes (Hamamatsu S1337-1010BQ or S2281)	350 nm to 1100 nm	0.2 % to 4 %
39075S	Special Tests of Near-Infrared Photodiodes	700 nm to 1800 nm	0.4 % to 4 %*
39077C	Ultraviolet to Near-Infrared Silicon Photodiodes (Hamamatsu S2281)	200 nm to 1100 nm	0.2 % to 4 %*
39078C	Retest of Ultraviolet to Near-Infrared Silicon Photodiodes (Hamamatsu S1337-1010BQ or S2281)	200 nm to 1100 nm	0.2 % to 4 %*
39080S	Special Tests of Radiometric Detectors	193 nm to 1800 nm	0.2 % to 5 %*
39081S	Special Tests of Photodetector Responsivity Spatial Uniformity	193 nm to 1800 nm	0.0024 % to 0.05 %*
39100S	Special Tests of Irradiance Detectors	193 nm to 1800 nm	4 % to 13 %*

* Depends on photodetector and signal level.

The three different curves are the relative expanded uncertainty (k=2)
for measurements with three different working standard types.   [D]

Figure 4. Graph of relative expanded uncertainty for measurements with three different working standard types.

  [D]
Figure 5. Graph of relative expanded uncertainty for typical (200 nm and above)
and Special Test 39080S (extended range to 193 nm) UV measurements.


Descriptions of each service ID number are provided below.

39071C - UV Silicon Photodiodes
NIST will supply customers with a UDT Sensors, Inc. model UV100 windowed silicon photodiode characterized in the ultraviolet (UV) spectral region. The UV silicon photodiode includes the measured spectral responsivity [A · W^-1] from 200 nm to 500 nm in 5 nm steps. The 1 cm² photosensitive area of the photodiodes is underfilled for the measurements with a beam of diameter 1.5 mm. The spectral responsivity is measured at radiant power levels of less than 20 µW. The bandpass of the measurement is 3 nm. The spatial uniformity of responsivity over the photosensitive area is also measured at 350 nm. The measurement uncertainty is found in the Photodetector Measurement Services and Uncertainties table.

39072C - Retest of UV Silicon Photodiodes
Special tests of UV silicon photodiodes previously supplied by NIST (under 39071C) are performed by measuring spectral responsivity from 200 nm to 500 nm.

39073C - Visible to Near-Infrared Silicon Photodiodes
NIST will supply customers with a Hamamatsu model S2281 (previously a Hamamatsu S1337-1010BQ) windowed silicon photodiode characterized in the visible to near-IR spectral region. The spectral responsivity of the photodiode is measured from 350 nm to 1100 nm in 5 nm steps. The 1 cm² photosensitive area of the photodiodes is underfilled for the measurements with a beam of diameter 1.1 mm. The spectral responsivity is measured at radiant power levels of less than 1 µW. The bandpass of the measurement is 4 nm. The spectral range can be extended to 200 nm for an additional fee (use Test # 39077). The spatial uniformity of responsivity over the photosensitive area is also measured at 500 nm. The measurement uncertainty is found in the Photodetector Measurement Services and Uncertainties table.

39074C - Retest of Visible to Near-Infrared Silicon Photodiodes
Special tests of visible to near-infrared silicon photodiodes previously supplied by NIST (under 39073C) are performed by measuring spectral responsivity from 350 nm to 1100 nm. The spectral range can be extended to 200 nm for an additional fee (use Test # 39078C).

39075S - Special Tests of Near-Infrared Photodiodes
Special tests of customer-supplied near-infrared photodiodes are performed by measuring spectral responsivity from
700 nm to 1800 nm. A beam of diameter 1.1 mm is centered on and underfills the photosensitive area. The spectral responsivity is measured at radiant power levels of less than 1 µW. The bandpass of the measurement is 4 nm. The relative expanded uncertainty depends on the wavelength and the individual item measured. Customers should communicate with one of the technical contacts listed below to discuss the measurement details before submitting a formal request. The measurement uncertainty is found in the Photodetector Measurement Services and Uncertainties table.

39077C - UV to Near-Infrared Silicon Photodiodes
NIST will supply customers with a Hamamatsu model windowed silicon photodiode characterized in the UV to near-IR spectral region. The spectral responsivity of the photodiode is measured from 200 nm to 1100 nm in 5 nm steps. The 1 cm2 photosensitive area of the photodiode is underfilled for the measurements. The spectral responsivity is measured with a beam of diameter 1.5 mm from 200 nm to 400 nm at radiant power levels of less than 20 µW. The bandpass of the measurement is 3 nm. From 405 nm to 1100 nm the spectral responsivity is measured with a beam of diameter 1.1 mm at radiant power levels of less than 1 µW. The bandpass of the measurement is 4 nm. The spatial uniformity of responsivity over the photosensitive area is also measured at 500 nm. The measurement uncertainty is found in the Photodetector Measurement Services and Uncertainties table.

39078C - Recalibration of UV to Near-Infrared Silicon Photodiodes
Recalibration of silicon photodiodes previously supplied by NIST (under 39077C or 39073C) is performed by measuring spectral responsivity from 200 nm to 1100 nm.

39080S - Special Tests of Radiometric Detectors
Special tests of radiometric detectors in the ultraviolet, visible, and near-infrared regions of the spectrum can be performed. Detector characteristics that can be determined in this special test include spectral responsivity and quantum efficiency (electrons per photon). For example detector responsivity can be measured between 193 nm and 1800 nm at power levels less than 4.0 µW. Since special tests of this type are unique, details of the tests should be discussed with one of the technical contacts listed below before submitting a formal request. The measurement uncertainty is found in the Photodetector Measurement Services and Uncertainties table.

39081S - Special Tests of Photodetector Responsivity Spatial Uniformity
Special tests consisting of measuring the relative changes in responsivity across the photosensitive area (spatial uniformity) can be performed for customer-supplied photodetectors. The uniformity is typically measured at a single wavelength in 0.5 mm spatial increments with a beam diameter of 1.5 mm in the 193 nm to 400 nm spectral region at power levels less than 20 µW, and a beam of diameter 1.1 mm in the 400 nm to 1800 nm spectral region at power levels less than 1 µW. Customers should communicate with one of the technical contacts listed below to discuss the measurement details before submitting a formal request. The measurement uncertainty is found in the Photodetector Measurement Services and Uncertainties table.

39100S - Special Tests of Irradiance Detectors
Special tests of irradiance detectors generally used in the ultraviolet, visible, and near-infrared regions of the spectrum can be performed. Irradiance responsivity of detectors can be measured between 193 nm and 1800 nm at power levels less than 200 µW/cm². The spectral irradiance responsivity of a detector can be determined expressed in the unit amperes · mm² per watt [A · mm²/W]. Since special tests of this type are unique, details of the tests should be discussed with one of the technical contacts listed below before submitting a formal request. The measurement uncertainty is found in the Photodetector Measurement Services and Uncertainties table.

Measurement Limitations

There are a few limitations on the types of photodetectors that can be measured. Because of the beam size of the comparators, the detector's active area must be greater than 3 mm in diameter. Due to the monochromator flux level an amplifier gain of 10⁵ to 10⁷ is typically required, thus the photodiode dynamic impedance (shunt resistance) must be greater than 10 kohms.

Physical size and weight are limited by the translation stages used in the UV SCF and Vis/NIR SCF. Detector packages submitted for testing are limited in size to approximately 20 cm by 20 cm by 20 cm and 2 kg.

Special tests with conditions greatly differing from those listed above may be accepted, but will take longer to complete. The photodetector signal (either voltage or current) must be provided via a BNC connector. Computer communication to a customer's detector package is not possible at this time.

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For technical information or questions, contact:
Jeanne Houston Phone: 301-975-2327 FAX: 301-975-6991 Email: jeanne.houston@nist.gov		Thomas Larason Phone: 301-975-2334 FAX: 301-869-5700 Email: thomas.larason@nist.gov		Yoshi Ohno Phone: (301) 975-2321 FAX: (301) 840-8551 Email: ohno@nist.gov

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Online: September 1997   -   Last updated: January 2007