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 TOOLS & INSTRUMENTS

Spectral comparator facilities
    
  Visible to near-infrared spectral comparator facility (Vis/NIR SCF)

The Vis/NIR SCF is a monochromator-based system that typically measures the spectral power responsivity of photodiodes in the spectral region of 350 nm to 1800 nm. The Vis/NIR SCF operates from 350 nm to 1100 nm using silicon photodiodes as working standards and from 700 nm to 1800 nm using indium gallium arsenide (InGaAs) photodiodes as working standards. The spatial uniformity of a detector's power responsivity can also be measured.

The Vis/NIR SCF uses automated translation stages to position the photodetectors for measurement. The test detectors as well as the working standards are fixed onto optical mounts that rotate and tilt for accurate alignment. A variety of sources can be selected. Typically a 100 W quartz-halogen lamp is used as the source in the Vis/NIR SCF. A shutter is located just after the monochromator exit slit. A monitor detector located after the monochromator measures source fluctuations. The detectors and the exit optics are enclosed in a light tight box. A diagram of the Vis/NIR SCF is shown below.



 
      Ultraviolet spectral comparator facility (UV SCF)

The UV SCF is a monochromator-based system that measures the uniformity and spectral power responsivity of photodetectors in the 200 nm to 500 nm spectral region. The UV SCF is very similar in configuration and operation to the Vis/NIR SCF.

UV enhanced silicon photodiodes serve as the working standards for the UV SCF. A rotary stage is used in the UV SCF. Currently, however, only one test detector can be measured at a time. The test and working standard detectors are fixed onto optical mounts that rotate and tilt. Motorized translation stages position the test detector in the horizontal and vertical planes while the working standards are positioned manually. A diagram of the UV SCF is shown below.
                  Optical / photometry / laser metrology and Calibration services
  
            Organizations
      
      NIST HeadquartersLaboratory ProgramsPhysical Measurement LaboratorySensor Science DivisionOptical Radiation Group
              Details
          Campus
                    Gaithersburg
              Contact
      
        

Jeanne M Houston
    
      
  jeanne.houston@nist.gov
  (301) 975-2327

  Thomas C Larason
    
      
  thomas.larason@nist.gov
  (301) 975-2334

  Eric L. Shirley
    
      
  eric.shirley@nist.gov
  (301) 975-2349
                      Related Projects
      
                  Spectral responsivity measurement
                                        Primary optical watt radiometer (POWR)
                                        Spectral irradiance and radiance responsivity calibrations using uniform sources (SIRCUS)
  Related Publications
      
                  Illuminance responsivity calibration of reference photometers at the NIST SIRCUS and SCF facilities
                                        Comparison of absolute spectral irradiance responsivity measurement techniques using wavelength-tunable lasers
                                        The New Ultraviolet Spectral Responsivity Scale Based on Cryogenic Radiometry at Synchrotron Ultraviolet Radiation Facility III

    
    Created October 3, 2011, Updated January 20, 2022
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