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 TOOLS & INSTRUMENTS

Reference Transmittance Spectrophotometer (RTS)
    
  The Reference Transmittance Spectrophotometer (RTS) is the national reference instrument for regular spectral transmittance measurements of non-fluorescent samples at room temperature. It is a custom-built instrument that uses a lamp-based, quasi-monochromatic system for illumination of the sample and broadband detection of transmitted radiation.

The illuminator consists two sources, a laser-driven light source (LDLS) and a quartz-tungsten-halogen (QTH) incandescent lamp, and a prism-grating monochromator. A sample carriage moves the sample in and out of the influx beam. The detection system consists of two detectors, a silicon (Si) photodiode and an extended indium-gallium-arsenic (InGaAs) photodiode. The combination of sources and detectors enable illumination and detection for wavelengths from the ultraviolet to the shortwave infrared.

We are currently implementing improvements to RTS including development of a new uncertainty budget.

Specifications/Capabilities
      
                          Conditions for transmittance measurements using RTS.



***Geometrical***Illumination Angle
			0°Viewing Angle
			0°Sampling Aperture
			4 mm to 20 mm***Spectral***Wavelength
			250 nm to 2500 nmBandwidth
			1.5 nm or 3 nmPolarization
			0° to 90°Sample Size
			10 mm to 50 mm***Measurand***Quantity
			Transmittance TTechnique
			AbsoluteRange
			0.001 to 1Uncertainty (*k*=2)
			0.1% to 0.5%
                  Optical / photometry / laser metrology and Optical physics and communications
  
            Organizations
      
      NIST HeadquartersLaboratory ProgramsPhysical Measurement LaboratorySensor Science DivisionSurface and Interface Metrology Group
              Details
          Campus
                    Gaithersburg
              Contact
      
        

Catherine Cooksey
    
      
  catherine.cooksey@nist.gov
  (301) 975-6208
                      Related Tools & Instruments
      
                  Transfer spectrophotometer
  Related Projects
      
                  Spectrophotometry
                                        Spectral Reflectance and Transmittance

    
    Created October 21, 2009, Updated December 5, 2022
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