A national measurement system for radiometry, photometry, and pyrometry based upon absolute detectors

Abstract

Gaithersburg, MD USA 20899-0001 Advancements in the performance and ease of use of absolute photodetectors based upon electrical substitution principals offers the possibility of a simplified and more accurate way to transfer the fundamental radiometric, photometric, and pyrometric units from NIST to the U.S. technical establishment. The history of electrical substitution radiometers at NIST is briefly reviewed and the implementation of the latest generation absolute cryogenic radiometer is discussed. Procedures to maintain fundamental units based upon a detector approach are reviewed in a general way with references to the technical literature for detailed discussion. It is proposed that NIST customers consider adopting the suggestions made in this technical note to simplify and improve their optical radiation based calibrations.

Realization of Optical Power Scale Based on Cryogenic Radiometry and Trap Detectors

“…1 The optical power measurement is obtained through the measurement of electrical power. By knowing the amount of electric power fed into the system, incident optical power levels ranging from 1 μW to 1 mW can be determined.…”

Spectroradiometric detector measurements :

“…A physical model was developed to interpolate the responsivity of silicon trap detectors over the spectral range from 405 nm to 920 nm [24]. Outside of this spectral range, the detector responsivity scale was based on pyroelectric detector with a spectrally flat responsivity [21]. [17,24,26], and no interference problem with laser emission.…”

“…The measurement equation for the "substitution method with monitor" (Fig. 3.3 x-^x=^x-Gx-^bsx-^x-^x, (3.21) and = K,^^-"^= s^^• p^sx '^x "^x • (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22) The ratio of these two signals is: Vis/NIR SCF using the 100 W quartz-halogen lamp and (b) UV SCF using the argon mini-arc as a source. The Optical Technology Division within NIST presently has two cryogenic radiometers that provide the basis for the spectral radiant power responsivity scale: the NIST-designed POWR (Figure 5.2), and the L-1 ACR [23] (Figure 5.3 intercomparison between POWR and the L-1 ACR showed that these two standards agreed to within 0.02 %, which is within their combined uncertainties as shown in Figure 5.4 [23].…”

High Accuracy Calibration Technology of UV Standard Detector

“…Outside of this spectral range, the detector responsivity scale was based on pyroelectric detector with a spectrally flat responsivity [13] . While the pyroelectric detector had a spectrally flat responsivity, its absolute responsivity value was low.…”