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Description

Certied values depends on serial number. This Standard Reference Material (SRM®) is intended for use in the verification of the transmittance and absorbance scales of spectrophotometers in the ultraviolet and visible spectral regions. NIST-2031c is a transfer standard certified using the NIST Materials Measurement Laboratory Transfer Spectrophotometer (MMLTS) with traceability through the NIST second generation High Accuracy Spectrophotometer (HAS II), modeled after the original instrument . A unit consists of three individual neutral-density filters in separate metal holders and one empty filter holder, all stored in a black anodized-aluminum container . The exposed surface of each filter is approximately 29 mm × 8 mm, measuring from a point 1.5 mm above the base of the filter holder. The filter holders are provided with shutters that protect the filters when not in use. Each filter-containing holder bears an identification number for the set and an individual filter number (10, 30, or 90) that corresponds to the nominal percent transmittance (100 × transmittance) of the filter. Certified transmittance density values, independently determined for each filter at 22 °C ± 1 °C and at ten wavelengths in the ultraviolet and visible portions of the electromagnetic spectrum.