Newport offers spectrophotometer calibration filters for use as secondary transmittance and spectral standards in the calibration of ultraviolet and visible spectrum spectrophotometers. All calibrations are derived from National Institute of Standards and Technology (NIST) certified standards.

Four absorptive glass optical density filters (AC-10, AC-30, AC-50 and AC-100) are offered which are used for visible wavelength calibration. Three metallic optical density filters (MC-10, MC-50 and MC-100), fabricated from evaporated inconel coating deposited on a quartz substrate, are offered for use in the calibration of ultraviolet and visible wavelength spectrophotometers. All filters are supplied with calibration data. Additional offerings include a holmium oxide filter and a blank filter holder.

The optical density filters are calibrated using NIST certified secondary standards and stated values of transmittance are accurate to ± 1.0%. Transmittance will not vary more than ± 1.0% of the stated value over the period of one year. The absorbing glass optical density filters (AC-series) are calibrated at five discrete wavelengths: 440.0, 465.0, 546.1, 590.0 and 635.0 nanometers. The metallic optical density filters (MC-series) are calibrated at eight wavelengths: 250.0, 280.0, 340.0, 360.0, 400.0, 465.0, 546.1 and 635.0 nanometers.

The holmium oxide filter is provided for use in wavelength calibration of spectrophotometers. A spectral scan is included for reference. The blank filter holder is provided for use in the reference path of dual beam spectrophotometers during calibration to allow balancing of the sample and reference beams.