Transmittance Standards
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Avian Technologies offers a wide variety of materials on both a standard and custom
basis. Standard products include:
Neutral Density Filter Sets
Neutral density filters are useful in the calibration of spectrophotrometric, photometric,
or radiometric systems. Calibrated filters are used to assess the dynamic range of detectors
and optical systems. Our standard sets are available as neutral density glass (best used in
the visible range only) and as metal (Inconel) on optical glass (Vis-NIR range) or fused silica
(UV-Vis range), in a variety of sizes. All calibrations are traceable to NRC/NIST.
We age our filters in an oxidizing atmosphere to aid in long term stability.
Inconel on Optical Glass Neutral Density Filter Sets
Part # |
Description |
| TFS-ND06-02c |
Six neutral density filters, Calibrated from 400-2000
nm. Nominal densities are 0.03, 0.1, 0.3, 0.5, 1.0, and 2.0 OD.
Filter size 2" x 2" x 2.0 mm. Boxed, calibration certificate
included. |
| TFS06M-02c |
Set of six standards, Inconel on glass, 50.8 mm square,
absorbance levels 0.3, 0.5, 1.0, and 2.0 A. Didymium oxide wavelength,
calibration filter. Blank in same configuration as filters.
Calibration certificate included. Calibration Certificate with data on
each filter from 400-2000 nm at 10 nm intervals. Wavelength calibration from 350-2000 nm.
Boxed. |
Metal On Fused Silica (UV-Vis Range) Neutral Density Filter Set-Cuvette Format
Part # |
Description |
| Part #TFS-NDU-03-Cuv |
Three neutral density filters, nominal transmittance of 0.3, 0.5, and 1.0A,
calibrated 250-700 nm. Traceable to NRC/NIST. Boxed, calibrated with tabular data at 10 nm
intervals and digital data on CD at 1 nm intervals. |
Glass Neutral Density Filters
| Part # |
Description |
| TFS-NDG06-02c |
Six neutral density filters, calibrated over the range of 360-780 nm (CIE color range).
Nominal densities of 0.1, 0.3, 0.5, 0.6, 1.0, and 2.0 OD. Filter size 2" x 2" (thickness varies by density) Boxed. |
This set of transmittance standards is a convenient way of checking the performance of
any spectrophotometer that accepts standard 10 mm cuvettes. The four neutral density filters
allow then user to check the photometric linearity of detector response. The standards are
Inconel on glass, canted so to eliminate inter-reflection error. The wavelength calibration
standard assures that the spectrophotometer's wavelength accuracy is within specifications.
The set is housed in a wooden box and is available with two different calibrations. Both
photometric and wavelength calibrations are traceable to NIST or NRC.
Part # |
Description |
| TFS-06M-Cuv |
Set of six standards, Inconel on glass, absorbance levels 0.3, 0.5, 1.0, and 2.0 A. Didymium
oxide wavelength, calibration filter. Blank in same configuration as filters. Calibration
certificate included. Calibration Certificate with data on each filter from 400-2000 nm at 10 nm
intervals. Wavelength calibration from 350-2000 nm. Boxed. |
| TFS-06GW-Cuv |
Set of five standards and blank, Schott color glass, absorbance levels 0.3, 0.5, 1.0, and
2.0 A. Didymium oxide wavelength, calibration filter. Blank in same configuration as filters.
Calibration certificate included. Calibration Certificate with data on each filter from 360-830
nm at 10 nm intervals, data on CD at 1 nm intervals. Wavelength calibration from 350-830 nm. Boxed. |
| TFS-06-Cuv |
Set of five standards and blank, Schott color glass, absorbance levels 0.1, 0.3, 0.5, 1.0, and 2.0 A.
Blank in same configuration as filters. Calibration certificate included. Calibration Certificate
with data on each filter from 360-830 nm at 10 nm intervals, data on CD at 1 nm intervals. Boxed. |
| TFS-06GWX-Cuv |
Set of six standards and blank, Schott color glass, absorbance levels 0.1, 0.3, 0.5, 1.0, and 2.0 A.
holmium oxide wavelength, calibration filter. Blank in same configuration as filters. Calibration
certificate included. Calibration Certificate with data on each filter from 360-830 nm at 10 nm
intervals, data on CD at 1 nm intervals. Wavelength calibration from 350-830 nm. Boxed. |
Transmittance Standards — Mid-Infrared
The National Physical Laboratory (UK), The National Research Council Canada,
and NIST have described a transfer standard for mid-infrared transmittance. This standard is
a Schott neutral density glass that is calibrated for transmittance at seven points in the
mid-IR between 4000 cm -1 and 2000 cm -1.
Avian Technologies MIR transmittance standard includes the filter, a standard filter
holder that fits all dispersive and Fourier transform infra red spectrometers and calibration
(traceable to NRC) at all seven points, along with a transmittance curve. Instructions on the
use of the standard are provided.

Rare earth oxide glass filters are for calibration of spectrophotometers in the UV-Vis-NIR range. Avian Technologies currently offers three filters; holmium oxide and didymium oxide glasses, plus the new multiple oxide filter WCT-2065. All three filters have peaks useable in the UV-Vis-NIR, although didymium oxide is usually used in the visible region of the spectrum, while holmium oxide and WCT-2065 are used over the entire UV-Vis-NIR range.
Avian Technologies, working in conjunction with the Analytical Chemistry Division of NIST, has released a new wavelength calibration standard for the Vis-NIR spectral range.
WCT-2065 Wavelength calibration Standard
The transmittance version of the standard, designated at WCT-2065, is the equivalent of NIST SRM-2065. The filter is currently available in 20 mm and 25.4 mm diameter configurations. This standard is extremely useful in the calibration of NIR spectrophotometers, both dispersive and Fourier transform, in the 400-2200 nm wavelength range. The filter material is glass made with a combination of rare earth oxides, including holmium oxide, samarium oxide, ytterbium oxide, and neodymium oxide in a base glass containing oxides of lanthanum, boron, silicon, and zirconium.
The reflectance version of the standard, designated WCR-2066, is the equivalent of NIST SRM-206. The standard is ideal for calibration of the wavelength scale of both scanning and Fourier transform near-infrared spectrometers used in the reflectance configuration. The standard consists of a 1.0” diameter WCT-2065 filter backed with Avian Technologies Fluorilon™ FW-99 diffuse reflectance material, in a black anodized aluminum holder designed to fit most spectrometers. This standard is useable in the 320-2200 nm range.
Pertinent references:
Wavelength Standards for the Near-Infrared Spectral Region
Standard Reference Material 2036 Near-Infrared Reflection Wavelength Standard,
Steven J. Choquette, David L. Duewer, Leonard M. Hanssen, and Edward A. Early,
Applied Spectroscopy, Vol. 59, Issue 4, pp. 496-504
Holmium Oxide Filters

Part # |
Description |
| WCT-HO-CUV |
Holmium oxide filter, in standard 10 mm cuvette format. Calibration traceable to
National Research Council Canada. UV-Vis-VNIR. |
| WCT-HO-02c |
2" Holmium oxide filter, Calibration traceable to National Research Council Canada. UV-Vis-NIR. |
Didymium Oxide Filters
|
Part # |
Description |
| WCT-DD-02 |
2" square Didymium oxide filter, 5 mm thick. Calibration traceable to
National Research Council Canada. UV-Vis-NIR. |
| WCT-DD-CUV |
Didymium oxide filter, in standard 10 mm cuvette format. Calibration traceable to
National Research Council Canada. UV-Vis-VNIR. |

Color filter sets are useful for checking calibration of spectrophotometers
and spectroradiometers in the color range (360-830 nm). Filters
are colored glass, not thin films, so they are rather broadband
rather than narrow band cut-off filters. Calibration is done on
a narrow bandpass high resolution UV-Vis-NIR spectrophotometer
with calibrations traceable to the National Research Council Canada.
Filters are available in 2" square size.
As some of the filters in our original color sets are no longer
being produced, we have had to make changes in the composition
of the original CFS-08 and CFS-12 sets. We regret any problems
this may cause.

Part # |
Description |
| CFS-08-02C |
Set of eight filters (blue, blue-green, green, yellow, orange, red, violet,
broadband visible), in wooden box. Calibration traceable to National Research Council Canada. |
| CFS-08-02U |
Set of eight filters (blue, blue-green, green, yellow, orange, red, violet, broadband
visible), in wooden box. Uncalibrated, spectral scans included. |
| CFS-12-02C |
Set of twelve (all of the above plus a different green and better coverage in the
yellow/orange/red range), in wooden box. Calibration traceable to National Research Council Canada. |
| CFS-12-02U |
Set of twelve (all of the above plus a different green and better coverage in the
yellow/orange/red range), in wooden box. Uncalibrated, spectral scans included. |
Individual Colored Glass Filters
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