Transmitance Standards

Transmitted light typically is the result of incoming light being reduced by light being reflected and by light being absorbed. From a qualitative standpoint, loss of light energy has little effect on the “identification” of the material under investigation. However, often degermining the amount of energy going into the material can reveal much infor­mation. For example, studies of plants provide significant growth information.

Typically, the total incoming energy is split between the energy reflected, the energy absorbed and the energy trans­mitted. Hence, it becomes pertinent to measure both the reflected energy and the transmitted energy. The balance is the absorbed energy.

Neutral density filters

It is relatively easy to determine a 100% level of transmitance. That can be done by arranging a setup where a material of interest is between a source of light and, typically, a spectrometer. Then, by removing any sample and any obstruction between the source and the spectrometer, the full light source will registger as the 100% level of transmittance. With the full 100% registered, the light signal through the material is in place and the resulting signal will be the transmitted signal, an identification may be readily determined.

Should quantitative data be wanted, it will be necessary to measure the reflectance and to figure the absorbance from:
Light in minus light reflected and minus light ill be light (energy) absorbed.

In most cases, for light hitting the magterial at 90°, available software can provide valid absorbance calculations.

In many cases, it is desireable to cali­brate the spectrometer, radiometer, etc., over the range of response. This is where use of neutral density filters be­comes valuable. Calibrated ND filters are used to assess the dynamic range of detecgtors and their associated optical systems. Avian‘s standard ND sets are available as neutral density glass (best used in the visible range only) and as metal (Inconel) on optical glass (Vis-NIR range). Alternately, fused silica filters (UV-Vis range) are available in a variety of sizes. All calibrations are traceable to NRC/NIST.

The Avian neutral density fiters which are available are noted below:

Inconel on Optical Glass Neutral Density Filter Sets:

Part number TS-ND06-02C includes 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" × 2" × 2.0 mm. Boxed, calibration certificate included.

Part number TFS06-02 M is a set of six standards, Inconel on glass, 50.8 mm square, absorbance levels 0.3, 0.5, 1.0 and 2.0 A. Also includes a dymium oxide wavelength cali bration filter. Calibrated from 400-2000 nm at 10 nm intervals.

Glass Neutral Density Filters:

Part number TS-NDG06-02 includes 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" × 2"

Neutral density filters in cuvette form

Transmittance standards in cuvette form is a convenient way of checking the performance of any specgtrophotometer that accepts standard 10 mm cuvettes. The four neutral density filters allow a user to check the photometric linearity of detector re­sponse. The standards are Inconel on glass, canted to to eliminate inter-reflection error. The wavelength calibration standard assures that the spectrometer’s wavelength accuracy is within specifications. The set is housed in a wooden box and is available with two different calibratons. Both photometric and wavelenth calibra­tions are traceable to NIST or NRC.

Part number TFS-06M is a set of six standards. They are inconel on glass, having absorbance levels 0.3, 0.5, 1.0 and 2,0 A. Includes a didymium oxide wavelength, calibration filter. Blank in same configuration as filters. Density calibration is from 400-2000 nm at 10 nm intervals. Wavelength calibration from 350-2000 nm.

Part number TFS-06GW includes five standards and a blank. The filters are Schott color glass, absorbance levels 0.3, 0.5, 1.0 and 2.0 A. Includes a didymium oxide wavelength calibration filter. Blank in same configuration as filters. Density calibration is from 360-830 nm at 10 nm intervals; data is on a CD at 1 nm intervals. Wave­length calibration from 350-830 nm.

Part number TFS-06 Sety of five standards and blank, similar to the TFS-06 but without the didymium oxide wavelength calibration filter.

Part number TFS-06GWX Set of six standards and blank. The filters are Schott color glass, absorbance levels 0.1, 0.3, 0.5, 1.0 and 2.0 A. with a holmium oxide wavelength calibration filter. Blank in same configuration as filters. Density calibration is from 360-830 nm at 10 nm intervals; data is on a CD at 1 nm intervals. Wavelength calibration from 350-830 nm.

Transfer Standard – Mid-Infrared

A valid transfer standard for mid-infrared transmittance is a Schott neutral den­sity glass that is calibrated for transmittance at seven points in the mid-IR between 5000 cm-1 and 2000 cm-1. The Avian Technolgies MIR transmittance standard includes the filter, a standard filter holder that fits all dispersive and Fou­rier transform infrared spectrophotometers and a calibration (traceable to NRC) at all seven points, along with a transmittance curve. Instructions on the use of the standard are provided.

Colored Glass Filter Sets

Color filter sets are useful for checking calibration of spectrophotometers and specroradiometers in the color range (360-830 nm). Filters are colored glass, not thin films, so they are somewhat broadband rather than narrow band cut-off filters. Calibration is done on a narrow bandpass high resolution UV-Vis-NIR speactrophotometer with calibrations traceable to the National Research Council Canada. FIlters are available in 2" square size.

Prices

Color Filter Sets
CFS-08-02 Set of eight filters (blue, blue-green, green, yellow, orange, red, violet, broadband visible) in wooden box  
CF-X-02 Individual Colored Glass Filter X is filter designation; contact us for details  
CFS-12-02 Set of 12 filters in wooden box  
Neutral Density Filters & Filter Sets
TFS-ND-03-cuv Neutral Density Filter Sets – Inconel on Optical Glass • Three cuvette format neutral density filters • Nominal densities of 0.3, 0.5, and 1.0 OD • Calibrated over the range of 400-2000 nm  
TFS-ND-06-02 Neutral Density Filter Sets – Inconel on Optical Glass • Six 2" square neutral density filters • Nominal densities of 0.03, 0.1, 0.3, 0.5, 1.0, and 2.0 OD • Calibrated over the range of 400-2000 nm  
TFS-ND-06-cuv Neutral Density Filter Sets – Inconel on Optical Glass • Six cuvette format neutral density filters • Nominal densities of 0.03, 0.1, 0.3, 0.5, 1.0, and 2.0 OD • Calibrated over the range of 400-2000 nm  
TFS-NDG-03-02 Neutral Density Filter Sets – Glass • Three 2" square neutral density filters • Nominal densities of 0.3, 0.5, and 1.0 OD • Calibrated over the range of 360-780 nm  
TFS-NDG-06-02 Neutral Density Filter Sets – Glass • Six 2" square ne1•utral density filters • Nominal densities of 0.1, 0.3, 0.5, 0.6, 1.0, and 2.0 OD • Calibrated over the range of 360-780 nm  
TFS-NDU-03-02 Neutral Density Filter Sets – Metal on Fused Silica • Three 2" square neutral density filters • Nominal transmittance of 0.3, 0.5, and 1.0A • Calibrated 250-700 nm  
TFS-NDU-03-cuv Neutral Density Filter Sets – Metal on Fused Silica • Three cuvette format neutral density filters • Nominal transmittance of 0.3, 0.5, and 1.0A • Calibrated 250-700 nm  
TFS-NDU-04-cuv Neutral Density Filter Sets – Metal on Fused Silica • Three cuvette format neutral density filters • Nominal transmittance of 0.04, 0.3, 0.5, and 1.0A • Calibrated 250-700 nm  
TF-NDG-xx-02c Individual Transmittance Neutral Density Filter – Glass • Calibrated 360-780 nm • xx = specify nominal density  
TF-NDU-xx-02c Individual Transmittance Neutral Density Filter – Metal on Fused Silica • Calibrated 250-700 nm • xx = specify nominal density  
TF-ND-xx-02c Individual Transmittance Neutral Density Filter – Inconel on Optical Glass • Calibrated 400-2000 nm • xx = specify nominal density  
Transmittance Wavelength Calibration Standards
WCT-2065-020 NIR Wavelength Calibration Standard 20 mm diameter x 1.5 mm thick  
WCT-2065-025 NIR Wavelength Calibration Standard 1" diameter x 1.5 mm thick  
WCT-2065-Cuv NIR Wavelength Calibration Standard Cuvette format  
WCT-Ho-UVVIS-02 Holmium Oxide Wavelength Calibration Filter 2" square, calibrated UV-VIS only  
WCT-Ho-UVVIS-cuv Holmium Oxide Wavelength Calibration Filter 1" x 9 mm cuvette format, calibrated UV-VIS only  
WCT-Ho-UVVISNIR-02 Holmium Oxide Wavelength Calibration Filter 2" square, calibrated UV-VIS-NIR  
WCT-Ho-UVVISNIR-cuv Holmium Oxide Wavelength Calibration Filter 1" x 9 mm cuvette format, calibrated UV-VIS-NIR  
WCT-DD-02 Didymium Oxide Wavelength Calibration Filter 2" square, calibrated 300-900 nm  
WCT-DD-02ext Didymium Oxide Wavelength Calibration Filter 2" square, calibrated 300-2200 nm  
WCT-DD-cuv Didymium Oxide Wavelength Calibration Filter 1" x 9mm cuvette format, calibrated 300-900 nm  
WCT-DD-cuvext Didymium Oxide Wavelength Calibration Filter 1" x 9mm cuvette format, calibrated 300-2200 nm  
WCT-2066/PS-025 Wavelength Calibration Standard- Long wavelength range in transmittance format 1.25" diameter  

Prices are in US dollars - Prices subject to change without notice - Products are FOB Ancal, California

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