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Neutral Density Filter Reference Set
For Validating the Visible Absorbance of your Spectrophotometer
Description Neutral Density filter set, with blank
Primary Usage Validate the visible absorbance scale of spectrophotometers
Useable Range 440nm to 635nm
Physical Configuration Three glass filters mounted in anodized aluminum holder with blank. Filters fit in standard 10mm cell holder of most instruments.
NIST Traceability Each set is supplied with a Certificate of Analysis and NIST Traceability
ISO Accredited Accredited by UKAS ISO 17025, ISO Guide34 and ISO 9001

Product Description

Our neutral density filter sets are based on and traceable to the NIST sets SRM 930e and SRM 1930. These sets are used to test the photometric scale in both Transmission and Absorbance in the visible range. The filters are made from Schott NG-type glass which blocks known transmission and absorbance values. We calibrate the glass type and thickness of the filters to produce the transmission and absorbance values. The approximate values are shown in the chart below. Each NIST traceable filter set is individually tested and certified to its transmission and absorbance values and the confidence limits of each reading.

The neutral density filters are mounted in a black anodized aluminum holder, 12.5mm x 12.5mm x 45mm high. The dimensions are the same as a standard instrument cell holder and will work with all standard spectrophotometers. The filters have been shown to be effective in instruments with an effective bandwidth up to to 6.5 nm.

The absorbance values are certified at the wavelengths specified by NIST which are:
440.0nm, 465.0nm, 546.1nm, 590.0nm and 635.0nm.

Catalog Number: RM-1N2N3N
Nominal Transmission Nominal Absorbance
10% 1.10 A
20% 0.78 A
30% 0.56 A
Catalog Number: RM-N1N35N
Nominal Transmission Nominal Absorbance
1% 2.10 A
3% 1.60 A
50% 0.30 A
Catalog Number: RM-D1D39N
Nominal Transmission Nominal Absorbance
0.1% 3.00 A
0.3% 2.50 A
92% 0.04 A

Suggestions for Use

Measure the absorbance or transmission of the filters against the supplied blank at the five wavelengths as specified by NIST traceable certificate. These wavelengths are 440.0nm, 465.0nm, 546.1nm, 590.0nm and 635.0nm.


Interpertation of Results

Consult your spectrophotometer's reference manual for the specification of your instrument's absorbance scale tolerance. This figure will be listed as a plus and minus (+/-) number in absorbance units. Add your instrument's absorbance tolerance to the confidence limit on the certificate supplied with the Neutral Density Filter set for your expected absorbance range. Compare the absorbance values measured on your instrument with the expected values calculated from your instrument manual and the NIST traceable certificate. If the readings are within the expected range for your instrument then your absorbance scale is correct. If not, consult your service techincian and have the instrument evaluated. Quite often if the results of your absorbance measurments are low, it shows that your lamp needs to be replaced.

Quality program

Each time that the analysis is repeated you can compare the new results with the previous results to check for any variance. If your instrument needs service because of a change in absorbance, the historical data will greatly assist the service technician.

How to Order

Catalog Number Description Price each
RM-1N2N3N Neutral Density Filter Set, 10, 20, 30%T US$ 1,190.00
RM-N1N35N Neutral Density Filter Set, 1, 3, 50%T US$ 1,190.00
RM-D1D39N Neutral Density Filter Set, 0.1, 0.3, 92%T US$ 1,190.00