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Oxide filter.
In the filter method, the didymium filter has two distinct absorbance peaks at 529nm
and 807nm. The Holmium filter has a distinct peak at 361nm. When the instrument is calibrated
properly you will find minimum Transmittance (maximum Absorbance) at the range +2nm from
these peaks. Note that the specific Transmittance values are not important as you are only
looking for the wavelength where the minimum transmittance (maximum Absorbance) occurs.
Holmium Oxide Filter Method:
1.
Turn instrument on and allow it to warm up for 15 minutes.
2.
Select the BASIC MODE.
1.
Set the wavelength to 350nm.
2.
Make sure the cuvette holder is empty in the sample compartment. Close the sample
compartment lid.
3.
Set zero Absorbance by pressing the 0A/100%T. The reading should then be 0.000A. If
not, press 0Abs/100%T again.
4.
Remove the cuvette holder and insert the Holmium filter into it. Place it in the sample
compartment and close the lid.
5.
Record the Absorbance reading on the LCD display.
6.
Advance the wavelength setting by 1nm and repeat steps 2 to 5.
7.
Repeat step 6 until the wavelength setting reaches 370nm.
8.
Look for the maximum absorbance reading obtained, and this should be found between 359
and 363nm.
Didymium Filter Method:
1.
Set the Wavelength to 800 nm.
2.
Make sure the cuvette holder is empty in the sample compartment. Close the sample
compartment lid.
3.
Set zero Abs by pressing the 0A/100%T. The reading should then be 0.000A. If not, press
0Abs/100%T again.
4.
Remove the cuvette holder and insert the Didymium filter into it. Place it in the sample
compartment and close the lid.
5.
Record the Absorbance reading on the LCD display.
