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Is there a Methods Database somewhere? I'm trying to ensure that I have created a good Method for Reflectance measurements.

GaryR

Hi- I have a Cary 5000 UV-Vis-NIR that I've inherited.  I'm starting with little prior knowledge and so am looking to build a knowledge base.

I'm wondering if there is a Methods database, or some other place like a forum or an Applications Group to which I could refer to make sure the Method I'm using is technically sound.

Specifically, today I want to verify that I'm using the right Baseline option for my Reflectance Method.  I have a Thorlabs Reference mirror (Thorlabs PN: PF10-03-F01) and the Baseline I've chosen is:

Zero x Std Ref Correction, and then I've "Retrieved the Std Ref File", the ascii file that came with the Ref mirror.

If this is correct, when I measure the Thorlabs mirror as an unknown, shouldn't it measure as 100% reflectance across the whole wavelength range?

Thank you very much for any input,

Gary

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  • +1

    Hi Gary - the correction is used to convert a relative reflectance measurement into an absolute reflectance measurement by correction using a known standard.  The reference mirror that you have is an aluminum mirror, so it's not 100% reflective - typically these mirrors have high reflectivity in the NIR and then a big "dip down" around 800nm before the %R climbs again through the visible and into the UV.  If you set up the method to use that mirror as your baseline, and then measure it back as a sample, the result you get should be very close to the certified values.

    NOTE: the reflectivity will change as a function of angle of incidence and polarisation.  The conditions used to generate the values in the ASCII file should be specified in the paperwork that came with the mirror, so you'll need to mimic these if you want to achieve high accuracy.

    What reflectance accessory are you using to make the measurements?  Do you have a polariser?

Reply
  • +1

    Hi Gary - the correction is used to convert a relative reflectance measurement into an absolute reflectance measurement by correction using a known standard.  The reference mirror that you have is an aluminum mirror, so it's not 100% reflective - typically these mirrors have high reflectivity in the NIR and then a big "dip down" around 800nm before the %R climbs again through the visible and into the UV.  If you set up the method to use that mirror as your baseline, and then measure it back as a sample, the result you get should be very close to the certified values.

    NOTE: the reflectivity will change as a function of angle of incidence and polarisation.  The conditions used to generate the values in the ASCII file should be specified in the paperwork that came with the mirror, so you'll need to mimic these if you want to achieve high accuracy.

    What reflectance accessory are you using to make the measurements?  Do you have a polariser?

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