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DLPNIRNANOEVM: Use of reference standard.

Sam Khoudair
Prodigy 60 points
Part Number: DLPNIRNANOEVM

Hi,

In getting accustomed to using the Nirscan Nano EVM, I'm wanting to make sure my use of the standard absorbance reference is just right.  I have a few questions in regard to this:

1) I read in an article that if I decide to use the factory standard then the sample scan settings must be the same as those of the reference ie collumn etc.  What if I want to use Hadamard or other settings different to those of the factory std?  Does this also apply to the sample settings if I use a new standard reference of my own choice?  Can I use a thick piece of virgin teflon as the standard?

2) Does the nirscan nano correct the sample spectra using the reference whether this is factory or new?

Need your guidance as these issues are not clear in the documentation.

Sam Khoudair

  • 0
    TI__Mastermind 28005 points

    Sam,

    The nirScan Nano EVM is factory calibrated. It is not recommended to try to recalibrate the system yourself as the original calibration data (which is unique to each unit) will be lost and unrecoverable.

    Will let the team comment further on your desired calibration method.

    Regards,

    Philippe

  • 0 in reply to Philippe Dollo
    TI__Mastermind 22830 points

    Hello Sam,

    I believe you are referring to White reference used to calculate the absorbance. 

    Sam Khoudair said:
    ) I read in an article that if I decide to use the factory standard then the sample scan settings must be the same as those of the reference ie collumn etc.  What if I want to use Hadamard or other settings different to those of the factory std?  Does this also apply to the sample settings if I use a new standard reference of my own choice?  Can I use a thick piece of virgin teflon as the standard?

    The system stores the reference intensity profile of the lamp in a abstract form.  It is converted into the format/parameter same a scan sample by the Spectrum library.  As a user you can use any of the supported method. The firmware will convert the reference scan data to match with scan sample. 

    You can use any material  can be used as standard. The challenge if its reflectance is not flat and >99%,  you will loose sensitivity for the wavelength where standard has lower reflectance.   Please scan the Teflon as sample and evaluate reflectance curve. Please make use only absorbance for this study. Actual intensity value will be misleading because lamp output is not flat.

    Sam Khoudair said:
    2) Does the nirscan nano correct the sample spectra using the reference whether this is factory or new?

    You question is not clear. There is no correction in the sample spectra. While calculating  Absorbance value it will use the reference value from factory reference or new reference stored locally in the machine.

    The lamp output varies with temperature and humidity, so does the  InGas sensor. The advantage of new reference is that you take the intensity profile of the in the same environment  condition as sample scan.

    If you are scan sample for a long time, I recommend that periodically take new reference. Use this for your scan measurement over factory reference.

    regards,

    Vivek 

  • 0 in reply to Vivek Thakur
    Prodigy 60 points

    Hi Vivek,

    Thanks for your very helpful answer - there's only one point to clarify; 

    You stated, "The firmware will convert the reference scan data to match with scan sample."  Does that mean that the scan configuration of the factory reference is matched to that of the sample being scanned thus verifying the sample spectrum?

    Sam

  • 0 in reply to Sam Khoudair
    TI__Mastermind 22830 points

    Hello Sam,

    The factory reference values (intensity of lamp) is processed to match  PGA gain and digital resolution of the sample scan. I believe Hadamard vs Column scan shouldn't be an issue because absorbance is comparing intensity of sample  Vs Lamp at specific wavelength. The Hadamard and Column are two different approach to generate same spectrum.

    regards,

    Vivek

  • 0 in reply to Vivek Thakur
    Prodigy 60 points

    Hi Vivek,

    Thanks for your persistence - you have filled all the gaps in my understanding of the white reference issue.

    Power to the Nano!!

    Sam