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DLPNIRSCANEVM: Calibration

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Replies: 7

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Part Number: DLPNIRSCANEVM

Hi

 

I’m planning to use the NIRscan Nano to regularly perform scans in a portable device.

I was wondering how this device copes with its calibration?

-        How? Is there a procedure? Calibration object?

-        Frequency? Do I have to perform a calibration on a regular base or can I detect it in the measurements that it’s needed to calibrate the device again?

-        What? What does it do? Does it change the device physically or is it just software settings?

-        Other? Am I forgetting things which I should definitely take into account?

 

Many thanks in advance for answering this question!

Best regards,

Nick

  • Hi Nick,

    Let us look into this question and we'll get back to you at the beginning of next week.

    Thanks,

    Kyle

  • In reply to Kyle Rakos:

    Hi Nick,

    The DLP NIR Scan Nano is calibrated at factory for optical engine , wavelength , InGass detector and alignment.  These calibration parameters should not change in normal use of the EVM.

    The calibration data also includes "Reference calibration" that is calibration of lamp intensity at all wavelength using a lab standard NIR 99% reflector. When you run a scan, the absorption plot is computed using this "Reference calibration"   

    The lamp's performance changes with time , temperature and humidity. It is prudent practice to periodically take a "reference calibration" i.e. intensity plot of lamp so that the absorption plot is accurate.

    The required  frequency of  reference calibration will depend on your application, environment and target accuracy.  You need to run your own experiment to find out optimum calibration frequency.

  • In reply to Vivek Thakur:

    Hi Thakur

    Many thanks for this explanation! 

    Do you have any advice / idea on the frequency of calibration? 

    I know it's hard to give values but do you know for example what the frequency can be in a lab environment and in the field? 

    Are we talking about once a for ten, hundredth, thousand, ... scans?

    Is a 'lab standard NIR 99% reflector.' the only way to calibrate?  Are there maybe other techniques which are easier / cheaper but maybe less accurate? 

  • In reply to Nick Verlooy:

    Hi Nick,

    Avian Technologies have product "Fluorilon-99W". It is relatively good low cost alternative to lab standards. Some of our customer are using it and happy with the result. 

    Frequency of calibration - If you are building any model and using for prediction then it will depend the target accuracy. It is very difficult to suggest a number. You need to experiment.  

    Consistency of sample presentation is also very critical for repeatable  result. My suggestion is address consistency of sample presentation for scan and evaluate if scan results are repeatable. Once you have addressed it then look at what are the other factors causing variability.

    Hope this helps.

    regards,

    Vivek

  • In reply to Vivek Thakur:

    Hi Nick,

    Do you still need the answer to your question? I'll be temporarily closing this thread due to inactivity. You can reopen anytime by replying.

    Thanks & Regards,

    Hirak.

  • In reply to Hirak Biswas:

    Hi Hirack

    I was actually looking for a 'general number' on the frequency of calibration. 

    I know It's really hard to say but I have someone telling me that he calibrates the device every 30 scans he does. 

    This seems way to much in my opinion since he's not in a lab environment and desired accuracies are not extremely high.

    Anyway, thanks for the advice. I have already a clearer view on what the calibration is and what it changes in the process / measurements. .

    Nick

  • In reply to Nick Verlooy:

    Hi Nick,

    I agree, every 30 scans may be very conservative  for taking reference. After initial 30-50 hours of usage lamp should   stabilize.  Some time doing a lamp burn-in for 30-50 hour may help minimize the variation due to lamp aging.

    I believe other environmental factors like temperature and humidly may have bigger impact on variability. If product is used every day, please try with once  in two weeks  and see how stable performance is. Then you can adjust in either direction depending on result.

    regards,

    Vivek

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