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DLP NIRscan Nano EVM for transmittance measurements

Info WAPTEL
Prodigy 30 points
Other Parts Discussed in Thread: TIDA-00554

Hello,

We intend to use the DLP NIRscan Nano EVM for transmittance measurements of solid samples. To that end, we are considering two options:

1) Use a reflective surface in front of the window and place the sample between the first condenser lens and the input slit.

2) Use an external IR source instead of the built-in lamps. In this case, it would be better to collimate the source light so that the sample is properly illuminated. However, we have to couple the light to the spectrometer. 

Which one is the best approach? What are the optical parameters of the input stage (condenser lens)?

Thank you in advance.

  • 0
    TI__Mastermind 28005 points

    Hello User,

    Thanks for your question. I'll relay your question to the team so we can give you a thorough answer early next week.

    Best Regards,

    Philippe

  • 0 in reply to Info WAPTEL
    TI__Mastermind 28005 points

    User,

    One of the experts on our team with regards to the optical configuration is looking at your question above. They should respond back here within the next day or two. Thanks again for your patience.

    Regards,

    Philippe

  • 0 in reply to Philippe Dollo
    TI__Mastermind 23070 points

    Hi,

    Thank you for your patience.

    The detailed specification of the components used in the EVM are available in the reference design:

    www.ti.com/.../TIDA-00554

    The file titled  "TIDA-00554 Stand-off Head Design CAD Files (Solidworks)" has design details for the reflective head.

    Info WAPTEL said:
    1) Use a reflective surface in front of the window and place the sample between the first condenser lens and the input slit

    Did you mean to say that place sample between window of EVM and reflective surface? If your sample is one piece and has flat surface , this approach should work.  Only issue is that the light is transmitted twice through sample and intensity of light  may be lower.

    If you were considering to separate the illumination head and place sample between illumination head and slit of the EVM base unit then I do see  following issues:

      1. The EVM is exposed and there is very high chances of dust and foreign particle getting into light path. It will impact EVM performance overtime.

    2. The optics in the Illumination head is designed to focus on the incoming light on windows to slit. Placing a object in the light path will impact coupling.

    Info WAPTEL said:
    ) Use an external IR source instead of the built-in lamps. In this case, it would be better to collimate the source light so that the sample is properly illuminated. However, we have to couple the light to the spectrometer

    Using an external light source for such use case  is always a good idea. It gives you flexibility of using powerful light source, incase transmitted light is week. You need to take white reference with external ight source. The light source should be able to fill the complete windows of EVM (after transmission through sample) to maximize coupling.

    The size and shape of the sample is an important factor and could be leverages for simplified approach. 

    If the sample is in one piece and can be cut into predefined size and shape then consider using a transmissive head (from TI third-party) and the sample could be placed in the cavity of the transmissive head in place of cuvette.

    If sample is in powder form then you can also use transmissive head and fill cuvette with sample.

    Hope this answer your questions. Please let us know if you have any follow up question.

    regards,

    Vivek

  • 0 in reply to Vivek Thakur
    Prodigy 30 points

    Thank you very much for your answer.

    This way, we think that it is better to use an external lamp. Our main concern was how to maximize coupling. I understand from your answer that a collimated beam may work in this case.