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DLPNIRNANOEVM: Non-integral wavelength numbers in scan results

Part Number: DLPNIRNANOEVM

I think I have not understood how the following are related:

1) Optical Resolution = 10 nm

2) Digital Resolution = 228 (default factory config stored in the EVM)

3) Width in nm = starts from 2.34 in the config window

In the Scan configuration window, for default settings of Column1, I see the following :

"Saved in Nirscan Nano"
Wavelength range                  : 900 - 1700 nm
width in nm                              : 7.02
num of wavelength points     : 228
Digital Resolution                   : 228

A) From the scan results that I have shared (for which I used the default factory Column 1 scan config), difference between 2 wavelengths is 3.89 nm.

B) for the factory default, 1700 - 900/228 = 3.50 nm. This does not match the "width in nm". Is it supposed to ?

How are these factory default settings and the scan results related to the optical resolution of 10 nm ?

Is "Digital Resolution" same as "Optical Resolution" ?

Why does A) not match "width in nm" or B) or "Optical Resolution" ?

  • Hi Giridhar,
    The spectral resolution is minimum distance (in wavelength) required between two impulse signals for the evaluation module to detect. It depends on the optical characteristics of the system.
    Please refer to following application notes for details and functioning of DLP technology based spectroscopy:
    - Texas Instruments DLP® Spectrometer Design Considerations; www.ti.com/.../dlpa049.pdf
    - Signal Chain Performance Optimizations in the TI DLP® Technology-Based Spectrometer; www.ti.com/.../dlpa072.pdf

    The system is capable of sampling the signal strength at smaller steps in wavelengths. I hope this explains why those two numbers are different.

    Regards,
    Vivek