Inside the DLP NIRscan Nano Evaluation Module

Jacktang

Inside the DLP NIRscan Nano Evaluation Module [Copy link]

As engineers and developers, our job is to find the best way to put all the components together. Whether it's a skyscraper or an integrated circuit, the internal engineering structure is one of the keys to whether it works well. But then again, who hasn't fantasized about being a "wrecker" and taking things apart to find out what's inside? Most of our earliest memories of engineering design come from being a child and taking apart things that seemed complex - even expensive - to pieces.

With that being said, we’re going to take a look at the internals of the DLP NIRscan Nano evaluation module (EVM) , and we’re going to do it the old-fashioned way—by taking it apart.

It is important to note that any disassembly of the light engine will void the warranty of the NIRscan Nano EVM. In addition, removing the cover from the light engine will allow dust and dirt to collect on the optics, which will affect the system performance. In addition, removing the cover will move the optics, slits and detectors, causing these components to be misaligned, requiring the manufacturer to re-align and recalibrate. Once the slit is removed, the InGaAs detector and DLP2010NIR will need to be returned to the factory for system alignment and calibration.

In short, this is not something you should try at home.

Let's take a quick look. A DLP-based spectrometer replaces the traditional linear array detector with a wavelength-selective digital micromirror device (DMD) and a single-point detector. By sequentially turning on a set of mirrors corresponding to a specific wavelength of light, the corresponding light is directed to the detector and captured. By scanning the set of mirrors on the DMD, the absorption spectrum can be calculated.

DLP technology within near infrared (NIR) spectroscopy offers the following benefits:

• Using a larger single-point 1 mm detector can achieve higher performance than using a linear array detector with very small pixels.
• Using unit detectors and low-cost optics can help achieve lower system costs. High-resolution DMDs enable custom graphics to compensate for the optical distortions of each individual system.
• The capture of larger signals benefits not only from the DMD's larger etendue compared to traditional technologies, but also from its fast, flexible, and programmable display mode and spectral filter design.
• With programmable display modes, DLP spectrometers can:
  • The intensity of light reaching the detector is varied by controlling the number of pixels in a mirror array.
  • The resolution of the system can be changed by controlling the width of the mirror array.
  • Capturing multiple wavelengths of light in one pattern is accomplished by using a set of Hadamard patterns. The individual wavelength data can then be decoded and retrieved. 50% of the number of DMD pixels are turned on in each pattern, resulting in a stronger signal to the detector than the column scanning method mentioned above.
  • Use custom spectral filters to select the specific wavelengths of interest.

Currently, the DLP NIRscan Nano EVM software supports variable resolution and Hadamard plots. Variable intensity and custom spectral filters are not supported yet.

In the picture below, you can see the main components of the DLP NIRscan Nano EVM:

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After removing the light engine cover, the DMD and detector circuit boards can be seen:

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Now, if we remove the reflective module, you can see the slits:

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Now that we have a full view of the device, let's take a look at how it manipulates light.

The light reflected from the sample is collected by the collection lens and focused on the light engine through the input slit. The slit size is chosen to balance the wavelength resolution and the signal-to-noise ratio (SNR) of the spectrometer. The spectrometer uses a slit with a length and width of 1.69 mm x 25 microns. The light passing through the slit is collimated on the first set of lenses, passes through an 885 nm long pass filter, and then hits a reflection grating. This grating combined with the focusing lens disperses the light source into its constituent continuous wavelengths (polychromatic light). The focusing lens spreads the slit image on the DLP2010NIR DMD. The different wavelengths of this slit image are horizontally distributed on the DLP2010NIR DMD. The optical system images the 900 nm wavelength on one end of the DMD and the 1700 nm wavelength on the other end, while spreading all other wavelengths sequentially in the middle.

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Today we found an excuse to tear the device apart and take a closer look. For more information on the DLPNIRscan Nano EVM, please refer to the DLP NIRscan Nano User Guide .

alan000345

Good stuff.

火辣西米秀

Nice, thanks for sharing