Snapshot hyperspectral image sensors use mosaic filters

February 04, 2015 // By Graham Prophet
Belgian research centre imec has disclosed a new set of snapshot hyperspectral CMOS image sensors featuring spectral filter structures in a mosaic layout, processed per-pixel on 4x4 and 5x5 ‘Bayer-like’ arrays.

These hyperspectral filter structures are processed at wafer-level on commercially available CMOS image sensor wafers, enabling extremely compact, low cost and mass-producible hyperspectral (multi-wavelength, beyond the visible) imaging solutions. This paves the way, imec says, to applications ranging from machine vision, medical imaging, precision agriculture to higher volume industries such as security, automotive and consumer electronic devices.

Andy Lambrechts, program manager at imec, comments, “The new mosaic architecture, and extended spectral range, brings unique advantages compared to our previously announced hyperspectral linescan sensors for applications in which scanning would not be practical. It enables spectral imaging in a truly compact, tiny form-factor, that can even be scaled to handheld devices. From the technology standpoint, we have now successfully demonstrated linescan and tiled sensors, in which spectral filters cover many pixels, to mosaic sensors, in which filters vary from pixel to pixel. At the same time, the spectral range is extended and now covers down to 470nm.”

The newly developed mosaic sensors feature one spectral filter per pixel, arranged in mosaics of 4x4 (16 spectral bands) or 5x5 (25 spectral bands) deposited onto a full array of 2 Million pixels 5.5 µm size CMOSIS CMV2000 sensor. Two versions of the mosaic hyperspectral image sensors have been developed:

  1. one 4x4 mosaic with 16 bands in the 470-630nm (visible range);
  2. one 5x5 mosaic with 25 bands in the 600-1000nm range (Visible – near-IR range).

“Imec’s hyperspectral imaging sensors (100bands linescan, 32bands tiled and 16/25bands mosaic designs) are off-the-shelf, commercially available engineering sample sensors that we developed to address the fragmented machine vision market and to trigger interest for this unique technology from potential end-users in other industries,” explains Jerome Baron, business development manager at imec. “We also offer customised spectral filtering solutions for companies that are already familiar with the technology and interested in developing proprietary solutions with a specific performance in terms of speed, compactness, spatial versus spectral resolution, bands selection, or