Airy3D Explains its Technology

LaserFocusWorld publishes an article "Diffraction mask design brings 3D imaging to standard CMOS image sensors" by Gil Summy (Director, Optics Group) and James Mihaychuk (Product Manager) from AIRY3D, Montreal, QC, Canada.

Airy3D's "DEPTHIQ technology places an optical encoding transmissive diffraction mask (TDM) on a standard CMOS image sensor to generate both high-quality 2D color images and near-field depth maps that are inherently correlated.

The addition of two thin layers of transmissive material, collectively making the TDM, over the top of most CMOS image sensors can provide 3D sensing capabilities with virtually no reduction in 2D image quality. These layers use the process of diffraction from a phase grating to realize compact, low-cost, low-compute solutions for 3D image capture.

The physics underlying the TDM is diffraction from a phase grating. Thus, the TDM is a transparent structure rather than a lossy mask and does not rely on opaque, lithographically patterned features. As such, a TDM can be added to any existing image-sensor design through a small number of postprocessing steps.

Because it is typically only a few microns thick, a TDM can normally be added to an image sensor without requiring changes to the lens or other camera-module components. However, as with any image sensor, it remains important to select a compatible lens in terms of numerical aperture (NA), chief-ray angle (CRA), and alignment tolerancing.

To date, these TDM design approaches have been successfully applied to implement single-sensor 3D imaging solutions based on a wide range of CMOS image sensors. The TDM approach has been adapted to both backside-illuminated mobile sensors for smartphones and frontside-illuminated, global-shutter machine-vision sensors. As such, TDM structures have been incorporated onto sensors having pixel pitches from about 1 to 3 µm and pixel counts from about 2 to 20 Mpixels."