Panchromatic Diffraction Gratings for Miniature Computationally Efficient Visual-bar-position Sensing

We describe the design and performance of an ultraminiature lensless computational sensor optimized for estimating the one-dimensional position of visual bars. The sensor consists of a special-purpose wavelength-robust optical binary phase diffraction grating affixed to a CMOS photodetector array. This grating does not produce a traditional high-quality human interpretable image on the photodetectors, but instead yields visual information relevant to the bar-position estimation problem. Computationally efficient algorithms then process this sensed information to yield an accurate estimate of the position of the bar. The optical grating is very small (120 µm diameter), has large angle of view (140 0), and extremely large depth of field (0.5 mm to infinity). The design of this sensor demonstrates the power of end-to-end optimization (optics and digital processing) for high accuracy and very low computational cost in a new class of ultraminiature computational sensors