Friday, November 3, 2017

3d face recognition

This morning, #45 announced a massive tax relief for the American people. Also as of this morning, the new iPhone X is available for purchase in Apple stores.

If you are investing your massive tax relief in an iPhone X, do not just look at the gorgeous OLED screen, but also at the 3d face recognition sensor, because you have been reading about the underlying physics on this blog.

It has been over a dozen years since Neil J. Gunther of Performance Dynamics, annoyed by a Harvard professor's claim of having disproved Bohr's complementarity principle, proposed to follow the idea of VLSI design rules to formulate practical design rules for quantum communications and quantum imaging devices.

We performed interference experiments in Neil's kitchen using a green laser and a paper clip to form an image. Sergio Magistri noticed that doing physics is good, but creating an artifact that we could sell would be better. He hooked us up with Edoardo Charbon, who had invented a CMOS SPAD array.

After lengthy discussions, Edoardo—who in the meantime had become a professor at EPFL—was willing to reduce our ideas to practice. We received a 500,000 franc grant from the Swiss National Science Foundation to buy the lab equipment and a matching grant from the European Union to hire Dmitri Boiko as a postdoc.

To form the image, we used the metal plate creating the nozzles in an ink jet cartridge to obtain an array of pinholes.

We performed experiments supporting the concept of a g2-camera, summarized on this blog. The statistical post-analysis was so challenging that Neil had to implement it in the fast processor of an oscilloscope. We wrote two papers with the early details:

The blog posts hot body, excited particles, and the north sky and chaotic light sources are the basis for telling apart the sources for the photons reaching the SPAD array.

It is amazing that today the computations can be done on a small, inexpensive smartphone. However, it took 13 years and hundreds if not thousands of people to get to today's device, a simpler version of which, by the way, is also used in Bosch measures.