[koromak]

I suppose if your lens is actually a vertical stack of lenses, each with hundreds of inputs and outputs, then why wouldn't this work? Although I cannot fathom fabricating it. Maybe start by finding the absolute simplest/smallest image classifier you can

[koromak]

EDIT: Of course people are already doing this. D2NN seems to be the keyword, Diffractive Deep Neural Networks

[TeMPOraL]

Yes, by "lens" I meant a possibly large stack of optical elements, each designed to perform a single computational step. Kind of like layers of an NN, but etched on sheets of plastic.

Thanks for finding the proper term for this!