ANTI-SPOOFING OF TWO-DIMENSIONAL FAKE OBJECTS WITH BRIGHT-DARK REVERSAL IMAGING IN OPTICAL SENSING MODULES

摘要

Optical sensing is provided to detect two-dimensional spoof objects using bright-dark reversal imaging. For example, embodiments can operate in context of an under-display optical fingerprint sensor integrated into an electronic device, such as a smartphone. An optical scanning system is configured so that direct illumination incident on a defined sensing region is redirected, by internal specular reflection off of a contact surface, onto an optical sensor in a bright-dark pattern corresponding to the pattern of contact an object and the contact surface. Masking of direct illumination in a certain region of the contact surface inhibits specular reflection in that region, such that optical information is directed to the optical sensor from that region only by non-specular reflection. Three-dimensional (real) and two-dimensional (spoof) objects tend to manifest different optical responses to the lack of specular reflection in the masked region, which can be exploited to detect such spoofs.