Systems and methods are described for providing reliable biometric access control using an optical biometric sensor in a miniaturized form factor. Some implementations include multiple light sources that can illuminate skin or other tissue at multiple locations during a single measurement session. An imaging array can be arranged to form images of the light exiting the tissue only after undergoing diffuse reflectance in the tissue. Some implementations use the images to perform biometric functions. For example, the images can be used to identify an individual, verify identity of an individual, estimate demographic characteristics of an individual, etc. Such biometric functions can further be used to determine and affect access to secured assets.
