In one aspect, a fingerprint sensor device for fingerprint detection includes a light source configured to emit light at a wavelength. The fingerprint sensor device includes an array of sensor pixels to acquire an optical image indicative of a fingerprint. Each sensor pixel includes a photodetector to detect the emitted light reflected off of a target finger and output an optical signal based on the detected reflected light. Each sensor pixel includes a collimator disposed over the photodetector to direct the reflected light in a substantially vertical direction from above the photodetector toward the photodetector. Each sensor pixel includes sensor signal detection circuitry communicatively coupled to the photodetector to acquire the outputted optical signal.