Vein imaging using detection of pulsed radiation — USPTO — “Vein identification systems that are known in the art transmit infrared illumination through the user’s hand, and capture a resulting image in which the veins within the hand appear as dark or bright lines due to variations in the captured infrared intensity… In the disclosed embodiments, an optical transmitter, such as a laser, emits a pulse or sequence of pulses of infrared radiation toward an area containing a body surface of a living subject, such as the skin of the subject’s face.”