Patent ID: 8494228

Claim:
A personal authentication method through measurement of a subcutaneous bloodstream comprising: expanding a laser beam and irradiating the expanded laser beam to a finger pad; focusing light reflected from a subcutaneous blood vessel layer onto an image sensor plane as laser speckles by using an optical system; determining an amount representing a rate of time variation of light intensity received at each pixel point in the laser speckles and setting a numerical value thus obtained as a two-dimensional map to thereby achieve obtain a bloodstream map of the finger pad; comparison-checking a fingerprint pattern appearing as the bloodstream map with pre-registered personal data for authentication; and calculating time variation of an average bloodstream in the whole area or some area, and comparing the time variation concerned with a predetermined reference for authentication, wherein said laser speckles are focused onto the image sensor plane using a region separate from a region irradiated by the laser beam as an observation region of the image sensor, the laser beam forms a linear spot, the image sensor is a linear sensor and the linear spot is arranged in parallel with the observation region of the linear sensor.