PURPOSE: To detect a fingerprint in a condition in which the output light wavelength of a semiconductor laser is stable by inputting a prescribed uneven pattern from an input surface and detecting the uneven pattern before the detection of the fingerprint with a fingerprint sensor.
CONSTITUTION: At the time of rising the fingerprint sensor, a concentric uneven pattern 11 prepared beforehand is brought into contact with the input surface, and uneven surface information is detected by an image pickup element 8. When the output light wavelength of a semiconductor laser 1 is not stable, since the width of the convex part of the detected uneven surface information is broadened, by counting the number of the picture elements occupied by a convex part on the image pickup element 8, the stability of the output light wavelength of the semiconductor laser 1 can be detected. Further, when the stability of the output light wavelength is satisfactory, the detection of the fingerprint can be started as it is, and when the stability is unsatisfactory, the maintenance of the semiconductor laser 1 can be urged.
IGAKI SEIGO
IKEDA HIROYUKI
