Biometrics performs personal authentication using individual bodily features including fingerprints, faces, etc. These
technologies have been studied and developed for many years. In particular, fingerprint authentication has evolved over many years, and fingerprinting is currently one of world's most established biometric authentication techniques.
Not long ago this technique was only used for personal identification in criminal investigations and high-security
facilities. In recent years, however, various biometric authentication techniques have appeared in everyday applications.
Even though providing great convenience, they have also produced a number of technical issues concerning operation.
Generally, fingerprint authentication is comprised of a number of component technologies: (1) sensing technology for
detecting the fingerprint pattern; (2) image processing technology for converting the captured pattern into feature data
that can be used for verification; (3) verification technology for comparing the feature data with a reference and
determining whether it matches. Current fingerprint authentication issues, revealed in research results, originate with
fingerprint sensing technology. Sensing methods for detecting a person's fingerprint pattern for image processing are
particularly important because they impact overall fingerprint authentication performance. The following are the current
problems concerning sensing methods that occur in some cases: Some fingers whose fingerprints used to be difficult to
detect by conventional sensors. Fingerprint patterns are easily affected by the finger's surface condition, such noise as
discontinuities and thin spots can appear in fingerprint patterns obtained from wrinkled finger, sweaty finger, and so on.
To address these problems, we proposed a novel fingerprint sensor based on new scientific knowledge. A
characteristic of this new method is that obtained fingerprint patterns are not easily affected by the finger's surface
condition because it detects the fingerprint pattern inside the finger using transmitted light.
We examined optimization of illumination system of this novel fingerprint sensor to detect contrasty fingerprint pattern
from wide area and to improve image processing at (2).