Abstract

Near-infrared (NIR) transillumination imaging is useful in many biomedical applications such as human biometrics and animal experiments. However, the image quality is generally poor due to the strong scattering in the body tissue. The authentication using the transillumination image of the palm vein and the finger vein is common these days, but there are some problems left such as misidentification and unidentifiability. To solve these problems with a simpler system than common ones, we have attempted to develop a biometric identification technique using the NIR transillumination and scattering suppression techniques. An array of LED's was placed at one side of the palm and a transillumination image was obtained with a low-cost CCD camera at another side of the palm. The image was processed by the deconvolution with the appropriate point spread function (PSF). The PSF was originally derived from the diffusion approximation of transport equation for the light source in turbid medium. We found that it can be applied for the scattering suppression in transillumination imaging of absorbing structure inside turbid medium. Even with the simple system, a clear vein image which was sufficient for authentication was obtained successfully.