Biometric authentication device and biometric authentication method

A biometric authentication device for carrying out biometric authentication using biometric information by collating pre-registered biometric data for authentication with biometric data acquired during authentication, the device comprising:

• a housing that defines a finger inserting section;
• a near-infrared light source configured to irradiate a finger in the finger inserting section with near-infrared light;
• a visible light source configured to irradiate the finger inserting section with visible light;
• a camera configured to capture a first image of the finger in the finger inserting section with the near-infrared light which penetrates through the finger while the visible light source irradiates the finger inserting section with the visible light;
• a memory configured to store the pre-registered biometric data and a predetermined luminosity;
• and
• a processor programmed by executable instructions to acquire biometric data from the first image,
• wherein the visible light source is configured to start irradiation of the visible light before the camera captures the image, and
• when a luminosity of the acquired biometric data from the first image is higher than the predetermined luminosity, the processor is further programmed by the executable instructions to:
• lower an irradiation luminosity from the visible light source
• cause the camera to capture a second image of the finger in the finger inserting section with the near-infrared light which penetrates through the finger while the visible light source irradiates the finger inserting section with the lowered visible light from the visible light source,
• acquire biometric data from the second image, and
• collate the acquired biometric data from the second image with the pre-registered biometric data for authentication.