A contactless fingerprint sensor provides deformation-free, high-quality fingerprint images and offers users a cleaner and more comfortable measurement environment. Here we propose and design an innovative prototype optical, contactless, compact, fingerprint sensor that quickly produces high-quality, high-contrast interoperable fingerprint images. A proofof- concept contactless, aliveness-testing (CAT) fingerprint sensor, which is connected to a PC via a firewire cable, was constructed and is currently operating in our laboratory. The CAT sensor affords a more user-friendly interface compared to existing contactless fingerprint sensors and also provides robust aliveness testing and spoof detection. In this paper, we present the imaging system design concepts, finger aliveness detection techniques, and the user-friendly interface approach. Various fingerprint matching results using the CAT sensor device are also presented and discussed.