Data recording on biological tissues and prostheses with femtosecond laser processing for personal identification is demonstrated. The target materials are human fingernails (fingernail memory) and dental prostheses (dental memory). Because they have unexpected movements and individual three-dimensional shapes, the processing system is required an adaptive focusing and highthroughput recording capability. The adaptive focusing is performed with a target surface detection. The high throughput is realized by parallel laser processing based on a computer-generated hologram displayed on a spatial light modulator. Two-dimensional and threedimensional parallel laser processing of glass is demonstrated.
2. Hayasaki, Y., H. Takagi, A. Takita, H. Yamamoto, N. Nishida, and H. Misawa, "Processing structures on human fingernail surface by a focused near-infrared femtosecond laser pulse," Jpn. J. Appl. Phys., Vol. 43, No. 12, 8089-8093, 2004.
3. Takita, A., H. Yamamoto, Y. Hayasaki, N. Nishida, and H. Misawa, "Three-dimensional optical memory using a human fingernail," Optics Express, Vol. 13, No. 12, 4560-4567, 2005.
4. Ichikawa, T., Y. Hayasaki, K. Fujita, K. Nagano, M. Murata, T. Kawano, and J. R. Chen, "Femtosecond pulse laser-oriented recording on dental prostheses," Dental Materials J., Vol. 25, No. 4, 733-736, 2006.
5. Takita, A., Y. Hayasaki, and N. Nishida, "Femtosecond laser processing system with target tracking feature," Journal of Laser Micro/Nanoengineering, Vol. 1, No. 3, 288-291, 2006.
6. Hayasaki, Y., T. Sugimoto, A. Takita, and N. Nishida, "Variable holographic femtosecond laser processing by use of spatial light modulator," Appl. Phys. Lett., Vol. 87, No. 3, 031101, 2005.
7. Hasegawa, S., Y. Hayasaki, and N. Nishida, "Holographic femtosecond laser processing with multiplexed phase Fresnel lenses," Opt. Lett., Vol. 31, No. 11, 1705-1707, 2006.
8. Hasegawa, S. and Y. Hayasaki, "Holographic femtosecond laser processing with multiplexed phase fresnel lenses displayed on the liquid crystal spatial light modulator," Opt. Rev., Vol. 14, No. 4, 208-213, 2007.
9. Takahashi, H., S. Hasegawa, and Y. Hayasaki, "Holographic femtosecond laser processing using optimal-rotation-angle method with compensation of spatial frequency response of liquid crystal spatial light modulator," Appl. Opt., Vol. 46, No. 23, 5917-5923, 2007.
10. Chaen, K., H. Takahashi, S. Hasegawa, and Y. Hayasaki, "Display method with compensation of the spatial frequency response of a liquid crystal spatial light modulator for holographic femtosecond laser processing," Opt. Commun., Vol. 280, No. 1, 165-172, 2007.