Development of Long-focal-depth Diffractive Lens for Femtosecond Laser Pulses

摘要

In recent years, in the field of laser processing, the femtosecond laser processing (1 femtosecond = 10~(-15) seconds) is attracting attention as a next-generation technology for such processing techniques as thermal damage-free processing, 3-dimensional processing and transparent material processing. On the other hand, high quality processing like thermal damage-free drilling of less-tapered microvias is being realized by controlling the power density change in the propagation direction of laser beam using optical elements. In this paper the authors describe the development of the long-focal-depth diffractive lens for focusing femtosecond laser pulses that have a wide spectrum wavelength of up to 10 nm.