Chromatic aberration at PHELIX
نویسندگان
چکیده
The influence of the dispersion of glass seams only relevant for femtosecond lasers with a pulse length below 100 fs. This commonly used approximation holds only for visible and IR light. For UV fs-laser Z. Bor stated out that due to the large dispersion in the UV regime fs-pulses with a duration of a few hundred femtoseconds are significantly affected in lenses by the group delay [1]. When a pulse travels through a lens, the pulse is more delayed in the center than on the the edge of the lens. A previously plane pulse get curved. When a curved pulse is focused, the intensity in the focal spot is reduced. The energy from the edge of the pulse reaches the focal spot at an earlier time than the energy in the center of the pulse. For a singlet lens the radius dependent delay can be calculated:
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