Background: The flashlamp-pumped dye laser is considered the treatment of choice for vascular lesions including port-wine stains. However, this treatment is associated with an intensive postoperative purpura and considerable pain. Objective: We tested a newly developed laser device with a 532-nm neodymium:YAG laser with variable pulse widths between 2 and 10 ms. Methods: Forty-two consecutive patients from our laser clinics were treated with the new laser system delivering energy through a chilled tip by means of circulating water (cooling temperature was between 4 and 5.5 °C). Forty of them had been pre-treated with an argon laser and an argon-pumped dye laser. Results: Out of the 42 patients, 1 patient had a complete clearing, 11 had an excellent result (more than 80% clearing), 21 patients had a good result (51–75% clearing), weak responses were seen in 9 patients. Significant success was already seen after 1 or 2 treatments. Side effects were rare. There was no purpura after treatment. Local anesthesia was only applied in 6 out of 42 patients. Conclusion: The variable pulse width frequency doubled neodymium:YAG laser seems to be an alternative to the flashlamp-pumped dye laser and deserves to be investigated in comparative trials.

Using modern Q-switched lasers, tattoos are removed successfully with minimal risk of scarring and permanent pigmentary alterations. Even multicoloured tattoos can be treated successfully and with a low rate of side-effects.

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It is shown that it should be possible to produce single exposure holograms as well as multiple exposure holograms with the same diffraction efficiency if appropriate exposure conditions are used. The amplitude ratios between object wave and reference wave which must be employed in forming the hologram are specified for the two storage techniques. The object waves are provided to originate from a periodic array of coherent radiating light sources.

Based on results of diffraction theory, it is shown that the proportions of storage plate and detector matrix, respectively, page-composer, of a fast holographic mass memory are strongly coupled. A high capacity fast data store needs a large detector array. Optimized geometry results if storage plate and detector matrix have the same size. A square detector matrix, able to read about 10(10) bits in an optimum designed memory, should have a diagonal extension of about 1 m.