RESUMO
Mode locking of a cw Nd:YLF laser is sensitive to cavity-length mismatch. When a cw mode-locked Nd:YLF laser is turned on the power dissipation from the lamps causes a slow change in the cavity length because of heating of mechanical resonator parts. A method is presented to eliminate these warming-up effects.
RESUMO
To assess the role of epidermal melanin in a patient with porphyria variegata and vitiligo, the MED was determined in pigmented and vitiliginous skin for wavelengths of 310, 405 and 500 nm. The energy required to elicit erythema by irradiating vitiliginous skin at 310 nm was half that for pigmented skin. For 405 nm the differences was 4-fold and at 500 nm 2-fold. A possible explanation for the different protection by melanin against light of 310, 405 and 500 nm is given. UV-B irradiation, as a potent stimulus for melanization of the skin, is proposed as an additive measure in the protection against photosensitivity reactions in porphyria patients.
Assuntos
Melaninas/biossíntese , Transtornos de Fotossensibilidade/prevenção & controle , Porfirias/metabolismo , Raios Ultravioleta/efeitos adversos , Vitiligo/metabolismo , Feminino , Humanos , Melaninas/efeitos da radiação , Pessoa de Meia-Idade , Transtornos de Fotossensibilidade/etiologiaRESUMO
The design of a holder for fast photodiodes is described. These holders have been tested with commercially available photodiodes in a standard TO-18 package using delta light pulses from a synchronously pumped cw dye laser. Results of the measurements are presented and the holder is shown to perform well even for an experimental photodiode with a rise time of less than 40 ps and a FWHM of 80 ps.
