Study on a quasi-CW Nd:YAG frequency-doubled laser at 660nm
A QCW Nd:YAG intracavity frequency doubled red laser was made. Using a flat—flat laser cavity, 2 Kr-lamps, KTP crystal and an AO Q-switch, 2 W output power at 660 nm was obtained. The relationship between laser cavity length and output power is analyzed.
Nearly-Noncritical Phase Matching in MgO:LiNbO3 Optical Parametric Oscillators
We propose and demonstrate nearly-noncritical phase-matched optical parametric oscillation in MgO:LiNbO3 crystal by temperature tuning. The tuning range of the OPO was 800-1700 nm with temperatures tuning from 83°C to 224.2 °C.
X-rays and photocarcinogenesis in hairless mice
It is well known that excessive X-ray radiation can cause non-melanoma skin cancers. With the increased incidence of sun-related skin cancer there is a need to investigate the combination of sunlight and X-rays. Immunocompetent C3.Cg/TifBomTac mice (n = 298) were divided into 12 groups. Mice were irradiated with 12, 29 or 50 kV X-rays. The mice received a total dose of 45 Gy. They were irradiated with 3 SED simulated solar radiation (SSR) either before or after irradiation with X-rays. The groups irradiated with X-rays alone, 0, 3, 9 and 10 mice (0, 12, 29 and 50 kV, respectively) developed squamous cell carcinoma. In the groups irradiated with SSR after X-rays the development of tumours was significantly faster in the 50 kV group than in the corresponding control group (175 vs. 194 days, p < 0.001). In the groups irradiated with SSR prior to the X-ray radiation the development of tumours was significantly faster in the 29 and the 50 kV groups than in the corresponding control group (175 vs. 202 days, p < 0.001 and 158 vs. 202 days, p < 0.001, respectively). In conclusion, X-ray radiation alone is a weak carcinogen in hairless mice. There is an added carcinogenic effect if X-ray radiation is given on prior sun-exposed skin or if the skin is sun-exposed after X-rays. We still believe that X-ray radiation is a safe and effective therapy for various dermatological diseases but caution should be observed if a patient has severely sun-damaged skin or has a high-risk sun behaviour.