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| TUPPH027 |
The Experimental Research of the SR-FEL Cavity Mirrors at 355nm and 248nm
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382 |
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- H. L. Gao, R. Q. Tan, D. L. Wang, Y. Wang, J. Wu
Institute of Electronics, Chinese Academy of Sciences, Beijing
- N. Y. Wang
CIAE, Beijing
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The cavity mirrors of the storage-ring free-electron laser (SR-FEL) at 355nm and 248nm central wavelengths have been investigated experimentally with the optical coating materials of Al2O3/HfO2/SiO2 on fused silica. They were deposited by the electron-beans evaporation technology and ion-beam sputtering technology, so that the mirror have high damage threshold to laser pulse and resist to the reflectance degeneration- induced by the synchrotron radiation. The experimental results show that the absolute reflectance of the broad-band mirror at reaches up to R=99.45%, the frequency-tunable range with reflectance higher 99.00% is 406nm-331nm=75nm. For the dual-central wavelength mirror, the absolute reflectance are R(248nm)=98.21% and R(355nm)= 99.69%. The frequency-tunable range is 373nm-314nm for 355nm central wavelength; 275nm-272nm and 240nm-234nm for 248nm central wavelength, it isn't continual due to the absorption of HfO2 optical materials. All of the samples have passed the high-temperature test under the condition 400°C-4hrs successfully, and shown very stable optical property.
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