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Laser-Induced Damage in Optical Materials
~2nm aer ~10 s of irradiation, which corresponds to a defocus term of approximately
5km for a spherical surface.
For comparison, Figure 17.16b shows the wavefront deformation of a CaF
2
sam-
ple recorded under identical conditions. In contrast to fused silica, which always
exhibits a positive lens eect, the wavefront deformation in CaF
2
shows a reversed
sign representing a negative lens. is can be explained by the negative dn/dT value
of CaF
2
. It is interesting to note that, despite an almost 40 times larger expansion
coecient as compared to quartz, the negative change of refractive index with tem ...