CORRELATION BETWEEN SUBSTRATE PREPARATION TECHNIQUE AND SCATTER OBSERVED FROM OPTICAL COATINGS

We present experimental evidence of the dependence of coating scatter on a substrate preparation technique for fused silica substrates. Samp les included conventionally polished, superpolished, and float-polishe d substrates. We used scatterometry and total internal reflection micr oscopy to investigate the effects of substrate preparation on the perf ormance of zirconium oxide thin films. Results indicate that scatter f rom coatings dominates the scatter signature of the coated optic. They also demonstrate that substrate preparation can affect the level of s catter produced in optical coatings. In addition it is observed that t he substrates with the lowest scatter do not necessarily result in the coatings with the lowest scatter.