2015 年 81 巻 832 号 p. 15-00291
In order to measure the two-dimensional distribution of the thickness of a metal layer coated on a dielectric layer at a time, we propose to use a micro-lens array (MLA), instead of a conventional single plano-convex lens, by which lots of surface-plasmon-resonance (SPR) dip patterns could be observed from a modified Otto configuration. The individual micro lenses produce circular ring-shaped SPR dip patterns in reflection, which enable us to estimate the thickness of the metal with high sensitivity and precision with ease. A spatial resolution is determined by the size of each lens and is 300 μm in diameter. As a proof-of the principle experiment, we measured the thickness of a 50nm-thickness Au film with precision ±0.9 nm for an area of 2.7 mm×2.7 mm. A method for improving the spatial resolution further is discussed.