Peak extraction in fluorophore-aided scattering microscopy

Abstract

Fluorophore aided scattering microscopy (FA-SM) can measure free-form optical elements with steep or transparent surfaces by depositing an ultra-thin and easily removable fluorescent film on the sample and collecting the fluorescent light carrying the sample surface information, which accomplishes a task impossible for conventional optical measurement methods. However, photo bleaching is incidental in FA-SM if the fluorescent film is scanned by a focusing laser spot for a long time, which requires the axial scanning pitch to be as large as possible to minimize the scanning time. In this case, fewer sampling data can be utilized to localize the confocal axial peak position, which is fundamental for height determination in FA-SM. Precision of height extraction algorithms is evaluated by Monte-Carlo based uncertainty analysis model. Key factors influencing the measurement uncertainty are the vertical sampling pitch and asymmetry of the sampling data. These results could offer a reference for determining the scanning parameters in FA-SM for high accuracy. The performance of various height extraction algorithms for FA-SM are compared in practical measurement.