Ten more times precision improved method for surface roughness estimation with weak measurement

TL;DR

This paper introduces two weak measurement-based methods for surface roughness estimation that significantly surpass classical precision limits, achieving sub-nanometer accuracy with practical experimental setups.

Contribution

The authors develop novel weak measurement schemes for surface roughness estimation that improve precision and sensitivity beyond traditional methods, enabling practical high-accuracy surface profiling.

Findings

Spectrum analysis scheme achieves about 10^-5 nm precision.

Intensity analysis scheme reaches 0.07 nm precision.

The methods maintain high sensitivity and precision over a wider dynamic range.

Abstract

High-precision surface roughness estimation plays an important role in many applications. However, the classical estimating methods are limited by shot noise and only can achieve the precision of 0.1 nm with white light interferometer. Here, we propose two weak measurement schemes to estimate surface roughness through spectrum analysis and intensity analysis. The estimating precision with spectrum analysis is about $10 ^{-5}$ nm by using a currently available spectrometer with the resolution of $\Delta \lambda= 0.04$ pm and the corresponding sensitivity is better than 0.1 THz/nm. And the precision and sensitivity of the light intensity analysis scheme achieve as high as 0.07 nm and 1/nm, respectively. By introducing a modulated phase, we show that the sensitivity and precision achieved in our schemes can be effectively retained in a wider dynamic range. We further provide the experimental design of the surface profiler based on our schemes. It simultaneously meets the requirements of high precision, high sensitivity, and wide measurement range, making it to be a promising practical tool.