Fast and accurate mean-shift vector based wavelength extraction for chromatic confocal microscopy

Abstract

Fast and accurate peak wavelength extraction of chromatic confocal signals is of vital importance for efficient chromatic confocal measurement. Existing peak extraction algorithms do not effectively balance calculation efficiency and extraction accuracy. For example, centroid algorithms have high computational efficiency but low accuracy; model-based fitting algorithms have high extraction accuracy but low calculation efficiency. In this paper, a fast and accurate mean-shift vector based peak wavelength extraction algorithm is proposed. In this algorithm, the initial peak wavelength is preset with a centroid algorithm; then the corresponding mean-shift vector is calculated, after which, a new peak wavelength can be calculated by shifting the peak wavelength along the mean-shift vector. This process is then iteratively carried out until a preset ending condition is met. Our experimental results show that the mean-shift vector based peak extraction algorithm has an accuracy equal to that achieved with Gaussian fitting while the efficiency improves by over 70 times.

Three-dimensional confocal reflectance microscopy for surface metrology

“…The fitting process enables a more accurate estimation of the peak position, that is, sample height. Since the peak detection is essential in confocal microscopy, various approaches are constantly being proposed to enhance the efficiency and accuracy of calculation, such as a modeling of confocal microscopy considering physical properties [49], mean-shift vector [50], and Monte Carlo analysis [51]. With peak detection algorithms, the axial resolution, or repeatability of confocal reflectance microscopy is much better than the FWHM of the axial response curve or the depth sampling interval [37,46].…”

光谱共焦显微技术研究进展

“…8 Relative deviation of each position under different peak wavelength extraction algorithms (2 μm step) [42] 图 9 不同算法峰值提取误差的期望值和标准差 ［45］ Fig. 9 Expectation value and standard deviation of the peak extraction errors of different algorithms [45] 表 2 不同算法峰值提取误差的均方根期望值和标准差 Table 2 RMS 10 Confocal scanning microscopy based on galvanometer [53] . (a) Schematic of the principle; (b) system structure 图 11 基于声光偏转器的共焦扫描方法。 (a) 单独使用 ［56］ ； (b) 组合使用 ［58］ Fig.…”