title: Iterative deconvolution technique for measurements of diffraction-limited images on optical microscopes.
abstract: Diffraction limit is usually a thorny problem in an optical inspection system. In this investigation, a model-based deconvolution technique was developed to recover diffraction-limited images, where images with sizes smaller than the diffraction limit could be recognized. Experiments were carried out with a traditional microscope at 200× magnification coupled with a halogen light source for a series of line width samples. The point spread function of the imaging optics was first obtained from an estimated model and then combined with a nonlinear deconvolution algorithm to calculate the full width at half maximum and reconstruct the line widths. Experimental results indicate that a measurement error below one pixel size of the measurement system is achievable. Accordingly, the target of nanoscale line width inspection based on a low cost and real-time image processing technique can be fulfilled, which greatly increases the ability of nanoscaling on optical microscopes.
authors.affiliation: The State Key Laboratory of Digital Manufacturing Equipment and Technology, Huazhong University of Science and Technology , Wuhan 430074 , China.
authors.forename: Wenlong
authors.initials: W
authors.lastname: Lu
authors.affiliation: The State Key Laboratory of Digital Manufacturing Equipment and Technology, Huazhong University of Science and Technology , Wuhan 430074 , China ; Department of Mechanical Engineering, Chung Yuan Christian University , Chung-Li 32023 , Taiwan ; Center for Biomedical Technology, Chung Yuan Christian University , Chung-Li 32023 , Taiwan.
authors.forename: Ming
authors.initials: M
authors.lastname: Chang
authors.affiliation: Department of Mechanical Engineering, Chung Yuan Christian University , Chung-Li 32023 , Taiwan.
authors.forename: Po-Cheng
authors.initials: PC
authors.lastname: Chen
authors.affiliation: Department of Mechanical Engineering, Chung Yuan Christian University , Chung-Li 32023 , Taiwan.
authors.forename: Wun-Mao
authors.initials: WM
authors.lastname: Luo
keywords: deconvolution; diffraction limit; line width inspection; optical microscope; point spread function