抄録
The modulation transfer function (MTF) is essential for assessing the spatial frequency characteristics of optical imaging systems. This study presents an innovative sinewave-based methodology for measuring the MTF, which demonstrates robustness against noise and applies to images exhibiting distortion. Slanted-sinusoidal fringe charts were utilized as test objects to simplify contrast calculations. The MTF for each frequency is determined by optimally fitting a sinusoidal function to unequally spaced pixel data using nonlinear least-squares estimation, enabling the derivation of optimal solutions that comply with Cramér–Rao bounds. This methodology enables MTF measurements in small-sized images with minimal distortion and at frequencies beyond the Nyquist limit. Numerical simulations and empirical camera experiments revealed that our proposed approach outperformed traditional edge-based methods.