Optical Transfer Function Measurement Based on Macroscopic Fourier Ptychography

When the slanted-edge method is applied to measure the optical transfer function (OTF), it not only can just accurately obtain the modulation transfer function (MTF) in a single direction, but also fails to measure the Zernike aberration coefficients. In contrast, Fourier ptychography can obtain super-resolution images and reconstruct the pupil function of the optical system, thereby achieving the simultaneous measurement of Zernike aberration coefficients, and the amplitude and phase of the two-dimensional OTF. The previous macroscopic Fourier ptychography method by aperture scanning during the translation of the whole camera is not applicable to the optical path for OTF measurement. Therefore, driving lighting fibers into motion with an electronically controlled translation platform is proposed to achieve pupil translation in the frequency domain, and this method has the advantages of adjustable moving intervals, high brightness, and favorable coherence. The experimental setup is built according to the optical path for OTF measurement, and a doublet and the presence of obstruction are measured by macroscopic Fourier ptychography. The corresponding pupil function is reconstructed, and Zernike aberration coefficients and the OTF are calculated. The effects of the number of acquisition steps and the overlap rate on accuracy are analyzed by measuring high-resolution imaging lens. The experimental results show that the mean square errors of the MTF measurement results in meridian and sagittal directions relative to the measurement results of the OTF measuring equipment are in the 10(-4) magnitude.