Pose calibration of light source in Fourier ptychographic microscopy

Fourier ptychographic microscopy （FPM） enables wide-field and high-resolution quantitative complex amplitude imaging by stitching low-resolution intensity images captured under angle-varied illuminations via synthetic aperture and phase retrieval techniques. The spectrum position of each captured image is crucial prior knowledge for reconstructing the high-quality image. Therefore，calibration of the light source pose，which determines the position of the spectrum，is a key to achieving robust FPM systems. Recently， various methods have been proposed to calibrate the misalignment of the light source，including mechanical calibration methods with multi-degree-of-freedom precision mechanical stages， data-driven calibration methods based on the intensity or spectrum information of the captured images，and imaging mechanism calibration methods based on the optical principle of microscope. This paper briefly introduces the basic principle of FPM and the pose deviation of light sources，then reviews the principles and characteristics of three calibration methods. The mechanical methods can eliminate the pose deviation essentially，but it is time-consuming and laborious. The data-driven methods can automatically calibrate the pose deviation， but long calibration time and coupling of parameters limit its application. The imaging mechanism method not only has high robustness，but also can decouple the accurate pose parameters from various systematic errors，which is a promising method with great potential for development and application.