Fast measurement system for fiber-optic imaging element modulation transfer function based on improved edge method

To meet stringent imaging quality requirements for fiber-optic imaging element in low-light night vision and particle detection applications, this study proposes a rapid modulation transfer function (MTF) measurement method. Innovating upon the conventional slanted-edge method, this approach achieves sub-pixel edge localization through Gaussian smoothing and adaptive gradient thresholding, while significantly enhancing edge detection accuracy via multi-stage Sobel gradient filtering. The edge spread function (ESF) is precisely modeled using bicubic interpolation, with subsequent plateau-region normalization and iterative optimization generating the MTF curve. Experimental results demonstrate effective suppression of fixed-pattern noise in low-light imaging, showing significant MTF₅₀ enhancement and the absolute error between the measured MTF and the laboratory contrast benchmark is within a very small range. This technique provides a high-precision, efficient solution for performance quantification of fiber-optic imaging element such as image intensifier windows, delivering critical engineering value for ensuring reliability in high-speed imaging assemblies.