Superposition of Double Amplitude Diffraction Gratings

Grating measurement techniques have revolutionized many fields of science and engineering and become more widely used than ever, a good generalized optical law of diffraction energy distribution and fringes patterns will make its performance better in high precision control and metrology. Here, we focus on the diffraction field of optical system which mainly composed of two identical sinusoidal amplitude gratings with dynamic rotation between them. We derive the light intensity on reception screen when the laser beam passing through the double-grating system by using Fourier optics theory. Simulation of diffraction field at different relative positions of two gratings show waveform changes of intensity along any linear direction in the screen plane, demonstrate continuous monotonic relationship between rotation angle θ and fringe spacing.