5 x 5 Spot array based on two crossed single-groove gratings

摘要

Compared to the reported 5 x 5 spot arrays, we propose a way of generating a 5 x 5 spot array with much higher efficiency and better uniformity by using two crossed single-groove gratings. Normally, a single-groove grating cannot generate a 1 x 5 equal-intensity array by employing traditional Fourier optics theory. In this letter, we will show by vector diffraction theory that when the period of a single-groove grating is more than twice that of the incident wavelength, it may generate a 1 x 5 equal-intensity array. Based on this discovery, we expand the 1 x 5 array into a 5 x 5 spot array straightforwardly by using two crossed single-groove gratings. The dependence on the refractive index for producing a 1 x 5 equal-intensity array is interesting and we explain the phenomenon from the perspective of energy distribution by the simplified modal method.