Aberration correction of aperture-divided off-axis simultaneous polarization super-resolution imaging optical system

Abstract

According to the requirements for broadband simultaneous polarization high-resolution imaging, a divided-aperture simultaneous polarization super-resolution imaging system based on reflective free-form surface optical system and digital micro-mirror device is proposed. It has the advantages of wide working wavelength band, simultaneous imaging of multiple polarization states, single detector, high resolution and lightweight. The aberration correction principle and design optimization method of the optical structure for this imaging system are given. The Wassermann-Wolf theory is further developed, and the reflective Wassermann-Wolf differential equations that eliminate a variety of aberrations are derived. At the same time, combined with Seidel aberration theory and using iterative method, the distortion elimination boundary condition is added when solving the Wassermann-Wolf equation. Through the iterative method, the optical initial structure is obtained, which can correct spherical aberration, coma, astigmatism and distortion at the same time. The initial structure is subjected to off-axis treatment and further optimized, and the user-defined optimization evaluation function is written to strictly control the position of the light falling point of each sub aperture and each field of view on the middle image plane and the final image plane, so as to effectively suppress the distortion in the final system and avoid the mismatch error between the mirror element and the pixel in the process of super-resolution reconstruction. The reconstruction quality can be improved. Finally, the design of the four-sub-aperture free-form surface off-axis reflective super-resolution imaging optical system is completed, which possesses a large relative aperture (<i>F</i># = 2.5) and compact structure. The imaging quality of each polarization channel is close to the diffraction limit. The above aberration correction principle and the image quality optimization method can effectively guide the design of the wide band simultaneous polarization super-resolution imaging optical system.