Design of a free-form off-axis three-mirror optical system with a low f-number based on the same substrate

Abstract

In this paper, we design a free-form off-axis three-mirror optical system with a low f -number and compact structure, which can be used as an infrared reflection imager. The initial structure is calculated from the near-axis optical transfer matrix based on third-order aberration theory. Particular constraints are designed to install all mirrors on the same substrate for simultaneous milling, which reduces the processing difficulty and effectively avoids errors caused by component assembly. Zernike free-form surfaces are introduced to correct aberrations. This optical system has a field of view of 5 ∘ × 5 ∘ and an f -number of 1.82; the modulation transfer function of the system is higher than 0.6 at 30 lp/mm. The results of the tolerance assignment of the system were verified by the Monte Carlo method, and the machining tolerance is reasonable and easy to achieve. This design not only improves the optical performance of the system but also enhances the feasibility of manufacturing.

Design of a Large Field of View and Low-Distortion Off-Axis Optical System Based on a Free-Form Surface

“…To date, the main parametric representations for optical free-form design include X-Y polynomials, Zernike polynomials, Q-polynomials, radial basis functions, and spline functions [21]. X-Y polynomial surfaces and Zernike polynomial surfaces have the same free-form surface characterization capability, have interconversion relationships, and are more often used in machining [22]. In recent years, an increasing number of research institutions have launched corresponding studies on the spatial application of free-form surfaces.…”