Optimize design of thermal infrared reflective baffle

Abstract

Baffle is the primary instrument for suppressing stray radiation outside of the field of view of optical system. Infrared optical systems detect thermal radiation from objects, which can be severely affected by the stray thermal radiation. The reflectivity of the vane of the reflective baffle is so high that it can reduce the stray radiation entering the optical system, and its own radiation is small, which meets the requirements of stray radiation suppression of thermal infrared optical systems. The Stavroudis baffle is the reflective baffle with ellipse and hyperboloid vane, which has a stable structure and great capability of suppression of stray thermal radiation. But its volume will increase sharply with the increase of the field of view of the optical system. In addition, the special shape of the baffle increases the difficulty of design and processing. This paper proposes an optimize design about conical reflective baffle, which can quickly and accurately design the baffle. The volume of optimized baffle is reduced by 25% compared with the baffle designed by the original method. In order to illustrate the performance of optimized baffle, comparing with the baffle with straight vane and unoptimized baffle, we simulate the stray radiation of three mirror anastigmat (TMA) with optimized baffle. The simulation results show that the point source transmittance (PST) of the optimized baffle is 1×10 -7 when the off-axis angle is more than 60 degrees, which is lower than the other two baffles. Finally we propose a high-efficiency and lowcost processing method for this baffle, and the mass of baffle is within 300g. The design and processing method of the reflective baffle proposed in this paper can complete the manufacture with high efficiency and low cost, which provides technical support for infrared optical systems.