Infrared imaging seeker is the main direction of optical imaging seeker technology. Infrared imaging system determines the detection performance and tracking accuracy of the infrared seeker, and it is also the key factor for the miniaturization and lightweight of the seeker. Optical structure layout is the design key of infrared optical system. This paper introduces the traditional refractive, reflection, catadioptric optical system layout as well as the new off-axis reflection, hybrid refractive-diffractive, Kuder optical path, free-form surface optical form, and analyses its advantages and disadvantages from weight, volume, image quality, installation and debugging. Fairing is a key part of the optical system of infrared imaging seeker. It plays a high transmittance to the infrared band and protects the seeker from adverse external environment. This paper introduces the common materials of the fairing, the design of the fairing under hypersonic speed and the design method of the conformal optical system. The advance technologies of optical system design are introduced, including binary optics based on light wave diffraction theory, computational optics based on geometric optics, information optics and modern signal processing, micro-optics with great prospects for minimizing the seeker optical system, and adaptive optics which can overcome and compensate for the effects of atmospheric turbulence, and super lens technology using nanotechnology. This paper believes that the optical system of the future seeker should be based on the etching, material and surface design, and the technology of computational optics and signal processing will be widely used in optic design of seeker.
