A static solution to aberrations and boresight error for tilted conformal aircraft windows at different look angles is reported, which is the use of tilted and decentered fixed correctors. The principle of the static solution is discussed, and three tilted and decentered fixed correctors are designed to correct the aberrations and boresight error for a conformal window. The correctors are fixed in position between the conformal window and the gimbaled imaging system, thus requiring no moving parts. The design result shows that the predominant astigmatism introduced by the conformal window is corrected by the tilted and decentered fixed correctors at different look angles. Moreover, the boresight error for the conformal window, as a function of look angle, is also corrected by the correctors. The root mean square wavefront aberration for the final conformal window imaging system is less than 0.2 wave across the full field of regard on the visible spectrum, and the boresight error is less than 0.5' across the full field of regard.
This paper discusses the optical design of an uncooled dual-band MWIR/LWIR optical system using a circular
unobscured three-mirror system which is particularly suitable for wide spectral range , large aperture and small volume
imaging systems. The system is designed at focal length 310mm, F-number 1.55 with field of view 1.77°×1.33°. A
coaxial three-mirror system is calculated by the paraxial matrix as a starting point. With the condition that the focal point
of each conic mirror is placed to coincide successively, elements in the system are tilted and decentered properly to make
the system unobscured and the mirrors are arranged to form a round configuration for compactness. The optical path is
folded inside the region surrounded by the mirrors. Zernike polynomial surfaces which are limited to be symmetric about
tangential plane are used to correct aberrations and to improve the image quality. The modulation transfer function of
this system is above 0.65 in MWIR band and above 0.5 in LWIR band all over the field of view at the Nyquist frequency
of 20 line pairs per millimeter. The result shows that the space can be utilized efficiently, the system is compact and
image quality is favorable.