James P. Mills

Conformal dome correction with counterrotating phase plates

Windows and domes that are shaped to aerodynamic requirements can increase range and speed for the host platform. This class of optical systems is referred to as conformal optics. The solution discussed here is intended for conformal missile systems having gimbals that point the optical line of sight through different parts of the dome. A conformal dome induces large amounts of varying aberration, tens to hundreds of waves across gimbal angle, and therefore requires dynamic correction. Space is very constricted in missile sensors, and it is therefore highly desirable to limit the number of motors used for aberration correction. This paper describes the performance of a new class of optical systems that employ counterrotating phase prisms to correct conformal dome aberrations while gimbaling the optical system. The phase surfaces on the prisms are described by Zernike circular polynomials. Since the shear across the phase surfaces is rotational, the only aberrations that are generated are those without rotational symmetry, such as tilt, coma, or astigmatism. Using this approach, CODE V® was used to analyze and design a compact, high-performance conformal optical system.

Conformal dome aberration correction with counter-rotating phase plates

ABSTRACT Domes have been designed that conform to the aerodynamic requirements of airborne systems, as well as the opticalrequirements. Such domes have large amounts of aberrations - lOs to lOOs of waves. Typical systems also have gimbals thatpoint the optical line of sight through different parts of the domes. Aberrations vary significantly with pointing angle andtherefore require dynamic correction. This paper describes the performance of a new class of optical systems that employcounter-rotating phase plates to correct conformal dome aberrations. The correctors are described by Zernike circularpolynomials. Since the shear is rotational, only aberrations with non-rotational symmetry can be created, like coma orastigmatism. A theoretical development shows the relationship between the corrector surface shapes and the aberrationscreated. Code V was used to model the correction capabilities of the angular shear corrector plates.Keywords: conformal optics, dome, window, aberration, correction, phase plate