Conformal optical design using counterrotating wedges and Zernike Fringe sag surfaces

Conformal domes are often deviated greatly from spherical surface descriptions, so severe aberrations which vary with the field-of-regard (FOR) angle are introduced by the domes. Therefore dynamic correction is required. Two counterrotating Risley prisms and two lenses are used to correct the dynamic aberrations. The inner surfaces of the counterrotating prisms and the two lenses are described by Zernike Fringe polynomials. The scan of the field of regard is achieved by counterrotating the Risley prisms about the optical axis. The performance after correction in terms of Zernike aberrations and RMS spot size versus FOR angle is reported by an example. For comparison, the RMS spot radius is reduced to 16-68μ.m after the final correction, which is approximately 0.8-4.5 times Ariy spot radius, which is much better than the 30.2-69.1 times in the baseline system. The design results show that the counterrotating wedges and the two lenses which both have Zernike fringe sag inner surfaces are good correctors in conformal optical design.