A new approach to correct chromatic aberrations utilizing a hybrid surface

Abstract

A diffractive surface provides a unique method of achromatizing an optical system. Conventional techniques of achromatization with refractive elements utilize the balancing of optical powers and lens material properties to provide a corrected system.1 This requires the introduction of more refractive power than necessary in the system to satisfy the first-order requirements. The addition of more optical power typically requires steeper surface radii and the general correction of the system performance becomes more difficult. A diffractive surface provides a more natural method of achromatizing a system because refractive and diffractive surfaces of the same sign of optical power provide an achromatic solution.2 Hence, the need to introduce excess amounts of optical power to satisfy the first-order properties is eliminated. The diffractive surface can also be utilized to provide aspheric correction, although the wavelength range must be limited to reduce the effects of spherochromatism. In addition, the potential operating wavelength range is limited because of loss in diffraction efficiency introduced from wavelength detuning.