Abstract

Many objective lenses designed for very high volume production now typically contain aspherical surfaces. One such example is an aspherized version of the traditional Cooke triplet. While these aspherical designs are better than their antecedents, the basic design limitations, astigmatism and manufacturing sensitivities, remain. An inverse triplet having a negative, positive, negative configuration and aspherical surfaces has no all-spherical counterpart, but instead depends on the aspheres to correct the primary aberrations. If a sufficient number of surfaces are aspherical, there are more degrees of freedom than required for aberration correction, so the lens can be optimized to reduce the manufacturing sensitivities by reducing the amount of aberration correction contribution by an individual element.

© 1998 Optical Society of America