An aspheric lens or asphere is a lens whose surfaces have a
profile that is neither a portion of a sphere nor of a circular
cylinder. In photography, a lens assembly that includes an
aspheric element is often called an aspherical lens.
The asphere's more complex surface profile can eliminate
spherical aberration and reduce other optical aberrations
compared to a simple lens. A single aspheric lens can often
replace a much more complex multi-lens system. The resulting
device is smaller and lighter, and possibly cheaper than the
multi-lens design.

The optical properties of COC are exceptional, and in many ways very similar to glass. COC materials offer exceptional transparency, low birefringence, high Abbe number and high heat resistance. The moisture insensitivity of COC is often an advantage over competing materials such as polycarbonate and acrylics. The high flow of COC enables higher aspect ratio (squatter and shallower) optical component fabrication than other optical polymers. High ultraviolet transmission is a hallmark of COC materials, with optimized grades the leading polymer alternatives to quartz glass in analytical and diagnostic applications.