Aspherical Lenses

Aspherical lenses are lenses with complex curved surfaces, such as where the radius of curvature changes according to distance from the optical axis.
Spherical lenses are subject to aberration and therefore cannot concentrate all the light into one point. Aspherical lenses, however, offer excellent aberration correction performance, which provides superior resolution, even with compact optics composed of a small number of elements.
The technology we introduce here is based on our long experience in aspherical fabrication.

High-precision ground and polished aspherical lenses

The surfaces of spherical lenses made of optical glass are ground into aspherical shapes by grindstones revolving at high speeds.
Utilizing expert craftsmanship, we established a system for high-speed aspherical grinding with nanometer-order precision.

In this process, the shape of a precisely ground master can be transferred to optical resin with the molding technique.
Nikon is especially good at this replica-forming technique, and applies it in manufacturing components for optical fiber communications and more.

High-precision grinding
After the grindstone is moved to grind the glass down to an aspherical curvature, the surface is polished.

Precision Glass Mold (PGM) aspherical lenses

In precision glass molding, optical glass is softened by heating, then shaped in an aspherical mold made of special heat-resistant material.

We have developed a special molding technique effective for medium- to large-diameter aspherical lenses, which were previously considered to be difficult to mold.
This technology is widely utilized in the manufacture of aspherical lenses for lenses for film-based and digital cameras.

PGM
The glass lens material is pressed at high temperature and pressure in the aspherical-shaped mold.

Hybrid aspherical lenses

This method is used to fabricate hybrid aspherical lenses combining glass and plastic.
UV-curable resin is injected between the spherical glass and the aspherical metal mold, and irradiated with UV to form a glass-resin hybrid aspherical lens.

Nikon has technology for each key factor, including materials, fabrication and measurement.

Renewed April 2007