Aspheric Lenses

Esco Optics is a world class manufacturer of Aspheric Lenses. Esco Optics fabricates OEM

and custom aspheric lenses to satisfy any requirement or specification. Example applications of

aspheres include cell phone and small digital cameras and progressive eye glass lenses. Small

molded aspheres are often used for collimating diode lasers. The term aspheric simply means not

spherical. Aspheric lenses differ from spherical lenses in several ways.

The inherent shape of a spherical lens creates a problem called spherical aberration. Spherical

aberration is created when parallel light rays that pass through the central region of the spherical

lens focus farther away than light rays that pass through the edges of the lens. This results in many

focal points, which in turn produce a blurry image. To get a clear image, all rays need to focus at the

same point.

Most aspheric elements are rotationally symmetric and the radius of the surface changes with the

distance from the optical axis. Aspherical lenses eliminate spherical aberration in addition to other

system aberrations. This is perhaps the greatest advantage to considering an asphere in an optical

system. Elimination of spherical aberration also reduces the number of optical elements required in

an optical system. This added benefit lowers the weight and the cost to manufacture the

system. Aspheres also reduce some distortions.

A spherical surface is defined by the radius of curvature only. An aspheric surface can be defined by

up to 12 or more aspheric terms. The general form of an asphere is defined by the conic constant

(k). This is very important when evaluating the manufacturability of aspheres.

Manufacturing aspheres presents a challenge regarding traditional fabrication and metrology

methods. At Esco Optics our aspheres are manufactured with the aid of computer controlled

polishing. (CCP). CCP incorporates CNC machine tools and utilizes an aspheric contouring tool

path. Variable pressure and a flexible tool surface are also an integral part of CCP type processing.

CCP is very efficient at manufacturing rotationally symmetric aspheres.

Esco Optics aspheric manufacturing capabilities incorporate grinding and polishing on our CNC

Optotech machine tools. At Esco Optics our Optotech manufacturing cell is capable of

manufacturing aspheres from prototypes to high production. Coupled with the CNC technology at

Esco Optics is the tenured expertise of our master opticians.

Esco Optics has invested heavily in the metrology aspect of our asphere manufacturing cell as well.

Our recently purchased Mahr Marsurf LD120 3D asphere profilometer assures our customers of

accurate and repeatable measurements of our aspheres. Esco also utilizes Zygo interferometry.

Esco Optics has also recently established relationships with partners utilizing MRF polishing

techniques and SSI interferometry to allow us to offer high precision aspheres.

The manufacture of aspheres is not a new technology however it does demand a top down

organizational commitment to invest in the proper equipment, metrology and trained personnel. Esco

Optics has satisfied this criterion and is excited to offer aspheres to our customers.

If you are interested in in discussing our capabilities in depth or have a specific requirement, we will

be happy to talk with you. You can visit our website at www.escooptics.com. You can also reach our

Business Development Manager Ron Schulmerich at 1-800-922-3726 ext. 101 or email him

at ron@escooptics.com.