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Aspheric Lenses

Posted by Ron Schulmerich on

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 criteria 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 You can also reach our Business Development Manager Ron Schulmerich at 1-800-922-3726 ext. 101 or email him at

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