a) b) c)
an aspheric polymer surface, says Cory Boone, an optical engineer at Edmund.
“Aspherized achromats are cost-effective lenses that achieve
excellent correction for both chromatic and spherical aberra-
tions by combining a glass achromatic lens with a photosensi-
tive polymer using a unique polymer molding process,” Boone
says. “The polymer is applied only on one face of the doublet
through an easily repeatable procedure.”
Boone explains that the polymer surface reduces wavefront
errors present in typical achromats while boosting numerical
aperture. “They have better color correction than standard
achromatic lenses, and they have similar spherical aberration
correction to machined aspheres,” he says. “This results in an
economical means of meeting the stringent demands of today’s
optical and visual systems.”
By incorporating aspherized achromatic lenses into lens sys-
tems, great improvements in chromatic and spherical aberration
can be made in applications including fiber-optic focusing or col-
limation, image relay, inspection, beam expanders, scanning, and
high-numerical-aperture imaging systems, Boone adds. For ex-
ample, in a 1: 1 relay pair using two standard achromatic lens-
es, one or both of the achromatic lenses could be replaced by an
aspherized achromat to greatly improve spherical aberration cor-
rection for little extra cost, resulting in a higher-resolution image.
Precision glass molding of optical components is not limited
to production of single lenses. A wide range of more-special-
ized shapes, including lens arrays and more, are available (see
Fig. 4), most of which would be difficult to make economically any other way (although embossing, a technique in which a
metal mold is pressed into softened glass, is another mass-production approach being developed, for example, to create microlens arrays for illumination uniformizers).
FIGURE 4. The precision glass-molding process allows for specialized shapes. An optical component made by Fisba, called the Beam
Twister, is used to improve the coupling of light from laser-diode bars into optical fibers (a). These microlens arrays (b) are made by Isuzu Glass
(Torrance, CA); such arrays are useful for improving light coupling into sensor arrays, as well as improving the uniformity of light in illuminators.
(Courtesy of Fisba and Isuzu Glass)
For More Information
Companies mentioned in this article include:
St. Gallen, Switzerland
FOR A COMPLETE LISTING OF COMPANIES making molded
optics, visit the Laser Focus World Buyers Guide (http://buyersguide.
DISCLAIMER: While we try to include information from the broadest possible number
of companies that manufacture the products featured in our Photonics Products
series, because of limited word count as well as deadlines that cannot always be met
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