20 Feb 2008
optics.org speaks to Edmund Optics about the performance improvements and cost savings it is predicting from its glass-polymer hybrid optics.
A range of hybrid optical components that combine both a glass and a polymer element is now available from Edmund Optics. The hybrid aspherized achromats are said to bridge the gap between colour-corrected achromats and spherical-aberration-corrected aspheres and suit applications such as fibre-optic focusing and high numerical aperture imaging.
"We saw a big gap in the market in terms of performance and cost," Gregg Fales of Edmund Optics told optics.org. "While the cost of machining aspheres does not scale well with volume, the cost of molding aspheres, and of manufacturing doublets, does. These components have better chromatic correction than typical achromats and nearly the same spherical correction as machined aspheres - all at a very affordable price."
According to Fales, these components will outperform machined aspheres in polychromatic applications with potentially an order of magnitude cost savings in volume. At the same time, he believes that they will outperform achromats in both monochromatic and polychromatic applications at very little extra cost.
The company creates its glass-polymer hybrid by manufacturing both a standard glass doublet and a mold for the aspheric surface. A liquid photopolymer is injected into the mold before the mold and the doublet are pressed together. The final step uses UV light to cure the polymer to the doublet and create the aspherized achromat.
Fales says that the polymer layer is typically just 100 microns thick and that the final component is greater than 99% glass. He adds that Edmund Optics can provide optical designers with all the information they need (an Abbe number and six reference index values) to model these lenses.
To date, Edmund Optics has successfully aspherized achromats from 9 mm in diameter up to 25 mm in diameter but is confident that this be extended down to 5 mm and up to 50 mm.
"The real advantage of this technology is with aspherizing achromats, but we could certainly apply it to singlets," commented Fales. "The radius can be concave, convex, or plano. The process is most advantageous for low f-number lenses (F/4 and below). Longer focal length lenses typically don't suffer from large amounts of spherical aberration so adding an aspheric surface will not upgrade the performance significantly."
Nine hybrid lenses are now available from Edmund Optics with diameters ranging from 9 to 25 mm and focal lengths from 12 to 50 mm. "We are eager to expand the family, and of course are eager to work with our customers to help integrate these designs, or custom designs, into their applications," concluded Fales.
Jacqueline Hewett is editor of Optics & Laser Europe magazine.