SCHOTT solutions no. 1/2012 > Fiber Optics

Ultrapure PURAVIS™ glass optical fibers are manufactured at the German site in Mainz using an environmentally friendly process that includes neither lead nor arsenic or antimony. Photo: SCHOTT/C. Costard

Environmentally Friendly Fibers

SCHOTT sets new standards for high-tech glass optical fibers by launching PURAVIS™.

Thilo Horvatitsch

Glass optical fibers have conquered a wide range of applications in the area of light and image transmission. They open up many different applications in medicine, endoscopy, dental treatment, surgical microscopy or light therapy, for instance. They also offer new lighting options for the automotive world and product design or can be used to illuminate the field of work in the area of stereo­microscopy and industrial image processing (machine vision). When used for these purposes, these hair-thin fibers that are drawn from special glass at high temperatures offer a number of benefits. For instance, they deliver extremely high light transmission, are highly resistant to aging and weathering, in addition to being chemically resistant and nonflammable. This means they are ideally suited for use in security-related or futuristic fields like medical, aviation and automotive technology.

Tomorrow’s industrial standards will demand yet another increasingly important trait from materials like glass: environmental compatibility. And SCHOTT has now achieved a breakthrough in this very area. The technology group is introducing innovative, environmentally friendly glass optical fibers under the product name PURAVIS™ that offer several improved performance parameters compared to other types of glass fibers.
These high-tech fibers from SCHOTT are manufactured without using lead. Many other optical glasses and glass optical fibers still contain lead because this heavy metal actually increases the refractive index and acts as an optical stabilizer. In this case, the challenge that arose from not using lead was to come up with the right type of glass recipe with a high refractive index and excellent transmission.
Due to the superior optical properties of PURAVIS™ fibers – the photo shows them wound up on spools – more light is transmitted to the objects, while they retain their natural colors. Photo: SCHOTT/C. Costard
Furthermore, this newly developed, environmentally friendly process does not use arsenic or antimony either. Karen Holst, Product Manager for glass optical fibers at SCHOTT Lighting & Imaging, says it also meets future environmental requirements. As she puts it, “Every product that contains PURAVIS™ already complies with both the current and future EU regulations RoHS and REACH.”

The transmission of white light can be increased by up to ten percent by using carefully selected raw materials. Due to the fact that the colors shift only slightly, the illuminated objects also retain their natural color. For this reason, these fibers are particularly well-suited for medical applications like endoscopy or surgical microscopy.

Thanks to its improved numerical aperture, these light guides absorb more light to start with. At the same time, low attenuation in the visible range results in higher light yield at the end of the light guide. This means the light guide can have a smaller diameter and is thus easier to install.

Its improved chemical stability also extends the lifespan of the fibers. This is particularly important when it comes to medical reprocessing, in autoclaving and cleaning, for instance, but also for applications in automobiles. For instance, the company managed to reduce transmission losses after 100 autoclave cycles by up to 70 percent in comparison to conventional glass fibers.
SCHOTT hopes to be able to capitalize on these advantages as soon as possible. “We are in the process of replacing all of our conventional glass fibers with PURAVIS™. After all, this will enable us to work together with our customers on finding solutions to new challenges that extend well beyond current areas of application,” Karen Holst concludes. <|

“Environmental topics are the pacemakers for innovations”

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