As anybody who wears reading glasses knows, having clean lenses is crucial when it comes to obtaining good results from optical systems. The Vertrel^® products are ideal for this application and several major customers have selected c to ensure their optical products are of the highest quality.

Naturally, the first question asked by designers and engineers is about the cleaning effectiveness of the solvent, which is easily documented and tested. But in the world of optical systems other important issues include materials compatibility (many lenses are plastic), compatibility with fragile coatings (used to improve the light-handling characteristics of the lenses), speed and throughput, cost and reliability. The Vertrel^® products offer great answers to these challenges.

The good news is that most lenses and prisms do not have complex shapes. They are simple, smooth, and gently curved. For most applications, it is relatively easy to clean these devices in inexpensive aqueous cleaning systems. But sometimes the aqueous systems cannot finish the job.

The primary contaminates on lenses are usually are dust, polishing media and water spots. The first two are artifacts of the manufacturing process and usually (but not always) organic in nature. These normally are removed with aqueous cleaning processes. Solvent cleaning for these contaminates usually is found only in small production runs, customized products or prototype work.

Vertrel^® specialty solvents are ideal answers for precision cleaning of optical components. The solvency of the cleaner can be tailored to meet the exact requirements of the application, while remaining compatible with materials and coatings.

Water spots are another story. It is almost impossible to remove water spots -- which are residues of the aqueous cleaning process -- with additional aqueous cleaning. These thin, fine but clearly visible imperfections can render an otherwise perfect lens a useless lump of glass. The fastest, most reliable, least energy-intensive and most consistent results are found by using high-performance vapor degreasers with Vertrel^® specialty fluids.

At the core of this problem is water itself. Water has high surface tension and a high boiling point. Surface tension causes water droplets to form on the lenses; the high boiling point means that it takes a long time for the water droplets to evaporate. (Surface tension-reducing surfactants and/or saponifiers usually cannot be used in the final rinse as they leave residues.) To overpower the the problems with water, it often is deionized to multiple megaohms, and heat and high-pressure air "knives" often are deployed. These "brute-force" techniques are less than ideal because they are slow, inconsistent, energy-intensive, require large areas of expensive floor space and are difficult to keep operating smoothly.

This means that vapor-phase cleaning is the technology of choice for final cleaning and for removing water spots. But the solvent choices are pretty limited. HCFCs were propular, but most of them are being phased out at the end of 2002. The brominated solvents are generally too aggressive, and they have significant toxicity, handling and environmental problems. The old style chlorinated solvents are not usually considered due to their toxicity and environmental problems.

Vertrel^® surmounts all of these issues. The Vertrel^® products are very dense, so they lift away inorganic contamination and dissolve organic oils, fingerprints and more. The Vertrel^® solvents can be tailored with additives to tweak the cleaning process to be perfect for the machine, components and coatings being used. These DuPont cleaners also have a much lower surface tension than water and they boil at low temperatures, so they evaporate quickly without spotting.

Cleaning lenses and optical systems with Vertrel^® is easy. A simple vapor degreaser is the only equipment required. Normally the parts are immersed only into the vapor of the solvent. The solvent condenses on the lenses, dissolves/displaces the contamination and rinses it down into the cleaning sump. Immersion and ultrasonics may be used to speed cleaning and boost the thoroughness of the cleaning.

Precision degreasing with Vertrel^® is simple, fast and very cost-effective. When quality counts, select Vertrel^®!

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The Vertrel^® solvents are used by several brand-name manufacturers of optical components and systems under non-disclosure agreements, so no case studies are available at this time.

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