By Judith Lee
Lens cleaning is a lot like the second or third leg in a four-man relay. It’s an essential step that can greatly affect the outcome, but it rarely gets the glory. “Lens cleaning is an important step, but it tends to be integrated with other processes,” noted John Quinn, president of Lens Technology International. “That’s even more the case as labs acquire in-house coating processes.”

What’s more, lens cleaning is fast evolving along with automated technology. That second or third leg in your optical lab “relay” is just as likely to be filled by man, machine or robot. Some labs (even large ones) still rely on hand cleaning, while others have gone to ultrasonic cleaning, and a few are looking to state-of-the-art robotics to cut labor costs and/or ensure quality.

“We don’t use anything complicated. We clean the lenses in soap and water and then dry them with a warm air blower,” said Mark Cohen, director of training and marketing for Tri-Supreme Optical.

Mike Cooper, vice president of lab operations said the lab has used other washing systems, but those became more labor intensive due to loading and unloading, and thus, produced no labor savings. Tri-Supreme cleans about 2,500 lenses a day, using Dawn liquid soap because it does not leave a residue. The lenses receiving AR coating are washed one more time according to Essilor standard operating procedure. “There is no plan or need to upgrade this process,” Cooper said.

Products for Manual Cleaning:
All Off Marking Ink Remover from Opti Source International This acetone-free product is safe on all lenses including polycarbonate, and removes progressive lens ink markings. No scrubbing is needed, and it dries quickly with no oily residue. All Off received the Optical Laboratories Association Award of Excellence.

Edmund Lens Cleaner from Edmund Optics Worldwide, This product was developed for use in the Edmund Optics manufacturing facility, and is safe for glass or hard plastic. Apply and wipe clean, does not leave residue.

This lens cleaning method is gaining quite a bit, in part because labs are bringing AR in-house.
“This is a ‘must have’ for lens cleaning prior to AR coating; ultrasonic cleaning comes as an integrated part of our coating equipment systems,” noted Brian Peterson, Satisloh director of coating technologies.

For instance, in Satisloh’s spin coat process, the lenses are surfaced, polished, receive a rough hand-wash, cleaned ultrasonically, baked in an “oven,” and then spin-coated. Satisloh’s T10 ultrasonic cleaner has six tanks, two containing tap water, two containing soap, and two containing deionized water. Along with using higher-pH soaps, the cleaner’s ultrasonic current bombards the lens surface to remove surface debris or residue, but does not damage the lens.

“The cleaning process is more aggressive but safer for the lens, and we minimize touching by human hands. These factors minimize breakage,” Peterson said.

Ultrasonic cleaning is not cheap, adding $60,000 to $80,000 to the equipment cost of your lab process. Peterson said the lab recoups the investment by saving on labor, reducing breakage, and producing a superior in-house lens coat.

Companies that offer ultrasonic cleaners as part of an integrated system include:
• Satisloh,
• Leybold Optics, Inc.,
• Coburn Technologies,
Companies that offer standalone ultrasonic cleaners:
• Satisloh,
• Crest Ultrasonics,
• Edmund Optics,

Two labs are intending to “leg up” from manual cleaning directly to a high-tech robotic lens cleaning system. FEA Industries currently employs a total of four full-time people to manually clean lenses on two shifts. They currently use Dawn or Joy diluted in water, and then blow dry the lenses. Owner Bill Heffner has a $150,000 robotic system on order.

“We’re getting the machine from OptoTech, who in turn is getting it from a German company called Team Henrich & Krall. These two machines will work together to allow us to improve the flow of our lab. De-blocking and removing tape can eat up a lot of time when doing it manually,” Heffner said.

You can see a video of both their deblocking and tape-stripping machines at Navigate on the left hand side to the “deblocking” and “tape stripping” video links.

Heffner said the system will pay for itself in 18 months: “In one year, we will save $99,000 in labor costs.”

At Maui Jim Prescription Lab, lenses are being cleaned manually because the company imprints a logo on the lenses. Ultrasonic lens cleaning would strip the logo off the lenses.
“We’ve looked at ultrasonic cleaning 10 ways from Sunday, and it doesn’t work for us,” said prescription lab manager, Paul Ponder.

Ponder has turned to a company called Cool Clean ( that has a robot called Sno Bot. The Sno Bot cleans with microscopic ice crystals. Currently the technology is being used to clean computer hard drives, and parts for medical devices such as artificial joints. Ponder has been working with Cool Clean for about a year to adapt it to optical lab use.

“We want a 100 percent automated system. Order trays would enter the system via conveyor where a robotic lens handling system would pick the lenses from the tray, place the lenses in a Sno Bot, then index the lenses into a rack that would be placed in an oven for degas prior to the thin film coating application,” Ponder said.

Right now Cool Clean is building the lens handling system. Ponder noted that this would be the first system of its kind in the optical business, and he expects it to cost “north of $500,000,” but it will be worth it.

“We will eliminate the use of chemicals, eliminate hand cleaning, and automate the front of our AR facility,” he said. “I haven’t found anything that would work for us.”


Labtalk June 2020