Power Vision Optical World article
Fast and flexible AR coating
A state of the art AR coating process will soon be introduced by PowerVision Ltd in an affordable and compact machine capable of fast cycle times, reports Editor Gerald Ward
Most consumers are now aware of the advantages of AR coating on lenses. Reduced glare and improved cosmetic appearance are the important drivers of sales. Traditionally, AR coatings have been deposited in large expensive machines operated by lens manufacturers or large wholesale laboratories. For varifocal lenses, this has meant a time delay while the prescriptions have been sent off to a lab which operates with all the necessary surfacing and coating equipment.
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| The PV Express to be launched soon by PowerVision. The machine deposits a premium quality AR coating in about 10 minutes. |
In markets such as France, Germany or Japan this has never been a problem because the industry is dominated by large laboratories and consumers tend not to question the waiting time. However, it has been more of a problem in English speaking markets such as the UK or United States, where fast service is available through a network of smaller labs and even labs operated by retail opticians in shopping malls. It is no coincidence that the take up of AR coatings in these markets has been slower.
Even now, only about one in three lenses in the United States is AR coated. In recent years, smaller less expensive AR coating systems have become available in an attempt to address this need. Now a new company has joined the fray with a machine that competes with the big systems on optical quality using state of the art coating technology.
OPTICAL WORLD has learned that UK-based PowerVision Ltd is about to launch a new small AR coating machine to coincide with the timing of SILMO and Vision Expo West. According to PowerVision’s CEO, Dr Tony Williams, this new machine called the PV Express, produces a top quality AR coating which is superior to most made using traditional big box coaters. Tony Williams says ‘In contrast to other small systems which use only one target, the PV Express uses two targets. One is a high refractive index material and the other is a low refractive index material. This means we can deposit a multilayer Hi-Lo stack just like the traditional box coaters and the coating quality is excellent. The difference is that our machine can slide through a standard door frame and fits in a corner’.
New magnetron sputtering process
The PV Express uses a new magnetron sputtering deposition process which PowerVision has patented. The process has been developed by the engineering team at PowerVision which has over 50 man-years of experience in this technology. The machine coats six lenses at a time up to 80mm in diameter. The machine has a vacuum load lock to minimise cycle time, which is about 10 minutes per side, depending on the coating design. The machine can coat all common lens materials, including CR39, polycarbonate, glass and high index plastic lenses. The machine is easy to use. It is addressed through a simple touch screen control panel.
Recipes for various lens refractive indices are preinstalled and the operator simply chooses the appropriate recipe and then presses ‘Start’. The machine is fully automated and can even be operated remotely using an internet connection. For the advanced user, coatings can be customised using ‘Engineer’ level software which is accessed using a security password.
UV-cured hard coating Coating adhesion and scratch resistance are key to customer satisfaction. Tony Williams told the writer ‘We’ve chosen our coating materials specifically to provide great adhesion and scratch resistance. Of course, the quality of the underlying hard coat is also very important. The PV Express coatings are compatible with virtually all stock lenses which carry a thermally cured hard coat and there are now ranges of UVcured hard coats available for the concave face which are excellent’.
It is possible to provide a complete turn key package that includes a spin coater with a recommended UV-cured hard coat lacquer. The advantage of using a UV cure formulation is speed. The lacquer can be applied by spin coating and cured in an operation that takes less than 3 minutes. The spin coater also incorporates a high pressure lens cleaning system as the first stage of the process.
PowerVision will be installing its machines in smaller laboratories looking to coat about 50 pairs of lenses each day on both sides. The company also believe that large laboratories will use the machine for urgent jobs or for small batches of special coatings such as AR coatings on glass lenses or fashion mirror coatings for sunwear or skiwear. The PV Express is also ideal for use by large retailers or optical superstores with inhouse laboratories. The firm is even negotiating with a leading lens manufacturer to supply lenses already AR coated on the front to minimise the overall process time to fit in with the ‘one hour’ concept. The machine is programmed to produce a reflection colour to exactly match the pre-coated convex side. This idea is no surprise once it is realised that Dean Butler, the founder of Lenscrafters in the United States and Vision Express in the UK, is chairman of the company.