Today’s AR Super Hydrophobic Lens

By Bill Markham
Today’s AR super hydrophobic lenses provide a major benefit for the consumer for ease-of-cleaning. Below are guidelines for successfully blocking, edging and mounting of AR super hydrophobic lenses.

Apply an edging enhancement sticker to the lens before applying the leap pad and block. This gives a better surface for the edging chuck to grip. A specific manufacturer offers a pad control layer and the enhancement sticker is not required. It is important to use a high-quality AR leap blocking pad. A high-quality AR leap pad will protect the lens from that unwanted lens slippage. Saving a few pennies on a leap pad can drive up spoilage and reduce the overall optical quality of the product.

It is important to use edging blocks that match the front curve of the lens. This is most critical on the flatter base curve lenses. During the blocking process the block must be clean and dry. Do not touch the block adhesive on the leap pad. Improper handling may cause block slippage during the edging process.

There are many edger manufacturers and edger models in the market place. It is best to contact the manufacturer for specific setup and instructions for edging AR super hydrophobic lenses.

The front side and backside chuck shapes must conform to the lens so there is no flexing of the lens. Be sure the edger chuck pads are clean and not worn out or damaged. Utilize the continuous lens rotation mode if available. Contact the manufacturer if the function is not available, many times a software upgrade is available. Calibrate the frame tracer to the edger, elongated A or B measurements are a greater concern for AR lenses.

• Fragile Mode – Use the fragile mode setting on the machine, if available. This setting can eliminate most issues or concerns during the edging process.

• Material Setting - Select the material option that corresponds to the lens to be edged.

• Sizing – Exact sizing is necessary, large lenses will create unwanted stress on the lens when mounted.

• Sharpness of the Cutting Wheel or Blade – A sharp and clean cutting wheel or edging blade is necessary. A dull cutting wheel or edger blade will cause a drag on the lens, which will promote slippage. If using a wet edger, make sure that the water is aimed primarily at the lens edges to keep good lens lubricity.

• Head Pressure and Feed Rate – Many technicians are interested in cutting lenses quickly as possible for high production. Reduce the edger head pressure and feed rate to the manufacturer’s specifications.

• Chuck Pressure – Clamping or chuck pressure that is set to0 low can allow for slippage but a high chuck pressure will allow for an excessive flexing of the center of the lens. Set the lowest amount of chuck pressure recommended by the machine manufacturer.

• Using blocks that match lens base curves is highly recommended to avoid undue lens center pressure.

• Keep in mind that the thinner the lens center is the more possible issues will be created when edging and mounting the lenses into a frame, so take special care with very thin lens centers.

* Deblocking the leap pad is a critical and final part of the process. Technicians many times will pry or pull the lens from the block; this can cause a flexing of the center of the lens. It is very critical that there be no prying or pulling on the block. The correct method for deblocking is to twist the leap block off of the lens using a special block holding device; the twisting action will cause no flexing of the center of the lens.

The ECP and the consumer deserve the best in an AR super hydrophobic lens. The advantages of today’s state-of-the-art super hydrophobic coatings far outweigh the care that is required in blocking, edging and deblocking AR super hydrophobic lens.

This article was provided by The Vision Council AR Steering Committee. To promote anti-reflective lenses, the committee provides education and marketing resources to the optical industry. For more information, please visit www.thevisioncouncil.org/ecp

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Labtalk-November/December 2017