Ever wondered how we actually make “OUR SPECS MEET YOUR SPECS?” Well, follow us on a brief tour of Three Rivers Optical’s 30,000 square foot, state-of-the art manufacturing facility. You’ll learn a little more about our equipment, our process, and our commitment to accuracy, craftsmanship and quality. By the way, strolling is optional but scrolling is required!

Every mail, phone, and online order arrives here first for preliminary processing. A Customer Service Representative records the basic prescription information on a job order form and places the order in a job tray that will carry it throughout the manufacturing process.

Most orders include the frames selected by the wearer. The frames are placed in a sophisticated 3D tracing device where a stylus measures the shape of the frame and inputs all 540 points of its geometric measurements into our main computer.

Rimless glasses and nylon or wire cord frames cannot be traced like traditional frames. Instead, a lens template, supplied by the frame manufacturer, is placed in the 3D tracer and the measurements of the finished glasses are computed based on its lenses rather than its frames.

While tracing is underway, the Customer Service Representative completes the job order form by entering special codes for any lens options and extra services, such as tinting or coatings, that will be applied to each lens prior to the edging process. The job order and frames are placed in the job tray and sent to Data Entry.

TRO’s data entry personnel transfer the information on the handwritten job order form to a digital form in the host computer. The computer then correlates the order’s prescription, tracing and coding data and automatically makes all of the technical calculations necessary for the lenses to be manufactured. A barcode identification label affixed to the job tray ensures proper processing and tracking of each order.

Before manufacturing begins, a Quality Control Inspector matches the handwritten order form to a printout of the computer form to verify its accuracy. The Inspector then selects the appropriate semi-finished blank lenses from our vast lens inventory, places them in the job tray with the computer order form, and delivers the job tray to the next inspection station.

Blocking is a critical step in determining the accuracy of the prescription grinding process. Each lens blank is positioned over a special screen which is integrated with the host computer. The bar code on the job tray is scanned and the computer projects all appropriate blocking and layout information on the screen. An operator positions the “sweet spot” of the lens over the computer generated image and the Step 1 Blocker blocks the lens.

A block is actually a fixture used to hold the lens steady throughout manufacturing process. It is attached to the front of the lens using a heated free bond adhesive or wax. Once the lens has been properly positioned, the Step 1 Blocker affixes it to the block. The blocked lens is set aside to allow the adhesive to cool and the lens substrate to stabilize.

The blocked lenses are placed in the job tray and taken to a generator station where the prescription is actually ground into the blanks. Each generator is intergrated with the host computer. So, when an operator keys in the job tray code number, the generator queries the host for the appropriate curve and prism data for that order and automatically surfaces the lenses.

Once the prescription has been ground into the lens, it appears translucent much like a frosted glass. A series of smoothing operations are necessary to make the lens transparent. TRO has a huge array of cast iron laps each with a different prescription curve set into its facing. The front curve of the lap is matched to the prescription ground into the back curve of the lens by the generator.

The matching lap is then covered with an ultra-fine pad and mounted in an automated surfacing machine along with the blocked lens. A two-step process uses progressively finer pads to smooth the lens without altering the prescription. A final step, using a polishing pad and a polish slurry system, brings the surface to a clear, high sheen that is totally transparent and scratch free.

Polycarbonate lenses and high-index plastic lenses (which are typically thinner and have flatter prescription curves) require a hard backside coating to protect them from scratching. In a single machine, each lens is cleaned, spin-coated with a chemical solution, and cured under ultra violet light. The backside coating is applied prior to the edging process.

TRO offers state-of-the-art Zeiss anti-reflective(AR) coatings. All are multi-layer, two-sided AR coatings. This means each coating is actually a series of different chemicals applied to the lens at different times and in different thicknesses to produce the overall result.

The polished lens is cleaned by hand and loaded into a holding ring - a fixture that uses tension springs to grip the edge of the lens and hold it steady throughout the AR coating process. Next, a robotic, ultrasonic cleaning machine deep cleans the lens in a series of five ultrasonic baths each with a different cleaning solution, rinse temperature, and ultrasonic action.

In the Zeiss process, the lens is mounted in a more typical vacuum chamber. The coating chemicals are burned and become a gas which circulates throughout the chamber depositing coating molecules on the lens surface. After the AR coating is applied, the lens is transferred to a separate vacuum chamber and coated with an atomized sealer.

Depending on the type of coating applied, the lens is either delivered to the insertion or shipping departments or undergoes further processing.

After another visual inspection for surface quality, the lens can receive a number of additional treatments.

TRO offers a full range of lens tints from light fashion and gradient tints to dark sun tints. The lens is placed in a tint bath that has been heated to more than 200 degrees Fahrenheit. The heat opens the pores on the lens surface and allows the tint to be absorbed into both sides. The longer the lens stays in the dye, the darker the tint.

Lenses must be tinted prior to any AR coating. Plastic monomer and high-index plastic lenses will absorb varying amounts of tint and most will absorb enough to become full sunglasses. Plain polycarbonate lenses will not absorb tint. These must first receive a special tintable coating and then be tinted.

To this point, the surface of the lens has been ground, polished and possibly tinted and coated. Now, it’s time to shape the outside perimeter of the lens so it will actually fit into the specified frame.

TRO uses brand new, state-of-the-art Triumph 3D edgers. The operator scans the bar code on the job tray and the Triumph pulls up the original 3D tracing information from the host computer. The operator verifies the correct frame shape which appears on the Triumph’s LCD status screen. The edger automatically senses the size and shape of lens and a series of servo-controlled diamond wheels grind the precise edge geometry from rough cut to bevel (or groove if nylon or wire cord frames are specified) to polish under 60 seconds.

Some severe prescriptions get a special cosmetic edge treatment that reduces their apparent thickness and improves their overall appearance. And TRO adds an extra high-luster edge polish not available with standard edging treatments. We believe all of our customers deserve the finest edge finish possible.

Lenses can be inserted into their frames in any of four ways:

Each completed order is carefully wrapped in various subpacking materials and boxes to provide extra protection during shipping. Depending on the customer’s preference, TRO ships via the US Postal Service, United Parcel Service, Airborne Express, or any of three private carriers.