Date post: | 03-Jan-2016 |
Category: |
Documents |
Upload: | alexander-mathews |
View: | 221 times |
Download: | 0 times |
Thanks to - Precision Optical Laboratory
A full service optical lab 7148 Midlothian Turnpike
Richmond, VA 23225For Information Call 804-745-0171
Fax at 804-745-5817
Surfacing Overview In Pictures
Also Called: Generating, GrindingThe creation of lens power
through the grinding of curvesDL = D1 + D2
Surfacing Is --- How a lens is created Lens begins as a chunk of plastic (or
glass) that is finished on the front but is just raw plastic (or glass) on the back
The back side is ground away with great precision with specific curves to match the curve on the front
This creates the necessary power or prescription
The Nominal Lens Formula DL= D1 + D2
DL = The power of a lens in diopters
D1 = The front curve or power D2 = The back curve or power DL = D1 is +8.00 D2 is -7.00 + 8.00 + -7.00 = +1.00 DL = +1.00
DL= D1 + D2
If the front base curve is a convex shape with positive or +8.00 power
And the desired Rx is +1.00 I will need to grind a concave
minus -7.00 curve on the back of the lens
Surfacing Is A 3 Step Process
Grinding (surfacing, generating) Removes material from back of lens
Fining Brings backside of lens to almost clear
Polishing Brings backside of lens to perfect
smooth clear finish that you can see through
Job Order FormsIt takes thousands of individual calculations to determine what curves will be ground.
Lens Blank StockS/V, Lined, Progressive, Transition, Polarized, Occupational, CR-39, Poly, Glass, Hi-Index…
Preparing Lens BlankFor all sphero-cylinder lenses axis position must be marked before blocking the lens
Protecting Lens BlankPlastic film placed over the front of the lens protects it from heat and scratching
Lens Is “Blocked”Alloy or wax is used to hold the lens blank to the surfacing blockThe block holds the lens in place through entire surfacing process
Lens blank is held to bock with alloy Block assures
proper alignment in grinder
Alloy creates bond with the lens & tape
Alloy is melted and reused
Surfacing Layout ScreenProvides all the information that the generator needs to complete the job
Job number Base curve Cross curve Center thickness Crib diameter Pin Bevel Layout Axis Prism Front curve Back curve Edge thickness Diameter Material Block Tool Aren’t you glad we have
computers!
Generator Cutting Wheel and Chuck Chamber The orange nozzle
sprays water on the lens and tool for cooling
The tool seen on the right has diamond blades that will cut away the back of the lens
The lens is seen on the left
Lens Off GeneratorNote Faint Red Axis LineLens back side is now an opaque smooth white with defined curves
Fining
Lens is chucked in machine Lens is sandwiched between block
and a mild abrasive pad Water or lubricant is sprayed on
pad while pad oscillates over a tool that matches the backside curves with near perfect precision
Machine holds lens in place using the block and pushes it against the tool which is covered with an abrasive pad.
Also See PowerPoint Presentation On Finishing
Finishing is the cutting of the surfaced lens to fit a frame
Labs Also Stock single vision un-cut lenses Tint lenses Drill lenses Assemble complete pairs Add decorative touches to lenses Some stock frames Some apply anti-reflective coatings in
house Labs can be as small as a few hundred
square feet or as large as a factory