Spectacle and Eyeglass Lenses, Blanks, Etc.
The manufacture of spectacle lenses by the American Optical Company was begun in 1883. Prior to that time all such lenses were imported. Annoying delays and the difficulty in obtaining them in sufficient quantity to keep apace with the manufacture of frames, together with the generally unsatisfactory quality of the lenses, forced the American Optical Company into what has since become a most important department of its business. No foreign spectacle lens manufacturers had attempted to apply the idea of interchangeability of sizes and systematic standards of foci to their products. Lenses were set into frames only by slow, tedious and painstaking hand edging. There existed no set standards of surface quality, or center, nor was there even an attempt to employ a raw material of uniform density and clarity.
Today we have Centex lenses representing the most perfect examples of the spectacle lens makers’ art. Interchangeable eye sizes - any one of a thousand pairs will fit its corresponding eye size in any frame, absolute and exact focal powers and uniformity in color and index.
This standardization was brought to the highest degree of success because of the general acceptance by the optical public of systems and reforms inaugurated by the American Optical Company. These are accepted the world over today, wherever spectacles are made and sold.
Furthermore, by setting certain high standards of quality to be measured by expert inspection and governed by strict supervision, we have succeeded in educating the optical world to expect and accept only the most perfect goods that modern mechanical equipment and scientific efforts can produce.
Our plant used exclusively for the manufacture of lenses is located at “Lensdale,” about one-third of a mile south of the main works.
The Lensdale plant covers about forty acres of ground. Its buildings are conveniently situated with respect to one another, so that intercommunication and the handling of raw stock and goods in process is a matter of progression without lost time or effort.
There are three main buildings in the Lensdale group, and several subsidiary structures for the purposes connected with this work. The first in importance is the Grinding Department, where the raw glass is blocked, ground and polished.
This building has two floors. The lower floor is devoted entirely to blocking, making of molds and other operations preparatory to sending the blanks to the second floor for grinding and polishing.
When the blocks are ready for grinding, they are carried up to the grinding room on automatic conveyors and delivered to their respective machines according to the curve and operation required. After being ground and polished, the blocks are returned to the lower floor, where the lenses are picked off, washed and sorted for inspection.
This grinding room is in every way ideally adapted to the work that is done there. Lighted by skylights as well as large windows, the work is carried on under perfect conditions of light and sanitation, an important factory in increasing the percentage of Centex lenses produced. The grinding room is 485 feet long and 128 feet wide, and is entirely taken up with grinding and polishing machinery. The construction of the machines permits the operator to stop any one spindle at a time, or an entire machine may be stopped, the machines being driven by independent electric motors, each capable of developing 35 to 55 horse-power.
Each grinding machine extends across the entire floor, being 108 feet long. The number of spindles to a machine depends, of course, upon the curvature of the lenses ground, and varies from 200 to 1000. The total grinding capacity is about 10,000 spindles.
To prevent lenses from “chilling” and thereby becoming loosened from the blocks, this building is provided with a complete hot air system of heating kept in constant operation during cold weather.
A feature of the work in this department is the grading of emery for the several stages of surface grinding, and for supplying this material to the optical trade. This work requires expertness and judgment which comes of long experience, for the accuracy with which emery grading is done determines the length of time necessary to complete the grinding and polishing operations.
In connection with the first operations in lens making, one of the most important steps is the molding of rough glass to the approximate size and curve of the lenses to be made. This work is carried on in a building devoted exclusively to such work. All high power lenses and lenses having strong base curve, as Meniscus and Toric, Trial Set Lenses, Amoptiscopes and Condensers, etc., are molded, which saves a great amount of time formerly consumed in “roughing out.”
From the grinding plant, the lenses are carried by tramway to the new Lensdale building. This building, devoted to inspection and various other operations after grinding, is admirably adapted to the work.
There are four floors devoted exclusively to these operations under ideal conditions. This building was erected farther away from the road than any of our buildings so there would be the least tendency to accumulate dust and foreign particles on the polished surfaces, which is one of the most serious problems with which the manufacturer of lenses must cope. Next in importance is the question of proper lighting for accurate inspection and classification, the result of which determines the quality of the finished product.
In this building, these two problems have been happily solved, the first, as explained above, by locating the work far from the dust of the street and railroad, and second, by providing exceptional lighting arrangements.
The building is of steel reinforced concrete construction, and, therefore, absolutely fireproof. The side windows are exceptionally large, being 18 feet wide and 14 feet high, extending from floor to ceiling. At the end of the building, the windows are even wider, the average width being 22 feet.
During the daytime, the interior is almost as light as out-of-doors.
The ground floor contains the intricate automatic machines for bevel and rimless edging. These are so constructed that they will grind almost any required size or shape. Here also lenses are cut. Hundreds of hands are required for these operations. The cutting is done with surprising dexterity, operatives becoming very expert in this branch of the work. A large department in this building is devoted to manufacturing special forms of bifocal lenses.
Lenses not applied on special orders go to the storehouse, occupying two-thirds of the second floor, and are put into American Optical Company stock. Almost every kind, color and focus is carried subject to the immediate call of customers. Finished lenses coming via tramway from the grinding plant or sent up from the first floor go to the second floor, where they undergo the many operations necessary to produce marketable goods. Hundreds of employees are kept constantly at work examining and classifying the various qualities, selecting for thickness, centering and axis marking.
Interchangeable and rimless edge lenses are all tagged with their focus numbers by wonderful little automatic tagging machines.
Every lens is focused independently, so that the possibility of error in tagging them is obviated. Trial set lenses must be separately focused and neutralized, and perfectly centered before they are set into the rims.
Here orders for set goods, that is, frames or mountings set with lenses, are handled, hundreds of dozens passing through daily. All drilling is also done in this department.
Rigid supervision is necessary to prevent carelessness, which might result in scratching the surfaces of lenses. No two lenses are allowed to touch one another, and no employee is permitted to have more than one lens in his or her hand at one time.
One entire department is devoted to wrapping or enclosing in envelopes, as the case may be, packing, labeling, shipping, etc.
An interesting feature of this big building is its Receiving Department, or, more properly, its Clearing House, situated at one end of the second floor. All goods coming from other buildings or passing from one department to another must go through this room, so that here the progress of every order is known and recorded. Thousands of dozens of lenses are “cleared” daily and so systematic is this work that there is a daily balance sheet kept, giving accurate statistics of work done in every part of the Lensdale organization.
The building upon the southern boundary of the Lensdale property is largely used as a warehouse for the storage of all materials necessary in lens manufacture. Here may be seen hundreds of tons of optical glass cut to approximate size and gauged to thickness. Tons and tons of emery, corundum, rouge and such materials are kept here; also parts of machinery, grinding discs and supplies, ready for instant use. Part of this building is devoted to the chemical and physical laboratories of our Research Bureau, looking toward improvements in goods and methods.
Designation of Lens Selections
In order that a quality designation might represent a definite standard in lens production, the American Optical Company has prescribed certain limits above which all lenses must qualify to be considered as the first selection. These high standards, with actual examples of lenses coming within their respective classes, are carefully recorded and filed. Lenses coming with the first selection are designated by the registered name, Centex.
The exacting demands of modern optical practice make it imperative that all lenses for high grade prescription work measure up to the requirements guaranteed under the Centex trademark and it is vitally important that lens orders should specify Centex.
Centex lenses are produced from colorless crown specially manufactured optical glass of unvarying refractive index, dispersion and hardness, free from defects such as decentration, and from surface defects as scratches, flakes, etc. Centex lenses represent the first selection of our output and are the most perfect spectacle and eyeglass lenses that it is possible to manufacture upon a commercial scale.
Secons , as the name implies, are the second selection from our output.
American Optical Company Glass
White Glass: American Optical Company white optical glass is a colorless crown specially manufactured stock of uniform density, great mechanical hardness and unvarying index of refraction, remarkable for its whiteness, its clearness, its freedom from “seeds,” pits, striae and bubbles. This company consumes the entire output of great European glass works where exist ideal conditions and environment for making a raw product eminently suited to the manufacture of spectacle lenses. This glass is of the highest quality in all its physical properties.
Blue and Smoke Glass: Great care and attention is devoted to the selection of these standards in shades and thickness. In focused lenses, it is necessary to allow a variation of one-half shade either way. Shades are classified from Nos. 0 to 7, light to dark.
Amber Glass: Within the past few years, there has developed an unusually large demand for amber lenses. They are used particularly for auto goggles, shooting and driving spectacles. In focused lenses, only one shade (light) is regularly supplied. In plano, bent, coquille and mi-coquille forms, we furnish both the light and dark amber.
Pink and Amethyst Glass: The demand for these colors is so limited that we furnish pink and amethyst lenses only upon special order.
Euphos Glass: This glass has come into use with the past few years and is preferred by many over amber glass. It is of a yellow-green shade. We carry a large stock of this material in the rough form as well as some forms of finished lenses, as may be noted on the following pages.
Roentgen Glass: As the name suggest, Roentgen glass is used in spectacles worn by X-Ray operators. It is said to exclude the injurious rays of the Roentgen light, protecting the operator’s eyes from X-Ray burn, a particularly dangerous affliction. Furnished in white only.
Pebble: The hardness of pebble makes its universal employment for spectacle lenses somewhat impractical, as it necessitates special machinery, slow and expensive processes in every operation of manufacture from sawing the raw stock to edging and drilling the finished lenses.
Instructions for Ordering Lenses
The following instructions, while intended particularly for the attention of our customers, contain many suggestions that may be found of great assistance to the entire trade and we recommend a careful reading:
1. Order Books: All orders for lenses should be written on order sheets furnished by us in book form free of charge. Two forms of order blanks are necessary for which separate order books are furnished, marked respectively “AOCo Lens Order” and “AOCo Sphero Cylinder Lens Orders.” Detailed information for the use of these forms is printed in the front of order books and is very important. Orders for all lenses except Sphero Cylinders, Sphero Cylinder Torics and Other Curve Wafers should be entered on the regular form.
2. Description of Goods: Avoid the use of questionable abbreviations and ditto marks. Use only descriptions and abbreviations employed in this catalogue in writing lens orders.
3. Dioptral System: All focal powers should be written in the dioptral system. All powers of prisms should be written in prism dioptries expressed by the exponent D.
4. Foci: When necessary to manufacture special foci to order, an extra charge is made.
5. Quantity: Lenses are always considered as pairs, the quantity being expressed in dozens or fractions of a dozen. Thus, orders for three pairs should be written “1/4 doz.” : an order for a single lens should be written “1/24 doz.”, etc. Particular emphasis is placed upon this rule as applying to orders written on ‘Sphero Cylinder order sheets.
6. Thickness: Order should so state when rimless ® thickness is desired, otherwise, standard thickness is supplied. Rough lenses and optical blanks should be ordered to mm. thickness. Sphero Cylinder lenses of standard and rimless thickness should be ordered on separate sheets.
7. Drilling: Holes are drilled in rimless lenses to an accepted standard measured from the nearest edge of the hole to the edge of the lens. In ordering rimless lenses, it is necessary to specify number of holes to the pair: in the absence of such instructions, lenses are sent undrilled, “no holes.” “Two holes” would be interpreted as one hole in each lens. Holes are always drilled on center unless otherwise specified.
8. Size of Eye: All edged lenses should be ordered by number or letter indicating size of eye desired; when special sizes are wanted, millimeter dimensions should be given. An extra charge is made for sizes other than regular.
9. Special Segments: Orders for special segments other than regular 1.25 curve and Plano should be entered on AOCo Sphero Cylinder order sheets giving the two curvatures desired, not the focal power, same as in ordering Sphero Cylinders.
10. Reserve and Advance Orders: By keeping statistics on previous sales, it is possible to foresee future requirements and place orders in advance for subsequent delivery. Under certain conditions, we accept Reserve Orders for lenses which are made ready and held subject to the call of customers.
Important: In ordering, it is essential that orders should be read over carefully to ascertain whether all necessary details are entered against each item. It is desirable, in writing orders, to be brief and explicit, and thus avoid misunderstandings and delays consequent to the sending of order inquiries.
Always specify whether Centex or Secons are desired.
AOCO Lens Stock
Few besides those directly concerned in the manufacture of spectacle and eyeglass lenses have any definite conception of the quantity and multiplicity of kinds of lenses that are necessary to meet even the ordinary (to say nothing of the special) requirements of the optical trade. The combination of focal powers, thickness, sizes, forms, colors, edges, special details, etc., run into many hundred thousand kinds and the quantity which must be carried in AOCo stock of each kind multiplies the actual number of lenses into millions.
This vast lens stock must be systematically stored and recorded and forms a most important link in the AOCo service to customers, representing a great investment of capital made so that orders for lenses may be filled with no delay.
By no means do we intend to imply that the sizes and foci given are all that can be furnished, as we are prepared to make and are making all lenses for which there is any demand, and when the demand for any goods is sufficient to warrant doing so, we, at once, add those kinds to AOCo stock. For instance, it would be manifestly impractical to carry edged Toric compounds in stock so these lenses are carried only in the uncut form.
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