Nanase factory, where ink coating is done, has high ratio of women working there. In addition to manipulating paint sticks with delicate fingertip dexterity, the process of applying a small amount of coating not only to the edge but also to an area of the element surface about 0.2 mm inside of the edge requires both skill and a sense of esthetics. Generally, women demonstrate skill in this area. The above photograph shows ink-coated lenses being loaded into a constant-temperature furnace to fix the antireflection optical coating to the glass. Since the elements are treated at a relatively low temperature for a lens manufacturing process, the trays are made of wood. The elements are carefully and gently manipulated as if by an esthetician.
At the moment when users open the package of a high-end optical device and hold it for the first time, they are struck by its “beauty.” That’s the goal we at Cosina have set in manufacturing. What’s more, we want our devices to endure the passage of time so that the users forever feel they are beautiful. Partial separation of the optical ink coating over time, a phenomenon referred to as “separation on round edges,” significantly damages the appearance of a lens. To prevent that from happening, the process in the constant-temperature furnace serves as an anti-aging measure. After coating the end face, the elements are washed again.
Once cleaned, the elements are installed inside the barrels. At this stage, individual elements are visually checked one by one, and washed again even if the slightest problem is detected in their appearance. Blemishes are not permissible even if they have no adverse effects on optical performance. In the installation process, an element that has passed the final inspection cannot be fitted inside the lens frame if of the exact same diameter. The diameter of the element must be slightly smaller than the frame, but not too much smaller. For easy installation that allows a perfect fit of the element inside the frame, the thickness of the ink coating is an important factor. An optical device exhibits its true beauty once several elements that have been accurately ink-coated are anchored in the specified positions and sequence. Esthetics are incorporated into every aspect of this process at Cosina.