Optical lens purchase and splinter generation and prevention

by:Crylight     2021-05-28

Generally speaking, lenses can be divided into two categories, namely optical lenses (glass) and resin lenses. There is a big difference between the two, and the purchase is carried out according to the different needs of the place of use and the individual. The main reference is as follows:

  Glass lenses include optical glass lenses and high-refractive-index lenses (known as super thin sheets), which have high hardness, good wear resistance, and dispersion Small (usually the dispersion coefficient is about 58), generally its quality and various parameters will not change with time, but the impact resistance and weight of glass lenses are slightly inferior to resin lenses, and glass lenses are not easy to be processed. It is often more difficult to process with frameless and half-frame glasses. Even if the frameless or half-frame glasses are processed, they will be particularly easily damaged during use due to the brittleness of the glass.

  Resin lenses are generally much lighter than glass lenses, and their impact resistance and post-processing performance are better than those of optical lens glass. The secondary processing of progressive multifocal lenses , The use of resin blanks can be well processed to achieve front and rear surfaces containing complex design curves. However, the disadvantage of resin lenses is that the surface hardness is low, which is easier to be scratched, and the dispersion is larger than that of glass lenses.

  Resin lenses and coated lenses are soft due to their characteristics, so you should always be careful not to let the mirror surface directly contact hard objects. It is best to use clean water (or wash with a small amount) when scrubbing. Clean it with detergent, and then use a special test cloth or high-quality tissue paper to absorb the water droplets on the lens, mainly to prevent dust from rubbing the surface of the lens.

   resin lenses have thermosetting materials and thermoplastic materials (such as PC films), but most lenses have multi-layer films. This kind of lens has poor high temperature resistance. Cracks will occur on the surface under high temperature. Be careful not to use it in places such as baths, saunas, etc. It is also easy to produce optical lenses in a car exposed to the sun for a long time. Coated lenses should also be used cautiously in places with dirty environmental conditions, so as to prevent dust from wearing the lenses or stains that are difficult to clean.

   reminds consumers that they should ask for the packaging of the lenses used in the glasses when matching glasses in the store to avoid difficulty in producing evidence when complaints about quality problems occur. And it is required to indicate the refractive index of the lens and the hardening condition of the film on the invoice (you can also indicate the item number and provide the lens packaging pocket corresponding to the item number at the same time). . At the same time, it is recommended that consumers should also properly understand the characteristics of various lenses, so that they can consume clearly.

   Generally speaking, spectacle frames can be divided into three categories, namely metal frames, plastic frames and metal-plastic hybrid frames. When choosing a spectacle frame, it should be done according to the different needs of the place where the spectacles are used and the individual. In addition to focusing on the price and beauty as the standard, pay special attention to matching the size of the selected frame with the interpupillary distance as much as possible, because this choice directly affects the internal optical quality and wearing comfort of the glasses.

  Lens splinters generation and prevention

  1. Improper lens molding conditions, residual stress, resulting in splinters.

   (1) The lens is tested for the presence of stress with a stress machine. The fewer patterns and colors, the better the vision.

   (2) Remove stress during annealing in drying furnace.

  2. The influence of the label on the 'split' of the lens.

   (1) The cut-shaped framed lens has a UV label, and it will split when it is washed or dried or placed on the label for a long time.

   (2) Check whether the label is acidic and the effect on the lens, cut the framed lens with a label, and use it for drying at 60°C and visual inspection after 4H.

  (3) Conclusion: Before using the UV label, it must be unfolded and then baked in an aspherical mirror oven at 80°C for more than 12 hours to volatilize the chemicals contained in it.

  3. Deformed frames or deformed lens framing combinations are prone to splinters. Before and after framing, a curvature meter must be used to measure whether the curvature of the frame is consistent with the curvature of the lens.

  4. When the cut-shaped lens body is too large, the curvature of the lens will be deformed, which is prone to splitting, the size of the lens body is moderate, and the force of the lens is moderate.

  5. Frame combination cleaning, drying, temperature should not be too high, below 60℃, time should not be too long, within 15 minutes. Otherwise, the lens will expand due to heat during the cleaning and drying process, causing cracks in the reinforced film.

  6. IPA: The IPA test is for the completely dried molded lens. After soaking for 20 minutes, there is no flake-like appearance. For lenses or cut-shaped pieces that have been placed for a long time and are framed, splits will occur after being soaked in IPA, which is not easy to use for inspection, and AC lenses are mostly present.

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