A lens blank is a piece of glass or other transparent material with a rough cut and unfinished, often used as a starting point for making optical lenses. It is essentially the raw material from which a finished lens is produced. There are several factors to consider when selecting a lens blank, such as its refractive index, dispersion, and size. Once the appropriate lens blank is selected, it undergoes a series of operations to shape and finish it into the desired lens.
The process of turning a lens blank into a finished lens typically comprises of the following step:
- Grinding: This step involves removing a portion of the blank to create the lens’s basic shape or curvature. It usually done with the help of CNC machines.
- Polishing: After the grinding process, the lens must be polished to make its surface smooth and to enhance its clarity and optical quality.
- Coating: In this step, the lens may be treated with different coatings to enhance its performance. For example, an anti-reflective coating can be applied to reduce glare and enhance night vision, or a scratch-resistant coating can improve the lens's durability.
Learn more:
- Eyeglass lens blanks | Materials, sizes and layout
- Lens (optics) - Wikipedia
- How Eye Glasses are Made - Zeiss