What does surface quality 20-10 mean?

Understanding Surface Quality 20-10

Surface quality is a critical parameter in optical engineering, indicating the precision and clarity of an optical component's surface. It is particularly important in applications where high performance and minimal light scattering are required, such as in lasers, telescopes, and high-quality lenses. The notation 20-10, often seen in specifications for optical components, refers to a specific standard of surface quality.

Surface quality is assessed based on the number and size of imperfections, such as scratches and digs, on the optical surface. These imperfections can scatter light, leading to a reduction in the performance of the optical system. The standard for measuring these imperfections is defined by organizations such as the Optical Manufacturers Association (OMA) and the American National Standards Institute (ANSI).

The 20-10 notation is derived from the Military Standard MIL-PRF-13830B, which specifies the criteria for evaluating surface imperfections. In this context, '20' refers to the visibility of scratches when inspected under controlled lighting and viewing conditions, with '20' indicating that scratches must be barely visible under such conditions. The '10' refers to the size of digs (small pits or craters), with '10' specifying that the diameter of any dig should not exceed 0.1 mm.

Therefore, a surface quality of 20-10 means that the optical surface has minimal imperfections, with scratches that are barely visible under specific inspection conditions and digs no larger than 0.1 mm in diameter. This level of surface quality is often required for high-performance optical systems where even minor surface imperfections can significantly affect the system's overall performance.

In summary, the 20-10 surface quality standard is a measure of the precision and clarity of an optical component's surface, indicating a high level of manufacturing quality and minimal surface imperfections. This standard ensures that optical components meet the rigorous demands of applications requiring high precision and minimal light scattering.