What are the requirements for polishing quartz optical glass after processing in surface accuracy?

Polishing quartz optical glass after processing has the following requirements for surface accuracy:

Surface roughness: generally, it is required to reach nanometer level or even higher accuracy. For example, for some high-precision optical lenses, the surface roughness may be required to be below Ra 0.1nm to reduce light scattering and improve optical transmittance and imaging quality.

Surface accuracy: usually measured by peak-valley value (PV) and root mean square value (RMS). For quartzite optical glass in ordinary optical system, the PV value of surface accuracy may be required to be between several microns and dozens of microns; For the optical elements in high-precision astronomical telescopes or mask aligner, the surface accuracy is extremely high, and the PV value may reach submicron or even nanometer level, and the RMS value is also very small, so as to ensure the accurate refraction and focusing of light and reduce optical aberration.

Surface defects: including scratches, pits, bubbles, etc. In high-precision optical glass polishing, obvious scratches and large pits are not allowed, and the number of bubbles needs to be controlled at a very low level. For example, in quartz optical glass used in high-end fields such as aerospace, the number of scratches and pits per square centimeter is usually required to be no more than a few, and the size should be controlled below a few microns.

Edge accuracy: the verticality, flatness and chamfering accuracy of the edge also have certain requirements. The verticality deviation of the edge is generally required to be within a few minutes, the flatness is required to be close to other areas of the surface, and the size and accuracy of chamfers should be uniform to ensure the stability and optical performance of optical elements during installation and use.