What are the requirements for processing accuracy of quartz optical glass after processing?

The precision requirements of quartz optical glass after processing are mainly reflected in the following aspects:

dimensional accuracy

Overall dimension: Generally speaking, it is common to control the overall dimension accuracy within ±0.05mm-±0.1mm for quartz optical glass elements used in general optics. For example, in some optical lens groups, the diameter dimension accuracy of the lens is usually ±0.05mm, and the thickness dimension accuracy is controlled within ±0.1mm to ensure accurate assembly with other optical elements. For components such as lithography objective lens with high accuracy requirements, the dimensional accuracy requirements may be higher, reaching ±0.01mm or even higher.

Aperture and groove depth, etc.: If there are structures such as aperture or groove depth on quartz optical glass, the aperture accuracy is usually required to be controlled within ±0.05mm-±0.1mm, and the groove depth accuracy is controlled within 0.1 mm-0.2 mm..

geometric accuracy

Flatness: The flatness requirement of ordinary optical lenses is generally λ/4-λ/2, where λ is the wavelength of visible light, which is about 0.4 μ m-0.7 μ m.. For high-precision optical plane mirrors, such as mirrors used in laser interferometer and other equipment, the flatness requirement can reach λ/10 or even higher.

Parallelism: The parallelism between two parallel quartz optical glass lenses is usually 10-30 arc seconds. In some high-end optical systems, such as the optical lens group of astronomical telescope, the parallelism requirement may reach 1-5 arc seconds.

Verticality: the verticality error between two adjacent surfaces of optical glass elements is generally required to be controlled within 10 arc minutes-30 arc minutes. In some special optical prism combinations, the verticality requirement may be higher, reaching 1 arc minute-5 arc minutes.

Angular accuracy: the angular accuracy of general optical prisms is required to be 1 arc minute-5 arc minutes. For prisms used in high-precision spectral analysis and other instruments, the angular accuracy may be required to reach 10-30 arc seconds.

surface accuracy

Surface roughness: For general quartz optical glass components, the surface roughness is required to be between Ra 0.1μ m and Ra 0.01μ m.. For components with higher optical performance requirements, such as lenses for high-resolution imaging and laser mirrors, the surface roughness may be required to reach Ra 0.001 μ m-Ra 0.005 μ m..

Surface defects: including scratches, pits, bubbles, etc. Generally speaking, for general optical elements, the scratch width should be less than 0.05mm and the length should be less than 1mm, and the number of scratches per square centimeter should not exceed 3-5; The diameter of pits should be less than 0.05mm, and the number of pits per square centimeter should not exceed 5-10. For high-end optical components, the defect requirements will be more stringent.

Optical accuracy

Refractive index uniformity: For ordinary optical glass, the refractive index uniformity should be 1× 10-5× 10. In some occasions that require extremely high optical performance, such as lenses of large optical telescopes and optical systems of high-end mask aligner, the refractive index uniformity can reach 1× 10-5× 10.

Birefringence: It is generally required that the optical path difference caused by birefringence is less than 5nm-10nm per cm thickness. In some optical systems that require strict polarization characteristics, the birefringence requirement may be lower, and the optical path difference per cm thickness is less than 1nm-2nm.