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Characteristics of quartz glass optical accessories

The optical performance of quartz glass has its unique characteristics. It can not only pass through far ultraviolet, but also is one of the best UV materials, able to pass through visible and near-infrared spectra. Quartz glass has advantages such as high temperature resistance, low coefficient of thermal expansion, good chemical stability, bubbles, stripes, uniformity, and birefringence, making it an optical material with high stability under various unfavorable conditions. According to their optical properties, they can be divided into three categories: K1 quartz glass, K2 quartz glass, and K3 quartz glass.

K1 is transparent within the UV and visible spectral range; No absorption band in the 185-2500nm wavelength range; There is a strong absorption band in the range of 2600-2800nm; Non luminescent, stable light radiation.

K2 is transparent in the ultraviolet and visible spectral range; No absorption band in the range of 200-2500nm; There is a strong absorption band in the range of 2600-2800nm; Non luminescent, stable light radiation.

K3 is transparent in both visible and infrared spectra, and there is no obvious absorption band in the 2600-2800nm wavelength range. Compared with ordinary silicate glass, transparent quartz glass has excellent transmission performance throughout the entire wavelength head.

In the infrared region, the spectral transmittance of quartz glass is higher than that of ordinary glass, and in the visible light region, the spectral transmittance of quartz glass is also higher. In the ultraviolet band, especially in the shortwave band, the multispectral transmittance is influenced by three factors: reflection, scattering, and absorption, and is superior to other glass. The reflection of quartz glass is generally 8%, with a larger ultraviolet region and a smaller infrared region. Therefore, the transmittance of quartz glass generally does not exceed 92%. The scattering of quartz glass is very small and can be ignored.

Spectral absorption is closely related to the impurity content and production process of quartz glass. The transmittance below 200nm represents the metal impurity content, the absorption at 240nm represents the anoxic structure, the absorption in the visible band is caused by the presence of transition metal ions, and the absorption in the visible band is caused by the presence of transition metal ions. The absorption peak at 2730nm is the hydroxyl absorption peak, It can be used to calculate the content of hydroxyl groups.

Method for calculating spectral transmittance using spectral absorption hydroxyl groups: A GE company’s calculation formula: C=910/T * LOG10 (Ta/Tb) mm-1 C: hydroxyl content (C, ppm) T: thickness (mm) Ta: 2600 nm wavelength transmittance Tb: 2730 nm wavelength transmittance B: China’s national standard calculation formula: C=96.5/d * LG10 (Ia/I) mm-1 C: hydroxyl content (ppm) d: thickness (cm) Ia: 2730 nm baseline to zero distance (mm) I: 2730 nm absorption peak to zero distance (mm) Spectral transmittance: thickness 1mm) Spectral transmittance of other thicknesses can be derived using the formula: T=(1-R) 2 e at T: transmittance R: single reflection loss. e: Natural logarithmic base

The impact on the thermal properties of quartz glass. The viscosity of quartz glass is a characterization of its thermal properties, which is closely related to temperature. The hydroxyl group defect in quartz glass causes the Si-O bond to break, thereby reducing the viscosity of quartz glass. At lower temperatures, the effect of hydroxyl groups on the viscosity of quartz glass is more pronounced.