Quartz Glass Transmittance Testing

Quartz Glass Transmittance Testing

Quartz glass is widely used in optics, electronics, lasers, and high-temperature applications, and one of its most important performance indicators is optical transmittance. Understanding how to accurately test the transmittance of quartz glass helps manufacturers ensure product quality, select the right material grade, and match components to demanding optical systems.

Transmittance refers to the percentage of incident light that passes through the glass within a specific wavelength range. Because quartz glass has excellent UV, visible, and infrared transparency, tests typically cover 190–2500 nm, depending on the application. For example, UV-grade fused silica requires measurements in the deep-UV band, while infrared-grade quartz may emphasize near-IR transmission.

The standard method for evaluating transmittance is the use of a UV-Vis-NIR spectrophotometer. During testing, a beam of light is directed toward the sample, and the instrument detects the intensity of light before and after passing through the glass. The difference between the two values is used to calculate transmittance. Samples must be cleaned thoroughly, placed perpendicular to the optical beam, and tested at multiple wavelengths to obtain a full spectral curve.

Several factors influence testing accuracy, including surface flatness, internal bubbles, micro-crystals, thickness variations, and coating layers. Therefore, manufacturers often conduct additional tests such as homogeneity inspection, refractive index measurement, and surface roughness evaluation to obtain a more comprehensive optical profile.

The resulting transmittance curve helps determine whether a piece of quartz glass meets optical-grade, semiconductor-grade, or industrial-grade standards. For precision optical devices—such as laser systems, UV curing machines, and scientific instruments—high transmittance and low absorption are critical to ensuring performance and minimizing thermal deformation.

By applying standardized testing methods and controlling material purity and production processes, manufacturers can ensure that quartz glass components deliver stable, high-efficiency optical performance across a wide range of industries.