Laser technology, recognized as one of the most pivotal inventions of the 20th century, has been extensively utilized across a wide range of fields, including industrial manufacturing, medical cosmetology, communication transmission, and scientific research. Within this technological framework, quartz plates play an indispensable role due to their unique physical and chemical properties. This article systematically examines the key applications and underlying principles of quartz plates in laser technology.

1. The basic characteristics of quartz plates

Quartz (SiO2) is a crystalline material composed of silicon-oxygen tetrahedral units and exhibits a range of excellent physical and chemical properties, making it an ideal choice for applications in laser technology.

To begin with, quartz exhibits exceptionally high optical uniformity, with refractive index homogeneity reaching 10⁻⁶. This property is critical for laser systems that demand precise control over the beam propagation path. Within a laser resonator, even minor refractive index variations can cause significant degradation of beam quality, while quartz plates can effectively mitigate such adverse effects.

Secondly, quartz plates exhibit excellent optical transmission performance. Quartz demonstrates high transmittance across a broad spectral range, from ultraviolet to near-infrared wavelengths (approximately 160–3500nm). In particular, for ultraviolet laser systems, conventional optical glass exhibits strong absorption of UV light, whereas quartz maintains relatively high transmittance. This property makes it an ideal window material for UV laser applications.

Furthermore, quartz exhibits high mechanical strength and hardness, with a Mohs hardness rating of 7, enabling it to withstand considerable mechanical shock and abrasion. These outstanding properties collectively establish quartz as an indispensable functional material in laser technology.

2. The application of quartz plates in the core components of lasers

(1) Laser resonator lenses

The laser resonator, a core component of laser systems, is typically constructed from two or more mirrors that provide optical feedback and enable mode selection. Quartz has emerged as the preferred substrate material for these mirrors owing to its low coefficient of thermal expansion and high thermal conductivity. Particularly in high-power laser applications, even a small fraction of absorbed laser energy can lead to temperature increases. The use of quartz substrates helps minimize undesirable thermal lensing effects, thereby helping to maintain high beam quality.

For certain special lasers, such as excimer lasers that operate within the ultraviolet spectrum, common glass exhibits strong absorption of UV radiation and is susceptible to rapid damage. In contrast, ultraviolet-grade fused quartz glass offers high transmittance and an elevated laser damage threshold in the UV spectral range, making it a feasible material for resonator lenses in such laser systems.

(2) Laser output window

Almost all laser systems require an output window to emit the generated laser beam while isolating the internal components from external environmental influences. Owing to their broad spectral transmission range, quartz windows are widely used in various laser applications, spanning from the deep ultraviolet to the near-infrared region.

In CO2 lasers operating at a wavelength of 10.6 μm, although the transmittance of quartz in this spectral region is relatively low, output windows that meet operational requirements can still be produced through specific doping techniques or the use of synthetic quartz materials. In contrast, for widely used laser systems such as YAG lasers (1.06 μm) and helium neon lasers (632.8 nm), quartz windows are standard optical components in these systems.

3. The application of quartz in laser transmission and shaping systems

(1) The mirror in the laser light guide arms

In industrial laser processing systems, light guide arms are commonly used to transmit the laser beam to the processing area. These arms incorporate multiple sets of mirrors to alter the beam’s propagation direction. Owing to their high thermal stability and reflectivity, quartz mirrors can maintain consistent optical performance over extended periods, making them an ideal choice for high-power laser guidance systems.

Especially in applications requiring precise control of beam direction, such as laser microprocessing and precision measurement systems, the stability of quartz mirrors ensures long-term positional accuracy of the system. Even under high-power laser irradiation, their surface deformation remains minimal, thereby avoiding introducing significant wavefront distortion.

(2) Laser focusing lenses

Laser processing usually requires focusing the beam to a very small spot to achieve high power density. Quartz lenses have become the preferred choice for high-power laser focusing systems due to their high damage threshold and excellent thermal performance. Compared with ordinary optical glass, quartz lenses are less likely to produce thermal lensing effects under high-power laser irradiation and can maintain stable focal length and spot quality.

In conclusion, quartz plates, owing to their unique overall performance, play an indispensable role in laser technology. With ongoing advancements in materials science and precision manufacturing techniques, quartz plates are expected to continue enabling the expansion of laser systems into increasingly diverse applications.