Common Materials of Optical Prisms and Their Corresponding Spectral Transmission Ranges
- Introduction of prisms
A prism is an optical component designed to alter the direction of light propagation. Common types include triangular, quadrilateral, and hexagonal prisms. Prisms are typically fabricated from optical glass or crystalline materials, with the choice of material directly influencing key performance parameters such as transmittance, dispersion characteristics, and durability. Optical glass offers high transmittance and cost-effectiveness, making it the preferred material for most standard prism applications. Crystalline materials (such as fused quartz and calcium fluoride) are used in applications requiring specific optical properties. Furthermore, certain crystals exhibit superior performance compared to normal glass, rendering them suitable for operation in high-temperature or high-humidity conditions. In practical implementation, it is necessary to select an appropriate material based on the specific spectral range.
- Comparing glass and quartz as prism materials
Glass is a prevalent optical material, distinguished by its high transparency and cost-effectiveness, and is well-suited for the visible light spectrum. The following glasses are commonly used: BK7 glass, SF6 glass and fused silica glass. When manufacturing prisms, the glass most commonly used is BK7 glass, which has stable optical properties and is not easily affected by environmental factors such as temperature and humidity.
Quartz is a colourless and transparent mineral with high levels of hardness. It boasts a range of excellent properties, including high light transmittance, heat resistance, acid and alkali resistance, and resistance to natural radiation. It is especially well-suited for applications in the ultraviolet spectrum. When manufacturing prisms, the most commonly used quartz types are super white quartz and common quartz. Among them, super white quartz is characterized by its higher purity, making it suitable for the production of high-precision optical devices.
- Thewavelength regions applicable to different prisms
Prisms fabricated from different optical materials exhibit distinct spectral transmission, making them suitable for specific wavelength regions. The common spectrum regions include visible, infrared, and ultraviolet light.
The visible light region consists of light with wavelengths ranging from 400 to 700 nanometres, encompassing colors such as red, orange, yellow, green, blue, indigo and violet. For applications within this spectral range, glass is the predominant material used for prism fabrication, with BK7 glass being the most widely used.
The infrared region refers to the light spectrum with wavelengths ranging from 800 nm to 1 mm. While it is not visible to the human eye, it can be captured by equipment such as thermal imagers. The most commonly used prism materials in the infrared region are semiconductor materials such as silicon and germanium.
The ultraviolet region refers to the optical area with wavelengths ranging from 10nm to 400nm. Due to its shorter wavelength, it is capable of generating very strong photochemical reactions and is widely used in fields such as fluorescence, ultraviolet analysis and blue laser. In the ultraviolet region, quartz is the prism material of choice, including super white quartz and common quartz.
- Conclusion
A prism represents a fundamental optical element, with glass and fused quartz serving as the primary material choices. Glass demonstrates optimal performance within the visible spectrum, whereas fused quartz is preferred for applications in the ultraviolet spectrum. Consequently, selection of prism materials must be based on the target spectral region to ensure optimal optical performance.
