Selected Materials for Ultraviolet Light Reflection and Visible Light Transmission in Optical Applications

Optical materials play a crucial role in the design and functionality of various devices and systems, such as filters, lenses, and other optics. In numerous applications, the requirement to selectively reflect ultraviolet (UV) light while allowing visible and infrared (IR) light to pass through presents a unique challenge. This article focuses on a specific material that excels in this regard—CR39 polycarbonate plastic lenses.

Introduction to CR39 Polycarbonate Lenses

CR39, a resin-like thermoplastic developed by Union Carbide in 1941, has become a popular material for producing various optical components due to its excellent optical properties, impact resistance, and ease of fabrication. CR39 polycarbonate lenses are ideal for applications requiring high clarity and light transmission while offering superior UV protection.

Material Properties and Benefits

CR39 is known for several key properties that make it an ideal choice for optical applications:

Transmit Visible Light: CR39 polycarbonate lenses provide high visible light transmission, ensuring that the clarity and sharpness of the visible spectrum are maintained. This makes it highly suitable for protective eyewear and photochromic lenses where maintaining natural color perception is crucial. Block UV Light: The polycarbonate material effectively blocks harmful UV rays, providing a layer of protection against ultraviolet radiation, which can cause various health issues such as eye damage and skin cancer. High Refractive Index: With a refractive index of approximately 1.6, CR39 polycarbonate lenses can bend light more efficiently than glass, allowing for thinner lens designs while maintaining equal diopter strength. This translates into lighter and more comfortable eyewear and other optical devices. Thermal Stability: CR39 lenses exhibit excellent thermal stability, making them robust even in extreme temperature conditions. This stability ensures that the optical properties of the lenses remain consistent over time and in various environments. Durability: These lenses are highly resistant to impact and can withstand repeated bending and flexing without losing their optical clarity. This makes them a preferred choice for protective eyewear and safety goggles.

Applications of CR39 Polycarbonate Lenses

Given its unique properties, CR39 polycarbonate lenses find extensive use in various applications, including:

Safety Eyewear: CR39 lenses are commonly used in safety goggles, face shields, and helmets, where protection against UV radiation and impact is essential. Laboratory Equipment: In environments where UV light exposure is a concern, such as laboratories, CR39 lenses provide a safe and effective solution for protecting eyes and skin. These lenses change tint when exposed to UV light, offering excellent UV protection and comfort for outdoor activities. Prescription Eyewear: The versatility of CR39 polycarbonate lenses makes them suitable for prescription glasses, bifocals, and other corrective eyewear, providing both UV protection and comfortable wear.

Comparison with Glass and Other Materials

When comparing CR39 polycarbonate lenses with traditional glass and other materials, it becomes clear why CR39 is the preferred option in many applications:

Weight: CR39 polycarbonate lenses are generally lighter than glass lenses due to their lower density. This lighter weight results in more comfortable wearing experience for users, especially in extended usage scenarios such as glasses. Thinness: The higher refractive index of CR39 allows for thinner lens designs, which is particularly advantageous for high-diopter prescriptions. This not only reduces the overall thickness of the lens but also improves the aesthetics of the eyewear. Shatter Resistance: CR39 lenses are more resistant to shattering and thus provide better protection in case of impact, compared to glass lenses which can be quite fragile. UV Protection: CR39 lenses offer better UV protection compared to many other materials. While some plastic lenses might have inferior UV blocking properties, high-quality CR39 polycarbonate lenses excel in this regard, ensuring that users remain protected from UV radiation.

Conclusion

In summary, CR39 polycarbonate lenses stand out as a superior choice for applications requiring the selective reflection of ultraviolet light while maintaining high visibility and infrared transmission. Their combination of high refractive index, superior UV protection, and thermal durability makes them the ideal material for a wide range of optical applications, from safety eyewear to prescription glasses.

If you are looking for optical materials that can effectively block harmful UV rays while ensuring clear and comfortable vision, CR39 polycarbonate lenses are an excellent choice. They offer a balanced combination of optical performance, durability, and comfort that meets the needs of various applications and users.