Optic lens is one of the main components in the optical experiment, which can be made of a variety of different optical materials for collimation, focusing and imaging of light beams. Various spherical and aspherical lenses provided by Newport are mainly made of BK7 glass, UVFS, infrared grade calcium fluoride (CaF2), magnesium fluoride (MgF2), and ZnSe. In the spectrum range from visible light to near-infrared which is less than 2.1 phenom, BK7 glass has good performance and moderate price. In the ultraviolet region up to 195nm, uv-fused quartz is a good choice. In the range of visible light to near-infrared 2.1 mm, fused quartz has higher transmittance, better uniformity and lower coefficient of thermal expansion than BK7 glass. Calcium fluoride and magnesium fluoride are suitable for deep uv or infrared applications.
- BK7 glass: BK7 is a common borosilicate corona glass, widely used as optical material in visible and near-infrared regions. Its high uniformity, low bubble and impurity content, and simple production and processing techniques make it a good choice for making transmission optical elements.The hardness of BK7 is also relatively high to prevent scratches. Transmission spectrum range of 380-2100nm. However, it has a high coefficient of thermal expansion, which is not suitable for the application of variable ambient temperature.
- UV Grade Fused Silica(UVFS): Ultraviolet fused quartz is a kind of synthetic amorphous fused quartz material with high purity.This amorphous quartz glass has low thermal expansion coefficient, good optical properties, and high uv transmittance, which can transmit ultraviolet light up to 195 nm. Its transmittance and uniformity are superior to those of crystal form quartz, and there are no such problems as orientation and thermal instability of quartz crystal. Due to its high laser damage threshold, molten quartz is often used in high-power laser applications. Its spectral transmission range can reach 2.1m, and has good refractive index uniformity and extremely low impurity content. Common applications include optical elements with transmittance and refraction, especially those with higher laser damage threshold.
- CaF2 calcium fluoride: Calcium fluoride is a kind of crystal material with simple cubic lattice structure. It has good transmittance in vacuum ultraviolet band and infrared band. This wide spectrum transmission, coupled with its absence of birefringence, makes it an ideal choice for uv-ir wide spectrum applications. Calcium fluoride has a transmittance above 90% in 0.25-7 fin m, and has a high laser damage threshold.Infrared calcium fluoride is usually grown from natural fluorite and is cheap.However, calcium fluoride has a high coefficient of thermal expansion and poor thermal stability. Calcium fluoride has a low refractive index, so it is usually not necessary to coat the film.
- MgF2 magnesium fluoride: Magnesium fluoride is a kind of crystal with positive birefringence, which can be grown by Stockbarger technology. The c axis is usually parallel to the optical axis during cutting to reduce birefringence.Magnesium fluoride is another optical material selected from deep uv to infrared, with a transmission range of 0.15-6.5 zea m.In addition, it can be used in fluorine-containing environment, can be used as a molecular laser lens, window, polarizer, etc.Magnesium fluoride has good thermal stability, hardness and high laser damage threshold.It also has a low refractive index and usually does not need to be coated. Magnesium fluoride is more durable than other optical materials that are deep ultraviolet to infrared. These properties make it an ideal choice for many biological and military applications of wide-band laser pulse imaging.
- Crystal Quartz Quartz Crystal: Quartz is a kind of uniaxial normal birefringence single crystal, which can be grown by hydrothermal method. It has good transmittance in vacuum ultraviolet to near infrared region. Because of its birefringence, quartz crystal is often used as wave plate material.
- Zerodur Microcrystalline glass: Zerodur is a glass ceramic material, the coefficient of thermal expansion close to zero, has excellent thermal stability. This makes Zerodur. It is an ideal choice for making optical lens substrate. Zerodur usually contains impurities, not suitable for making transmission optical elements.
- ZnSe zinc selenide: Zinc selenide can be prepared by chemical vapor deposition and is often used in thermal imaging and medical systems. Zinc selenide is a widely used infrared lens material with a wide transmission spectrum domain of 600nm-16 sodium m. It has a high refractive index and generally needs to be coated on the surface to reduce reflection. The zinc selenide material is soft and easy to be scratched, so it is not suitable for the rough environment.Pay extra attention to cleaning and installation. Due to its high transmittance and heat resistance, zinc selenide is the best choice of optical element materials for high power co2 laser.