Common infrared materials and parameters

1. Zinc selenide (ZnSe)

CVD zinc selenide (ZnSe) is a chemically inert material with high purity, strong environmental adaptability, and easy processing. It has low light transmission loss and good light transmission performance. It is the material of choice for high power CO2 laser optical components. Because of its uniform and consistent refractive index, this infrared material is also ideal for protecting windows and optical components in forward-looking infrared (FLIR) thermal imaging systems. At the same time, the material is also widely used in windows and lenses in medical and industrial bolometers and infrared spectrometers.

2. Zinc sulfide (ZnS)

CVD zinc sulfide is a chemically inert material with high purity, insoluble in water, moderate density, easy processing, etc. It is widely used in the production of infrared windows, dome and infrared optical components. Like zinc selenide (ZnSe), zinc sulfide (ZnS) is also a material with good refractive index uniformity and consistency. It has good image transmission performance in the 8000nm-12000nm band. The transmittance, but as the wavelength becomes shorter, the absorption and scattering increase. Compared with zinc selenide (ZnSe), zinc sulfide has low price, high hardness, twice the breaking strength of zinc selenide, strong resistance to harsh environments, and is very suitable for the manufacture of infrared windows for missile fairings and military aircraft.

3. Calcium Fluoride and Magnesium Fluoride

Calcium fluoride (CaF2) and magnesium fluoride (MaF2) crystals, high hardness, strong resistance to mechanical shock and thermal shock, good transmittance in ultraviolet, visible and infrared bands, widely used in laser, infrared optics, ultraviolet Optics and high-energy detectors and other scientific and technological fields, especially their optical performance in the ultraviolet band are very good. They are currently known optical crystals in the ultraviolet cut-off band, with high transmittance and small fluorescence radiation. They are ultraviolet photodetectors. Ideal material for lasers and UV optics. Unlike calcium fluoride (CaF2), magnesium fluoride (MgF2) is a birefringent crystal.

4. Barium fluoride (BaF2)

Barium fluoride (BaF2) has an optical transmittance close to 90% in the spectral range of 200-9500nm. It is usually used in lenses, beam splitters, filters, prisms and windows in cryogenic refrigeration imaging systems, aerospace optical systems and laser optical systems. The material has a certain degree of water solubility and is suitable for use in dry environments.

5. Lithium fluoride (LiF)

Lithium fluoride (LiF) crystal has the smallest refractive index among commonly used infrared optical materials, and its transmission spectrum ranges from 120nm to 7000nm. It is usually used in lenses, prisms and windows of thermal imaging systems, aerospace optical systems and excimer laser optical systems . The material has a high water solubility and a large coefficient of thermal expansion.

6. Gallium Arsenide (GaAs)

Gallium arsenide (GaAs) crystal has good chemical stability, high hardness, and strong resistance to harsh environments. It has good transmittance in the 2um-14um spectral range, and is widely used in thermal infrared imaging systems, high-power CO2 laser optics system and the FLIR system. Gallium arsenide (GaAs) is often used to replace zinc selenide (ZnSe) as the material of infrared lens or window when the on-site environment is poor and the optical lens or window needs to be wiped repeatedly.

7. Germanium single crystal (Ge)

Germanium (Ge) single crystal is a chemically inert material. Its transmission spectrum ranges from 2-12um. It is a very commonly used infrared optical material. It has the characteristics of high hardness, good thermal conductivity, and insoluble in water. Widely used in infrared imaging systems and infrared spectrometer systems. Germanium single crystal has good mechanical properties and thermal conductivity, and the absorption at 10.6um is very small. It is an ideal material for CO2 laser lenses, windows and output coupling mirrors. Germanium single crystal is also used as the base material of various infrared filters.

8. Silicon single crystal (Si)

Silicon (Si) single crystal is a chemically inert material with high hardness and insoluble in water. It has good light transmission performance in the 1-7um band, and it also has good light transmission performance in the far infrared band 300-300um, which is a feature that other optical infrared materials do not have. Silicon (Si) single crystals are usually used as substrates for 3-5um mid-wave infrared optical windows and optical filters. Due to the good thermal conductivity and low density of this material, it is also a common material for making laser mirrors.