Zinc Selenide is transparent from 600 nm - 16 µm and is ideal for IR applications. It is well-suited for optical elements in high resolution thermal imaging equipment. ZnSe also transmits some visible light, unlike Germanium and silicon, thereby allowing for visual optical alignment. However, it is quite soft and will scratch easily. ZnSe has an index of refraction of 2.403 at 10.6 µm.
    Standard CO2 ZnSe focus lens from D12mm to D38.1mm with different focal length from Yutai Optics are ready for customers. Customized ZnSe Lens and windows service is available as well. Other elements are made by Yutai Optics include ZnSe Spherical and Aspherical, Cylindrical lens, ZnSe plano or wedge windows, ZnSe prism.

Highly recommended ZnSe Optics from Yutai Optics:
D12/15/18/20/25/38.1mm focus lens,
ZnSe Prism,
0.5"/1"/1.5"2" ZnSe Windows,
2X/3X/4X/5X/6X/7X/8X ZnSe Beamexpander,
ZnSe beam combiner,
M85*1 F-Theta lens scan filed for 50*50/70*70/110*100....

 ZnSe Transmittance Chart: