N-BK7 is a Schott borosilicate material. N-BK7 Optical Lens and Windows have the following characteristics: clear and uniform color, almost no bubbles and inclusions, high purity and uniformity, excellent chemical resistance and stain resistance , Has excellent transmittance and low absorptivity in the VIS to NIR spectrum. Therefore, in the manufacture of optical windows and optical mirror applications, N-BK7 windows are most often selected as the production material. It should be noted that N-BK7 is a very temperature-sensitive material, so it is not suitable for applications subject to thermal shock.