Silicon (Si) lenses and windows are an ideal choice for applications using wavelengths in the near-IR range and parts of the mid-IR range. Silicon offers high thermal conductivity and low density, making it suitable

for laser mirrors. However, since silicon has a strong absorption band at 9 μm, it is not suitable for use with CO2 laser transmission applications. Silicon optics are also particularly well suited for imaging, biomedical, and military applications.