THE OPTICAL-PROPERTIES OF HOT-PRESSED MAGNESIUM FLUORIDE AND SINGLE-CRYSTAL MAGNESIUM FLUORIDE IN THE 0.1 TO 9.0 MU-M RANGE

A polycrystalline high-density magnesium fluoride, fabricated into plates or shapes by hot-pressing, exhibits high in-line transmittance from 2.5 to 6.0-mu-m, and single-crystal magnesium fluoride extends from 0.1 to 6.0-mu-m. The ultimate and practical transmittance of hot-pressed magnesium fluoride using intrinsic and extrinsic reflectance, absorptance and scattering mechanisms, are investigated. The intrinsic scattering mechanism due to the polycrystalline structure is basically responsible for the tremendous difference in transmittance in the short wavelength region of the spectrum. The in-line transmittance of polycrystalline and single-crystal MgF2 is discussed in terms of sample thickness.