| 摘要 |
PROBLEM TO BE SOLVED: To prevent the generation of fog even under a condition generating dewing usually and to impart excellent abrasion resistance by constituting an anti-fogging coating layer of a porous MgF2 membrane. SOLUTION: An anti-fogging coating layer formed on the surface of a base material selected from a lens, a prism, cover glass, a filter and a mirror is composed of a porous MgF2 membrane. When steam in the vicinity of the surface of the porous MgF2 membrane is in a saturated state, the porous MgF2 membrane develops anti-fogging action such that steam adsorbed on the surface of the MgF2 membrane is not re-evaporated and a liquid droplet becomes a nucleus and water molecules in the atmosphere collide with the nucleus to grow the nucleus. When the liquid droplet becomes a size of a certain degree, the anti-fogging effect absorbed into the porous MgF2 membrane is generated by the pores of the membrane. The membrane filling ratio of the porous MgF2 membrane is set to a range of 20-80% and, by setting the filling ratio to 20% or more, the strength of the porous MgF2 membrane can be enhanced and, by setting the filling ratio to 80% or less, moisture is made easy to penetrate into the porous MgF2 membrane. The membrane filling ratio can be adjusted by a vacuum degree by a vacuum process and film forming temp. |
