PURPOSE: To obtain an infrared-transmitting lens by forming glass capable of efficiently transmitting infrared ray emitting from a human body and having 8-12μm wavelength by minimizing absorption peak near 12.5μm wavelength assigned to Ge-O stretching vibration.
CONSTITUTION: The objective glass contains germanium and sulfur as main components and carbon in an amount of 0.00015-1.0atom.%. As a carbon raw material, active carbon, graphite or decomposed material from benzene formed in the inner face of a glass melting vessel 1 is used. The decomposed material from benzene is formed by no-load firing the glass melting vessel 1 at 1100°C while evacuating a melting vessel 1 to a vacuum and then introducing benzene vapor and immediately thereafter thermally decomposing the vapor to form a carbon film on the inner wall of the glass melting vessel. Infrared ray lens for infrared ray sensor can be prepared in good productivity by subjecting the glass obtained using the above-mentioned constitution and capable of transmitting infrared ray and visible light and free from toxicity to thermal press forming.
SUGAI MASAKATSU
IKEDA MASAKI
YOSHIDA AKIHIKO
