The present invention provides an infrared-transmitting glass that is a chalcogenide glass, has a reduced Ge content, can sufficiently cover atmospheric windows, is free from highly toxic elements, such as Se and As, and is suitable for mold forming. Specifically, the present invention provides an infrared-transmitting glass suitable for mold forming, comprising, in terms of molar concentration: 0 to 2% of Ge, 3 to 30% of Ga, 10 to 40% of Sb, 45 to 70% of S, 3 to 30% of at least one member selected from the group consisting of Sn, Ag, Cu, Te, and Cs, and 0 to 30% of at least one member selected from the group consisting of Cl, Br, and I.

A mold for molding a glass product is provided. The mold includes a lower mold and an upper mold. The lower mold includes a lower pressing surface. The upper mold includes an upper pressing surface. The upper pressing surface includes a plurality of upper molding surfaces and an upper mold closing surface connecting the plurality of upper molding surfaces. The lower pressing surface includes a plurality of lower molding surfaces and a lower mold closing surface for connecting the plurality of lower molding surfaces. The upper mold closing surface and/or the lower mold closing surface include at least two mold closing regions sequentially arranged from center to outside. The at least two mold closing regions have surface roughnesses increasing from center to outside. The disclosure achieves the technical effect of even filling, synchronous demoulding, and reduced error between mold cavities.

Provided is a method for producing an inexpensive chalcogenide optical element having high performance. An inside of chalcogenide glass is also heated uniformly by heating the chalcogenide glass with an infrared ray (light LI). Therefore, a molded lens LE hardly causes a crack or the like, a work piece WP as a block of the chalcogenide glass can be softened in a short time, and time required for molding can be shortened. In addition, direct heating with an infrared ray (light LI) allows heating and cooling to be performed in a short time. Therefore, an effect of volatilization, oxidation, crystallization, or the like can be reduced, and the lens LE having a high transmittance can be molded. Press molding can be performed while the temperature of the second mold die 12 is lower than that of the glass. Therefore, the lens LE hardly causing fusion and having an excellent appearance can be molded with a low maintenance frequency.

A method for treating a mold includes grinding an outer metal surface of a mold body of the mold with a first material; lapping the outer metal surface after the grinding with a second material that is finer than the first material; and polishing the outer metal surface after the lapping to achieve an average surface roughness (R.sub.a) less than or equal to about 0.15 m and a waviness height (W.sub.a) less than or equal to about 100 nm. A mold for shaping glass-based material can include a mold body having an outer metal surface, wherein the outer metal surface has an average surface roughness (R.sub.a) less than or equal to about 0.15 m and a waviness height (W.sub.a) less than or equal to about 100 nm.

A method of manufacturing a plurality of glass members comprises bringing a first main surface of a glass substrate in contact with a first working surface of a first mold substrate, the first working surface being provided with a plurality of first protruding portions, and bringing a second main surface of the glass substrate in contact with a second working surface of a second mold substrate, the second working surface being provided with a plurality of second protruding portions. The method further comprises controlling a temperature of the glass substrate to a temperature above a glass-transition temperature to form the plurality of glass members, removing the first and the second mold substrates from the glass substrate, and separating adjacent ones of the plurality of glass members.