A device for manufacturing SiO.sub.2TiO.sub.2 based glass by growing a glass ingot upon a target by a direct method. The device includes the target, comprising a thermal storage portion that accumulates heat by being preheated, and a heat insulating portion that suppresses conduction of heat from the thermal storage portion in a direction opposite to the glass ingot.

A glass including at least one type of oxide selected from TiO.sub.2, Nb.sub.2O.sub.5, WO.sub.3, and Bi.sub.2O.sub.3 as a glass component therefor, having a total TiO.sub.2, Nb.sub.2O.sub.5, WO.sub.3, and Bi.sub.2O.sub.3 content of at least 20 mol %, and having a OH value indicated in formula (1) that fulfills the relationship indicated in formula (2).
OH=[ln(B/A)]/t(1);
OH0.4891ln(1/HR)+2.48(2).

A mold which is made of a porous heat-resistant material comprises a first surface and a second surface opposite to the first surface. A plurality of light guide spots are formed on the first surface. The light guide spots are light guide spots. The first surface is a smooth polished surface, the mold enables direct manufacture of light guide plates for less heat expended.

A process deciding method in a method of manufacturing an optical element by heating and press-molding an optical material to mold the optical element using a molding die on which a release film is formed, includes a basicity degree identifying process in which a degree of basicity of the optical material is identified; and a removing process determining process of determining whether to perform one or both of first removing process in which an oxidizing substance is removed and a second removing process in which a basic substance is removed from at least one of a surface of the optical material and a surface of the release film by comparing the degree of basicity of the optical material identified in the basicity degree identifying process with a predetermined reference value, before press-molding the optical material.

According to various embodiments, a back surface plate configured to form a back surface of an electronic device may include: a first glass part including a first pattern area including a pattern having a predetermined shape on a first surface; and a second glass part, at least a portion of which is disposed on the first surface of the first glass part, the second glass part including a first shape complimentary to the first pattern area, wherein the second glass part may have a color different from the color of the first glass part.

According to various embodiments, a back surface plate configured to form a back surface of an electronic device may include: a first glass part including a first pattern area including a pattern having a predetermined shape on a first surface; and a second glass part, at least a portion of which is disposed on the first surface of the first glass part, the second glass part including a first shape complimentary to the first pattern area, wherein the second glass part may have a color different from the color of the first glass part.

The present invention relates to an apparatus and method for purifying materials using a rapid directional solidification. Devices and methods shown provide control over a temperature gradient and cooling rate during directional solidification, which results in a material of higher purity. The apparatus and methods of the present invention can be used to make silicon material for use in solar applications such as solar cells.

[Problem] The transmittance of glass can be dramatically improved as a result of this glass production method. In addition, the amount of rare metal, such as platinum, that melts into glass can be greatly reduced. [Solution] A glass production method whereby the water content in molten glass is increased, in a melting step (i) in which a glass raw material including at least one type of component among TiO.sub.2, Nb.sub.2O.sub.5, WO.sub.3, and Bi.sub.2O.sub.3 is heated inside a melting container and melted, and a molten glass is obtained.

An aspect of the present invention relates to optical glass, which is oxide glass including cation components in the form of 10 to 40 cation % of P.sup.5+, equal to or more than 50 cation % of a combined quantity of Ti.sup.4+, Nb.sup.5+, W.sup.6+, Bi.sup.3+, and Te.sup.4+, with a cation ratio of a combined content of Ti.sup.4+ and Nb.sup.5+ to a combined content of W.sup.6+ and Bi.sup.3+ being equal to or less than 1.3, a combined quantity of B.sup.3+, Li.sup.+, Na.sup.+, K.sup.+, Rb.sup.+, Cs.sup.+, Mg.sup.2+, Ca.sup.2+, Sr.sup.2+, Ba.sup.2+, and Zn.sup.2+ which amounts to equal to or less than of a combined content of Ti.sup.4+, Nb.sup.5+, W.sup.6+, Bi.sup.3+, and Te.sup.4+, and more than 0 % of Li.sup.+, Na.sup.+, K.sup.+, Rb.sup.+, and Cs.sup.+ combined, and which has a refractive index of equal to or higher than 2.02.

An aspect of the present invention relates to optical glass, which is oxide glass including cation components in the form of 10 to 40 cation % of P.sup.5+, equal to or more than 50 cation % of a combined quantity of Ti.sup.4+, Nb.sup.5+, W.sup.6+, Bi.sup.3+, and Te.sup.4+, with a cation ratio of a combined content of Ti.sup.4+ and Nb.sup.5+ to a combined content of W.sup.6+ and Bi.sup.3+ being equal to or less than 1.3, a combined quantity of B.sup.3+, Li.sup.+, Na.sup.+, K.sup.+, Rb.sup.+, Cs.sup.+, Mg.sup.2+, Ca.sup.2+, Sr.sup.2+, Ba.sup.2+, and Zn.sup.2+ which amounts to equal to or less than of a combined content of Ti.sup.4+, Nb.sup.5+, W.sup.6+, Bi.sup.3+, and Te.sup.4+, and more than 0 % of Li.sup.+, Na.sup.+, K.sup.+, Rb.sup.+, and Cs.sup.+ combined, and which has a refractive index of equal to or higher than 2.02.