Glass has a refractive index of 1.55 or more, and has, in an x-ray absorption fine structure (XAFS) analysis of platinum, a peak intensity ratio expressed by A.sub.max/A.sub.ave of 1.13 or more, where A.sub.max denotes a maximum value of a white line within an energy range of 13,270 eV to 13,290 eV, and A.sub.ave denotes an average absorption in an energy range of 13,290 eV to 13,390 eV.

A glass includes a first surface; and a second surface that is opposite to the first surface, wherein an absorption coefficient of the glass at light of wavelength 550 nm is less than or equal to 1 m.sup.−1, and a ratio (α.sub.max /α.sub.min) of a maximum value α.sub.max (m.sup.−1) to a minimum value α.sub.min (m.sup.−1) of absorption coefficients of the glass at light within a range of wavelengths from 400 nm to 700 nm is less than or equal to 10, and wherein a two-dimensional arithmetical mean height of a selectable area of 1790 μm×1330 μm of the first surface is less than or equal to 1 nm.

An optical glass has a refractive index (n.sub.d) of 1.64 or more. A P value represented by the following formula (1) is in a range of 7.0<P value<10.0: P value=log(A.sub.450×P.sub.450+A.sub.550×P.sub.550+A.sub.650×P.sub.650+A.sub.750×P.sub.750) (1). A.sub.450, A.sub.550, A.sub.650 and A.sub.750 are absorbances of the optical glass with a plate thickness of 10 mm at a wavelength of 450 nm, 550 nm, 650 nm and 750 nm, respectively. P.sub.450, P.sub.550, P.sub.650 and P.sub.750 are radiances of light having a wavelength of 450 nm, 550 nm, 650 nm and 750 nm, respectively, at 1,300° C. according to Planck's radiation law. All of internal transmittances in terms of a 10-mm thickness at wavelengths of 450 nm, 550 nm, 650 nm and 750 nm are 91% or more.

A method for producing glass by removing coloring ions through reduction is described, as are products obtained by this method.

An imaging system, includes: a laser light source having a wavelength from 380 nm to 490 nm; and a beam guidance element, the laser light source configured for generating an average surface power density of more than 10 W/cm.sup.2, the beam guidance element including a glass which has a quality factor F(436 nm)=S(436 nm)*(Abs.sub.0(436 nm)+Abs.sub.1(436 nm))/k, wherein S(436 nm) is a thermality at a wavelength of 436 nm, Abs.sub.1(436 nm) is an additional absorbance in comparison to Abs.sub.0(436 nm) at a wavelength of 436 nm after an irradiation with a power density of 345 W/cm.sup.2 for 72 hours with a laser light having a wavelength of 455 nm, Abs.sub.0(436 nm) is an absorbance at a wavelength of 436 nm of a sample having a thickness of 100 mm without the irradiation, k is the thermal conductivity, and the quality factor F(436 nm) is <15 ppm/W.

Provided is an optical glass that contains TiO.sub.2 and/or Nb.sub.2O.sub.5 as components of a glass composition, achieves a high light transmittance, and has excellent mass productivity. An optical glass contains TiO.sub.2 and Nb.sub.2O.sub.5 in a total amount of 20% by mole or more as components of a glass composition and has a basicity of 12 or more.

A flat glass is provided that exhibits high transmittance to electromagnetic radiation in a range of wavelengths from 200 nm to 1500 nm. The transmittance for the flat glass having a thickness of 1 mm is 20% or more at a wavelength of 254 nm, 82% or more at a wavelength of 300 nm, 90% or more at a wavelength of 350 nm, 92% or more at a wavelength of 546 nm, 92.5% or more at a wavelength of 1400 nm, 91.5% or more in a wavelength range from 380 nm to 780 nm, and 92.5% or more in a wavelength range from 780 nm to 1500 nm.

A glass ceramic article including a lithium disilicate crystalline phase, a petalite crystalline phased, and a residual glass phase. The glass ceramic article has a warp (μm)<(3.65×10.sup.−9/μm×diagonal.sup.2) where diagonal is a diagonal measurement of the glass ceramic article in μm, a stress of less than 30 nm of retardation per mm of glass ceramic article thickness, a haze (%)<0.0994t+0.12 where t is the thickness of the glass ceramic article in mm, and an optical transmission (%)>0.91×10.sup.(2−0.03t) of electromagnetic radiation wavelengths from 450 nm to 800 nm, where t is the thickness of the glass ceramic article in mm.

A glass article has a refractive index n.sub.G≥1.95 and an R-number in a range of from 0.900 to 1.050. The R-number is calculated according to the following formula:

[00001]$R=\left(n_G-1\right)\left(\frac{\ln \left[\frac{{\lambda }_G^2-{\lambda }_{\min }^2}{{\lambda }_G^2-{\lambda }_{\max }^2}.Math.\frac{{\lambda }_{\max }^2}{{\lambda }_{\min }^2}\right]}{42\ln \left[\frac{{\lambda }_B^2-{\lambda }_{\min }^2}{{\lambda }_B^2-{\lambda }_{\max }^2}.Math.\frac{{\lambda }_R^2-{\lambda }_{\max }^2}{{\lambda }_R^2-{\lambda }_{\min }^2}\right]}+\frac{1}{2.8}\right).$

λ.sub.R=656 nm, λ.sub.G=587 nm and λ.sub.B=486 nm, λ.sub.min=33 nm, and n.sub.G is a refractive index of the glass article at a wavelength of 587 nm.

A method of producing flint glass using submerged combustion melting involves introducing a vitrifiable feed material into a glass melt contained within a submerged combustion melter. The vitrifiable feed material is formulated to provide the glass melt with a glass chemical composition suitable for producing flint glass articles. To that end, the glass melt comprises a total iron content expressed as Fe.sub.2O.sub.3 in an amount ranging from 0.04 wt % to 0.06 wt % and also has a redox ratio that ranges from 0.1 to 0.4, and the vitrifiable feed material further includes between 0.008 wt % and 0.016 wt % of selenium or between 0.1 wt % and 0.2 wt % of manganese oxide in order to achieve an appropriate content of selenium or manganese oxide in the glass melt.