| abstract |
An optical member comprising silica glass containing TiO 2 , the glass having a TiO 2 concentration of 3-10 mass%, a Ti 3+ concentration of 100 wt. ppm or lower, a coefficient of thermal expansion at 0-100ºC, CTE 0-100 , of 0±150 ppb/ºC, and an internal transmittance in the wavelength region of 400-700 nm, T 400-700 , of 80% or higher per mm of the thickness. In the surface to be used for an optical purpose, the proportion of Ti 3+ concentration unevenness to average Ti 3+ concentration, ΔTi 3+ /Ti 3+ , is 0.2 or lower. |