Silica glass member, method for producing the same, and projection aligners using the same

摘要

A silica glass member for use with a light having a specific wavelength of 250 nm or shorter, in which the difference in the maximum and the minimum values of hydroxyl group concentration as measured in a plurality of points within a plane vertical to an optical axis whose center is the crossing point of its optical axis with the optical axis of the silica glass member is 50 ppm or lower; and in which the plurality of signed birefringence values obtained based on the birefringence values measured on several points within a plane vertical to an optical axis whose center is the crossing point of its optical axis with the optical axis of the silica glass member and the direction of the fast axis fall within a range of from -2.0 to +2.0 nm/cm. Thus, a silica glass member having high optical transmittance and a high resistance against ultraviolet radiations is provided.