When from the quartz vitreous body for blank where the quartz vitreous body and OH

摘要

PROBLEM TO BE SOLVED: To provide a method for simply and accurately measuring the trace OH group concentration in a quartz glass body. SOLUTION: Test pieces having facing two planes are manufactured respectively from a measuring quartz glass body and a blank quartz glass body having a known OH group content. After setting the imaginary temperature difference of the two test pieces within 200 deg.C, the test pieces are put in the infrared spectrophotometer. An infrared ray having the wavelength in the range of about 2,500 nm-about 2,950 nm is allowed to enter vertically one plane of the facing two planes successively, and simultaneously an outgoing ray is detected from the other plane. The difference spectrum between outgoing ray spectrums of each test piece is determined, and an OH group absorption peak in the wavelength of 2,720 nm is selected, and the OH group content is calculated from the peak height by using mathematical expression 1. Csample=CblankA/L(MH+MO)/103 (Csample is the OH group concentration in the measuring test piece (wt.ppm), Cblank is the OH group concentration in the blank test piece (wt.ppm), A is the peak height (ABS.), L is an optical path length (cm), is an absorption coefficient (1.mol-1.cm-1), MH is the atomic weight of hydrogen, MO is the atomic weight of oxygen, and is the density of the quartz glass (g.cm-3).).