부산대학교 도서관

A new type of measuring system for coefficient of linear thermal expansion (CTE) of ultralow expansion (ULE) material by using a fiber ring laser is introduced in this letter. The lasing frequency of the laser is stabilized to one of the transmission peaks of the etalon filter by controlling the resonant frequency of the tunable filter. The spacer of the (Fabry–PÉrot type) etalon filter is made of ULE material. We could measure the CTE of ULE by measuring the optical frequency change caused by the temperature change of the etalon spacer. The combined standard uncertainty is estimated as the value of $\pm \hbox{36.6}$ ppb/$^{\circ }$C in the temperature range from 5 $^{\circ}$C to 60 $^{\circ}$C.