Abstract: The CdTe crystals were processed optically and the parallelism was measured by using two precision goniometers with measurement accuracy of 1″ and a optical flat with parallelism better than 1″, the measured parallelism was compared with that of CaF2 crystal which was processed together with CdTe crystals.The parallelism of CaF2 crystal was measured by a laser plane interferometer.Additionally, the source and magnitude of error in this method were analyzed.The results show that the difference of the parallelism of CdTe and CaF2 is less than 3″.The error mainly come from the measurement error of precision goniometer and the parallelism error of optical flat, and the total error is no more than 5″,which can meet the precision require of parallelism measurement for CdTe crystal.

Key words: The CdTe crystals were processed optically and the parallelism was measured by using two precision goniometers with measurement accuracy of 1″ and a optical flat with parallelism better than 1″, the measured parallelism was compared with that of CaF2 crystal which was processed together with CdTe crystals.The parallelism of CaF2 crystal was measured by a laser plane interferometer.Additionally, the source and magnitude of error in this method were analyzed.The results show that the difference of the parallelism of CdTe and CaF2 is less than 3″.The error mainly come from the measurement error of precision goniometer and the parallelism error of optical flat, and the total error is no more than 5″,which can meet the precision require of parallelism measurement for CdTe crystal.