Abstract
Null tests using two different kinds of null corrector have been discussed. A parabolic mirror was used as a surface under test. After designing, encoding, and fabricating the CGH (computer generated hologram), the null CGH test was performed. An autocollimation test was also performed using a flat mirror. The reliability of the null CGH test has been discussed by comparing the result obtained by both null tests.
서로 다른 null optics를 사용하는 null test의 측정결과를 상호 비교함으로써 null CGH test 신뢰성을 알아보았다. 회전대칭 포물면경(90mm, F/0.76) 형상측정 및 측정장치 정렬용 null CGH를 설계, encoding, 제작 후 null CGH test를 실시하였다. 결과를 평면경을 null optics로 사용하는 autocollimation test측정치와 비교하여 null CGH test의 정확성을 평가하였다.