Nowadays, because of advancements of nano-technology and biotechnology, demand on the technology about surface manufacturing, precision measurement and positioning have been increased. Accordingly, lots of precision measurement systems have been developed. Among these, systems using optical metrology methods, for example, high resolution and non des- tructive to specimen, get many merits, special applications on laser scanning confocal microscopy (LSCM) characterized by high resolution images using confocal aperture i.e. pinhole, optical sectioning to serially produce thin sections of a specimen and 3D reconstructions of a variety of biological specimens. Also, another example is Differential Heterodyne Interferometer (DHI) which are for great interest as high-resolution performance thanks to their stability against noise of the optical system, which is constructed according to the common-path scheme. Since a few years ago, a system using both confocal principle and differential heterodyne skill at the same time has been made, but most of its researches were focused on stage-scanning method which took a lot of time to measure.
In this study, confocal heterodyne Interference system using beam scanning method to acquire information of a specimen quickly was suggested. However, this system has a disadvantage of optical path difference (OPD) between two first order beams experienced by most of the optical system components during scanning. Therefore, method to overcome this problem i.e. compensation procedure of optical path difference between two beams was also suggested. And then, a specimen which has a step height over λ / 4 by using this was measured, the result measured in four positions of field of view (FOV) was analyzed.
수년전부터 공초점의 원리와 디퍼렌셜 헤테로다인간섭의 원리를 동시에 이용한 시스템이 만들어져 오고 있으나, 그 대부분의 연구가 스테이지 스캐닝방법으로서 시간이 많이 걸리는 단점이 있었다. 본 연구에서는 시편의 정보를 빨리 얻기위해 빔스캐닝 방식을 채택한 공초점 헤테로다인 간섭측정시스템을 제안하였다. 그러나, 스캐닝 중 시스템 구성요소에 의해 발생하는 두 일차빔 사이의 광경로차가 문제가 된다. 따라서 이에 대한 보상이 필요하며 그 보상절차를 제안하였다. 또한 파장의 4분의 1을 넘는 높이단차의 시편을 FOV의 네 곳에서 비교 측정하였으며, 그 결과를 분석하였다.
