전자 빔 증착에 의한 협대역 H-α imaging 광학필터 제작 및 특성연구 (The fabrication and characteristic for H-α imaging narrow bandpass optical filter by e-beam deposition)

서지정보

· 발행기관 : 대한시과학회
· 수록지 정보 : 대한시과학회지 / 15권 / 3호 / 217 ~ 226페이지
· 저자명 : 박문찬, 고견채, 이화자

초록

목 적: 중심파장이 656.3nm에서 반치폭이 약 8nm이고 투과율이 92%인 협대역 H-α imaging 필터를 설계·제작하고, 이 필터의 박막 특성을 연구하고자 한다.
방 법: 전자빔 증착기를 이용하여 Ti₃O₅/SiO₂다층박막으로 656.3nm 대역투과필터와 Hb600 적외선 차단필터를 만든 후, 분광광도계로 투과율과 대역폭을 확인하였다. SEM사진을 이용하여 적외선차단필터 단면을 관찰하였고, XRD 데이터로부터 박막의 구조를 알 수 있었으며, XPS 분석으로부터 박막 성분을 확인하였다.
결 과: 협대역 H-α imaging 필터에서 대역투과필터의 최적조건은 30층, 반사방지막 코팅층은 6층, 적외선차단필터는 32층으로 설계·제작되었다. 제작된 H-α imaging 필터의 최대파장피크가 이론치에 비교했을 때 약 0.7nm로 공차가 거의 없는 것을 알 수 있었다. XRD 분석으로 대역투과 필터와 반사방지막 코팅 층은 비정질로, 적외선 차단 필터는 결정질으로 코팅되는 것을 확인하였다. SEM 사진에 의해 적외선 차단 필터의 코팅 층을 확인하였고, XPS 분석에 의해 대역필터의 가장 바깥층이 SiO₂층임을 확인할 수 있었다.
결 론: Ti₃O₅/SiO₂ 다층박막을 이용하여 30층의 대역투과 필터와 32층의 적외선차단필터를 제작하여 657nm 중심파장에서 8nm 반치폭을 가지며 투과율은 92%인 협대역 H-α imaging 필터를 제작하였으며, 제작된 필터는 설계치와 거의 비슷한 투과율과 반치폭을 가짐을 알 수 있었다.

영어초록

Purpose: The H-α imaging narrow bandpass optical filter with a 656.3nm central wavelength and 8nm FWHM was designed and fabricated, and its characteristics and structure were studied.
Method: The bandpass filter with 656.3nm central wavelength and IR cut–off filter using Ti₃O₅/SiO₂ multilayer were made by electron beam evaporation apparatus and the transmittaces of the filters were measured by spectrophotometer. The number of layers and the thicknesses of filters were measured from the cross section of IR cut-off filter by SEM image and the structures of the bandpass filter and IR cut-off filter and AR coating layer of IR cut-off filter were known by XRD and the composition of bandpass filter was analysed by XPS analysis.
Results: The optimization of the narrow bandpass layer for H-α filter was composed of 30 layers and that of AR coating layer was composed of 6 layers and that of IR cut-off layer was composed of 32 layers. The maximun central wavelength of fabricated H-imaging filter have a little tolerance of 0.7nm when compared to the designed peak wavelength. XRD patterns from the bandpass filter and anti-reflective coating layer were found to be amorphous, the infrared cut-off filter was coated as a crystal growth. It was known that the IR cut-off filter was composed of 32 layers by SEM image and the top layer of bandpass filter was SiO₂ layer by XPS analysis.
Conclusions: The H-α filter combing 30 layers bandpass filter and 32 layers IR cut-off filter with a 657nm central wavelength and 8nm FWHM using Ti₃O₅/SiO₂ mutilayer was designed and fabricated, and it was known that the transmittance and FWHM of fabricated H-α filter were similar to that of designed H-α filter.

참고자료

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