• 한국광학회지
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• 제28권2호
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• pp.53-58
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• 2017

본 논문은 집적화된 소형의 분광모듈 구현을 위한 나노회절격자의 설계 및 제작에 관한 연구이다. 제안된 평면 구조의 나노회절격자는 회절격자로부터 반사된 빛을 집광하기 위하여 비등간격의 구조로 설계되었으며, 400 nm에서 650 nm까지의 파장 대역폭에서 균등한 분해능을 가지도록 비대칭 V 홈 구조를 가지도록 설계되었다. 최적 설계된 나노회절격자를 저가, 대량 생산에 적합한 UV-NIL 공정을 통해 제작하기 위하여 FT-IR 흡수스펙트럼을 분석하였으며, 이를 통해 5 nm 이내의 치수 정밀도를 가진 고분자 나노회절격자를 제작 할 수 있었다. 제작된 고분자 기반 나노회절격자를 이용한 집적형 분광모듈은 250 nm의 파장 대역폭에서 각 첨두파장의 기준으로 5 nm의 균등한 파장 분해능을 확인하였으며, 이는 다양한 분광모듈의 적용분야에 적용될 것으로 기대된다.

• 마이크로전자및패키징학회지
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• 제22권3호
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• pp.73-77
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• 2015

본 논문에서는 저가로 쉽게 제작할 수 있는 구조를 지닌 단일칩 형태의 고분자 기반 평판형 분광모듈을 제안하였다. 제안된 분광모듈은 UV 임프린트 기법에 의해 제작되어진 비등간격 나노회절격자와 오목거울이 포함된 평판형 광도파로로 구성되어진다. 회절효율을 향상시키기 위해 나노회절격자의 구조는 $25^{\circ}$의 블레이징 각도와 100nm의 선폭을 가지도록 설계, 제작되었다. 평판형 분광모듈은 700 nm 대역폭과 10 nm 분해능을 가짐을 확인하였다. 이러한 집적형 고분자 분광모듈은 다양한 센서 시스템에 적용될 수 있을 것으로 기대된다.

• Journal of the Optical Society of Korea
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• 제15권3호
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• pp.216-221
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• 2011

A diffraction grating is a highly symmetric optical element with a physical structure that is invariant under translational spatial movements. The translational symmetry is reflected in the fields that are diffracted from the grating. Here, we introduce a plane-parallel mirror pair onto the grating, which translates the fields through double reflections, and we describe a method of exploiting the symmetry to enhance the spectral resolution of a diffraction grating beyond the limit that is set by the number of grooves. The mirror pair creates another virtual grating beside the original one, effectively doubling the number of grooves. Addition of more mirror pairs can further increase the effective number of grooves despite the increased complexity and difficulty of experimental implementation. We experimentally demonstrate the spectral linewidth reduction by a factor of four in a neon fluorescence spectrum. Even though the geometrical restriction on the mirror deployment limits our method to a certain range of the whole spectrum, as a practical application example, a bulky spectrometer that is nearly empty inside can be made compact without sacrificing the resolution.

• 한국광학회지
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• 제13권3호
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• pp.189-196
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• 2002

파장 50 $\AA$ 이하의 연엑스선 영역에서 사용될 평면결상형 연엑스선 분광기의 구성요소와 정렬조건을 결정하고 분광기의 분광학적 특성을 해석하였다. 평면결상형 연엑스선 분광기는 토로이드거울, 실틈, 비등간격 오목에돌이발, 연엑스선 검출기로 구성되어 있다. 토로이드거울과 홈간격이 2400 grooves/mm인 비등간격 오목에돌이발을 사용하여 공간분해된 빛띠가 단일 평면 위에 결상되도록 분광기를 구성하였다. 토로이드거울은 연엑스선 광선이 에돌이발에 비스듬하게 입사할 때 발생되는 비점 수차를 보상하기 위해 사용되었다. 파면수차 이론을 적용하여 분광기가 가지는 파장분해와 공간분해를 계산하고, 에돌이 현상에 대한 스칼라 이론을 적용하여 에돌이발의 에돌이효율을 계산하였다.

• Journal of the Optical Society of Korea
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• 제17권4호
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• pp.312-316
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• 2013

A novel fiber-optic sensor system is suggested in which fiber Bragg grating sensors are demodulated by a wavelength-sweeping fiber laser source and a spectrometer. The spectrometer consists of a diffraction grating and a 512-pixel photo-diode array. The reflected Bragg wavelength information is transformed into spatial intensity distribution on the photo-diode array. The peak locations linearly correspond to the Bragg wavelengths, regardless of the nonlinearities in the wavelength tuning mechanism of the fiber laser. The high power density of the fiber laser enables obtaining high signal-to-noise ratio outputs. The improved demodulation characteristics were experimentally demonstrated with a fiber Bragg grating sensor array with 5 gratings. The sensor outputs were in much more linear fashion compared with the conventional tunable band-pass filter demodulation. Also it showed advantages in signal processing, due to the high level of photo-diode array signals, over the broadband light source system, especially in measurement of fast varying dynamic physical quantities.

• Current Optics and Photonics
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• 제1권4호
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• pp.295-307
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• 2017

An innovative system for the alternative continuous wide spectral spatial heterodyne spectrometer (ACWS-SHS) is proposed. The relationship between the ACWS-SHS and the wide spectral spatial heterodyne spectrometer (WS-SHS) at the resolution limit, the spectral range, the grating diffraction efficiency and the interference fringes contrast ratio has been analyzed theoretically. Through the comparison of the theoretical analysis and simulation results, it is found that the two systems for the WS-SHS and the ACWS-SHS have the same resolution limit and spectral range, which are ${\delta}{\sigma}$ and ${\sigma}_{01}$, while in the ACWS-SHS system the critical diffraction efficiency of echelle grating is 68.39% and the critical contrast ratio of interference fringes is 0.4135, which is much better than the performance of the WS-SHS system. Therefore, the ACWS-SHS reduces the high requirements for the precision of equipment and expands the application field of SHS effectively.

• 센서학회지
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• 제26권1호
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• pp.28-34
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• 2017

An NIR grism Si optical area sensor spectrometer with in-band reference wavelength is designed and fabricated. It is composed of a transmission type diffraction grating (spatial density 300 line/mm), a rectangular N-BK7 prism (apex angle 30 degree), NIR filter(cutoff wavelength 720 nm), an imaging convex lens(focal length 50 mm F1.8) and an IR modified DSLR camera (Canon EOS40D) of Si optical area sensor ($3,888{\times}2,592$ pixels, pixel size $5.710{\mu}m$). "In-band reference wavelength function" is implemented using non-dispersive 0th diffraction order optical beam. The NIR grism spectrometer is tested in a laboratory using a halogen lamp and a Neon lamp. And the spectrometer is used in an astronomy field for obtaining the planet Jupiter NIR spectrum. In-band reference wavelength i.e. un-deviation wavelength is 846 nm, an wavelength resolution is 0.3027 nm/pixel, an wavelength resolving power is 2,794 and an wavelength range is 650~1,000 nm.

• Journal of the Optical Society of Korea
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• 제20권6호
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• pp.669-677
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• 2016

A miniaturized FTIR spectrometer based on lamellar grating interferometry is being developed for passive remote-sensing. Consisting of a pair of micro-mirror arrays, the lamellar grating can be fabricated using MEMS technology. This paper describes a method to compute the optical field in the interferometer to optimize the design parameters of the lamellar grating FTIR spectrometer. The lower limit of the micro-mirror width in the grating is related to the formation of a Talbot image in the near field and is estimated to be about $100{\mu}m$ for the spectrometer to be used for the wavelength range of $7-14{\mu}m$. In calculating the far field at the detection window, the conventional Fraunhofer equation is inadequate for detection distance of our application, misleading the upper limit of the micro-mirror width to avoid interference from higher order diffractions. Instead, the far field is described by the unperturbed plane-wave combined with the boundary diffraction wave. As a result, the interference from the higher order diffractions turns out to be negligible as the micro-mirror width increases. Therefore, the upper limit of the micro-mirror width does not need to be set. Under this scheme, the interferometer patterns and their FT spectra are successfully generated.

• 대한의용생체공학회:의공학회지
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• 제11권1호
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• pp.19-24
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• 1990

A simple diffraction grating spectrometer is successfully utilized to distinguish the similar red colored sediments obstained from both of cancer and non-cancer urine reactions caused by the the previous developed reagent for the cancer diagnosis by examining their spectral absorption bands in order to improve its sensitivity and specficity. It is found that the cancer and non-cancer absorp- tion band regions lie between 4250 A and 4750 A and between 5250 A and 5400 A, respectively.

• 대한화학회지
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• 제49권6호
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• pp.584-590
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• 2005