• 한국정밀공학회지
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• 제16권10호
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• pp.53-58
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• 1999

Even I the Electronic Speckle Pattern Interferometry(ESPI) method that measure the strain of object within wavelength of light is less visibility than Holographic Interferometry(HI) method, the merits of application, convenience and time-save have made the method practical in industry. However, the existing ESPI methods that are based on dual-exposure, real-time and time-average method have difficulties for accurate measurement, due to irregular intensity and shake of phase. Recently, in order to solve this problem, phase shifting method have been proposed. In this method, the path of reference light in interference is shifted to make improvement in distinction and precision. But this method includes too many noise, caused by the problem of relationship between object and phase. Therefore, a method to reduce noise muse be introduced. In this paper, least square fitting method is proposed. As results, the phase-map is influenced by precise phase shifting and current of notes and speckle pattern obtained by phase shifting method is improved on the existing method driven from time-average method.

• 한국광학회지
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• 제5권1호
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• pp.120-124
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• 1994

LPE와 간섭노광법을 이용하여 $1.55\mu\textrm{m}$ 파장의 InGaAsP/InP PBH-DFB-LD를 제작하여 스펙트럼 특성을 평가하였다. 제작된 PBH-DFB-LD의 발진 임계전류는 15mA 이하이며, $1.55\mu\textrm{m}$ 파장에서 광출력 7mW 이상까지도 단일 종모우드로 동작하였으며 측모우드 억제율 35dB 이상을 얻었다. 본 연구에서 제작된 PBH-DFB-LD 발진파장의 온도 의존 특성은 $0.9\AA/^{\circ}C$ 이며, 금지대역폭 측정에 의한 회절격자의 결합계수(k)는 97cm-1로 평가되었다.