학술지/매거진
Current Optics and Photonics
Vol. 5, No.4(Aug. 2021)
한국광학회지
Vol. 32, No.4(Aug. 2021)
K-Light
Vol4, No.4(Oct. 2021)
Current Optics and Photonics
Vol. 5, No.4(Aug. 2021)
한국광학회지
Vol. 32, No.4(Aug. 2021)
K-Light
Vol4, No.4(Oct. 2021)
![[Editors Pick] Current Optics and Photonics Vol. 5 no. 5 (2021 October)](http://osk.inforang.com/upload/posts_thumb/2021/10/1635412068_86434200_703763786-thumb.png)
[Editors Pick] Current Optics and Photonics Vol. 5 no. 5 (2021 October)
Absolute Depth Estimation Based on a Sharpness-assessment Algorithm for a Camera with an Asymmetric Aperture
Beomjun Kim, Daerak Heo, Woonchan Moon, and Joonku Hahn *
School of Electronic and Electrical Engineering, Kyungpook National University, Daegu 41566, Korea
Current Optics and Photonics Vol. 5 No.5 (2021 October) pp. 514-523
DOI: https://doi.org/10.3807/COPP.2021.5.5.514
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(b)
Fig. 1 Defocus model. (a) Geometry of the camera, and (b) the radius of the CoC when half of the aperture size is 7 mm.
Keywords: Coded aperture, Depth estimation, Image reconstruction
OCIS codes: (100.2000) Digital image processing; (100.3008) Image recognition, algorithms and filters; (100.3020) Image reconstruction-restoration; (120.3940) Metrology; (170.1630) Coded aperture imaging
Abstract
Methods for absolute depth estimation have received lots of interest, and most algorithms are concerned about how to minimize the difference between an input defocused image and an estimated defocused image. These approaches may increase the complexity of the algorithms to calculate the defocused image from the estimation of the focused image. In this paper, we present a new method to recover depth of scene based on a sharpness-assessment algorithm. The proposed algorithm estimates the depth of scene by calculating the sharpness of deconvolved images with a specific point-spread function (PSF). While most depth estimation studies evaluate depth of the scene only behind a focal plane, the proposed method evaluates a broad depth range both nearer and farther than the focal plane. This is accomplished using an asymmetric aperture, so the PSF at a position nearer than the focal plane is different from that at a position farther than the focal plane. From the image taken with a focal plane of 160 cm, the depth of object over the broad range from 60 to 350 cm is estimated at 10 cm resolution. With an asymmetric aperture, we demonstrate the feasibility of the sharpness-assessment algorithm to recover absolute depth of scene from a single defocused image.
![[하이라이트 논문] 한국광학회지 Vol. 32 No.5 (2021 October)](http://osk.inforang.com/upload/posts_thumb/2021/10/1635123810_60975100_719336922-thumb.jpg)
[하이라이트 논문] 한국광학회지 Vol. 32 No.5 (2021 October)
1018 nm 파장의 고출력 Yb 광섬유 레이저
High-power Operation of a Yb Fiber Laser at 1018 nm
오예진 ㆍ박혜미 ㆍ박종선 ㆍ박은지ㆍ김진필ㆍ정 훈ㆍ김지원 † ㆍ김태형ㆍ정성묵ㆍ김기혁 ㆍ양환석
한국광학회지 Vol. 32 No.5 (2021 October) pp. 209-214
DOI: https://doi.org/10.3807/KJOP.2021.32.5.209
Fig. 1 Numerical calculation and simulation of laser signals. (a) Theoretical gain spectra of the Yb fiber for different Yb 3+ ion excitation levels. (b) Numerical simulation of the laser signal power and the Yb 3+ ion excitation level as a function of the position of the Yb fiber used in the experiment.
Abstract
본 논문에서는 단파장 영역인 1018 nm에서 최고 출력 626 W를 가진 고출력 이터븀(ytterbium, Yb) 첨가 광섬유 레이저에 대해 보고한다. Yb 광섬유 레이저에서 이득률이 낮은 단파장 영역인 1018 nm에서 레이저를 발진시키기 위한 조건을 이론적으로 조사해보고, 광섬유 끝 단단면 조건에 따른 되먹임 신호를 측정하여 안정적인 레이저 발진 조건에 대하여 연구하였다. 그 결과를 바탕으로 제작한 단일 공진기 구조의 Yb 광섬유 레이저 시스템으로부터 729 W의 펌프 출력에서 최고 출력 626 W의 1018 nm 파장 레이저 출력을 안정적으로 얻을 수 있었으며 그때 기울기 효율은 86.6%로 측정되었다. 본 연구에서 얻은 1018 nm 파장의 Yb 광섬유 레이저 결과는 지금까지 국내에서 보고된 1030 nm 이하 단파장에서 발진된 Yb 광섬유 레이저 출력 중 가장 높은 출력이며, 세계적으로도 상용 Yb 광섬유와 광부품을 사용한 결과 중 가장 높은 출력에 해당된다. 그리고 향후 더 높은 출력을 얻기 위한 방법에 대해 논의하고자 한다.
