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A Study on Reconstruction Performance of Phase-only Holograms with Varying Propagation Distance

전파 거리에 따른 위상 홀로그램 복원성능 분석 및 BL-ASM 개선 방안 연구

  • 차준영 (경희대학교 소프트웨어융합학과) ;
  • 반현민 (경희대학교 컴퓨터공학부) ;
  • 최승미 (경희대학교 컴퓨터공학부) ;
  • 김진웅 (한국전자통신연구원 미디어연구본부) ;
  • 김휘용 (경희대학교 컴퓨터공학부)
  • Received : 2022.11.15
  • Accepted : 2023.01.20
  • Published : 2023.01.30

Abstract

A computer-generated hologram (CGH) is a digitally calculated and recorded hologram in which the amplitude and phase information of an image is transmitted in free space. The CGH is in the form of a complex hologram, but it is converted into a phase-only hologram to display through a phase-only spatial light modulator (SLM). In this paper, in the process of including the amplitude information of an object in the phase information, when a technique that includes subsampling such as DPAC is used, we showed experimentally that the bandwidth of the phase-only hologram increases, and as a result, aliasing that was not present in the complex hologram can occur. In addition, it was experimentally shown that it is possible to generate a high-quality phase-only hologram by restricting the spatial frequency range even at a distance where the numerical reconstruction performance is degraded by aliasing.

물체의 진폭과 위상 정보가 free space에서 전달되는 과정을 디지털로 계산하여 기록한 것을 컴퓨터 생성 홀로그램(CGH)라고 한다. 이 CGH는 복소 홀로그램의 형태이지만, 이를 Phase-only 공간광 변조기(SLM)를 통해 디스플레이 하기 위해 위상 홀로그램의 형태로변환하게 된다. 본 논문에서는, 물체의 진폭 정보를 위상 정보에 포함시키는 과정에서 DPAC 등 subsampling이 포함된 기법을 사용한다면 위상 홀로그램의 대역폭이 커지며, 그 결과로 복소 홀로그램 복원 시에는 없던 aliasing이 발생할 수 있음을 실험적으로 밝혔다. 또한, 이렇게 aliasing에 의해 복원성능이 저하되는 거리에서도 공간 주파수 범위를 제약하는 방법을 통해 좋은 화질의 위상 홀로그램 생성이 가능함을 보였다.

Keywords

Acknowledgement

이 논문은 삼성전자미래기술육성센터의 지원을 받아 수행된 연구임(과제번호SRFC-IT2201-03). 이 연구는 2020학년도 경희대학교 연구비 지원에 의한 결과임(KHU-20201116).

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