전자 스페클 등고선 추출법을 이용한 3차원 물체의 형상측정에 관한 연구 = (A) study on shape measurement of 3-D object by using electronic speckle contouring

다국어 초록 (Multilingual Abstract)

Measurements of surface shapes or height profiles of engineering components have been achieved by two main techniques : stylus-based probing methods and optical non-destructive methods. In order to obtain full-field data, the former has to scan the measuring surface line by line and the process is thus time consuming. Bur optical methods are advantageous over probe-based techniques in that the optical methods are of high speed, non-contact and are capable of providing full-field results with high spatial resolution. Several optical techniques are available : holographic interferometry, speckle pattern correlation, grating projection of moire´ method, and structured light techniques.
Electronic Speckle Pattern Interferometry has been used to measure surface deformations and vibration modes of engineering components and materials in industrial areas. One of the important application using ESPI is Electronic Speckle Contouring of a diffused object for 3-D shape analysis and topography measurement. In this study, we proposed ESC, an optical shape measurement method using correlation interference of speckle patterns. ESC has been investigated for absolute shape measurement. Conventional in-plane and out-of-plane sensitive optical ESPI instruments have been used to measure shape without alterations to the optical hardware. The shape of three-dimensional diffuse objects is measured by small shifts of optical fibers carrying the object illumination and reference beams and small tilts of optical mirrors.
In this study, we described the contouring method by the shift of the two illumination beams through optical fiber in modified in-plane sensitive speckle interferometer and the tilt of the optical mirror through rotational stage in out-of-plane sensitive speckle interferometer to obtain the contour fringe patterns. We also described formation process and characteristics of depth contour fringes and grid contour fringes by shifting direction of the illumination beams. Grid contour fringes are generally sets of parallel fringes superimposed upon the TV image of the object and spatially modulated by the target-surface shape. One major drawback of grid contour fringes was not easily understood, and quantitative analysis required knowing the fringe order and the use of curve-fitting routines to interpolate the data. Depth contour fringes represent parallel planes in space perpendicular to the line of sight. They are more useful in that they describe areas of constant target-surface height and can be analyzed directly with the use of the same techniques as are used for analyzing displacement fringes.
Before the experiments, we performed the geometric vector analysis for dual-beam-shifted ESPI contouring. And to support the theoretical analysis of ESC, we performed experiment with various specimens from micrometer unit to centimeter unit. For quantitative analysis of the contour fringes, we used 4-frame phase shifting method with PZT and digital image processing.
Finally, we obtained good agreement between the geometric analysis and experimental results. It is concluded that Electronic Speckle Contouring method turns out to be very effective method for the three dimensional measurement of surface profiles. This ESC can be applied in general areas such as on-line inspection, robotics, medical diagnosis, CAD/CAM, and NC machine.

목차 (Table of Contents)

• 목차
• Abstract = III
• Nomenclature = VI
• 제1장 서론 = 1
• 1.1 연구배경 = 1
• 1.2 연구목적 및 내용 = 3
• 제2장 광학식 형상측정 기술개발 현황 = 6
• 2.1 무아레 토포그래피에 의한 형상측정 = 6
• 2.2 능동적 주사에 의한 형상측정 = 8
• 가. 점모양의 광원을 이용한 형상측정 = 8
• 나. 선모양의 광원을 이용한 형상측정 = 10
• 다. 여러 줄무늬 광원을 이용한 형상측정 = 10
• 2.3 스테레오 정합에 의한 형상측정 = 12
• 2.4 Time-of-Flight에 의한 range 측정 = 12
• 제3장 ESPI 기본 원리 및 ESC 해석 이론 = 13
• 3.1 레이저 스페클 이론 = 13
• 가. 객관적 스페클 = 14
• 나. 주관적 스페클 = 15
• 3.2 스페클 패턴의 상관간섭 = 18
• 3.3 벡터에 의한 기하학적 해석 = 22
• 3.4 등고선 간섭무늬 = 26
• 3.5 위상 이동법 = 30
• 제4장 실험내용 및 결과 = 32
• 4.1 실험시편 = 32
• 4.2 ESC 시스템 구성 = 33
• 4.3 실험결과 = 36
• 제5장 결론 = 57
• 參考文獻 = 59