광학 단층 촬영과 단면 영상화에서의 수치적 영상 조절에 대한 디지털 홀로그래피의 응용

Abstract

Numerical adjustments based on special features of digital holography was applied to two kinds of tomographic imaging techniques. In optical diffraction tomography, an error correction method using digital holography was presented and applied to the measurements of several kinds of optical fibre. The refractive index distributions are reconstructed from a sinogram which is a set of quantitative phase maps obtained as the object is rotated for 180 degrees. The defocus error in the phase delay maps, which was caused by the unwanted shift of the object, was corrected using numerical field propagation. The resultant tomographic images show the proposed method works effectively.And a new tomographic imaging method that can generate section images on arbitrarily tilted planes is developed and applied to illumination-angle-scanning digital interference holography.A set of complex object fields are acquired as the illumination angle is varied with a uniform interval. The modification of the object fields set was done by multiplying phase ramps corresponding to the tilt of a desired observation plane. Thus, the tomographic image of a slice of the object along the tilted plane is obtained from their superposition. The axial resolution of the system was verified with a step-height-standard and applied to the tomographic inspection of a micro-electro-mechanical system.