KEYWORDS: Optical coherence tomography, Deconvolution, Image segmentation, Point spread functions, Resolution enhancement technologies, Super resolution, Signal detection, In vivo imaging, Eye, Infrared imaging
A method of lateral superresolution for Fourier domain optical coherence tomography is presented. This method consists of intentional defocus and its numerical compensation using a spatial frequency- phase filter. The designing process of the phase filter is described, and the superresolution effect is discussed theoretically. Experimental results of a knife-edge test prove that the frequency filter enhances the lateral resolution better than a diffraction-limited resolution. This method is applied to the investigation of an in vivo human iris and shows the effect of the cancellation of defocus.
A numerical deconvolution method that cancels the blurring due to lateral defocus in line field Fourier domain optical coherence tomography (LF-FDOCT) using imaging optics is proposed. This method employs an inverse filter designed from the point spread function (PSF) that is calculated by Fresnel diffraction. The inverse filter can eliminate the lateral defocus, and consequently, the out-of-focus lateral resolution can be improved to a level comparable with the in-focus resolution over the entire axial measurement range. In this paper, we describe the process of calculating the PSF and the inverse filter designed from it in LF-FDOCT. The effect of deconvolution is also schematically discussed and estimated. A knife-edge method also verifies the effect of in-focus resolution experimentally.
A method of lateral superresolution for Fourier domain optical
coherence tomography is presented.
This method consists of intentional defocus and its numerical
compensation using a spatial frequency- phase filter.
The designing process of the phase filter is described, and
the superresolution effect is discussed theoretically.
Experimental results of knife-edge test prove that
the frequency filter enhances the lateral resolution better than
a trans-form limited resolution.
We propose a new method for synthesizing computer-generated holograms (CGHs) of three-dimensional (3-D) and full-color real existing objects. This method requires a series of color projection images of R, G, and B components recorded by color CCD. A CGH for one color component is extracted and synthesized from the Fourier spectrum of the same color component of the color projection images. By the geometrical consideration of the extraction process, the most efficient scanning method, namely azimuth scanning, is determined. Both numerical and optical experiments are presented in order to demonstrate the verification and the effectiveness of our method.
A method for synthesizing computer-generated holograms of real-existing objects is described. A series of projection images are recorded both vertically and horizontally with an incoherent light source and a color CCD camera. According to the principle of computer tomography(CT), the 3-D Fourier spectrum is calculated from several projection images of objects and the Fresnel computer-generated hologram(CGH) is synthesized using a part of the 3-D Fourier spectrum. This method has following advantages. At first, no-blur reconstructed images in any direction are obtained owing to two-dimensionally scanning in recording. Secondarily, since not interference fringes but simple projection images of objects are recorded, a coherent light source is not necessary for recording. The use of a color CCD in recording enables us to record and reconstruct colorful objects. Finally, we demonstrate color reconstruction of objects both numerically and optically.
In this report, computer-generated holograms(CGHs) synthesized from projection images of real existing objects
are considered. A series of projection images are recorded both vertically and horizontally with an incoherent light
source and a color CCD. According to the principles of computer tomography(CT), the 3-D Fourier spectrum is
calculated from several projection images of objects and the Fresnel CGH is synthesized using a part of the 3-D
Fourier spectrum. This method has following advantages. At first, no-blur reconstructed images in any direction
are obtained owing to two-dimensionally scanning in recording. Secondarily, since not interference fringes but
simple projection images of objects are recorded, a coherent light source is not necessary. Moreover, when a color
CCD is used in recording, it is easily possible to record and reconstruct colorful objects. Finally, we demonstrate
color reconstruction of objects both numerically and optically.
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