Spatial phase filtering with a porphyrin derivative as phase filter in an optical image processor

Sendhil, Kaladevi; Vijayan, C.; Kothiyal, M. P.

doi:10.1016/j.optcom.2005.03.014

Cited by 17 publications

(9 citation statements)

References 11 publications

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“…Castillo et al utilized the Kerr-type nonlinear property of bacteriorhodopsin film for self-induced Zernike-type filter and obtained phase contrast images [45]. Sendhil et al exploited the intensity dependent refractive index of zinc tetraphenyl porphyrin for phase contrast imaging [46].In these methods, the zero order of the Fourier spectrum induces intensity dependent refractive index changes thereby modifying its phase. Since only the zero order induces a phase shift and not the higher orders, a phase filter is created and phase contrast imaging is performed.…”

Section: Phase Contrast Imaging Of Biological Specimensmentioning

confidence: 99%

Optical Fourier techniques for medical image processing and phase contrast imaging

Yelleswarapu

Kothapalli

Rao

2008

Optics Communications

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This paper briefly reviews the basics of optical Fourier techniques (OFT) and applications for medical image processing as well as phase contrast imaging of live biological specimens. Enhancement of microcalcifications in a mammogram for early diagnosis of breast cancer is the main focus. Various spatial filtering techniques such as conventional 4f filtering using a spatial mask, photoinduced polarization rotation in photosensitive materials, Fourier holography, and nonlinear transmission characteristics of optical materials are discussed for processing mammograms. We also reviewed how the intensity dependent refractive index can be exploited as a phase filter for phase contrast imaging with a coherent source. This novel approach represents a significant advance in phase contrast microscopy.

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Section: Phase Contrast Imaging Of Biological Specimensmentioning

confidence: 99%

Optical Fourier techniques for medical image processing and phase contrast imaging

Yelleswarapu

Kothapalli

Rao

2008

Optics Communications

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“…where λ is the wavelength, Δn is the refractive-index difference between the sites of the zero order frequency component and the higher order frequency component on the photopolymer, and d is the thickness of photopolymer [9]. In order to get a desired phase shift , we need to generate proper refractive index difference Δn by illuminating the central part, which is the zero frequency component site of the photopolymer according to Eq.…”

Section: Characteristic Of Photopolymer As Phase Contrast Filtermentioning

confidence: 99%

“…It draws a new attention in the microprojector application for mobile devices due to its superior light efficiency over the conventional amplitude modulation method. As a phase contrast filter, these previous works have used photorefractive crystals [8], Kerr medium [3], zinc tetraphenylporphyrin [9], or optical disk with a small pit on the center [6,7].…”

Section: Introductionmentioning

confidence: 99%

Phase Contrast Projection Display Using Photopolymer

Piao

Kim

Park

2008

Journal of the Optical Society of Korea

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We propose a phase contrast filter using photopolymer, for the phase contrast projection display. The photopolymer has high photosensitivity such that its optically induced refractive index change has a linear dependency on the illuminating light intensity. We implemented a phase contrast projection display using photopolymer as a phase contrast filter. By controlling the refractive index change of the photopolymer, we successfully convert an input phase image into a high contrast intensity image. We also investigated the effect of the photopolymer illumination condition on the quality of the displayed intensity image. As a projector, we achieved 82% phase to intensity conversion efficiency, which implies that the proposed method can potentially have much higher light efficiency than conventional projection display.

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“…Nonlinear PC blends the robustness of the phase contrast methods with an optical nonlinear intensitydependent medium and the usefulness of the traditional interferometric techniques to measure and visualize phase objects. Nonlinear PC has been demonstrated on a variety of materials including bacteriorhodopsin films [4], absorbing films [5], optically addressed spatial light modulators [6][7][8] and liquid crystals [9]. The obvious advantage of the nonlinear phase filters over the standard phase filters is simplicity, self-aligned, tunable and are object-size independent.…”

Section: Introductionmentioning

confidence: 99%

Polarization-dependent nonlinear phase contrast by using dye-doped nematic liquid crystals

et al. 2008

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Nonlinear phase contrast microscopy is an optical technique that uses an intensity-dependent refractive index material to produce high-contrasted images of transparent specimens. Earlier proposal of liquid crystals as phase filters for phase contrast applications used optically addressed spatial light modulators fabricated with photoconductive film. Here, we propose the use of a simpler planar nematic liquid crystal cell doped with 1% wt methyl red. Owing to their polarization dependent enhancement factor a tunable phase filter can be photoinduced efficiently. Thus, images of different degree of contrast (and even contrast reversal) can be obtained either by rotating the polarization vector. All optical real-time imaging of dynamic events can be performed and image processing such as edge enhancement is demonstrated.

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Spatial phase filtering with a porphyrin derivative as phase filter in an optical image processor

Cited by 17 publications

References 11 publications

Optical Fourier techniques for medical image processing and phase contrast imaging

Optical Fourier techniques for medical image processing and phase contrast imaging

Phase Contrast Projection Display Using Photopolymer

Polarization-dependent nonlinear phase contrast by using dye-doped nematic liquid crystals

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