Angular high-speed massively parallel detection spectral-domain optical coherence tomography for speckle reduction

Watanabe, Yuuki; Hasegawa, Haruyuki; Maeno, Seiya

doi:10.1117/1.3589093

Cited by 8 publications

(8 citation statements)

References 11 publications

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“…The SNR is defined as SNR = μ b /σ b , where μ b and σ b are the mean and the standard deviation of the intensity, which is calculated in the background region of the image (for the retinal image it is the vitreous-humor area). 4 The CNR is calculated as follows:…”

Section: Resultsmentioning

confidence: 99%

“…Among them, the two most widely used approaches involve either hardware-or software-based techniques. The hardware-based techniques rely on the uncorrelated speckle between different angles, positions, or wavelengths, such as the angular 4,5 and frequency 6 compounding techniques. Another recent hardware-based approach to speckle reduction is the technique of strain compounding, 7,8 which compresses the sample to create the uncorrelated speckle.…”

Section: Introductionmentioning

confidence: 99%

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Speckle reduction in optical coherence tomography imaging by affine-motion image registration

2011

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Abstract. Signal-degrading speckle is one factor that can reduce the quality of optical coherence tomography images. We demonstrate the use of a hierarchical model-based motion estimation processing scheme based on an affine-motion model to reduce speckle in optical coherence tomography imaging, by image registration and the averaging of multiple B-scans. The proposed technique is evaluated against other methods available in the literature. The results from a set of retinal images show the benefit of the proposed technique, which provides an improvement in signal-to-noise ratio of the square root of the number of averaged images, leading to clearer visual information in the averaged image. The benefits of the proposed technique are also explored in the case of ocular anterior segment imaging. C 2011 Society of Photo-Optical Instrumentation Engineers (SPIE).

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Speckle reduction in optical coherence tomography imaging by affine-motion image registration

2011

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“…In parallel approaches, the sample is usually illuminated with a single high NA beam, and angle is encoded in a specific domain. Examples include spatial encoding and array detection [44,47,48], path-length encoding [49] and Doppler frequency shift encoding [50]. Most encoding domains degrade the OCT signal: Array approaches are prone to poor sensitivity due to detector noise, cross-talk and/or lower spectral resolution, whereas path length encoding suffers from sensitivity roll-off and decreased imaging range.…”

Section: Theory: Hardware Speckle Reduction Collection Efficiencymentioning

confidence: 99%

“…In contrast, in JA-OCT an OCT signal can only be detected if the passive channels are perfectly aligned. In other parallel approaches, the numerical aperture (NA) is the same for illumination and detection, which is often a direct consequence of the underlying free-space interferometer layout [44,47,48]. Thus, the confocal gate is either not present at all [44,47,48], which leads to signal-degrading cross-talk, or the confocal gate is the same for all angles [49,50], such that the scattering direction is not unambiguously defined.…”

Section: Theory: Hardware Speckle Reduction Collection Efficiencymentioning

confidence: 99%

Joint aperture detection for speckle reduction and increased collection efficiency in ophthalmic MHz OCT

Klein

André

Wieser

et al. 2013

Biomed. Opt. Express

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Joint-aperture optical coherence tomography (JA-OCT) is an angle-resolved OCT method, in which illumination from an active channel is simultaneously probed by several passive channels. JA-OCT increases the collection efficiency and effective sensitivity of the OCT system without increasing the power on the sample. Additionally, JA-OCT provides angular scattering information about the sample in a single acquisition, so the OCT imaging speed is not reduced. Thus, JA-OCT is especially suitable for ultra high speed in-vivo imaging. JA-OCT is compared to other angle-resolved techniques, and the relation between joint aperture imaging, adaptive optics, coherent and incoherent compounding is discussed. We present angle-resolved imaging of the human retina at an axial scan rate of 1.68 MHz, and demonstrate the benefits of JA-OCT: Speckle reduction, signal increase and suppression of specular and parasitic reflections. Moreover, in the future JA-OCT may allow for the reconstruction of the full Doppler vector and tissue discrimination by analysis of the angular scattering dependence.

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“…A number of methods have been used to reduce speckle noise in OCT, such as frame averaging [1][2][3][4][5][6][7] (or space compounding [8]), angular compounding, [9,10] frequency compounding, [11] strain compounding, [12] and single Bscan filtering. [13,14] Among them, frame averaging technique is widely used in clinical OCT systems, such as RTVue (Optovue, CA), Spectralis (Heidelberg Engineering, Heidelberg, Germany), Spectral OCT/SLO (OPKO/OTI, Miami, FL), Cirrus (Zeiss Meditec, CA) and 3D OCT-2000 (Topcon, Japan).…”

Section: Introductionmentioning

confidence: 99%

Speckle reduction in swept source optical coherence tomography images with slow-axis averaging

Tan

Wang

et al. 2012

SPIE Proceedings

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The effectiveness of speckle reduction using traditional frame averaging technique was limited in ultrahigh speed optical coherence tomography (OCT). As the motion between repeated frames was very small, the speckle pattern of the frames might be identical. This problem could be solved by averaging frames acquired at slightly different locations. The optimized scan range depended on the spot size of the laser beam, the smoothness of the boundary, and the homogeneity of the tissue. In this study we presented a method to average frames obtained within a narrow range along the slow-axis. A swept-source OCT with 100,000 Hz axial scan rate was used to scan the retina in vivo. A series of narrow raster scans (0-50 micron along the slow axis) were evaluated. Each scan contained 20 image frames evenly distributed in the scan range. The imaging frame rate was 417 HZ. Only frames with high correlation after rigid registration were used in averaging. The result showed that the contrast-to-noise ratio (CNR) increased with the scan range. But the best edge reservation was obtained with 15 micron scan range. Thus, for ultrahigh speed OCT systems, averaging frames from a narrow band along the slow-axis could achieve better speckle reduction than traditional frame averaging techniques.

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Angular high-speed massively parallel detection spectral-domain optical coherence tomography for speckle reduction

Cited by 8 publications

References 11 publications

Speckle reduction in optical coherence tomography imaging by affine-motion image registration

Speckle reduction in optical coherence tomography imaging by affine-motion image registration

Joint aperture detection for speckle reduction and increased collection efficiency in ophthalmic MHz OCT

Speckle reduction in swept source optical coherence tomography images with slow-axis averaging

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