Complex master slave interferometry

Rivet, Sylvain; Maria, Michaël; Bradu, Adrian; Feuchter, Thomas; Leick, Lasse; Podoleanu, Adrian Gh.

doi:10.1364/oe.24.002885

Cited by 57 publications

(79 citation statements)

References 23 publications

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“…In this manuscript, we will refer to an improvement to the MS method, recently reported, complex master/slave (CMS) [1].…”

Section: Procedures Of Producing Images In Octmentioning

confidence: 99%

“…The parameters k g and k h take into account the non-linear dependence of the phase on the wavenumber and on dispersion left unbalanced in the interferometer respectively [1]. Let us compare two strategies of producing reflectivity profiles in OCT: FT based (conventional) and CMS based.…”

Section: Strategies Of Producing Reflectivity Profiles In Octmentioning

confidence: 99%

“…We discuss here the advantages of the novel MS-OCT technology [1][2][3][4][5][6][7][8]. The MS technique delivers a single reflectivity point from a selected depth, by comparing the acquired channeled spectrum (CS) with many replicas of the CS (masks).…”

Section: Introductionmentioning

confidence: 99%

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Replacing the Fourier transformation in optical coherence tomography with multiple comparison operations

2017

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The conventional spectral domain (SD) and Fourier domain (FD) OCT method deliver a 1D reflectivity profile in the sample investigated by applying a Fourier transform (FT) to the channeled spectrum, CS, at the interferometer output. We discuss here the advantages of a novel OCT technology, Master Slave (MS). The MS method radically changes the main building blocks of a SD (FD)-OCT set-up. The serially provided electrical signal in conventional technology is replaced by multiple signals, a signal for each OPD point along an electrical output for each depth in the object investigated. In this way, it is possible to: (1) direct access to information from selected depths; (ii) eliminate the process of resampling, required by the FT based conventional technology, with immediate consequences in improving the decay of sensitivity with depth, achieving the expected axial resolution limit, reduction in the time to display an image and lower cost OCT assembly; (iii) OCT interferometer tolerant to dispersion left unbalanced. INTRODUCTIONBoth implementations of the Fourier domain optical coherence tomography, spectrometer based (Sp)-OCT and swept source (SS)-OCT, can be used to produce both cross-sectional (B-scan) and en-face (C-scan) images with high resolution and high sensitivity.Traditionally, in order to produce a volumetric image, in both implementations, each channeled spectrum acquired while scanning the probing beam over the sample is subject to a fast Fourier transform (FFT). However, before the FFT, several preparatory signal processing steps such as zero padding, spectral shaping, apodization, dispersion compensation or data resampling are required to produce high axial resolution and sensitivity images. As all these steps are sequentially executed and require time, therefore, the need to perform them impact production of the images in real-time.So far, several techniques involving both hardware and/or software solutions have been demonstrated to successfully eliminate or diminish the execution time of the preparatory steps. Correct resampling and compensation for dispersion mismatch are extremely important as an incorrect k-mapping or dispersion left unbalanced in the system generates a broadening of the coherence peak. To eliminate the resampling step, in Sp-OCT a solution using a prism after the diffraction grating was proposed. However, this complicates the optics hardware, requires careful hardware adjustment of several components, introduces losses and the resampling is prone to errors. In SS-OCT, the swept sources are often equipped with a supplementary clock signal (k-clock) that adds not only to the cost of the source, but requires a specialized, more sophisticated digitizer that in the end does not warranty a perfect resampling and also limits the axial range of the image. Other techniques such as using an additional light source, parametric iteration methods, phase linearization techniques, and automatic calibrations have been also proposed.All these methods are normally computationally expens...

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“…In this manuscript, we will refer to an improvement to the MS method, recently reported, complex master/slave (CMS) [1].…”

Section: Procedures Of Producing Images In Octmentioning

confidence: 99%

Section: Strategies Of Producing Reflectivity Profiles In Octmentioning

confidence: 99%

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Replacing the Fourier transformation in optical coherence tomography with multiple comparison operations

2017

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“…A solution to increase the axial range in SS-OCT is the use of the coherence revival exhibited by some external cavity tunable laser (ECTL) swept sources [1][2][3][4][5][6]. The CR method is easy to implement, as only the optical path difference between the two arms of the interferometer needs to be altered.…”

Section: Introductionmentioning

confidence: 99%

“…In the present report, based on reference [6], we demonstrate, as an alternative to the FFT method, the utilization of the recently introduced master/slave method in combination with the coherence revival technique, which eliminates the drawbacks specified above and allows real-time production of cross-sectional images.…”

Section: Introductionmentioning

confidence: 99%

Master/slave based optical coherence tomography for in-vivo, real-time, long axial imaging range of the anterior segment

2017

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In this report, we demonstrate that in a coherence revival (CR) based swept source optical coherence tomography (SS-OCT) set-up, real-time cross-sectional long-range images can be produced via the Master Slave (MS) method. The total tolerance of the MS method to nonlinear tuning, to dispersion in the interferometer and to dispersion due to the laser cavity, makes the MS ideally suited to the practice of coherence revival. In addition, enhanced versatility is allowed by the MS method in displaying shorter axial range images than that determined by the digital sampling of the data. This brings an immediate improvement in the speed of displaying cross-sectional images at high rates without the need of extra hardware such as graphics processing units or field programmable gate arrays. The long axial range of the coherence revival regime is proven with images of the anterior segment of healthy human eye.

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Downconversion Master Slave OCT With a Bidirectional Sweeping Laser

Martinez Jimenez,

Cernat,

Bradu

et al. 2024

Journal of Biophotonics

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This paper explores the challenges of signal processing when using optical coherence tomography (OCT) imaging instruments driven by asymmetric MHz bidirectional sweeping lasers. A downconversion master–slave (DMS) method is proposed as a viable alternative to the traditional OCT protocol. Unlike conventional swept source OCT, which requires a separate calibration for each sweep, the DMS approach does not require calibration of the acquired channeled spectra; its operation is independent of the tuning direction. We demonstrate the practicality of the DMS method with en‐face OCT images obtained with an OCT instrument equipped with a fast bidirectional swept laser (tuning speed 1.6 MHz) and a slow acquisition card of only 2.5 MS/s sampling rate.

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Complex master slave interferometry

Cited by 57 publications

References 23 publications

Replacing the Fourier transformation in optical coherence tomography with multiple comparison operations

Replacing the Fourier transformation in optical coherence tomography with multiple comparison operations

Master/slave based optical coherence tomography for in-vivo, real-time, long axial imaging range of the anterior segment

Downconversion Master Slave OCT With a Bidirectional Sweeping Laser

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