Noise in optical low-coherence reflectometry

Takada, K.

doi:10.1109/3.687850

Cited by 54 publications

(28 citation statements)

References 11 publications

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“…The theoretical results presented in Sections 2 and 4 show that this incoherent light and the associated beat noise severely limit the DR at source powers above 10 mW. Our results confirm earlier reports [4][5][6] that beat noise plays a critical role in limiting the DR of OCT instruments utilizing balanced interferometers and balanced detection. In Section 3 we report the first-to our knowledge-experimental confirmation of the presence of beat noise in a simple Michelson interferometer-based OCT instrument utilizing a single photodetector.…”

Section: ͑1͒supporting

confidence: 87%

“…This effect has been reported previously, especially for balanced configurations. 4,6 The dashed-dotted curves in Fig. 4 are calculated with R incoh = 3.5ϫ 10 −4 but without the beat noise terms in Eqs.…”

Section: Simulation Resultsmentioning

confidence: 99%

“…Rollins et al 7 used balanced detectors to cancel photon bunching and other fluctuations in light source intensity, sometimes referred to collectively as relative intensity noise. However, Takada 4 has shown that some photon bunching, referred to as beat noise, is not eliminated by balanced detection. Yoshino et al 8 have demonstrated that the beating of different frequencies within the source spectrum generates the usual photon bunching, and that interference between the partially coherent beams returned from the two arms of a Michelson interferometer results in an additional beat noise term and hence additional photon bunching.…”

Section: ͑1͒mentioning

confidence: 99%

“…2, but the additional beat noise term survives. 4 The beam powers in Eqs. (2) and (5) can be written in terms of the source power P s and the cross efficiency ␥ bal of the fiber splitter of the balanced configuration:…”

Section: ͑5͒mentioning

confidence: 99%

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Role of beat noise in limiting the sensitivity of optical coherence tomography

et al. 2006

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The sensitivity and dynamic range of optical coherence tomography (OCT) are calculated for instruments utilizing two common interferometer configurations and detection schemes. Previous researchers recognized that the performance of dual-balanced OCT instruments is severely limited by beat noise, which is generated by incoherent light backscattered from the sample. However, beat noise has been ignored in previous calculations of Michelson OCT performance. Our measurements of instrument noise confirm the presence of beat noise even in a simple Michelson interferometer configuration with a single photodetector. Including this noise, we calculate the dynamic range as a function of OCT light source power, and find that instruments employing balanced interferometers and balanced detectors can achieve a sensitivity up to six times greater than those based on a simple Michelson interferometer, thereby boosting image acquisition speed by the same factor for equal image quality. However, this advantage of balanced systems is degraded for source powers greater than a few milliwatts. We trace the concept of beat noise back to an earlier paper [J. Opt. Soc. Am. 52, 1335 (1962)].

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Section: ͑1͒supporting

confidence: 87%

Section: Simulation Resultsmentioning

confidence: 99%

Section: ͑1͒mentioning

confidence: 99%

Section: ͑5͒mentioning

confidence: 99%

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Role of beat noise in limiting the sensitivity of optical coherence tomography

et al. 2006

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“…(2) and (4), respectively, into the denominator of Eqn. (1). The results for the DR are plotted in Fig.…”

Section: Dual-balanced Configurationmentioning

confidence: 99%

Limits to performance improvement provided by balanced interferometers and balanced detection in OCT/OCM instruments

et al. 2004

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, "Limits to performance improvement provided by balanced interferometers and balanced detection in OCT/OCM instruments", Proc. SPIE 5316, 467 (2004) ABSTRACTWe compare the dynamic range of OCT/OCM instruments configured with unbalanced interferometers, e.g., Michelson interferometers, with that of instruments utilizing balanced interferometers and balanced photodetection. We define the dynamic range (DR) as the ratio of the maximum fringe amplitude achieved with a highly reflecting surface to the rootmean-square (rms) noise. Balanced systems achieve a dynamic range 2.5 times higher than that of a Michelson interferometer, enabling an image acquisition speed roughly 6 times faster. This maximum improvement occurs at light source powers of a few milliwatts. At light source powers higher than 30 mW, the advantage in acquisition speed of balanced systems is reduced to a factor of 4. For video-rate imaging, the increased cost and complexity of a balanced system may be outweighed by the factor of 4 to 6 enhancement in image acquisition speed. We include in our analysis the "beat-noise" resulting from incoherent light backscattered from the sample, which reduces the advantage of balanced systems. We attempt to resolve confusion surrounding the origin and magnitude of "beat-noise", first described by L. Mandel in 1962. Beat-noise is present in both balanced and unbalanced OCT/OCM instruments.

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