Self-Mixing Laser Doppler Spectra of Extracorporeal Blood Flow: A Theoretical and Experimental Study

Norgia, M.; Pesatori, Alessandro; Rovati, Luigi

doi:10.1109/jsen.2011.2131646

Cited by 78 publications

(47 citation statements)

References 11 publications

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“…An integrated photodiode inside the laser package is commonly used to monitor the laser intensity changes. To observe the Doppler frequency, a Fast Fourier Transform (FFT) is performed on the amplified photodiode current [8].…”

Section: Methodsmentioning

confidence: 99%

“…4. Power spectra for varying concentration rates from 2 to 100% w/w with 50µl/min flow rate sum of Doppler shift contribution to the OFI signal from particles flowing at different positions from one wall to the other in the channel [20], the signals at higher concentrations show a more complex light-particles interaction such as attenuation, multiple scattering [8] , speckle [21], etc . .…”

Section: B Ofi Signal Spectramentioning

confidence: 99%

“…OFI was then applied to measure physical parameters such as displacement, absolute distance, velocity, flow, and refractive index [3], [4]. Apart from industrial implementations, OFI is also used for biomedical applications [5], [6] including blood flow measurement [7], [8], blood perfusion measurement [9], and tissue phantom imaging [10].…”

Section: Introductionmentioning

confidence: 99%

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Optical Feedback Flowmetry: Impact of Particle Concentration on the Signal Processing Method

et al. 2018

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Section: Methodsmentioning

confidence: 99%

Section: B Ofi Signal Spectramentioning

confidence: 99%

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Optical Feedback Flowmetry: Impact of Particle Concentration on the Signal Processing Method

et al. 2018

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“…Use of SMI has been demonstrated for imaging [3], distance [4], flow [5], biomedical [6], embedded [7] and mechatronics [8] applications etc.…”

Section: Introductionmentioning

confidence: 99%

All Analog Processing of Speckle Affected Self-Mixing Interferometric Signals

et al. 2017

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Self-mixing (SM) or optical feedback interferometry has been extensively used for high precision displacement and vibration sensing. However, presence of speckle can significantly degrade the SM interferometric signal and cause changes in signal amplitude as well as in the operating optical feedback regime, resulting in reduction in measurement precision. Previously, different advanced digital signal processing techniques have been proposed to undo the effects caused by speckle. However, their complex and computationally heavy nature inhibits their use for real-time, high bandwidth sensing applications. In this regard, an all analog signal processing algorithm has been presented in this paper which allows realtime processing of speckle affected SM signal while using standard analog circuits. Various simulations indicated that it is able to correctly process speckle affected SM signals having amplitude variation of at least one order and optical feedback parameter C reduction till 0.5. This proposed algorithm has been tested on experimentally acquired speckle affected SM signals and found capable of dealing with variations in optical feedback regime and amplitude modulation of SM signals, in accordance with simulation results. The developed hardware prototype circuit measures maximum displacement amplitude of 0.4 mm at maximum target velocity of 8 mm/s for an SM sensor with laser wavelength of 785 nm as long as C > 0.5. The proposed all analog processing could be a significant step towards a robust, low-cost, integrated, real-time SM displacement sensor.

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“…LFI flowmetry can be performed for flow or micro-fluidic [79] channels with different diameters and flow rates. Further potential applications of this technique include blood flow measurement in medicine [80] and parallel readout of flow channels [81]. Selfmixing velocimetry has been developed using a semiconductor laser diode [82].…”

Section: Laser Feedback Interferometry 21mentioning

confidence: 99%

Skin cancer detection using laser imaging

Mowla¹

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Endeavors to develop a non-invasive and reliable device to detect different types of skin cancer in its early stages have been undertaken over the past few years. Although some advances have been made towards such developments, there remains great scope for the development of a non-expensive, compact, reliable, safe, easy to use, fast, sensitive, and non-invasive device. This project will apply the innovative laser feedback interferometry (LFI) technique to skin cancer detection via laser imaging using near-infrared vertical cavity surface emitting lasers (VCSELs). In this project, the science behind lighttissue interactions has been explored and skin imaging modalities have been elaborately studied. As a result, LFI has been exploited in various configurations to image different modalities such as Doppler flowmetry and confocal reflectance. In addition to single modality imaging, dual-modality imaging has also been proposed and conducted experimentally, to image Doppler flowmetry and confocal reflectance at the same time, using an integrated LFI system. It is shown that dual-modality imaging can yield images with higher contrast which provide more information about morphological and functional characteristics of a target under test.In addition to two-dimensional LFI imaging, three-dimensional imaging systems have also been studied and employed in the laboratory. A tomographic image identifies tissue volume with altered optical properties due to cancerous or other malignant tissue processes. We applied the three-dimensional imaging system to different types of keratinocyte skin cancer phantoms and results show high level of sensitivity in providing tomographic images. Using high numerical aperture lenses, making images at resolutions down to micrometer scales is possible, which is promising for microscopy of biological structures.Furthermore, parallel LFI imaging using an array of 24 VCSELs was also studied theoretically and experimentally as a part of this work. A VCSEL array was used in a parallel read-out LFI imaging system to develop a fast and high resolution device, which eliminates the need to scan mechanically in one dimension.Investigating the complex interactions of the laser beam and tissue requires a powerful and robust simulation technique. Monte Carlo was used as a simulation technique to model the light-tissue interactions occurring in the optical systems in this work. Firstly, we tested and validated the Monte Carlo main engine which was developed in the group, by studying morphological aspects of the simulated and experimental signals in a laser Doppler velocimetry system, and deep insight into the nature of the LFI Doppler spectrum and further conclusions were drawn. Secondly, the Monte Carlo engine was used in iii modeling and analyzing of optical systems, in this work.We developed tissue phantom making techniques which were used to examine the experimental ideas in place of biological samples which are difficult to obtain and work with. Therefore, tissue phantom techniques were studie...

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Self-Mixing Laser Doppler Spectra of Extracorporeal Blood Flow: A Theoretical and Experimental Study

Cited by 78 publications

References 11 publications

Optical Feedback Flowmetry: Impact of Particle Concentration on the Signal Processing Method

Optical Feedback Flowmetry: Impact of Particle Concentration on the Signal Processing Method

All Analog Processing of Speckle Affected Self-Mixing Interferometric Signals

Skin cancer detection using laser imaging

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