Influence of scattering and birefringence on the phase shift between electric field components of polarized light propagated through biological tissues

Borovkova, Mariia; Bykov, Alexander; Попов, А. П.; Meglinski, Igor

doi:10.1117/12.2526394

Cited by 2 publications

(3 citation statements)

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“…[19][20][21] Moreover, it has been demonstrated that utilizing circularly polarized light in frame of Stokes-vector polarimetry approach, complemented by the use of Poincaré sphere as a quantitative graphical tool, has a high potential for tissue characterization and evaluation of cancer aggressiveness. [22][23][24][25][26][27] In terms of optical properties, besides absorption, biological tissues are characterized by scattering (typically, in the order of tens of mm −1 for visible light) and high anisotropy of scattering (g ≈ 0.8). 28 In addition to scattering of light, due to heterogeneous fibrous structure, biological tissues often exhibit linear form birefringence, which is a measurable quantity; its changes may act as a metric for certain structural abnormalities of biological tissues.…”

Section: Introductionmentioning

confidence: 99%

Role of scattering and birefringence in phase retardation revealed by locus of Stokes vector on Poincaré sphere

et al. 2020

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Significance: Biological tissues are typically characterized by high anisotropic scattering and may also exhibit linear form birefringence. Both scattering and birefringence bias the phase shift between transverse electric field components of polarized light. These phase alterations are associated with particular structural malformations in the tissue. In fact, the majority of polarizationbased techniques are unable to distinguish the nature of the phase shift induced by birefringence or scattering of light. Aim: We explore the distinct contributions of scattering and birefringence in the phase retardation of circularly polarized light propagated in turbid tissue-like scattering medium. Approach: The circularly polarized light in frame of Stokes polarimetry approach is used for the screening of biotissue phantoms and chicken skin samples. The change of optical properties in chicken skin is accomplished by optical clearing, which reduces scattering, and mechanical stretch, which induces birefringence. The change of optical properties of skin tissue is confirmed by spectrophotometric measurements and second-harmonic generation imaging. Results: The contributions of scattering and birefringence in the phase retardation of circularly polarized light propagated in biological tissues are distinguished by the locus of the Stokes vector mapped on the Poincaré sphere. The phase retardation of circularly polarized light due to scattering alterations is assessed. The value of birefringence in chicken skin is estimated as 0.3 × 10 −3 , which agrees with alternative studies. The change of birefringence of skin tissue due to mechanical stretch in the order of 10 −6 is detected. Conclusions: While the polarimetric parameters on their own do not allow distinguishing the contributions of scattering and birefringence, the resultant Stokes vector trajectory on the Poincaré sphere reveals the role of scattering and birefringence in the total phase retardation. The described approach, applied independently or in combination with Mueller polarimetry, can be beneficial for the advanced characterization of various types of malformations within biological tissues.

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Section: Introductionmentioning

confidence: 99%

Role of scattering and birefringence in phase retardation revealed by locus of Stokes vector on Poincaré sphere

et al. 2020

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“…For that end, we used a polarized light, controlled pressure, a video camera, and image processing. The use of crossed circular polarizers attenuates the reflection component of light captured by the digital camera, enabling visualization of deeper regions of the skin [38,39]. Our system produced successful measurements in subjects with dark skin (phototypes V and VI), which are a challenge for visual CRT measuring method [28,40,41], and has not been demonstrated by other studies.…”

Section: Discussionmentioning

confidence: 99%

“…In another study to be published elsewhere, we noticed that application of high pressure in the forearm (23kPa) increased noise, decreased fit quality, and repeatability. Our success with using low pressure (7 kPa) may be attributed not only to the higher sensitivity of digital cameras but also to the use of crossed circular polarizers, which improves SNR by attenuating the component due to reflection on the skin surface [36,38,39]. We believe that with adequate image processing for removal of reflection, the polarizers will be unnecessary.…”

Section: Discussionmentioning

confidence: 99%

Skin-color-independent robust assessment of capillary refill time

Souza

Cardoso

2023

Preprint

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Capillary Refill Time (CRT) is a visual method used to evaluate peripheral perfusion, particularly in low-resource environments. However, CRT’s repeatability and reproducibility are limited, particularly for dark-skinned individuals. This paper presents quantitative CRT measurements with good performance and repeatability for all Fitzpatrick skin phototypes. Tests were conducted on the forearm of 22 volunteers, using 7 kPa controlled compression, an RGB video camera, and white LED cross-polarized light. The CRT was determined by the time constant of an exponential regression to the green channel mean pixel intensity. An adaptive algorithm was developed to determine the best regression region to reduce noise, and incorrect and outlier CRT readings were flagged from the regression uncertainties. Results showed 80% of measurements were within 20% of the expected CRT value of a given volunteer, suggesting repeatable and reproducible quantitative CRT methods could be developed for robust measurements in patient triage, monitoring, and telehealth.

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Influence of scattering and birefringence on the phase shift between electric field components of polarized light propagated through biological tissues

Abstract: Influence of scattering and birefringence on the phase shift between electric field components of polarized light propagated through biological tissues," Proc.

Cited by 2 publications

References 9 publications

Role of scattering and birefringence in phase retardation revealed by locus of Stokes vector on Poincaré sphere

Role of scattering and birefringence in phase retardation revealed by locus of Stokes vector on Poincaré sphere

Skin-color-independent robust assessment of capillary refill time

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