Polarimetry encompasses a collection of optical techniques broadly used in a variety of fields.Nowadays,such techniques have provided their suitability in the biomedical field through the study of the polarimetric res...Polarimetry encompasses a collection of optical techniques broadly used in a variety of fields.Nowadays,such techniques have provided their suitability in the biomedical field through the study of the polarimetric response of biological samples(retardance,dichroism and depolarization)by measuring certain polarimetric observables.One of these features,depolarization,is mainly produced by scattering on samples,which is a predominant efiect in turbid media as biological tissues.In turn,retardance and dichroic efiects are produced by tissue anisotropies and can lead to depolarization too.Since depolarization is a predominant efiect in tissue samples,we focus on studying difierent depolarization metrics for biomedical applications.We report the suitability of a set of depolarizing observables,the indices of polarimetric purity(IPPs),for biological tissue inspection.We review some results where we demonstrate that IPPs lead to better performance than the depolarization index,which is a well-established and commonly used depolarization observable in the literature.We also provide how IPPs are able to significantly enhance contrast between difierent tissue structures and even to reveal structures hidden by using standard intensity images.Finally,we also explore the classificatory potential of IPPs and other depolarizing observables for the discrimination of difierent tissues obtained from ex vivo chicken samples(muscle,tendon,myotendinous junction and bone),reaching accurate models for tissue classification.展开更多
Polarization cameras including 4-directional micro-polarizer array sensors are a very novel technology that have shown potential for fast and in-situ polarimetric measurement,which results in very appealing in applica...Polarization cameras including 4-directional micro-polarizer array sensors are a very novel technology that have shown potential for fast and in-situ polarimetric measurement,which results in very appealing in applications,such as biomedical,astronomy,remote sensing,or industry.However,the use of these cameras leads to overdetermined measurement that needs a calibration method according to the particular design and measurement scheme.We presented the required considerations by successfully use the eigenvalue calibration method,which was implemented in the Mueller polarimeters based on polarimetric cameras,where the number of analyzed polarization states was n≥8.We also studied the optimal set of calibration samples to achieve a more robust calibration.The proposed combination of calibration samples was independent of the dimensions and condition of the instrument matrices and can be extended to other variants of the eigenvalue calibration method.The calibration method and implementation of the polarimeter were validated through experimental measurements of the Mueller matrices of rotating polarizers and quarter-wave plates.展开更多
基金the financial support of Spanish MINECO(PID2021-126509OB-C21,and Fondos FEDER)Catalan Government(2017-SGR-001500).
文摘Polarimetry encompasses a collection of optical techniques broadly used in a variety of fields.Nowadays,such techniques have provided their suitability in the biomedical field through the study of the polarimetric response of biological samples(retardance,dichroism and depolarization)by measuring certain polarimetric observables.One of these features,depolarization,is mainly produced by scattering on samples,which is a predominant efiect in turbid media as biological tissues.In turn,retardance and dichroic efiects are produced by tissue anisotropies and can lead to depolarization too.Since depolarization is a predominant efiect in tissue samples,we focus on studying difierent depolarization metrics for biomedical applications.We report the suitability of a set of depolarizing observables,the indices of polarimetric purity(IPPs),for biological tissue inspection.We review some results where we demonstrate that IPPs lead to better performance than the depolarization index,which is a well-established and commonly used depolarization observable in the literature.We also provide how IPPs are able to significantly enhance contrast between difierent tissue structures and even to reveal structures hidden by using standard intensity images.Finally,we also explore the classificatory potential of IPPs and other depolarizing observables for the discrimination of difierent tissues obtained from ex vivo chicken samples(muscle,tendon,myotendinous junction and bone),reaching accurate models for tissue classification.
基金supported by the Ministerio de Ciencia e Innovación,Fondos FEDER,Spain(Grant Nos.PID2021-562,126509OB-C21,and PDC2022-133332-C21)Generalitat de Catalunya,Spain(Grant No.2021SGR00138).
文摘Polarization cameras including 4-directional micro-polarizer array sensors are a very novel technology that have shown potential for fast and in-situ polarimetric measurement,which results in very appealing in applications,such as biomedical,astronomy,remote sensing,or industry.However,the use of these cameras leads to overdetermined measurement that needs a calibration method according to the particular design and measurement scheme.We presented the required considerations by successfully use the eigenvalue calibration method,which was implemented in the Mueller polarimeters based on polarimetric cameras,where the number of analyzed polarization states was n≥8.We also studied the optimal set of calibration samples to achieve a more robust calibration.The proposed combination of calibration samples was independent of the dimensions and condition of the instrument matrices and can be extended to other variants of the eigenvalue calibration method.The calibration method and implementation of the polarimeter were validated through experimental measurements of the Mueller matrices of rotating polarizers and quarter-wave plates.
