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Imaging and visualization of the polarization state of the probing beam in polarization-sensitive optical coherence tomography
摘要： We propose a simple and ef?cient method of color-encoded Stokes parameters to visualize the polarization states for polarization-sensitive optical coherence tomography (PS-OCT) of biological tissue. In this method, polarization states of the probing light are detected and described in the Stokes domain. Three primary colors of red, green, and blue are used to code Stokes parameters of Q, U, and V, respectively, which can be used to represent and visualize each unique polarization state. A strategy that uses the polarization state as the PS-OCT imaging parameter is ?rst introduced to obtain high contrast images of the birefringent samples. Then, color-based automatic segmentation of birefringent components from 3D scanned tissue volume is proposed to isolate the network of the 3D nerve bundles in a mouse brain without cutting the brain into slices. Experimental validation and demonstrations are given by imaging ex vivo mouse tail and brain tissues to show the usefulness of proposed polarization state imaging and segmentation methods.
关键词： automatic segmentation,Stokes parameters,birefringent tissue,polarization-sensitive optical coherence tomography,polarization state imaging
更新于2025-09-04 15:30:14
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Recent Advances in the Functional 2D Photonic and Optoelectronic Devices
摘要： 2D layered materials such as graphene, black phosphorus (BP), transition metal dichalcogenides (TMDCs), and their hybrid systems exhibit wide coverage of bandgaps, unique crystal structures, and the facile integration for potential applications in photonic and optoelectronic devices. In the recent two years, various 2D functional systems have been developed with novel optoelectronic properties, thereby expanding the functional applications. Beyond the speed, efficiency, or sensitivity, these 2D crystals can offer additional advantages and distinct applications in terms of spectrum range, polarization, intensity, and structural designs. The main contents here focus on optoelectronic and photonic devices with unique functional applications, especially mentioning areas as follows: long-wavelength photodetector, 2D polarization-sensitive photodetector, 2D optoelectronic memory, and 2D material-based optical modulator. For each section, the device design, performance, and operational principles are investigated and systematically discussed. Finally, the current research status is summarized and perspectives on possible applications in future are offered.
关键词： optical modulators,2D materials,polarization-sensitive photodetectors,long-wavelength photodetectors,optoelectronic memory
更新于2025-09-04 15:30:14
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Melanin Pigmentation in Rat Eyes: In Vivo Imaging by Polarization-Sensitive Optical Coherence Tomography and Comparison to Histology
摘要： The purpose of this study was to demonstrate polarization-sensitive optical coherence tomography (PS-OCT) for imaging pigmented structures in the posterior eye segments of albino and pigmented rats and to correlate depolarization contrast of the retinal pigment epithelium (RPE) and choroid in in vivo PS-OCT to melanin pigmentation detected in postmortem histologic serial sections. In vivo three-dimensional PS-OCT imaging was performed in adult albino and pigmented rat eyes at 70-kHz A-line rate. Degree of polarization uniformity (DOPU) fundus maps and radial DOPU pro?les were generated. Postmortem histomorphologic analysis was performed in order to investigate melanin pigmentation of the RPE and choroid. Fundus pigmentation maps were extracted from histologic serial sections. Pigmentation pro?les were correlated to DOPU pro?les of the same eyes. Strong depolarization was found in the RPE/choroid complex of pigmented rats, whereas the same structures exhibited uniform polarization in albino rats. The difference between the depolarization characteristics between albino and pigmented animals was statistically signi?cant. In the fundus pigmentation maps, optical pigment density was zero in albino rat eyes. In pigmented rat eyes, a strong negative correlation between optical pigment density and DOPU was observed. This in vivo and ex vivo investigation of posterior rat eyes indicates that melanin is the cause of depolarization in retinal PS-OCT images. It further demonstrates that melanin pigmentation in the RPE and choroid can be quanti?ed via depolarization imaging and therefore suggests that PS-OCT is a useful tool for the noninvasive quantitative assessment of pigmentary changes in vision-threatening diseases such as age-related macular degeneration.
关键词： choroid,melanin,optical coherence tomography,depolarization,retinal pigment epithelium,polarization sensitive devices
更新于2025-09-04 15:30:14