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Different scattering processes take place when photons propagate inside turbid media. Many powerful experimental techniques exploiting these processes have been developed and applied over the years in a large variety of situations from fundamental and applied research to industrial applications. In the present paper, we intend to take advantage of...
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... theory allows the prediction of the angular intensity distribution of the light scattered by particles with a radius (R) resulting to be much smaller than the wavelength of the impinging light (R < λ/20). The employed experimental setup is reported in Figure 4. Tens of milliwatts from a doubled Nd:YAG laser (λ = 532 nm, Excel, Laser Quantum, maximum power 1.8 W) were used. ...
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In this paper, we present a method of embedding physics data manifolds with metric structure into lower dimensional spaces with simpler metrics, such as Euclidean and Hyperbolic spaces. We then demonstrate that it can be a powerful step in the data analysis pipeline for many applications. Using progressively more realistic simulated colli...
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... In practice, two types of phantoms are discerned depending on the way the light is scattered inside of the material. These include internal scattering and scattering induced by nanoparticles or microparticles [10,11]. ...
Optical phantoms are used to validate optical measurement methods. The stability of their optical parameters over time allows them to be used and stored over long-term periods, while maintaining their optical parameters. The aim of the presented research was to investigate the stability of fabricated porous phantoms, which can be used as a lung phantom in optical system. Measurements were performed in multiple series with an interval of 6 months, recreating the same conditions and using the same measuring system consisting of an integrating sphere, a coherent light source with a wavelength of 635 nm and a detector. Scattering and absorption parameters were determined on the basis of the measured reflectance and transmittance. The tested samples were made of silicone and glycerol in various proportions.
... To simulate the properties of the human skin, the optical phantom should have similar scattering coefficient, absorption coefficient, and refractive index in the wavelength range of interest [6]. To achieve this matching, the phantom is composed of 3 parts: namely, the scattering element, the absorbing element, and the background matrix. ...
MEMS FTIR parallel-core spectrometer is presented for biochemistry analysis. The fabricated chip comprising 2 interferometers shows an SNR of about 1000:1 on the human skin using diffuse reflectance interface and a single photodetector.
Millions of people die each year from cancer, which is caused by a combination of lifestyle and hereditary factors. It is characterized by unregulated cell division and proliferation. Mohs micrographic surgery, which involves tissue excision followed by H&E staining, is the most common procedure for cancer diagnosis. However, this procedure is time-consuming, necessitates the use of qualified professionals, and there is a considerable risk of misdiagnosis, resulting in ineffective treatment. Cancer cells have different optical characteristics than healthy tissues due to their abnormal nature. Polarization-resolved techniques can take advantage of this feature for faster, more accurate, and non-invasive disease diagnosis. The principles and applications of several polarization-enabled cancer detection approaches are described in this chapter. The techniques outlined include fluorescence spectroscopy, near-infrared (NIR) spectroscopy, hyperspectral spectroscopy, Raman spectroscopy, fluorescence microscopy, confocal microscopy, two-photon (2p) fluorescence microscopy, second-harmonic generation (SHG), third-harmonic generation (THG), coherent anti-stokes Raman scattering (CARS), stimulated Raman scattering (SRS) microscopy, surface-enhanced Raman scattering (SERS), and optical coherence tomography (OCT).KeywordsPolarizationMicroscopySpectroscopyCancer diagnosisTumor
A method that combines Lucy-Richardson deconvolution algorithm (LRA) with a multiview projection setup to improve imaging reconstruction of objects embedded in scattering media is presented. In the first step, the medium was illuminated with a laser beam and single-shot multiple images of the object were obtained from different viewpoints. Next, the above procedure was performed under the same conditions but only the medium, without the object, was illuminated by a light point source to obtain the system PSF. Third, each sub-image of the object was digitally cropped, extracted from the array, and deconvolved with the average PSF image following the LRA. Finally, all the sub-deconvolved images were shifted to a common point and superimposed to reveal the shape of the hidden object. Various setup conditions including medium turbidity, thickness, target shape, and illumination state were tested and compared. Results indicate an effective performance of the proposed method.
In the work described in this paper, we experimentally demonstrate an efficient method to improve reconstruction of objects embedded in turbid media. The method combines multiple polarized speckle projections and a fully automated sorting algorithm. In the experimental setup, the medium was illuminated with a polarized laser beam and multiple polarized images of the object were obtained from different viewing perspectives using a lens array and captured by a camera. In offline image processing, each sub-image was digitally cropped, extracted from the array, and qualitatively evaluated by contrast-to-noise ratio (CNR) and entropy metrics. Sub-images were sorted based on quality as determined by CNR and entropy values, with high CNR and low entropy considered as highest quality with the best resolution and contrast. The images were then shifted to a common center and then summed with other sub-images to form a single average image. Experiments to demonstrate the effectiveness of the proposed algorithm were carried out on targets with different geometrical shapes embedded within scattering media in transmission configuration. Analysis of image metrics indicated improvement in object reconstruction by using circular polarization as compared to the use of linear polarization or non-polarization states. The overall experimental results obtained in this work illustrate effective performance of the proposed method.
