scispace - formally typeset
Search or ask a question
Author

Tzachi Tal

Bio: Tzachi Tal is an academic researcher from Ariel University. The author has contributed to research in topics: Medical imaging & Imaging science. The author has an hindex of 1, co-authored 2 publications receiving 6 citations.

Papers
More filters
Journal ArticleDOI
TL;DR: Results are presented of an experimental technique that was developed for acquiring the impulse response, based upon the Kramers-Kronig algorithm, and have been applied for optical imaging of objects hidden behind clothing.
Abstract: Optical impulse-response characterization of diffusive media can be of importance in various applications, among them optical imaging in the security and medical fields. We present results of an experimental technique that we developed for acquiring the impulse response, based upon the Kramers–Kronig algorithm, and have been applied for optical imaging of objects hidden behind clothing. We demonstrate three-dimensional imaging with 5mm depth resolution between diffusive layers.

7 citations

Proceedings ArticleDOI
31 May 2009
TL;DR: In this article, the Kramers-Kronig technique is used to reconstruct the impulse response of a diffusive media with picosecond resolution, and an object within clothing at a distance of 3m from the detection system is detected.
Abstract: The Kramers-Kronig technique is used to reconstruct the impulse-response of a diffusive media with picosecond resolution. We demonstrate the ability to image an object within clothing at a distance of 3m from the detection system.

Cited by
More filters
Journal ArticleDOI
01 Jan 2019-Optik
TL;DR: In this article, a method via combined static and dynamic analysis extinction performance is presented, combining with the reflection spectra measured by a Nicolet FT-IR spectrometer, and transmittance determined by smoke box test of microbial materials in 3 ∼ 5 μ m.

6 citations

Journal ArticleDOI
TL;DR: This is the first report of the estimation of the spectral CRI of a mouse head following injury obtained in the spatial frequency domain and indicates variations in the CRI among brain tissue suffering from injury.
Abstract: Spectral data enabling the derivation of a biological tissue sample's complex refractive index (CRI) can provide a range of valuable information in the clinical and research contexts. Specifically, changes in the CRI reflect alterations in tissue morphology and chemical composition, enabling its use as an optical marker during diagnosis and treatment. In the present work, we report a method for estimating the real and imaginary parts of the CRI of a biological sample using Kramers-Kronig (KK) relations in the spatial frequency domain. In this method, phase-shifted sinusoidal patterns at single high spatial frequency are serially projected onto the sample surface at different near-infrared wavelengths while a camera mounted normal to the sample surface acquires the reflected diffuse light. In the offline analysis pipeline, recorded images at each wavelength are converted to spatial phase maps using KK analysis and are then calibrated against phase-models derived from diffusion approximation. The amplitude of the reflected light, together with phase data, is then introduced into Fresnel equations to resolve both real and imaginary segments of the CRI at each wavelength. The technique was validated in tissue-mimicking phantoms with known optical parameters and in mouse models of ischemic injury and heat stress. Experimental data obtained indicate variations in the CRI among brain tissue suffering from injury. CRI fluctuations correlated with alterations in the scattering and absorption coefficients of the injured tissue are demonstrated. This technique for deriving dynamic changes in the CRI of tissue may be further developed as a clinical diagnostic tool and for biomedical research applications. To the best of our knowledge, this is the first report of the estimation of the spectral CRI of a mouse head following injury obtained in the spatial frequency domain.

5 citations

Journal ArticleDOI
TL;DR: This is the first report, to the best of the knowledge, on using an LC lens to reconstruct 3D images and this proposed method does not need any mechanical movements to acquire a 3D image.
Abstract: In this paper, we present a relatively simple method to acquire a 3D image based on an electrically controlled liquid crystal (LC) lens. Its advantage is that this proposed method does not need any mechanical movements to acquire a 3D image. The tunable-focus LC lens combined with a high-resistance layer (PEDOT) is applied by an overdrive method to become a key optical component for use in a 3D imaging system. Multiple 2D images of slightly different perspectives are recorded, respectively, and 3D images, according to a proposed mapping and projection method, can be reconstructed. This is the first report, to the best of our knowledge, on using an LC lens to reconstruct 3D images. The proposed 3D imaging system is novel for its compact and smart features, so it is attractive for some compact 3D imaging systems.

5 citations

Journal ArticleDOI
23 Sep 2020
TL;DR: In this article, a novel application of Kramers-Kronig analysis was exploited to identify both smooth and rough film-type macroplastics with unknown thickness, which can be particularly useful in the in-situ identification of unknown film-like microplastics; although the sample is large, the ratio function is detected from an area that corresponds to the size of a MP.
Abstract: The knowledge of the plastic type, thickness, and the nature of the surface is important towards the monitoring of microplastic pollution in water bodies, especially when vis-NIR spectroscopy is utilized. Factors such as complex environment and surface roughness induced-light scattering of the probing light limit the optical detection of these parameters in in-situ measurements, however. In this paper, a novel application of Kramers–Kronig analysis was exploited to identify both smooth and rough film-type macroplastics with unknown thickness. This method is particularly useful in the in-situ identification of unknown film-like macroplastics; although the sample is large, the ratio function is detected from an area that corresponds to the size of a MP. Therefore, it can be applied for the case of large size MPs. The validity of the method was demonstrated using transmittance data for smooth and roughened plastics given in Kanyathare et al., 2020.

3 citations

Proceedings ArticleDOI
01 Mar 2019
TL;DR: In this article, a method based on spatial frequency domain imaging platform and different back-processing algorithms are used together to present the refractive index (RI) of mouse brain tissue in the NIR spectral range.
Abstract: A method based on spatial frequency domain imaging platform and different back-processing algorithms are used together to present the refractive index (RI) of mouse brain tissue in the NIR spectral range. Structured light patterns at two frequencies of six wavelengths ranging between 690 and 970 nm were serially projected onto mouse scalp while a camera mounted above the head captures the reflected diffuse light. In the computer, the recorded images at each wavelength were converted to spatial absorption and scattering maps, respectively. Then, algorithms based on Maxell equations, Hilbert Transform, and Kramers-Kronig relations are used separately to calculate the RI. Once the value of RI at each wavelength was obtained, the wavelength dependence of RI was fitted using four well-known dispersion models. In addition, three-dimensional surface-profile distribution of RI was achieved based on phase profilometry principle. During this study, RI was evaluated in mouse model of heatstress (HS) showing a decrease in RI with increasing wavelength and overall differences pre-and-post HS. An in-house system was built to control the body temperature and thermal camera together with IR laser temperature meter gun was used to measure brain temperature. The changes in RI we observed reflect the pathophysiology of the brain during HS and present an additional advantage of spatial frequency domain imaging technique to characterize brain function. Overall, this work demonstrates a proofof- concept of the proposed method which we believe will be beneficial to the Biophotonics' community.

2 citations