Spectral reflectance in human skin tissue has been studied through Monte Carlo simulation using the Nine-layered skin tissue model. It is important to estimate absorption and scattering parameters of human skin tissue to know the condition of human skin. In this study, we investigated a method for estimating the absorption and scattering parameters by considering the effect of specific layers on the spectral band in the spectral reflectance database of human skin generated by Monte Carlo simulation.
Similarity in skin reflectance spectra with different combination of absorption and scattering conditions makes erroneous estimation of parameters for any measured spectrum through the database containing simulated spectra. In this study, such similar reflectance spectra are investigated by Monte Carlo simulation and phantom experiment.
In this study, we report spatial resolution enhancement and image quality improvement of a digital holographic microscopy using speckle patterns generated from a moving diffuser. In this method, speckle patterns are produced by moving a diffuser in the in-plane directions and incident on an object. In comparison with other methods for generating speckle illuminations, it realizes a simple and low-cost optical setup in digital holographic microscopy.
To measure optically physiological condition inside skin tissue, it is important to estimate optical parameters in skin tissue. In this study, we investigated a method to estimate absorption and scattering parameters in skin tissue from the spectral reflectance database constructed by using Monte Carlo simulation with a nine-layered skin tissue model.
Skin spectral reflectance can be used for estimate optical properties of human skin tissue, but there is a potential problem. We investigated skin conditions producing similar reflectance spectra but different point spread functions of reflected intensity on the skin surface in the framework of Monte Carlo simulation.
KEYWORDS: Digital holography, 3D image reconstruction, Speckle, Holograms, Image sensors, Image quality, Digital recording, Image processing, Digital imaging, Denoising
In this study, we demonstrate reduction of speckle noises of digital holography using speckle correlation properties in the longitudinal direction. In this method, it is assumed that digital holograms of diffuse objects are recorded on an image sensor. Using multiple holograms recorded by moving the image sensor to the longitudinal direction, the speckle noise of a reconstructed image is reduced and therefore the image quality is improved by the proposed method.
Blood coagulation is an important role in the hemostasis process. In the observation using microscopies, an aggregation structure of red blood cells indicates the degree of blood coagulation. Recently, it has been proposed that digital holographic microscopy (DHM) is a powerful tool for biomedical cell imaging on the basis of quantitative phase information. DHM has the advantage in that the real-time and three-dimensional (3-D) quantitative phase imaging can be realized in the wide field of view, which means that the 3-D morphological parameters of biological cells without a staining process are obtained in real time. We report the complete 3-D quantitative phase imaging of blood coagulation structures by optical projection tomography in a flow cytometry using DHM.
We have developed so far the method for imaging simultaneously blood flow and blood concentration change in skin tissue by using two-wavelength near infrared laser speckle patterns. We conducted experiments for human volunteers to confirm the feasibility of the method for estimating temporal response in the blood flow and blood concentration change in a human finger to occlusion on a human arm with different pressures from 50 to 150 mmHg. The results demonstrated that the response may depend on individual minimum and maximum blood pressure values.
Digital holographic microscopy (DHM) is actively investigated in the field of bio-imaging as a quantitative phase microscopy. In recent years, digital holographic technique for enhancing the spatial resolution using speckle patterns has been reported by several research groups, and we reported the enhancement of the spatial resolution in DHM using speckle illuminations generated from a ring-slit aperture. In this study, by applying the two-wavelength method to DHM using speckle illuminations, we realize the enhancement of spatial resolution and the extension of measurement range of shape measurement in DHM.
Blood coagulation is an important role in hemostasis process. In microscopic observation, an aggregation structure of red blood cells (RBCs) indicates the degree of blood coagulation. In this study, we demonstrate a tomographic imaging of phase distributions of aggregation structures of RBCs in blood coagulation using digital holographic microscopy.
In this study, we propose digital holographic microscopy using speckle illuminations and two-wavelength method. In this method, the spatial resolution is enhanced by speckle illuminations, and the measurement range in depth direction is extended by two-wavelength method. We demonstrate the proposed method experimentally.
We have developed the method for imaging blood flow and blood concentration change by using laser speckle in fiber
illumination. We experimentally discuss the relationship of blood occlusion condition and individual response of blood
concentration change measured by the method.
Human skin surface has unevennesses called sulcus cutis and crista cutis. It is known that these affect the light propagation in
human skin. In this study, we made a prototype of skin tissue phantom and investigated its spectral properties and problems
to be solved.
In this study, we propose a method to enhance the spatial resolution of digital holographic microscopy with
speckle illuminations. In this method, speckle patterns are generated from coherence light passing through ringslit
apertures instead of the most typical circular apertures, to obtain higher numerical aperture. The results
show that a reconstructed image with the higher resolution is obtained using ring-slit apertures.
Skin surface texture has an influence on light propagation in tissue and changes the impression of the skin appearance. We use Monte Carlo simulation for estimating spectral reflectance in human skin. However, the simulation was made for parallel layered model having a flat surface. In this study, we investigated to use texture-added skin model in the simulation. We confirmed that a change of intensity distribution was found when the skin surface texture was changed.
KEYWORDS: Color reproduction, Skin, RGB color model, Reflectivity, Monte Carlo methods, CCD cameras, Error analysis, Databases, Color difference, Blood
Skin measurements based on spectral reflectance are widely studied in the fields of medical care and cosmetics. It has the advantage that several skin properties can be estimated in the non-invasive and non-contacting manner. In this study, we demonstrate the color reproduction of human skin by spectral reflectance using RGB images and the Wiener estimation method.
There are sulcus cutis and crista cutis on human skin surface. It is known that these affect the light propagation in human skin. To investigate it experimentally, it is desirable to reproduce sulcus cutis and crista cutis in skin tissue phantom. In this study, we made a prototype of skin tissue phantom having a shape of sulcus cutis and crista cutis, and investigated its optical properties and problems to be solved.
Digital holography is a useful technique for recording and reconstruction of the complex amplitude of an optical field. In this technique, an interference pattern of two waves is detected by an image sensor, and digital holograms are acquired in computer. The wavefront is reconstructed by a numerical calculation. In this study, we present the real-time threedimensional counting and shape measurement of RBCs using flow cytometry with digital holographic microscopy.
Light propagation into human skin tissue is studied by using Monte Carlo simulation (MCS) with the multi-layered skin tissue model. In this study, we analyzed light propagation in various internal conditions of skin tissue by calculating photon fluence based on Monte Carlo simulation. And we examined a method for quantitative evaluation on the depth and spread of light propagation in skin tissue.
In this study, we propose a method to enhance the spatial resolution of digital holographic microscopy with speckle-illumination. In this method, speckle patterns are generated from coherence light passing through ring-slit apertures instead of the most typical circular apertures, to obtain higher numerical aperture. The results show that a reconstructed image with the higher resolution is obtained using ring-slit apertures.
In the imaging of blood concentration change using near infrared bio-speckles, temporal averaging of speckle images is
necessary for speckle reduction. To improve the temporal resolution in blood concentration imaging, use of spatial
averaging is investigated to measured data in rat experiments. Results show that three frames in temporal averaging with
(2×2) pixels in spatial averaging can be accepted to obtain the temporal resolution of ten concentration images per
second.
We present an image quality improvement using the speckle method in an in-line digital holography by means of a multi-mode fiber. In the proposed method, we use the speckle field emitted from the multi-mode fiber as both the reference wave and the wavefront illuminating the object. To capture multiple holograms, the speckle fields are changed by vibrating the multi-mode fiber using a vibrator. This method has an advantage in that the alignment of an optical setup becomes ease due to the introduction of an optical fiber and the speckle method can be readily performed by means of a vibrator.
When a diffuser is illuminated by the coherent light with intensity distributions obeying a negative power law, speckle fields with fractal properties are produced. Such a random field is called fractal speckles. Fractal speckles have extremely long spatial correlation functions of the intensity distributions in comparison with ordinary speckles. It implies that fractal speckles may extend measurement ranges in various metrological applications based on the spatial correlation of speckles. We report the generation of fractal speckles using computer-generated holograms based on the method of stationary phase and the iterative Fourier transform algorithm, and its application to speckle correlometry is discussed.
With a newly-developed 16-sample wavelength-shifting algorithm, Fizeau phase-shifting interferometry with a laser
diode (LD) suppresses alignment errors in a test plate. This phase-shifting algorithm includes the elimination of phase
errors due to changes in laser power by LD currents. The measurement phase errors on a 16-sample phase-extraction
algorithm are numerically and experimentally estimated. The surface-profile measurement of a plane-parallel plate is
experimentally shown free from systematic errors.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.