scholarly journals Bidirectional Reflectance Measurement and Reflection Model Fitting of Complex Materials Using an Image-Based Measurement Setup

2018 ◽  
Vol 4 (11) ◽  
pp. 136 ◽  
Author(s):  
Aditya Sole ◽  
Ivar Farup ◽  
Peter Nussbaum ◽  
Shoji Tominaga
Keyword(s):  
Optical Properties ◽  
Model Fitting ◽  
Complex Materials ◽  
Bidirectional Reflectance ◽  
Reflectance Measurement ◽  
Visual Appearance ◽  
Reflection Model ◽  
Packaging Industry ◽  
Reflection Models

Materials with a complex visual appearance, like goniochromatic or non-diffuse, are widely used for the packaging industry. Measuring optical properties of such materials requires a bidirectional approach, and therefore, it is difficult and time consuming to characterize such a material. We investigate the suitability of using an image-based measurement setup to measure materials with a complex visual appearance and model them using two well-established reflection models, Cook–Torrance and isotropic Ward. It was learned that the complex materials typically used in the print and packaging industry, similar to the ones used in this paper, can be measured bidirectionally using our measurement setup, but with a noticeable error. Furthermore, the performance of the reflection models used in this paper shows big errors colorimetrically, especially for the goniochromatic material measured.

scholarly journals Bidirectional reflectance measurement of tungsten samples to assess reflection model in WEST tokamak

2021 ◽  
Vol 92 (9) ◽  
pp. 093501
Author(s):  
M. Ben Yaala ◽  
M.-H. Aumeunier ◽  
R. Steiner ◽  
M. Schönenberger ◽  
C. Martin ◽  
...  
Keyword(s):  
Bidirectional Reflectance ◽  
Reflectance Measurement ◽  
Reflection Model

scholarly journals A Novel Approach to Droplet’s 3D Shape Recovery Based on Mask R-CNN and Improved Lambert–Phong Model

Micromachines ◽  
2018 ◽  
Vol 9 (9) ◽  
pp. 462 ◽  
Author(s):  
Shizhou Lu ◽  
Chenliang Ren ◽  
Jiexin Zhang ◽  
Qiang Zhai ◽  
Wei Liu
Keyword(s):  
Final Height ◽  
Three Dimensional ◽  
Shape From Shading ◽  
Droplet Surface ◽  
Running Speed ◽  
Droplet Shape ◽  
Fast Running ◽  
Reflection Model ◽  
Novel Approach ◽  
Reflection Models

Aiming at the demand for extracting the three-dimensional shapes of droplets in microelectronic packaging, life science, and some related fields, as well as the problems of complex calculation and slow running speed of conventional shape from shading (SFS) illumination reflection models, this paper proposes a Lambert–Phong hybrid model algorithm to recover the 3D shapes of micro-droplets based on the mask regions with convolutional neural network features (R-CNN) method to extract the highlight region of the droplet surface. This method fully integrates the advantages of the Lambertian model’s fast running speed and the Phong model’s high accuracy for reconstruction of the highlight region. First, the Mask R-CNN network is used to realize the segmentation of the highlight region of the droplet and obtain its coordinate information. Then, different reflection models are constructed for the different reflection regions of the droplet, and the Taylor expansion and Newton iteration method are used for the reflection model to get the final height of all positions. Finally, a three-dimensional reconstruction experimental platform is built to analyze the accuracy and speed of the algorithm on the synthesized hemisphere image and the actual droplet image. The experimental results show that the proposed algorithm based on mask R-CNN had better precision and shorter running time. Hence, this paper provides a new approach for real-time measurement of 3D droplet shape in the dispensing state.

Development of a System to Measure the Optical Properties of Facial Skin using a 3D Camera and Projector

2021 ◽  
Author(s):  
Kumiko Kikuchi ◽  
Shoji Tominaga ◽  
Jon Y. Hardeberg
Keyword(s):  
Optical Properties ◽  
Diffuse Reflection ◽  
Specular Reflection ◽  
Three Dimensional ◽  
Depth Image ◽  
Facial Skin ◽  
Subsurface Scattering ◽  
Surface Reflection ◽  
Reflection Model ◽  
Reflection Component

We have developed a system to measure both the optical properties of facial skin and the three-dimensional shape of the face. To measure the three-dimensional facial shape, our system uses a light-field camera to provide a focused image and a depth image simultaneously. The light source uses a projector that produces a high-frequency binary illumination pattern to separate the subsurface scattering and surface reflections from the facial skin. Using a dichromatic reflection model, the surface reflection image of the skin can be separated further into a specular reflection component and a diffuse reflection component. Verification using physically controlled objects showed that the separation of the optical properties by the system correlated with the subsurface scattering, specular reflection, or diffuse reflection characteristics of each object. The method presented here opens new possibilities in cosmetology and skin pharmacology for measurement of the skin’s gloss and absorption kinetics and the pharmacodynamics of various external agents.

Accurate and Fast Estimation of Optical Properties Using Optical Path Length and Spatially Resolved Reflectance Measurement

2011 ◽  
Vol 222 ◽  
pp. 318-321 ◽  
Author(s):  
Takayuki Yamashita ◽  
Masatsugu Niwayama ◽  
Toshitaka Yamakawa
Keyword(s):  
Optical Properties ◽  
Light Intensity ◽  
Path Length ◽  
Continuous Wave ◽  
Practical Method ◽  
Optical Path Length ◽  
Optical Path ◽  
Phase Detector ◽  
Reflectance Measurement ◽  
Spatially Resolved

We developed a new practical method for determining the absorption coefficient and reduced scattering coefficient simultaneously by using the spatial light intensity profile and the optical path length based on the results of a Monte Carlo simulation. The proposed system is optically and electrically robust and practical because (1) light intensity detection of a continuous wave for the spatially resolved reflectance is stable, convenient, and fast, and (2) the optical path length calculated from the phase can be measured precisely using the digital phase detector of a laser rangefinder. The optical properties of the tissue-like medium were measured accurately and quickly.

scholarly journals MAGNETO-TRANSPORT AND MAGNETO-OPTICAL PROPERTIES OF FERROMAGNETIC (III,Mn)V SEMICONDUCTORS: A REVIEW

2004 ◽  
Vol 18 (08) ◽  
pp. 1083-1118 ◽  
Author(s):  
JAIRO SINOVA ◽  
T. JUNGWIRTH ◽  
JOHN ČERNE
Keyword(s):  
Optical Properties ◽  
Material Research ◽  
Ferromagnetic Coupling ◽  
Effective Hamiltonian ◽  
Hamiltonian Approach ◽  
Complex Materials ◽  
Local Moments ◽  
Bulk Properties ◽  
The Past ◽  
Theoretical Approaches

Rapid developments in material research of metallic ferromagnetic (III,Mn)V semiconductors over the past few years have brought a much better understanding of these complex materials. We review here some of the main developments and current understanding of the bulk properties of these systems within the metallic regime, focusing principally on the magneto-transport and magneto-optical properties. Although several theoretical approaches are reviewed, the bulk of the review uses the effective Hamiltonian approach, which has proven useful in describing many of these properties namely in (Ga,Mn)As and (In,Mn)As. The model assumes a ferromagnetic coupling between Mn d-shell local moments mediated by holes in the semiconductor valence band.

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