Study on influence of integrating sphere test position on measuring accuracy of optical parameters of LED chip

Abstract The behaviour of light interaction with biological tissue is determined by micro-optical parameters: refractive index (n), absorption coefficient (µa), scattering coefficient (µs), and anisotropy (g). The goal of this study is to measure the optical properties of normal whole blood using He-Ne laser (wavelength 632.8 nm). The refractive index is measured using the traveller microscope. The integrating sphere method is used to measure the macro-optical parameters: total diffusive reflectance, transmittance, and collimated transmittance at wavelength 632.8 nm. The macro-optical parameters are fed to Inverse Adding Doubling (IAD) theoretical technique, to estimate the micro-optical parameters (µs, µa, g). An alternative practical method is used to measure the g value based on utilising the goniometric table. The study reveals that the refractive index (n) equals 1.395±0.0547, absorption coefficient (µa) equals 2.37 mm−1, scattering coefficient (µs) equals 55.69 mm−1, and anisotropy (g) equals 0.82. In conclusion, these findings approved, in general, the applicability of the suggested experimental set up. The set up depend on using three devices: the integrating sphere method to estimate (µs, µa, g), traveller microscope (n) and goniometer (g).

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Analysis of Factors Affecting Optical Performance of GaN-Based Micro-LEDs with Quantum Dots Films

Crystals ◽

10.3390/cryst10030203 ◽

2020 ◽

Vol 10 (3) ◽

pp. 203

Author(s):

Zhili Zhao ◽

Xinzhong Wang ◽

Kaidong Yang ◽

Fang Fan ◽

Dan Wu ◽

...

Keyword(s):

Quantum Dots ◽

Contrast Ratio ◽

Integrating Sphere ◽

Testing System ◽

Optical Parameters ◽

Optical Performance ◽

Mass Ratio ◽

Factors Affecting ◽

Light Emitting ◽

Light Efficiency

Optical performance in terms of light efficiency, color crosstalk and ambient contrast ratio were analyzed for blue GaN-based micro-light emitting diodes (micro-LEDs) combined with red/green quantum dots (QDs)-polymethyl methacrylate (PMMA) films. The thickness and mass ratio of QDs films are two critical factors in affecting the performance of micro-LEDs. Firstly, the precise optical modeling of QDs-PMMA films is established based on the double integrating sphere (DIS) testing system and inverse adding doubling algorithm (IADA) theory. Red and green QDs-PMMA films are composed of ZnCdSe/ZnS QDs and green ZnCdSeS/ZnS QDs, respectively. The fundamental optical parameters of QDs-PMMA films, including scattering, absorption and anisotropy coefficients, are obtained successfully. Secondly, based on these optical parameters, the Monte Carlo ray tracing method is applied to analyze the effect of a QDs-PMMA film’s thickness and mass ratio on the optical performance of micro-LEDs. Results reveal that the light efficiency first increases and then decreases with the increase of a QDs film’s thickness or mass ratio, owing to the scattering characteristics of QDs. Different from the variation tendencies of light efficiency, the crosstalk between adjacent pixels increases as the QDs-PMMA film’s thickness or mass ratio increases, and the ambient contrast ratio is kept stable when the thickness increases. The mass ratio variation of QDs film can change the optical performance of micro-LEDs more effectively than thickness, which demonstrates that mass ratio is a more important factor affecting the optical performance of micro-LEDs.

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Porous Phantoms Mimicking Tissues—Investigation of Optical Parameters Stability Over Time

Materials ◽

10.3390/ma14020423 ◽

2021 ◽

Vol 14 (2) ◽

pp. 423

Author(s):

Paulina Listewnik ◽

Monika Ronowska ◽

Michał Wąsowicz ◽

Valery V. Tuchin ◽

Małgorzata Szczerska

Keyword(s):

Optical Measurement ◽

Measuring System ◽

Integrating Sphere ◽

Optical Parameters ◽

Coherent Light ◽

Multiple Series ◽

Lung Phantom ◽

The Stability ◽

Over Time

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.

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Estimation of Optical Parameters of Chicken Liver Tissue via Single Integrating-Sphere System

2018 Medical Technologies National Congress (TIPTEKNO) ◽

10.1109/tiptekno.2018.8596961 ◽

2018 ◽

Author(s):

Bahar Pehlivanoz ◽

Halil Arslan

Keyword(s):

Liver Tissue ◽

Chicken Liver ◽

Integrating Sphere ◽

Optical Parameters

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The Influence of Particle Sizes on the Optical Characteristics of Nanocrystalline TiO2 Films for Dye-Sensitized Solar Cells

MRS Proceedings ◽

10.1557/proc-1101-kk09-02 ◽

2008 ◽

Vol 1101 ◽

Author(s):

Peter Chao-Yu Chen ◽

Guido Rothenberger ◽

Michael Grätzel

Keyword(s):

Solar Cells ◽

Dye Sensitized Solar Cells ◽

Light Flux ◽

Integrating Sphere ◽

Optical Parameters ◽

Particle Sizes ◽

Tio2 Films ◽

Nanocrystalline Tio2 ◽

Dye Sensitized ◽

Sensitized Solar Cells

AbstractIncreasing the light harvesting efficiency (LHE) of photovoltaic devices is important for improving the conversion efficiency of solar light into electricity. The optical properties of mesoporous TiO2 films for Dye-Sensitized Solar Cells (DSCs) were investigated by varying the size of the particles (20–150 nm). A four–flux optical model was used to describe the light absorption and scattering within the film. Reflectance and transmittance spectra were recorded by a spectrophotometer equipped with an integrating sphere. The wavelength-dependent absorption coefficient k(λ) and scattering coefficient s(λ) were determined for different films. The absorptance G(λ) (absorbed light flux) for films made of different particle sizes and of varying thicknesses can be calculated from these optical parameters. This study helps in improving the optical design of dye-sensitized solar cells.

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Correlation analysis of radiation damage

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100108210 ◽

1978 ◽

Vol 36 (1) ◽

pp. 214-215

Author(s):

R. Hegerl ◽

A. Feltynowski ◽

B. Grill

Keyword(s):

Electron Microscopy ◽

Independent Random Variables ◽

Optical Parameters ◽

Bright Field Image ◽

Bright Field ◽

Expectation Value ◽

All Optical ◽

Image Element ◽

Stochastic Series ◽

The Common

Till now correlation functions have been used in electron microscopy for two purposes: a) to find the common origin of two micrographs representing the same object, b) to check the optical parameters e. g. the focus. There is a third possibility of application, if all optical parameters are constant during a series of exposures. In this case all differences between the micrographs can only be caused by different noise distributions and by modifications of the object induced by radiation.Because of the electron noise, a discrete bright field image can be considered as a stochastic series Pm,where i denotes the number of the image and m (m = 1,.., M) the image element. Assuming a stable object, the expectation value of Pm would be Ηm for all images. The electron noise can be introduced by addition of stationary, mutual independent random variables nm with zero expectation and the variance. It is possible to treat the modifications of the object as a noise, too.

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