An Experimental Method for Determination of the Refractive Index of Liquid Samples Using Michelson Interferometer

Abbas, B.; Khalil, M. Alshikh

doi:10.12693/aphyspola.129.59

Cited by 10 publications

(3 citation statements)

References 12 publications

(11 reference statements)

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“…The applied method allowed for quick and simple characterization of the material characteristics in entire operation spectral range in a single measurement. This contrasts with other applied techniques in which birefringence is retrieved based on measurements performed for each wavelength independently, such as when using the Abbe refractometer [36], the wedge-cell [37], the Fabry-Perot etalon [38] or the Michelson [39] or Mach-Zehnder [40] interferometer. It also appears to be improved when compared to other spectroscopic methods in which the birefringence can be determined only at some particular wavelengths [41] or multiple measurements [42], S-transform [43] or advanced equipment [44] are required in order to obtain the birefringence of liquid crystal materials at any wavelength.…”

Section: Resultsmentioning

confidence: 91%

Tunable Polarization Gratings Based on Nematic Liquid Crystal Mixtures Photoaligned with Azo Polymer-Coated Substrates

et al. 2020

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Liquid crystal polarization gratings are of great interest for optical communications as elements performing beam steering, splitting, multiplexing or beam combining. Material birefringence, cell thickness or a period of the liquid crystal director pattern influence, among other features, spectroscopic and electro-optical characteristics of fabricated devices, determining thus their functionality and applicability. Here, we report on liquid crystal polarization gratings that allow for complete maximization of the first-order diffraction efficiency (resulting in total elimination of the zeroth-order diffraction) for any wavelength of an incident beam from green to the near-infrared spectral region by applying a low electric voltage. The gratings with periods as small as 10 μm were obtained by holographic exposure of the cell substrates coated with light-sensitive azo polymer alignment layers, and then filled with three different liquid crystal mixtures. The influence of gold nanoparticle dopants in the liquid crystalline mixtures on spectroscopic and electro-optical properties of the devices is presented. Moreover, on the basis of the measured transmittance spectra of the fabricated gratings, the unknown birefringence of liquid crystal mixtures as well as their effective birefringence due to molecular reorientation in the electric field in the visible and near IR region were determined.

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Section: Resultsmentioning

confidence: 91%

Tunable Polarization Gratings Based on Nematic Liquid Crystal Mixtures Photoaligned with Azo Polymer-Coated Substrates

et al. 2020

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“…Thus, simple and highprecision measurement methods of liquid refractive index are required for the liquid material analysis and also for its applications. At present, there are many optical methods for the measurement of liquid refractive index, including digital hologram method [1], Snell's law [2], grating diffraction method [3,4], Michelson interferometer method [5], and so on.…”

Section: Introductionmentioning

confidence: 99%

A method of liquid refractive index measurement based on image correlation coefficient

Xie,

Chen,

Zhou

et al. 2024

J. Phys.: Conf. Ser.

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According to the difference of speckle image caused by the axial displacement due to the refraction of a transparent medium, the liquid refractive index is measured by using the image correlation coefficient. An optical measurement system based on laser speckle is built into the experiment. Firstly, the CCD camera is adjusted to move along the optical axis in air, and multiple speckle images at different positions are collected, which are correlated with the speckle image at zero position to obtain the image correlation coefficients, and then the exponential calibration relation between the correlation coefficient and the axial displacement can be obtained. Secondly, two speckle images are collected when the laser speckle spreads respectively through the liquid to be measured and water as the internal standard, and the correlation coefficient between them is calculated. Finally, according to the above calibration relation, the corresponding axial displacement between the liquid to be measured and water can be derived, and then the refractive index of the liquid to be measured is calculated using the axial displacement formula. The results show that this method can realize the measurement of liquid refractive index, and the optical structure is simple and easy to operate.

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“…Most of LCs are uniaxial and their optical birefringence, defined as a difference between an extraordinary and ordinary refractive index (Δn=n e −n o ), together with their chromatic dispersion, are the most important parameters to be determined in order to ensure proper design, fabrication and functionality of LC-based photonic elements and devices. It is critical thus to deliver and elaborate a convenient and accurate method for refractive index measurements, specifically in a broad spectral range and as a function of temperature [1][2][3][4][5][6][7]. Typically, optical characterization of liquid crystalline materials in terms of chromatic dispersion is performed at room temperature, while the thermal dependence of refractive indices is usually given for one wavelength only (e.g.…”

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confidence: 99%

Wedge-cell technique as a simple and effective method for chromatic dispersion determination of liquid crystals

Rutkowska

Orzechowski²,

Sierakowski³

2016

Photon. Lett. Poland

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Abstract-In this letter we present a wedge-cell method and then compare it with other techniques that can be used to determinate refractive indices of liquid crystalline materials. This simple goniometric technique is of particular significance when used for liquid crystalline materials characterized by high refractive indices, for which refractometric methods are approaching their upper limits. Importantly, the measurement technique proposed here requires a relatively small amount of liquid crystalline material and gives appropriate results for different light sources from the wide spectral range, allowing thus for chromatic dispersion curves (in different temperatures) to be obtained.Liquid crystals (LCs) are unique anisotropic materials with special optical properties. In particular, their refractive indices strongly depend on temperature and molecular orientation, which plays an important role in practical applications of LCs in photonics. Most of LCs are uniaxial and their optical birefringence, defined as a difference between an extraordinary and ordinary refractive index (Δn=n e −n o ), together with their chromatic dispersion, are the most important parameters to be determined in order to ensure proper design, fabrication and functionality of LC-based photonic elements and devices. It is critical thus to deliver and elaborate a convenient and accurate method for refractive index measurements, specifically in a broad spectral range and as a function of temperature [1][2][3][4][5][6][7]. Typically, optical characterization of liquid crystalline materials in terms of chromatic dispersion is performed at room temperature, while the thermal dependence of refractive indices is usually given for one wavelength only (e.g. 589nm which is characteristic for D-sodium-line). Such information is insufficient when needed for proper design and operation of LC-based photonic devices.The experimental setup proposed here, schematically shown in Fig. 1, allows for various monochromatic lasers sources, as well as tunable light source as a monochromator to be applied in order to determine the refractive indices of liquid crystalline materials under tests. A critical issue in the method described here is to place a liquid crystalline material between two glass plates forming a wedge-cell of relatively small angle (of a single degree) and to introduce planar alignment of liquid crystalline molecules on glass substrates. For experimental procedure, the wedge angle has to be known and it can be determined by illuminating an empty cell with a beam perpendicular to one of the glass plates, measuring the distance between the spots coming from the reflection (d 1 on screen A).When a liquid crystal is placed inside the wedge-cell two spots are observed on screen B due to the anisotropy of the LC material. These spots correspond to ordinary and extraodinary rays and are distanced by d 2o and d 2e , respectively, with respect to the initial spot given by the beam passing through the wedge-cell when it was empty. Relatively long distanc...

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An Experimental Method for Determination of the Refractive Index of Liquid Samples Using Michelson Interferometer

Cited by 10 publications

References 12 publications

Tunable Polarization Gratings Based on Nematic Liquid Crystal Mixtures Photoaligned with Azo Polymer-Coated Substrates

Tunable Polarization Gratings Based on Nematic Liquid Crystal Mixtures Photoaligned with Azo Polymer-Coated Substrates

A method of liquid refractive index measurement based on image correlation coefficient

Wedge-cell technique as a simple and effective method for chromatic dispersion determination of liquid crystals

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