scholarly journals Non-Contact Roughness Measurement in Sub-Micron Range by Considering Depolarization Effects

Sensors ◽  
2019 ◽  
Vol 19 (10) ◽  
pp. 2215
Author(s):  
Franziska Pöller ◽  
Félix Salazar Bloise ◽  
Martin Jakobi ◽  
Shengjia Wang ◽  
Jie Dong ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Michelson Interferometer ◽  
Experimental Results ◽  
Quarter Wave Plate ◽  
Contact Method ◽  
Reference Mirror ◽  
Small Surface ◽  
Measuring Surface ◽  
Quarter Wave

The characteristics of a surface, particularly the roughness, play an important role in different fields of the industry and have to be considered to ensure quality standards. Currently, there are numerous sophisticated methods for measuring surface roughness but plenty of them cause long-term damage because they are in contact with the sample. This article presents a non-contact method to accurately determine small surface roughnesses resulting from the consideration of the depolarization effects caused by the rough surface. This technique can be applied as an extension in various roughness measurements and improves the approach of Chandley’s technique, which does not take into account the depolarization of the light scattered by the sample. The experimental setup and the measurements are easy to perform. The essential component is a quarter wave plate, which is incorporated into a Michelson interferometer. With the resulting two different contrasts and the recorded intensities of the sample and the reference mirror, the surface roughness can be estimated straightforwardly. This article details the theoretical approach, followed by the experimental results and the corresponding uncertainties. The experimental results are compared with Chandley’s method. In order to have reference roughness values of the samples, measurements with a stylus profilometer and with a confocal microscope are performed and compared.

scholarly journals Extension and Limits of Depolarization-Fringe Contrast Roughness Method in Sub-Micron Domain

Sensors ◽  
2021 ◽  
Vol 21 (16) ◽  
pp. 5572
Author(s):  
Franziska Pöller ◽  
Félix Salazar Bloise ◽  
Martin Jakobi ◽  
Jie Dong ◽  
Alexander W. Koch
Keyword(s):  
Scattered Light ◽  
Measurement Techniques ◽  
Michelson Interferometer ◽  
Measurement Range ◽  
Quarter Wave Plate ◽  
Contact Method ◽  
Reference Mirror ◽  
Fringe Contrast ◽  
Contrast Technique ◽  
Quarter Wave

To guarantee quality standards for the industry, surface properties, particularly those of roughness, must be considered in many areas of application. Today, several methods are available on the market, but some damage the surface to be tested as they measure it by contact. A non-contact method for the precise estimation of sub-micron roughness values is presented, which can be used as an extension of existing roughness measurement techniques to improve them further considering the depolarized light reflected by the sample. This setup is based on a Michelson interferometer, and by introducing a quarter-wave plate on a half part of the reference mirror, the surface roughness can be directly derived by measuring the fringe contrasts. This article introduces a simple model describing the intensity distortions resulting from the microscopic roughness in divided interferograms when considering depolarization. This work aimed to extend the measurement range of the technique developed in a previous work, in which depolarization effects are taken into account. For verification, the experimental results were compared with the fringe contrast technique, which does not consider the depolarization of the scattered light, especially regarding the extended wavelength interval, highlighting the limits of the technique. In addition, simulations of the experiments are presented. For comparison, the reference values of the sample roughness were also generated by measurements with a stylus profiler.

Surface characterization of paper and paperboard using a stylus contact method

2020 ◽  
Vol 35 (1) ◽  
pp. 78-88
Author(s):  
Young Chan Ko ◽  
Lili Melani ◽  
Na Young Park ◽  
Hyoung Jin Kim
Keyword(s):  
Surface Roughness ◽  
Surface Characterization ◽  
Paper Industry ◽  
Surface Friction ◽  
Operating Conditions ◽  
Contact Method ◽  
Measuring Surface ◽  
Two Samples ◽  
Friction Measurements

AbstractSurface characterization is important and has many applications in the paper industry. Surface characterization requires both surface roughness and surface friction. The relationship between the two has not been fully established for paper and paperboard. It has been a common practice that only the average property and the standard deviation with the coefficient of variation (COV) are reported for surface roughness and friction measurements. This practice, however, provides few information on surface structure and can lead to wrong judgments because two samples having the same average and the COV can have different physical properties. To avoid such mistake, a new surface characterization method has been developed. To this end, surface roughness- and friction-profiles have been obtained using a latest version of Kawabata surface tester (Model: KES-SESRU, Kato Tech, Kyoto Japan). This new version uses the same stylus for both measuring surface roughness and friction under the same operating conditions. It was found that a correlation between the surface roughness and surface friction was very low. This indicates that they should be independent of each other. Therefore, both should be determined for surface characterization.

Phase-Shifting Interferometry for Surface Roughness Measurement on Glass Substrates

2014 ◽  
Vol 979 ◽  
pp. 463-466 ◽  
Author(s):  
S. Suriyasirikun ◽  
S.T. Khlayboonme ◽  
W. Thowladda
Keyword(s):  
Surface Roughness ◽  
Michelson Interferometer ◽  
Ccd Camera ◽  
Rf Magnetron Sputtering ◽  
Film Coating ◽  
Phase Shifting ◽  
Reference Mirror ◽  
Phase Shifting Interferometry ◽  
Glass Slides ◽  
Phase Calculation

Phase shifting interferometry based on Michelson interferometer is purposed to measure surface roughness of glass slides which are widely used as substrates for thin-film coating processes. For the interferometry system, an optical flat with a flatness of λ/20 is used as a reference mirror. The high accuracy of the phase shifting is achieved by a piezoelectric-driven linear translation stage of the reference mirror. The reference-phase difference between the two-interfering beams is shifted by every π/2 in phase shifting. Five frames of interferograms under various phase differences of 0, π/2, π, 3π/2 and 2π are recorded by a CCD camera. Each image pixel of these frames is interpreted to access interference intensity information by five-step phase shifting algorithm for phase calculation, which in turn relates to surface height. The purpose-built interferometry is tested by the surfaces of two optical flats with flatness of λ/10 and λ/4, which are used as the test surfaces. Our measured flatness results are consistent with those of the commercial optical profilometer. The usefulness of the purpose-built interferometry is demonstrated on two types of the glass slides. Aluminum thin films are also deposited on these glass slides by the RF magnetron sputtering method to enhance reflectivity of the glass slide surfaces. The surface profiles and flatness parameters of these glass slides have been reported.

Investigation of particulate systems using optical pathlength spectroscopy

2000 ◽  
Vol 627 ◽  
Author(s):  
Gabriel Popescu ◽  
Aristide Dogariu
Keyword(s):  
Path Length ◽  
Random Media ◽  
Michelson Interferometer ◽  
Industrial Process ◽  
Optical Path Length ◽  
Industrial Applications ◽  
Optical Path ◽  
Interference Signal ◽  
Optical Length ◽  
Reference Mirror

ABSTRACTIn many industrial applications involving granular media, knowledge about the structural transformations suffered during the industrial process is desirable. Optical techniques are noninvasive, fast, and versatile tools for monitoring such transformations. We have recently introduced optical path-length spectroscopy as a new technique for random media investigation. The principle of the method is to use a partially coherent source in a Michelson interferometer, where the fields from a reference mirror and the sample are combined to obtain an interference signal. When the system under investigation is a multiple-scattering medium, by tuning the optical length of the reference arm, the optical path-length probability density of light backscattered from the sample is obtained. This distribution carries information about the structural details of the medium. In the present paper, we apply the technique of optical path-length spectroscopy to investigate inhomogeneous distributions of particulate dielectrics such as ceramics and powders. The experiments are performed on suspensions of systems with different solid loads, as well as on powders and suspensions of particles with different sizes. We show that the methodology is highly sensitive to changes in volume concentration and particle size and, therefore, it can be successfully used for real-time monitoring. In addition, the technique is fiber optic-based and has all the advantages associated with the inherent versatility.

scholarly journals Experimental and Analytical Study on Creep Characteristics of Box Section Bamboo-Steel Composite Columns under Long-Term Loading

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 983
Author(s):  
Shixu Wu ◽  
Keting Tong ◽  
Jianmin Wang ◽  
Yushun Li
Keyword(s):  
Load Level ◽  
Experimental Results ◽  
Creep Model ◽  
Composite Column ◽  
Composite Columns ◽  
Creep Coefficient ◽  
Creep Characteristics ◽  
Section Size ◽  
Steel Composite

To expand the application of bamboo as a building material, a new type of box section composite column that combined bamboo and steel was considered in this paper. The creep characteristics of eight bamboo-steel composite columns with different parameters were tested to evaluate the effects of load level, section size and interface type under long-term loading. Then, the deformation development of the composite column under long-term loading was observed and analyzed. In addition, the creep-time relationship curve and the creep coefficient were created. Furthermore, the creep model of the composite column was proposed based on the relationship between the creep of the composite column and the creep of bamboo, and the calculated value of creep was compared with the experimental value. The experimental results showed that the creep development of the composite column was fast at first, and then became stable after about 90 days. The creep characteristics were mainly affected by long-term load level and section size. The creep coefficient was between 0.160 and 0.190. Moreover, the creep model proposed in this paper was applicable to predict the creep development of bamboo-steel composite columns. The calculation results were in good agreement with the experimental results.

scholarly journals None sharp corner localized surface plasmons resonance based ultrathin metasurface single layer quarter wave plate

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Qinyu Qian ◽  
Pengfei Liu ◽  
Li Fan ◽  
Liang Zhao ◽  
Chinhua Wang
Keyword(s):  
Surface Plasmons ◽  
Amplitude Ratio ◽  
Single Layer ◽  
Quarter Wave Plate ◽  
Localized Surface Plasmons ◽  
Sharp Corner ◽  
Wave Plate ◽  
Nanophotonic Devices ◽  
Elliptical Ring ◽  
Quarter Wave

AbstractWe report on a non-sharp-corner quarter wave plate (NCQW) within the single layer of only 8 nm thickness structured by the Ag hollow elliptical ring array, where the strong localized surface plasmons (LSP) resonances are excited. By manipulating the parameters of the hollow elliptical ring, the transmitted amplitude and phase of the two orthogonal components are well controlled. The phase difference of π/2 and amplitude ratio of 1 is realized simultaneously at the wavelength of 834 nm with the transmission of 0.46. The proposed NCQW also works well in an ultrawide wavelength band of 110 nm, which suggests an efficient way of exciting LSP resonances and designing wave plates, and provides a great potential for advanced nanophotonic devices and integrated photonic systems.

scholarly journals High-Contrast and Scattering-Type Transflective Liquid Crystal Displays Based on Polymer-Network Liquid Crystals

Polymers ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 739 ◽  
Author(s):  
Cheng-Kai Liu ◽  
Wei-Hsuan Chen ◽  
Chung-Yu Li ◽  
Ko-Ting Cheng
Keyword(s):  
Liquid Crystal ◽  
Polymer Network ◽  
Liquid Crystal Displays ◽  
Quarter Wave Plate ◽  
High Contrast ◽  
Trade Off ◽  
Twisted Nematic ◽  
Quarter Wave ◽  
The Common ◽  
Linear Polarizer

The methods to enhance contrast ratios (CRs) in scattering-type transflective liquid crystal displays (ST-TRLCDs) based on polymer-network liquid crystal (PNLC) cells are investigated. Two configurations of ST-TRLCDs are studied and are compared with the common ST-TRLCDs. According to the comparisons, CRs are effectively enhanced by assembling a linear polarizer at the suitable position to achieve better dark states in the transmissive and reflective modes of the reported ST-TRLCDs with the optimized configuration, and its main trade-off is the loss of brightness in the reflective modes. The PNLC cell, which works as an electrically switchable polarizer herein, can be a PN-90° twisted nematic LC (PN-90° TNLC) cell or a homogeneous PNLC (H-PNLC) cell. The optoelectric properties of PN-90° TNLC and those of H-PNLC cells are compared in detail, and the results determine that the ST-TRLCD with the optimized configuration using an H-PNLC cell can achieve the highest CR. Moreover, no quarter-wave plate is used in the ST-TRLCD with the optimized configuration, so a parallax problem caused by QWPs can be solved. Other methods for enhancing the CRs of the ST-TRLCDs are also discussed.

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