Utilization of the cyclic interferometer in polarization phase-shifting technique to determine the thickness of transparent thin-films

Kaewon, Rapeepan; Pawong, Chutchai; Chitaree, Ratchapak; Lertvanithphol, Tossaporn; Bhatranand, Apichai

doi:10.37190/oa200106

Cited by 5 publications

(3 citation statements)

References 25 publications

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“…The sample placed in the common path of the interferometer as in [10,16] may not be optically flat or causes surface anomalies, therefore, the sample can be placed before or after interferometer system as reported in [17]. As depicted in figure 2, the sample is placed in one arm at the output for real-time measurement.…”

Section: Phase Retardation With Presence Of Samplesmentioning

confidence: 99%

“…Furthermore, by utilizing the white light scanning interferometry combined with reflectometry, the thickness and surface measurement of transparent thin-film layers was achieved, where the thickness and profile of the reflectometry and interferometry modes were separately determined [9]. The modified Sagnac interferometer in [10][11][12] were presented to measure a phase-shifting in real time by dividing the beam into testing and reference arms using a BS. However, various polarization stepping algorithms were described, but no conclusions have been reached as to which is the best.…”

Section: Introductionmentioning

confidence: 99%

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The comparison of multi-stepping algorithms for real-time thickness measurement of transparent thin films using polarization settings

Usman¹,

Jiraraksopakun²,

Kaewon³

et al. 2022

Laser Phys.

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This paper presents the comparison of three-, four- and five-step techniques for measuring transparent thin-film thickness of T a 2 O 5 and W O 3 deposited on BK-7 substrates. The Sagnac interferometer was modified with phase shifting approach for the determination of thin-film thickness. The input light beam was split into reference and testing beams. Before the output light reaching the balanced photodetectors, the real-time signal detection was performed to obtain the output intensities of both beams using three-, four-, and five-polarization settings of an analyzer. The thicknesses could then be efficiently translated from the measured intensities. Thicknesses from three-, four- and five-stepping algorithms were compared with ones from the conventional FE-SEM measurement, and it was discovered that the former performed better with less errors. The findings show that the phase-shifting technique using three-polarization settings is more suitable for the thickness measurement of the transparent thin film.

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Section: Phase Retardation With Presence Of Samplesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The comparison of multi-stepping algorithms for real-time thickness measurement of transparent thin films using polarization settings

Usman¹,

Jiraraksopakun²,

Kaewon³

et al. 2022

Laser Phys.

Self Cite

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show abstract

“…To reduce measurement costs, simpler non-contact measurement approaches based on physical optics, such as interferometric or holographic arrangements, have been developed [2]. These techniques offer lower costs, require less maintenance, and still provide satisfactory results compared to device-based measurements [3][4][5][6][7][8]. In perovskite solar cells, the thickness of various layers such as the absorber layer (perovskite), electron transport layer (ETL), holes transport layer (HTL), and interface layers play a crucial role in improving the field factor and overall efficiency of the solar cell.…”

Section: Introductionmentioning

confidence: 99%

Polarization phase shifting for thickness measurement of NiO material transport layer using Sagnac interferometer

Usman,

Thonglim,

Bhatranand

et al. 2023

Applied Optical Metrology V

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The optical interferometric technique with polarization phase shifting has been realized as one of the most important techniques for optical non-contact measurements. However, the measurement of thin film thickness using field emission scanning electron microscopy (FE-SEM) or scanning electron microscopy (SEM) has been inconvenient due to the high cost of maintenance. This research aims to measure the thickness of the Hole Transport Material Nickel (II) oxide (NiO) layer deposited on a glass substrate (NiO/FTO layer) using phase shifting in a Sagnac interferometer. In the experimental setup, the signal is split into the FTO reference arm and the NiO/FTO sample arm using a nonpolarizing beam splitter. The split signals are then detected through a balanced photodetector. By analyzing the signal intensities at polarization settings ranging from 0° to 90°, the phase shift and thickness of the NiO layer can be determined. In this study, a NiO thickness value of 281.64 nm was successfully achieved. To evaluate the accuracy of the proposed measurement method, the percentage error between the proposed technique and the conventional SEM method was computed. The percentage error was found to be 0.23%. These results indicate that the proposed setup holds promise as a cost-effective alternative to SEM for measuring thin film thickness.

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Phase-shifting determination and pattern recognition using a modified Sagnac interferometer with multiple reflections

Usman,

Bhatranand,

Jiraraksopakun

et al. 2024

Appl. Opt.

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This work has implemented a diverse modification of the Sagnac interferometer to accommodate various measurement requirements, including phase shifting, pattern recognition, and a morphological analysis. These modifications were introduced to validate the adaptability and versatility of the system. To enable phase shifting using the multiple light reflection technique, a half-wave plate (HWP) was utilized with rotations at 0, π/8, π/4, and 3π/8 radians, generating four interference patterns. It is possible to observe a distinct circular fringe width as the polarized light experiences diffraction at the interferometer’s output as it travels through a circular aperture with various diameters ranging from 0.4 to 1 mm. Further modifications were made to the setup by inserting a pure glass and a fluoride-doped tin oxide (FTO) transparent substrate into the common path. This modification aimed to detect and analyze a horizontal fringe pattern. Subsequently, the FTO substrate was replaced with a bee leg to facilitate morphology recognition. A deep learning-based image processing technique was employed to analyze the bee leg morphology. The experimental results showed that the proposed scheme succeeded in achieving the phase shift, measuring hole diameters with errors smaller than 1.6%, separating distinct transparent crystals, and acquiring the morphological view of a bee’s leg. The method also has successfully achieved an accurate surface area and background segmentation with an accuracy over 87%. Overall, the outcomes demonstrated the potential of proposed interferometers for various applications, and the advantages of the optical sensors were highlighted, particularly in microscopic applications.

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Utilization of the cyclic interferometer in polarization phase-shifting technique to determine the thickness of transparent thin-films

Cited by 5 publications

References 25 publications

The comparison of multi-stepping algorithms for real-time thickness measurement of transparent thin films using polarization settings

The comparison of multi-stepping algorithms for real-time thickness measurement of transparent thin films using polarization settings

Polarization phase shifting for thickness measurement of NiO material transport layer using Sagnac interferometer

Phase-shifting determination and pattern recognition using a modified Sagnac interferometer with multiple reflections

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