Method of thickness measurement for transparent specimens with chromatic confocal microscopy

Yu, Qing; Zhang, Kun; Cui, Changcai; Zhou, Ruilan; Fang, Cheng; Ye, Ruifang; Zhang, Yi

doi:10.1364/ao.57.009722

Cited by 42 publications

(18 citation statements)

References 18 publications

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“…Once the damage area was determined, the microscope was then replaced by a chromatic confocal scanner for a detailed scanning (Yongqing Wang et al 2021). The physical principle of the chromatic confocal scanner is mainly from the wavelength dependence of a longitudinal chromatic aberration and the analysis of the spectral components from the reflection of light (Miks et al 2010;Yu et al 2018). The technical specializations of the device are listed in Table 1.…”

Section: Scanning Systemmentioning

confidence: 99%

Non-Contact 3D Characterization System of Scratch-Induced Surface Damage on Monolithic Glass Panel

Pan

Yang

Wang

et al. 2022

CGC

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Glass material has been widely used in modern architecture. Scratch-induced surface damage of aged monolithic glass panel leads to the strength degradation of material and thus threatens the glass safety. Therefore, in order to accurately evaluate the strength of aged glass elements, it is crucial to extract key damage features including the damage location and depth in a precise way. This study aims to develop a non-contact stage-wise scanning method to extract 3D damage characteristics on glass surface, which can further facilitate the investigation into the associated influences on the flexural strength of glass. Coaxial double ring tests on annealed glass specimens under various magnitudes of applied loads were performed, which aimed to explore the influence of the surface damage on the flexural strength. Monocular microscope equipped with an industrial camera was used to detect damage area throughout the glass panel in the first stage rapidly. It was then followed by a chromatic confocal scanner to precisely measure the damage depth within local damage area. The results via confocal microscope scanning were considered as the reference values. It shows that the proposed method can be a potentially alternative solution instead of confocal microscope for damage quantification.

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Section: Scanning Systemmentioning

confidence: 99%

Non-Contact 3D Characterization System of Scratch-Induced Surface Damage on Monolithic Glass Panel

Pan

Yang

Wang

et al. 2022

CGC

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“…On the other hand, the recent system research works in confocal microscopy have been focused on the non-scanning type, so-called chromatic confocal microscopy (CCM), to use the chromatic aberration of optical components instead of adopting axial scanning mechanisms [ 57 , 58 , 59 ]. Corresponding to the chromatic focal positions, each wavelength of the reflected light is detected by a spectrometer, and the relationship between the focal positions and the wavelength shifts enables calculating the surface height of the specimen.…”

Section: Technology and Analysis In Optical Film Metrologymentioning

confidence: 99%

“…In the dual-confocal fiber-optic sensor [56], as shown in Figure 8A, a geometrical-ray model as illustrated in Figure 8B was used to obtain the analytical dependence between the thickness and the refractive index of a transparent plate with high accuracy, although the minimum measurable thickness was 1.7 μm. On the other hand, the recent system research works in confocal microscopy have been focused on the non-scanning type, so-called chromatic confocal microscopy (CCM), to use the chromatic aberration of optical components instead of adopting axial scanning mechanisms [57][58][59]. Corresponding to the chromatic focal positions, each wavelength of the reflected light is detected by a spectrometer, and the relationship between the focal positions and the wavelength shifts enables calculating the surface height of the specimen.…”

Section: Confocal Microscopymentioning

confidence: 99%

Recent Progress on Optical Tomographic Technology for Measurements and Inspections of Film Structures

Joo

Park

2022

Micromachines

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In this review, we present the recent progress on film metrology focused on the advanced and novel technologies during the last two decades. This review consists of various technologies and their measurement schemes to provide the inspiration for understanding each of the measurement principles and applications. In the technology and analysis section, several optical techniques used in film metrology are introduced and described with their benefits and limitations. The temporal, spatial and snapshot measurement schemes of optical film metrology are introduced in the measurement scheme section, and finally, the prospect on optical film metrology will be provided and discussed with the technology trend.

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“…In 2017, Boettcher T et al [18] proposed a new hybrid single-shot imaging scheme that combined chromatic confocal and interference technology, to simultaneously measure the thickness and refractive index for translucent materials. In 2018, Zhang K et al [19] established a thickness measurement model by adding an auxiliary reflector below the specimen. This model was able to significantly enlarge the tolerance of the specimen placement.…”

Section: Of 16mentioning

confidence: 99%

Thickness Measurement for Glass Slides Based on Chromatic Confocal Microscopy with Inclined Illumination

Zhang

Shang

et al. 2021

Photonics

Self Cite

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Chromatic confocal microscopy is a widely used method to measure the thickness of transparent specimens. In conventional configurations, both the illumination and imaging axes are perpendicular to the test specimen. The reflection will be very weak when measuring high-transparency specimens. In order to overcome this limitation, a special chromatic confocal measuring system was developed based on inclined illumination. This design was able to significantly improve the signal-to-noise ratio. Compared with conventional designs, the proposed system was also featured by its biaxial optical scheme, instead of a coaxial one. This biaxial design improved the flexibility of the system and also increased the energy efficiency by avoiding light beam splitting. Based on this design, a prototype was built by the authors’ team. In this paper, the theoretical model of this specially designed chromatic confocal system is analyzed, and the calculating formula for the thickness of transparent specimen is provided accordingly. In order to verify its measurement performance, two experimental methodology and results are presented. The experimental results show that the repeatability is better than 0.54 μm, and the axial measurement accuracy of the system could reach the micron level.

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Method of thickness measurement for transparent specimens with chromatic confocal microscopy

Cited by 42 publications

References 18 publications

Non-Contact 3D Characterization System of Scratch-Induced Surface Damage on Monolithic Glass Panel

Non-Contact 3D Characterization System of Scratch-Induced Surface Damage on Monolithic Glass Panel

Recent Progress on Optical Tomographic Technology for Measurements and Inspections of Film Structures

Thickness Measurement for Glass Slides Based on Chromatic Confocal Microscopy with Inclined Illumination

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