Novel system for simultaneously measuring the thickness and refractive index of a transparent plate with two optical paths

Liu, Chien-Sheng; Wang, Tse Yen; Chen, Yu-Ta

doi:10.1007/s00340-018-7052-4

Cited by 10 publications

(3 citation statements)

References 33 publications

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“…We demonstrate the viability of the technique by measuring the position of the anterior and posterior reflections from air-glass and glass-air interfaces of a glass slab and ultimately obtaining the thickness of the sample. The resulting setup performed satisfactorily and provides a very simple, low cost solution to the thickness measurement of transparent plate and can be custom designed to accommodate a wide range of thickness from << 1 mm to several millimetres as opposed to other techniques that can be applied to either smaller values, the case of ellipsometry, or millimetre-sized values, triangulation methods [9]. We found this system particularly suitable for use in off-line quality control.…”

Section: Commonly Thementioning

confidence: 93%

Transparent glass slab thickness measurement by binary-spot focus signal

Aguilar¹,

Torga²

2019

Opt. Pura Apl.

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Focus error systems based on the astigmatic principle relying on four quadrant photo detectors as the signal generation element have widely been used in many different applications. Nevertheless, its working principle is not particularly suitable for measurements involving more than one spot. In this work we propose a new method that uses a CCD as the detection device as well as a method of processing acquired data. A side effect of this change is the loss of the parameter key to these techniques. To overcome this issue a new parameter named focus signal is proposed. The thickness measuring process of a transparent sample with two reflective layers using this technique is also presented.

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Section: Commonly Thementioning

confidence: 93%

Transparent glass slab thickness measurement by binary-spot focus signal

Aguilar¹,

Torga²

2019

Opt. Pura Apl.

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“…However, since the range and accuracy of refractive index measurement are generally limited by the conditions required by the test method itself, there are some drawbacks in the currently commonly used measurement methods. The triangulation methods are limited by the spatial resolution of the beam, for example, the minimum deflection angle method, which requires high accuracy of the test prisms and is difficult to process [4]. The differential confocal methods [5,6], which needs to repeatedly search for the differential confocal method in the measurement process needs to repeatedly look for the position of the focusing spot and accurate alignment, measurement of cumbersome cycle time.…”

Section: Introductionmentioning

confidence: 99%

Simultaneous measurement of thickness and group refractive index in birefringent crystals

Yangmei,

Qiukun

2024

Meas. Sci. Technol.

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In order to measure the group refractive index and thickness of birefringent crystals simultaneously, a method based on spectral-domain interferometry is proposed. The optical path of each reflection layer of birefringent crystal is converted into spectral interference fringe of corresponding frequency by the principle of spectral-domain interferometry, and the accurate optical path calculation is realized by fast Fourier transform and Hanning-windowed energy centrobaric method. A two-step measurement method was designed to measure the crystal thickness and group refractive index of ordinary(o) and extraordinary(e) light synchronously by comparing the changes of the optical path before and after the insertion of the sample. The comparison between experimental and theoretical results of LiNbO3 crystals shows that the accuracy of the thickness measured by this system is better than 1μm and the relative error of the group refractive index is better than 0.15%. The measurement method is simple to implement and has high precision, which is of practical significance for realizing the rapid and high-precision measurement of optical parameters of birefringent crystals.

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“…Especially when using an optical coherence tomography system, it will affect the contrast of the image and the subsequent calculation of tissue thickness [22][23][24]. As a result, there are various measurement techniques proposed over the last decade for the simultaneous measurement of the refractive index and thickness of samples [25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44]. However, to the best of our knowledge, there is not any existing method to simultaneously measure the thickness and refractive index for each layer of multilayered samples.…”

Section: Introductionmentioning

confidence: 99%

Thickness and Refractive Index Measurement System for Multilayered Samples

Liu

Weng

2021

IEEE Access

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In order to simultaneously obtain the thickness and refractive index for each layer of multilayered samples, this paper proposes a novel measurement system with a simple structure by using geometric optics. The key point of the overall structure is that the binary linear equation relation between the upper and lower planes of the layer can be known by the distances between laser spots reflected from the layer. Using two optical paths with different incident angles of laser beams, the CCD sensors capture the spot signal for image processing binarization and data sampling. After the obtained laser spots' spacing is substituted into the equations, the thicknesses and refractive indexes of the multilayered samples can be calculated and measured. The proposed measurement system is characterized numerically using simulations on the commercial software program Zemax and then experimentally tested using a laboratory-built prototype. The experiment results show that the refractive indexes and the thicknesses of three-layer samples were measured with high accuracy (with maximum measurement errors of 2.4% and 2% for a refractive index n and thickness d, respectively).INDEX TERMS Auto-focusing microscopy, multilayered samples, optical system, refractive index, Thickness.

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Novel system for simultaneously measuring the thickness and refractive index of a transparent plate with two optical paths

Cited by 10 publications

References 33 publications

Transparent glass slab thickness measurement by binary-spot focus signal

Transparent glass slab thickness measurement by binary-spot focus signal

Simultaneous measurement of thickness and group refractive index in birefringent crystals

Thickness and Refractive Index Measurement System for Multilayered Samples

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