Simultaneous measurement of refractive index and thickness distributions using low-coherence digital holography and vertical scanning

Watanabe, Kaho; Ohshima, Masashi; Nomura, Takanori

doi:10.1088/2040-8978/16/4/045403

Cited by 18 publications

(5 citation statements)

References 18 publications

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“…Digital holographic microscopy (DHM) is a label-free, noncontact, high resolution and full-field technique for measuring the surface profiles of nano-fabricated samples or the tomography of biological samples in the microscale with quantitative phase information [1]. Over recent decades, DHM has been fully developed and successfully applied in a wide range of applications, including live cell research [2,3], the characterization of MEMS or other microstructures [4][5][6][7], the inspection of micro-optics [8,9], and measurements of ternary diffusion [10].…”

Section: Introductionmentioning

confidence: 99%

LED-based digital holographic microscopy with slightly off-axis interferometry

Guo

Min

Zhou

et al. 2014

J. Opt.

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An LED illuminated Linnik-type digital holographic microscope (DHM) for high-quality phase imaging is presented by the adoption of slightly off-axis two-step blind-phase-shifting interferometry (TB-PSI). Slightly off-axis interferometry lowers the requirement on the angle between the object and the reference waves as well as the requirement on the resolving power of the charge-coupled device (CCD) camera. In addition, the apparatus is cost-effective and offers ease of alignment. The phase-shifting DHM is simply implemented by mechanically moving the reference mirror while disposing of a precise phase modulator such as a piezoelectric transducer (PZT). The phase shift between the two interferograms is extracted by Fourier transformation analysis, and then the phase image is reconstructed. The performance of the TB-PSI used in the scheme is analyzed. The phase imaging for nanostructured specimens is conducted, and the results demonstrate the feasibility of the scheme. The phase noise is reduced by 73% when compared to the result obtained with coherent illumination.

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Section: Introductionmentioning

confidence: 99%

LED-based digital holographic microscopy with slightly off-axis interferometry

Guo

Min

Zhou

et al. 2014

J. Opt.

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“…Wen Chen and Xudong Chen propose a novel method via phase reservation and compression to enhance double random phase encoding security [28]. Kaho Watanabe et al use low-coherence digital holography with vertical scanning for simultaneous measurement of refractive index and thickness distributions [29]. And Rongli Guo et al present an LED illuminated Linnik-type digital holographic microscope for high-quality phase imaging through the adoption of slightly off-axis two-step blind-phase-shifting interferometry [30].…”

Section: Information and Communication Opticsmentioning

confidence: 99%

Recognising recent advances in photonics: the JOPT Highlights of 2014

McKenna¹

2015

J. Opt.

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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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Simultaneous measurement of refractive index and thickness distributions using low-coherence digital holography and vertical scanning

Cited by 18 publications

References 18 publications

LED-based digital holographic microscopy with slightly off-axis interferometry

LED-based digital holographic microscopy with slightly off-axis interferometry

Recognising recent advances in photonics: the JOPT Highlights of 2014

Thickness and Refractive Index Measurement System for Multilayered Samples

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