Improvement of measurement accuracy in digital holographic microscopy by using dual-wavelength technique

Di, Jianglei; Zhang, Jiwei; Xi, Teli; Ma, Chaojie; Zhao, Jianlin

doi:10.1117/1.jmm.14.4.041313

Cited by 26 publications

(8 citation statements)

References 15 publications

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“…A synthetic wavelength (Λ) is generated by using two wavelength (λ 1 and λ 2 ) lasers using the formula Λ = (λ 1 • λ 2 )/ |λ 2 − λ 1 |, such that it helps in shape measurements of components with larger step heights. Synthetic wavelengths being longer than its individual components help in extending the measurement range up to micrometers from nanometres [24,25]. The proposed dual-wavelength setup can be easily employed for an extended range of measurements with very easy to align configuration and high temporal stability and uniform illumination.…”

Section: Resultsmentioning

confidence: 99%

Speckle-free common-path quantitative phase imaging with high temporal phase stability using a partially spatially coherent multi-spectral light source

et al. 2019

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Quantitative phase imaging (QPI) has been an important technique for the determination of various biophysical parameters, such as the refractive index and morphology of biological cells and tissues. The technique has been implemented using off-axis and common path digital holographic microscopy (DHM). Off-axis DHM, though being ideal for QPI, offers lower temporal phase stability compared to common path techniques. Common path DHM offers a higher temporal phase stability but, being a coherent imaging technique, suffers from speckle artefacts and spurious interference fringes due to the high coherence of the light source. Both artefacts not only degrade the image quality, but also affect the phase measurement results. In this paper, we report the implementation of common path QPI set-up using a partially spatially coherent multi-spectral light source. The spatial coherence of the red and green color lasers is reduced by using a rotating diffuser. Also, a speckle free QPI was implemented using common path Fresnel biprism interferometer. A Fresnel biprism is used in the self-referencing mode, thus offering the advantage of no optical power loss in addition to high temporal stability and the least speckle artefacts. Furthermore, it is very easy to implement, as the system completely replaces the need for spatial filtering at the source end as well as for the reference beam generation. The experiments have been carried out on industrial and biological samples to prove the effect.

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Section: Resultsmentioning

confidence: 99%

Speckle-free common-path quantitative phase imaging with high temporal phase stability using a partially spatially coherent multi-spectral light source

et al. 2019

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“…Another method proposed by Wang et al utilizes a linear programming phase unwrapping approach to enhance the robustness of dual-wavelength unwrapping process. 20 A short synthetic-wavelength method using the sum of phases was proposed to suppress noise and a more accurate result could be obtained, [21][22][23] but this method fails to measure high aspect-ratio objects. Xiong et al 24 proposed a method by combining the short wavelength synthesis method and immune algorithm to suppress the enlargement of the noise coefficient, but the effectiveness of noise reduction was limited.…”

Section: Introductionmentioning

confidence: 99%

“…utilizes a linear programming phase unwrapping approach to enhance the robustness of dual-wavelength unwrapping process 20 . A short synthetic-wavelength method using the sum of phases was proposed to suppress noise and a more accurate result could be obtained, 21 – 23 but this method fails to measure high aspect-ratio objects. Xiong et al 24 .…”

Section: Introductionmentioning

confidence: 99%

Synthetic-wavelength phase guided phase unwrapping method for dual-wavelength digital holography

Li,

Cai

2023

Opt. Eng.

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Dual-wavelength or multi-wavelength digital holography extends the axial measurement range to the order of several microns or more, but the noise enlargement effect greatly affects the measurement accuracy. To address this problem, an unwrapping method is proposed based on synthetic-wavelength phase and searching process. This methodology implements noise suppression using phase unwrapping at the single-wavelength level and averaging. We introduce the analytical approach and provide a simulation analysis to demonstrate the effectiveness of this noise suppression method. The proposed method is used to measure a standard step and the results demonstrated the feasibility of the proposed method in practical usage.

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“…Among the TPU algorithms, many researchers used the multi-frequency heterodyne (MFH) algorithm because of its high measurement accuracy. The MFH algorithm can be divided into the dual-frequency heterodyne (DFH) [ 24 , 25 ], the three-frequency heterodyne (TFH) [ 26 , 27 ], and also can be extended to more frequencies [ 16 , 28 , 29 ]. Compared with the DFH and more frequency methods, the TFH phase unwrapping algorithm has a higher resolution of details, a larger measurement field, and a higher measurement accuracy.…”

Section: Introductionmentioning

confidence: 99%

An Improved Synthesis Phase Unwrapping Method Based on Three-Frequency Heterodyne

Liu

Tian

et al. 2022

Sensors

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An improved three-frequency heterodyne synthesis phase unwrapping method is proposed to improve the measurement accuracy through phase difference and phase sum operations. This method can reduce the effect of noise and increase the equivalent phase frequency. According to the distribution found in the phase difference calculation process, the Otsu segmentation is introduced to judge the phase threshold. The equivalent frequency obtained from the phase sum is more than those of all projected fringe patterns. In addition, the appropriate period combinations are also studied. The simulations and related experiments demonstrate the feasibility of the proposed method and the ability to improve the accuracy of the measurement results further.

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Improvement of measurement accuracy in digital holographic microscopy by using dual-wavelength technique

Cited by 26 publications

References 15 publications

Speckle-free common-path quantitative phase imaging with high temporal phase stability using a partially spatially coherent multi-spectral light source

Speckle-free common-path quantitative phase imaging with high temporal phase stability using a partially spatially coherent multi-spectral light source

Synthetic-wavelength phase guided phase unwrapping method for dual-wavelength digital holography

An Improved Synthesis Phase Unwrapping Method Based on Three-Frequency Heterodyne

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