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Zeng Y, Guo Q, Hu X, Lu J, Fan X, Wu H, Xu X, Xie J, Ma R. Improving the Signal-to-Noise Ratio of Axial Displacement Measurements of Microspheres Based on Compound Digital Holography Microscopy Combined with the Reconstruction Centering Method. SENSORS (BASEL, SWITZERLAND) 2024; 24:2723. [PMID: 38732829 PMCID: PMC11086274 DOI: 10.3390/s24092723] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2024] [Revised: 04/08/2024] [Accepted: 04/23/2024] [Indexed: 05/13/2024]
Abstract
In 3D microsphere tracking, unlike in-plane motion that can be measured directly by a microscope, axial displacements are resolved by optical interference or a diffraction model. As a result, the axial results are affected by the environmental noise. The immunity to environmental noise increases with measurement accuracy and the signal-to-noise ratio (SNR). In compound digital holography microscopy (CDHM)-based measurements, precise identification of the tracking marker is critical to ensuring measurement precision. The reconstruction centering method (RCM) was proposed to suppress the drawbacks caused by installation errors and, at the same time, improve the correct identification of the tracking marker. The reconstructed center is considered to be the center of the microsphere, rather than the center of imaging in conventional digital holographic microscopy. This method was verified by simulation of rays tracing through microspheres and axial moving experiments. The axial displacements of silica microspheres with diameters of 5 μm and 10 μm were tested by CDHM in combination with the RCM. As a result, the SNR of the proposed method was improved by around 30%. In addition, the method was successfully applied to axial displacement measurements of overlapped microspheres with a resolution of 2 nm.
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Affiliation(s)
- Yanan Zeng
- College of Engineering and Technology, Tianjin Agricultural University, Jinjing Road, Tianjin 300384, China
- State Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University, Weijin Road, Tianjin 300072, China
| | - Qihang Guo
- College of Engineering and Technology, Tianjin Agricultural University, Jinjing Road, Tianjin 300384, China
| | - Xiaodong Hu
- State Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University, Weijin Road, Tianjin 300072, China
| | - Junsheng Lu
- School of Life Sciences, Tiangong University, Tianjin 300387, China
| | - Xiaopan Fan
- College of Engineering and Technology, Tianjin Agricultural University, Jinjing Road, Tianjin 300384, China
| | - Haiyun Wu
- College of Engineering and Technology, Tianjin Agricultural University, Jinjing Road, Tianjin 300384, China
- Tianjin Key Laboratory of Intelligent Breeding of Major Crops, Jinjing Road, Tianjin 300392, China
| | - Xiao Xu
- College of Engineering and Technology, Tianjin Agricultural University, Jinjing Road, Tianjin 300384, China
| | - Jun Xie
- College of Engineering and Technology, Tianjin Agricultural University, Jinjing Road, Tianjin 300384, China
| | - Rui Ma
- College of Engineering and Technology, Tianjin Agricultural University, Jinjing Road, Tianjin 300384, China
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Jamali R, Rad VF, Razaghi M, Mohamadnia Z, Khorasani M, Moradi AR. Digital holographic microscopy of spiropyran-based dynamic materials. J Microsc 2023; 292:78-89. [PMID: 37694978 DOI: 10.1111/jmi.13222] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Revised: 08/30/2023] [Accepted: 08/30/2023] [Indexed: 09/12/2023]
Abstract
Spiropyran (SP)-based dynamic materials undergo structural changes in response to external stimuli. In this paper, we show that digital holographic microscopy (DHM) is an effective candidate for characterisation of SPs (embedded in polymer matrices) and for monitoring of their dynamical changes. The polymer matrices are polylactic acid (PLA) and poly(methyl methacrylate) (PMMA) films, which are decorated with SPs and immobilised on graphene quantum dots (GQDs). GQDs are modified by benzylamines prior to the loading of SP species because of the enhancement of hydrophobic characteristics. UV irradiation is used as the external stimulus and the dynamical changes of the samples before and after UV irradiation are measured. DHM is arranged on a novel self-referencing setup, which substantially reduces the sensitivity of DHM to environmental vibrations. Morphometric information for characterisation of the samples is obtained by analysis of the recorded digital holograms. The experimental results demonstrate the potential of the presented technique to serve as an alternative technique for surface measurement methodologies such as atomic force microscope and stylus profiler for surface characterisation of similar materials.
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Affiliation(s)
- Ramin Jamali
- Department of Physics, Institute for Advanced Studies in Basic Sciences (IASBS), Zanjan, Iran
| | - Vahideh Farzam Rad
- Department of Physics, Institute for Advanced Studies in Basic Sciences (IASBS), Zanjan, Iran
| | - Masoumeh Razaghi
- Department of Chemistry, Institute for Advanced Studies in Basic Sciences (IASBS), Zanjan, Iran
| | - Zahra Mohamadnia
- Department of Chemistry, Institute for Advanced Studies in Basic Sciences (IASBS), Zanjan, Iran
| | - Mojtaba Khorasani
- Department of Chemistry, Institute for Advanced Studies in Basic Sciences (IASBS), Zanjan, Iran
- Research Center for Basic Sciences & Modern Technologies (RBST), Institute for Advanced Studies in Basic Sciences (IASBS), Zanjan, Iran
| | - Ali-Reza Moradi
- Department of Physics, Institute for Advanced Studies in Basic Sciences (IASBS), Zanjan, Iran
- School of Nano Science, Institute for Research in Fundamental Sciences (IPM), Tehran, Iran
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