- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Super-Bandwidth Two-Step Phase-Shifting Off-Axis Digital Holography by Optimizing Two-Dimensional Spatial Frequency Sampling Scheme
摘要： The presence of the auto correlation and twin cross correlation noises restrict the available spatial bandwidth of the holographic microscopy to much less than the available bandwidth of the digital sensor. Therefore, in order to record the same image area as conventional 2D intensity imaging techniques, several images should be taken. We present two-step phase-shifting off-axis digital holography with maximum space-bandwidth product for three-dimensional (3D) digital holography. Removing the autocorrelation term using a two-step phase-shifting technique significantly increases the available bandwidth for off-axis interferometry. An optimizing super-diagonal two-dimensional (2D) spatial frequency sampling scheme at the sub-Nyquist frequency is employed for performing off-axis interferometry in the absence of the autocorrelation term. The spatial bandwidth of the proposed two-step phase-shifting technique is 400% of that in square scheme off-axis digital holography. Experimental results demonstrate the feasibility of this technique in extracting the 3D morphology of transparent microscopic objects with a larger bandwidth.
关键词： Holography,sampling methods,interferometry,microscopy
更新于2025-09-11 14:15:04
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[IEEE 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Paris, France (2018.7.8-2018.7.13)] 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Four Terminal Pair Digital Sampling Impedance Bridge up to 1 MHz
摘要： This paper describes a new four terminal pair digital sampling impedance bridge for frequency range up to 1 MHz. The bridge was primarily designed for a calibration of a phase angle of the current shunts. However, the bridge is capable of comparing any impedance standards up to approximately 100 kW in a full complex plane. The experimental measurements of the known standards showed the bridge deviations is below 50 μW/W and below 500 μrad at 1 MHz.
关键词： Bridge circuits,sampling methods,impedance measurement,shunts (electrical),phase comparators
更新于2025-09-10 09:29:36