High-throughput spatial sensitive quantitative phase microscopy using low spatial and high temporal coherent illumination (original) (raw)
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Geometric phase-shifting for low-coherence interference microscopy
Optics and Lasers in Engineering, 2002
A low-coherence Linnik interference microscope using high numerical aperture optics has been constructed. The system uses a tungsten halogen lamp and Ko.hler illumination, with separate control over field and aperture stops, so that experiments can be conducted with a range of different operating conditions. The novel feature of the system is the use of an achromatic phase-shifter operating on the principle of the geometric phase, achieved by using a polarising beam splitter, a quarter wave plate and a rotating polariser. Image information is extracted from the visibility of the fringes, the position of the visibility peak along the scanning axis yielding the height of the test surface at the corresponding point.
Geometric phase low-coherence interference microscopy at high numerical apertures
Proceedings of SPIE, 2001
A low-coherence Linnik interference microscope using high numerical aperture optics has been constructed. The system uses a tungsten halogen lamp and a Koehier illumination, with separate control over field and aperture stops, so that experiments can be conducted with a range of different operating conditions. The novel feature of the system is the use of anachromatic phase shifter operating on the principle geometric phase which is achieved by using a polarising beam splitter, a quarter wave plate and a rotating polariser. Image information is extracted from the visibility of the fringes, and the position of the visibility peak along the scanning axis, yielding the height of the test surface at the coresponding points.
Determination of Fringe Order in White-Light Interference Microscopy
Applied Optics, 2002
Combining phase and coherence information for improved precision in white-light interference microscopy requires a robust strategy for dealing with the inconsistencies between these two types of information. We correct for these inconsistencies on every measurement by direct analysis of the difference map between the coherence and the phase profiles. The algorithm adapts to surface texture and noise level and dynamically compensates for optical aberrations, distortions, diffraction, and dispersion that would otherwise lead to incorrect fringe order. The same analysis also provides the absolute height data that are essential to relational measurements between disconnected surfaces.
Low-coherence interference microscopy at high numerical apertures
Proceedings of SPIE, 2000
A white-light Linnik interference microscope using high numerical aperture optics has been constructed. The system uses a tungsten halogen source and Köhler illumination with separate control over field and aperture stops, so that experiments can be conducted with a range of different operating conditions. Infinity tube length objectives are used in the two arms. Images are recorded with a CCD camera. Different algorithms have been investigated for extraction of information from the image data. These are based on phase stepping, which is achieved based on the principle of the geometric phase, using a polarizing beam splitter, a quarter wave plate and a rotating polarizer. Image information extracted from the visibility of the fringes and also from the phase of the interference fringes has been investigated.
Real-time phase shift interference microscopy
Optics Letters, 2014
A real-time phase shift interference microscopy system is presented using a polarization-based Linnik interferometer operating with three synchronized, phase-masked, parallel detectors. Using this method, several important applications that require high speed and accuracy, such as dynamic focusing control, tilt measurement, submicrometer roughness measurement, and 3D profiling of fine structures, are demonstrated in 50 volumes per second and with 2 nm height repeatability.
Optics Express, 2020
Phase shifting interferometric (PSI) techniques are among the most sensitive phase measurement methods. Owing to its high sensitivity, any minute phase change caused due to environmental instability results into, inaccurate phase measurement. Consequently, a well calibrated piezo electric transducer (PZT) and highly-stable environment is mandatory for measuring accurate phase map using PSI implementation. Here, we present an inverse approach, which can retrieve phase maps of the samples with negligible errors under environmental fluctuations. The method is implemented by recording a video of continuous temporally phase shifted interferograms and phase shifts were calculated between all the data frames using Fourier transform algorithm with a high accuracy ≤ 5.5 × 10 −4 π rad. To demonstrate the robustness of the proposed method, a manual translation of the stage was employed to introduce continuous temporal phase shift between data frames. The developed algorithm is first verified by performing quantitative phase imaging of optical waveguide and red blood cells using uncalibrated PZT under the influence of vibrations/air turbulence and compared with the well calibrated PZT results. Furthermore, we demonstrated the potential of the proposed approach by acquiring the quantitative phase imaging of an optical waveguide with a rib height of only 2 nm and liver sinusoidal endothelial cells (LSECs). By using 12-bit CMOS camera the height of shallow rib waveguide is measured with a height sensitivity of 4 Å without using PZT and in presence of environmental fluctuations.
Optics Express, 2006
A problem with conventional techniques of interference microscopy, when profiling surfaces with an extended range of heights, is that only points on a single plane are in sharp focus. Other points, which are higher or lower, may be out of focus, with a consequent loss of lateral resolution. We show that white-light interference microscopy, with an achromatic phase-shifter, makes it possible to produce a three-dimensional representation of such surfaces with high lateral resolution over the entire range of heights.