An official website of the United States government
We proposed a Wollaston-prism-based snapshot phase-shifting diffraction phase microscope (WP-SPDPM) for low-coherence snapshot quantitative phase imaging and videography. Wollaston prism separates two orthogonally linearly polarized beams with high degrees of polarization at a sufficiently small separation angle; one of the beams passing through a pinhole serves as the reference beam. Four phase-shifted interferograms are simultaneously acquired with a polarization camera to accurately retrieve a high spatial resolution phase map. The system is nearly common-path in configuration and can achieve a large slope range and high accuracy. In addition to the ability to resist environmental noise, the WP-SPDPM is suitable for phase measurement using low-coherence light. The accuracy and large measurable slope range of the proposed system is validated and compared experimentally with a commercial profilometer. We believe WP-SPDPM is a powerful tool for the accurate and robust quantitative phase measurement and has a significant potential of the real-time phase imaging.
more »
« less
Snapshot phase-shifting diffraction phase microscope
We propose a novel and simple snapshot phase-shifting diffraction phase microscope with a polarization grating and spatial phase-shifting technology. Polarization grating separates the incident beam into left and right circular polarization beams, one of which is used as the reference beam after passing through a pinhole. Four phase-shifted interferograms can be captured simultaneously from the polarization camera to reconstruct the high spatial resolution phase map. The principle is presented in this Letter, and the performance of the proposed system is demonstrated experimentally. Due to the near-common-path configuration and snapshot feature, the proposed system provides a feasible way for real-time quantitative phase measurement with minimal sensitivity to vibration and thermal disturbance.
more »
« less
- Award ID(s):
- 1918260
- PAR ID:
- 10158214
- Publisher / Repository:
- Optical Society of America
- Date Published:
- Journal Name:
- Optics Letters
- Volume:
- 45
- Issue:
- 12
- ISSN:
- 0146-9592; OPLEDP
- Format(s):
- Medium: X Size: Article No. 3208
- Size(s):
- Article No. 3208
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Channeled spectropolarimetry measures the spectral dependence of the polarization states of light. This technique is marked by its snapshot feature, in that the complete polarization states can be determined simultaneously from a single intensity spectrum. However, without athermalization, it suffers from high sensitivity to temperature, which in turn, degrades the polarimetric reconstruction accuracy. In this paper, we present a calibration technique for a fiber-based channeled spectropolarimetry that leverages phase-shifting interferometry to accurately demodulate the retarders' phase, thereby improving the accuracy of the acquired Stokes parameters. Additionally, it enables robust spectropolarimetric performance that is insensitive to environmental perturbations. Experimental results demonstrate that calibrations using phase-shifting interferometry improve the Stokes reconstruction results by approximately a factor of 3 when compared to the reference beam calibration method.more » « less
-
Neutron grating interferometry provides information on phase and small-angle scatter in addition to attenuation. Previously, phase grating moiré interferometers (PGMI) with two or three phase gratings have been developed. These phase-grating systems use the moiré far-field technique to avoid the need for high-aspect absorption gratings used in Talbot–Lau interferometers (TLI) that reduce the neutron flux reaching the detector. We first demonstrate, through theory and simulations, a novel phase grating interferometer system for cold neutrons that requires a single modulated phase grating (MPG) for phase-contrast imaging, as opposed to the two or three phase gratings in previously employed PGMI systems. The theory shows the dual modulation of MPG with a large period and a smaller carrier pitch P, resulting in large fringes at the detector. The theory was compared to the full Sommerfeld–Rayleigh diffraction integral simulator. Then, we proceeded to compare the MPG system to experiments in the literature that use a two-phase-grating-based PGMI with best-case visibility of around 39%. The simulations of the MPG system show improved visibility in comparison to that of the two-phase-grating-based PGMI. An MPG with a modulation period of 300 µm, the pitch of 2 µm, and grating heights with a phase modulation of (π,0, illuminated by a monochromatic beam produces visibility of 94.2% with a comparable source-to-detector distance (SDD) as the two-phase-grating-based PGMI. Phase sensitivity, another important performance metric of the grating interferometer, was compared to values available in the literature, viz. the conventional TLI with the phase sensitivity of 4.5 × 103 for an SDD of 3.5 m and a beam wavelength of 0.44 nm. For a range of modulation periods, the MPG system provides comparable or greater theoretical maximum phase sensitivity of 4.1 × 103 to 10.0 × 103 for SDDs of up to 3.5 m. This proposed MPG system appears capable of providing high-performance PGMI that obviates the need for the alignment of two phase gratings.more » « less
-
Abstract There is a significant gap in cost-effective quantitative phase microscopy (QPM) systems for studying dynamic cellular processes while maintaining accuracy for long-term cellular monitoring. Current QPM systems often rely on complex and expensive voltage-controllable components like Spatial Light Modulators or two-beam interferometry. To address this, we introduce a QPM system optimized for time-varying phase samples using azobenzene liquid crystal as a Zernike filter with a polarization-sensing camera. This system operates without input voltage or moving components, reducing complexity and cost. Optimized for gentle illumination to minimize phototoxicity, it achieves a 1 Hz frame rate for prolonged monitoring. The system demonstrated accuracy with a maximum standard deviation of ±42 nm and low noise fluctuations of ±2.5 nm. Designed for simplicity and single-shot operations, our QPM system is efficient, robust, and precisely calibrated for reliable measurements. Using inexpensive optical components, it offers an economical solution for long-term, noninvasive biological monitoring and research applications.more » « less
-
A photonic Bragg grating is a fundamental building block that reflects the direction of wave propagation through spatial phase modulation and can be implemented using sidewall corrugation. However, due to the asymmetric aspect ratio of a waveguide cross section, typical Bragg gratings exhibit a strong polarization sensitivity. Here, we show that photonic Bragg gratings with cladding asymmetry can enable polarization-independent notch filters by rotating input polarizations. Such Bragg gratings strongly couple transverse electric (TE) and transverse magnetic (TM) modes propagating in opposite directions, filtering the input signal and reflecting the rotated mode. We analyzed this polarization-rotating Bragg grating using the coupled-mode theory and experimentally demonstrated it on a silicon-on-insulator platform. Our device concept is simple to implement and compatible with other platforms, readily available as polarization transparent Bragg components.more » « less
