Recording of a holographic cylindrical vector beam converter with a truncated cone prism.

This Letter proposes a holographic cylindrical vector beam converter (HCVBC) design that incorporates a continuously polarization-selective volume hologram circular-grating. A specially designed truncated cone prism is adopted for recording, which is conducted with a single incident, expanded, radially polarized beam. A prototype of this HCVBC was recorded and tested successfully. This design has the advantages of high diffraction efficiency, a narrow band, compactness, and planar configuration; thus, it is especially suitable for low-cost mass production and has high potential for application in related fields.

Dual-Retarder Mueller Polarimetry System for Extraction of Optical Properties of Serum Albumin Protein Media.

A dual liquid-crystal variable retarder Mueller polarimetry system incorporating a gold-based surface plasmon resonance prism coupler was proposed for extracting the optical properties of serum albumin protein media in the reflectance configuration. The feasibility of the proposed system was demonstrated by measuring the circular dichroism and circular birefringence properties of glucose tissue phantom solutions with different albumin concentrations. The results showed that the circular dichroism increased with albumin concentration, while the optical rotation angle increased with glucose concentration. Both properties reduced over time as a result of the protein glycation effect, which led to a gradual reduction in the glucose content of the sample.

Scattering Analysis and Efficiency Optimization of Dielectric Pancharatnam-Berry-Phase Metasurfaces.

In this study, the phase modulation ability of a dielectric Pancharatnam-Berry (PB) phase metasurface, consisting of nanofins, is theoretically analyzed. It is generally considered that the optical thickness of the unit cell of a PB-phase metasurface is λ/2, i.e., a half-waveplate for polarization conversion. It is found that the λ/2 is not essential for achieving a full 2π modulation. Nevertheless, a λ/2 thickness is still needed for a high polarization conversion efficiency. Moreover, a gradient phase metasurface is designed. With the help of the particle swarm optimization (PSO) method, the wavefront errors of the gradient phase metasurface are reduced by fine-tuning the rotation angle of the nanofins. The diffraction efficiency of the gradient phase metasurface is thus improved from 73.4% to 87.3%. This design rule can be utilized to optimize the efficiency of phase-type meta-devices, such as meta-deflectors and metalenses.

Evaluation of structural and molecular variation of starch granules during the gelatinization process by using the rapid Mueller matrix imaging polarimetry system.

Starch is an essential and widely distributed natural material, but its detailed conformation and thermal transition properties are not yet well understood. We present a rapid Mueller matrix imaging system to explore the structural characteristics of starch granules by using 16 measurements with different incoming and outgoing polarizations. Due to the minimum rotation of the optical elements and the self-calibration ability of this system, the full Mueller matrix images can be accurately obtained within ten-odd seconds. Both structural and molecular features of the starch granule were investigated in the static state and gelatinization process by means of multiple optical characteristics deduced from the Mueller matrix. The experimental results for the structural changes during the gelatinization were close to other nonlinear optical approaches; moreover, the crystallinity and optical rotation of the starch granule are also determined through the use of this approach.

Prism-hologram-prism sandwiched recording method for polarization-selective substrate-mode volume holograms with a large diffraction angle.

We propose a prism-hologram-prism sandwiched recording method for the fabrication of polarization-selective substrate-mode volume holograms with a large diffraction angle. In fabrication, the C-RT20 photopolymer is sandwiched between two 45°-90°-45° prisms and the interference fringes can be easily recorded in the recording material. The experimental results are in good agreement with the theoretical predictions. The proposed method features of a reflection-type recording setup for a transmission element and belongs to a technique of longer-wavelength construction for shorter-wavelength reconstruction. In addition, the method is much easier than the traditional recording method of two incident beam interference and has application potential in holographic photonics.

Dual field-of-view midwave infrared optical design and athermalization analysis.

A step-zoom and reimaging structure were utilized to construct a dual field-of-view optical design for high-magnification switching in the 3-5 microm spectral band. The design has a flexible optomechanical layout, which means it can be utilized for multipurpose applications. The effects of the surrounding environmental temperature and axial gradient temperature are analyzed using the concept of thermal resistance, and the thermal compensation is discussed. A description of the zooming mechanism and optomechanical control is offered.

Determining thickness of films on a curved substrate by use of ellipsometric measurements.

A three-intensity measurement technique has been employed in polarizer-sample-analyzer imaging ellipsometry to measure the two-dimensional ellipsometric parameters of a coated cylindrical lens. Since azimuth deviation alpha of a polarizer can also be measured with this three-intensity measurement technique, we tilted a well-calibrated thin-film wafer to identify the orientation of the measured alphawith respect to the incident plane. Using the analytic property of this measurement technique, we can correct the deviation and determine the thickness profile of the thin film coated on a cylindrical lens.

Determination of optical parameters of a twisted-nematic liquid crystal by phase-sensitive optical heterodyne interferometric ellipsometry.

What is believed to be a novel phase-sensitive optical heterodyne interferometric ellipsometer is set up to characterize a twisted-nematic liquid crystal (TN-LC) by the elliptical parameters of the output polarization state. This ellipsometer presents the advantages of both polarized optical heterodyne interferometry and optical photometry, which introduce a polarization modulation that is capable of performing with high-sensitivity on phase detection in real time. The twist angle phi and the untwisted phase retardation gamma of TN-LC are measured precisely. The experimental results verify that a TN-LC can be treated as identical to an elliptical retarder.

Circularly polarized optical heterodyne interferometer for optical activity measurement of a quartz crystal.

Phase retardation between two orthogonal circularly polarized light waves that propagate in an optical active medium is proportional to its optical activity. The measurement of optical activity of a quartz depolarizer in terms of the phase difference of two orthogonal circularly polarized waves is proposed. A circularly polarized optical heterodyne interferometer with a Zeeman laser to measure the optical activity of a quartz crystal is demonstrated experimentally. The accuracy of the measurement is discussed. In addition, the effect of elliptical polarization and nonorthogonality of linearly polarized light waves of a Zeeman laser on the optical activity measurement is analyzed.