A concave diffraction grating with a tunable radius of curvature R is fabricated by embedding a nitinol wire within an elastomeric grating replica. Curvature of the grating is controlled via the shape memory effect, where strain in the wire is recovered due to martensite-austenite phase transformations induced by resistive heating. The generated force bends the grating into a variable curvature determined by applied current. The radius of curvature for the concave grating is variable from 170 to 44 mm over a current range of 0 to 2.5 A. Actuation of R redirects the grating normal, resulting in a scanning motion of the diffracted beam.
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http://dx.doi.org/10.1364/AO.49.003634 | DOI Listing |
As a novel method for solid-state light detection and ranging (LiDAR), optical phased arrays (OPAs) cater to the growing market requirement for mass-produced chip-scale beam steering devices. Waveguide grating antennas (WGAs) with low loss, high efficiency and large emitting aperture are strongly desirable to achieve low beam divergence and high resolution for OPAs. In this paper, we report two kinds of silicon ridge-waveguide-based WGAs with ultra-sharp instantaneous field-of-view (IFOV) for LiDAR applications.
View Article and Find Full Text PDFSensors (Basel)
October 2024
Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, China.
The unique diffractive properties of gratings have made them essential in a wide range of applications, including spectral analysis, precision measurement, optical data storage, laser technology, and biomedical imaging. With advancements in micro- and nanotechnologies, the demand for more precise and efficient grating fabrication has increased. This review discusses the latest advancements in grating manufacturing techniques, particularly highlighting laser interference lithography, which excels in sub-beam generation through wavefront and amplitude division.
View Article and Find Full Text PDFIn this paper we design a high-performance multispectral telescope with a concave elliptical grating for a field of view of 3° in the VNIR spectral range of 0.48-0.82 µm, at an altitude of 760 km from the ground, with total length of 140 mm, which has a small volume and a simple structure.
View Article and Find Full Text PDFA multi-wavelength confocal displacement sensor based on a flat-field concave grating (FFCG) was proposed and designed; the large dispersion and small volume of the FFCG make it an ideal candidate for replacing the complex dispersive lens group. The designed displacement sensor was calibrated by displacement meter, and the characteristics were measured. Consequently, for the proposed displacement sensor, the displacement range of 6.
View Article and Find Full Text PDFIn this paper we present the design and fabrication of the reflection varied-line-space concave grating (VLSCG) for the project of CAFE (the Census of warm-hot intergalactic medium, Accretion, and Feedback Explorer), which aims to detect and map the warm-hot circumgalactic medium via OVI emission at 103.2 nm and 103.8 nm, using two off-Rowland-circle spectrograph channels.
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