Holographic optical element based single-mode hybrid fiber optic interferometer for realizing zero-order fringe

Distributed fiber sensing (DFS) can provide real-time signals and warnings. The entire length of fiber optic cable can act as a sensing element, but the accuracy is sometimes limited. On the other hand, point-to-point fiber sensing (PPFS) is usually implemented using one or more fiber Bragg gratings (FBGs) at specific positions along with the fiber for the monitoring of specific parameters (temperature, strain, pressure, and so on). However, the cost becomes expensive when the number of FBGs increases. A hybrid fiber sensing scheme is thus proposed, combining the advantages of DFS and PPFS. It is based on a Brillouin optical time-domain analysis (BOTDA) fiber system with additional FBGs embedded at certain positions where it is necessary to detect specific parameters. The hybrid fiber sensing system has the advantages of full sensing coverage at essential locations that need to be carefully monitored. In our work, the test results showed that the proposed system could achieve a sensing distance of 16 km with the single-mode fiber with a 2 m spatial resolution. For FBG parameter measurements, the temperature variation was 52 °C, from 25 °C to 77 °C, with a temperature sensitivity of 23 pm/°C, and the strain was from 0 to 400 µε, with a strain sensitivity of 0.975 pm/µε, respectively, using two FBGs.

Download Full-text

The Full Color Maxwellian-view Display Based on Holographic Optical Element

Proceedings of the International Display Workshops ◽

10.36463/idw.2019.3dp1_3dsap1-7 ◽

2019 ◽

pp. 1027

Author(s):

Shao-Kui Zhou ◽

Wen-Kai Lin ◽

Bor-Shyh Lin ◽

Wei-Chia Su

Keyword(s):

Optical Element ◽

Full Color ◽

Holographic Optical Element ◽

Maxwellian View

Download Full-text

The Holographic Information Projection System Based on Holographic Optical Element

Proceedings of the International Display Workshops ◽

10.36463/idw.2019.3d2_3dsa2-4 ◽

2019 ◽

pp. 958

Author(s):

Wen-Kai Lin ◽

Hung-Pin Chen ◽

Bor-Shyh Lin ◽

Wei-Chia Su

Keyword(s):

Optical Element ◽

Projection System ◽

Holographic Optical Element ◽

Information Projection

Download Full-text

Sensing, Actuation, and Control of the SmartX Prototype Morphing Wing in the Wind Tunnel

Actuators ◽

10.3390/act10060107 ◽

2021 ◽

Vol 10 (6) ◽

pp. 107

Author(s):

Nakash Nazeer ◽

Xuerui Wang ◽

Roger M. Groves

Keyword(s):

Wind Tunnel ◽

Optical Fibers ◽

Fiber Optic ◽

Experimental Testing ◽

Single Mode ◽

Fiber Optic Sensor ◽

Sensor Data ◽

Random Errors ◽

Morphing Wing ◽

Actuator Dynamics

This paper presents a study on trailing edge deflection estimation for the SmartX camber morphing wing demonstrator. This demonstrator integrates the technologies of smart sensing, smart actuation and smart controls using a six module distributed morphing concept. The morphing sequence is brought about by two actuators present at both ends of each of the morphing modules. The deflection estimation is carried out by interrogating optical fibers that are bonded on to the wing’s inner surface. A novel application is demonstrated using this method that utilizes the least amount of sensors for load monitoring purposes. The fiber optic sensor data is used to measure the deflections of the modules in the wind tunnel using a multi-modal fiber optic sensing approach and is compared to the deflections estimated by the actuators. Each module is probed by single-mode optical fibers that contain just four grating sensors and consider both bending and torsional deformations. The fiber optic method in this work combines the principles of hybrid interferometry and FBG spectral sensing. The analysis involves an initial calibration procedure outside the wind tunnel followed by experimental testing in the wind tunnel. This method is shown to experimentally achieve an accuracy of 2.8 mm deflection with an error of 9%. The error sources, including actuator dynamics, random errors, and nonlinear mechanical backlash, are identified and discussed.

Download Full-text

Nanooptical elements for visual verification

Scientific Reports ◽

10.1038/s41598-021-81950-w ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Alexander Goncharsky ◽

Anton Goncharsky ◽

Dmitry Melnik ◽

Svyatoslav Durlevich

Keyword(s):

Electron Beam ◽

Electron Beam Lithography ◽

Mass Production ◽

Optical Element ◽

Visual Image ◽

Zero Order ◽

Diffractive Optical Elements ◽

Optical Elements ◽

Standard Equipment ◽

Diffractive Element

AbstractThis paper focuses on the development of flat diffractive optical elements (DOEs) for protecting banknotes, documents, plastic cards, and securities against counterfeiting. A DOE is a flat diffractive element whose microrelief, when illuminated by white light, forms a visual image consisting of several symbols (digits or letters), which move across the optical element when tilted. The images formed by these elements are asymmetric with respect to the zero order. To form these images, the microrelief of a DOE must itself be asymmetric. The microrelief has a depth of ~ 0.3 microns and is shaped with an accuracy of ~ 10–15 nm using electron-beam lithography. The DOEs developed in this work are securely protected against counterfeiting and can be replicated hundreds of millions of times using standard equipment meant for the mass production of relief holograms.

Download Full-text