Integrated Test System for Large-aperture Telescopes Based on Astrophotonics Interconnections

This study aims to improve the integrated testing of large-aperture telescopes to clarify the fundamental principles of an integrated testing system based on astrophotonics.Our demonstration and analyses focused on element-position sensing and modulation based on spatial near-geometric beams,high-throughput step-difference measurements based on channel spectroscopy,distributed broadband-transmittance testing,and standard spectral tests based on near-field energy regulation.Comprehensive analyses and experiments were conducted to confirm the feasibility of the proposed system in the integrated testing process of large-aperture telescopes.The results demonstrated that the angular resolution of the light rays exceeded 5arcsec,which satisfies the requirements for component-position detection in future large-aperture telescopes.The measurement resolution of the wavefront tilt was better than 0.45μrad.Based on the channel spectral method—which combined a high signal-to-noise ratio and high sensitivity,along with continuous-spectral digital segmentation and narrowband-spectral physical segmentation—a resolution of 0.050μm and a range of 50μm were obtained.After calibration,the measurement resolution of the pupil deviation improved to exceed 4%accuracy,and the transmission measurements achieved a consistency of over 2%accuracy.Regarding fringe-broadband interferometry measurements,the system maintained high stability,ensuring its operation within the coherence length,and robustly detected the energy without unwrapping the phase.The use of a projector for calibrating broadband-spectrum measurements led to a reduction in contrast from 0.8142 to 0.6038,which further validates the system's applicability in the integrated testing process of large-aperture telescopes.This study greatly enhanced the observational capabilities of large-aperture telescopes while reducing the integrated system's volume,weight,and power consumption.

Autonomous and Mobile Prototype of Curvature Sensor with Remote Reliable Communication of Spectral Curvature

Through the creation and construction of a curvature sensor of accelerometer type, using the spectral curvature concept or curvature energy that measures curvature in Volts/m3, an autonomous and mobile censorship of curvature sensing with reliable data transmission/reception in real time and remote position is designed and constructed considering the spectra of curvature of the measured curvature energy during the advance of the prototype as the normed measure by with β , a constant rationalized parameter according with the required advance of the mobile device in the control scale of their velocity. Likewise, the sensed curvature data are digitalized through wireless interconnectivity using a HC-05 Module with a programmable device that includes logic blocks whose interconnection and functionality can be configured according to the sensor measure in situs. Also an application is planted to the obtaining of an energy plus due to the curvature that could be used in the displacement of a vehicle.

Temperature-and Strain-Compensated Directional Curvature Sensor Based on Bragg Gratings in Three-Core Fiber with Bridged Waveguides

Fiber-based curvature sensors,especially those capable of discerning the direction of curvature,have attracted more and more interest due to their promising applications in structural health monitoring,high-precision measurement,medical and biological diagnosis-treat instruments,and so on.Here,we propose and demonstrate a compact directional curvature sensor that comprises two bridged waveguides and three Bragg gratings in a section of three-core fiber(TCF).Both the waveguides and gratings are integrated by femtosecond laser micromachining method.The waveguides,connecting the TCF outer cores to the lead-in single-mode fiber core,function as beam couplers to realize simultaneous interrogation of all three gratings without any separate fan-in/out component.Owing to the spatial specificity,the outer-core gratings exhibit high and direction-dependent sensitivity to curvature,whereas the central-core grating is nearly insensitive to curvature but shows similar sensitivities to ambient temperature and axial strain as the outer-core gratings.It can be used to compensate the cross impact of temperature and strain when the outer-core gratings are applied for curvature detection.Moreover,the wavelength interval between two outer-core gratings is also proposed as an indicator for curvature sensing.It features with a much higher sensitivity to curvature and reduced sensitivities to temperature and axial strain.The corresponding maximum sensitivity to curvature is as high as 191.89 pm/m-1,while the sensitivities to temperature and strain are only 0.3 pm/℃and 0.0218 pm/με,respectively.Therefore,our proposed device provides a compact and robust all-infiber solution for directional curvature sensing.It not only offers high sensitivity and accuracy but also immunity to temperature and axial strain fluctuations,making it a promising tool for a wide range of applications.

Simultaneous Curvature and Temperature Sensing Based on a Novel Mach-Zehnder Interferometer

A novel fiber inline Mach-Zehnder interferometer(MZI)is proposed for simultaneous measurement of curvature and temperature.The sensor composes of single mode-multimode-dispersion compensation-multimode-single mode fiber(MMF-DCF-MMF)structure,using the direct fusion technology.The experimental results show curvature sensitivities of−12.82 nm/m^(−1) and−14.42 nm/m^(−1) in the range of 0−0.65 m^(−1) for two resonant dips,as well as temperature sensitivities of 57.6 pm/and 74.3℃pm/within the range of 20℃℃−150.In addition,℃the sensor has unique advantages of easy fabrication,low cost,high fringe visibility of 24 dB,and high sensitivity,which shows a good application prospect in dual-parameters of sensing of curvature and temperature.

Soft curvature sensors for measuring the rotational angles of mechanical fingers

The design, fabrication, and testing of soft sensors that measure elastomer curvature and mechanical finger bending are described in this study. The base of the soft sensors is polydimethylsiloxane (PDMS), which is a translucent elastomer. The main body of the soft sensors consists of three layers of silicone rubber plate, and the sensing element is a microchannel filled with gallium-indium-tin (Ga-In-Sn) alloy, which is embedded in the elastomer. First, the working principle of soft sensors is investigated, and their structure is designed. Second, the relationship between curvature and resistance is determined. Third, several sensors with different specifications are built in accordance with the structural design. Experiments show that the sensors exhibit high accuracy when the curvature changes within a certain range. Lastly, the soft sensors are applied to the measurement of mechanical finger bending. Experiments show that soft curvature sensors can effectively reflect mechanical finger bending and can be used to measure the bending of mechanical fingers with high sensitivity within a certain working range.