In the MBZIRC 2020 competition, an Unmanned Aerial Vehicle (UAV) is required to intercept a moving balloon and put it into a specific location. The core of the task is to accurately identify the balloon’s centroid, which is also the purpose of this article. The process is composed of two sections: first identify the balloon candidate region based on Faster-RCNN, an end to end object detection algorithm, following a new method based on the color of balloon to extract the centroid finally. In terms of Faster-RCNN, images of balloon sample library are used to generate a number of target candidate regions by region proposal network(RPN), next the neural network is trained to generate a model, which can finally output the boundary box of the balloon, which we called candidate region. Next, in the candidate region, the process includes three parts: feature extraction, target segmentation and centroid marking. Improve the saturation to enhance the image, thus reducing the impact of reflection of sunlight. Then replace the color of the balloon to pure black, with the use of adaptive filtering to segment the balloon region preliminarily. Finally, to minimize the affections of noise, the largest connected region in the image is chosen to calculate its centroid position. Experimented with different backgrounds of images such as sky, grass, flowers and buildings, our method has gotten wonderful results, thus verifying the high accuracy of our method.
We investigate a millimeter-size Calcium fluoride (CaF2) microdisk resonator fabricated by a customized machining procedure. Stable coupling can be realized in our microdisk resonator coupled by a special tapered fiber. The mcirodisktaper coupling system exhibits an ultra-high Q factor up to ~108. In particularly, our coupling system exhibits a freespectral- range low to ~0.03 nm (~3.91 GHz). The frequency is suitable in microwave photonic systems, such as optical filters, optoelectronic oscillators, and optical gyroscopes for several technological applications such as radar, light-wave technology, frequency synthesis, detection inertial navigation system.
The whispering-gallery-mode(WGM) resonators have a number of advantages, including ultra-high quality factor(Q factor), extremely small mode volume and so on. It has been widely used in many fields related to high sensitivity sensing measurement, photonics material, linear and non-linear optics, and optical communication. Here we built an experimental platform for microrod resonator fabrication with a high power CO2 laser. Based on this experimental fabrication platform, a microrod resonator with an approximate 2.5mm diameter has been made, which has an ultra-smooth surface. We also designed a test platform used a tapered fiber to measure optical performances of the fabricated microrod resonator. With this test platform, we measured the maximum Q factor of the fabricated resonator, which can reach 1.52×108 under the condition of 1550nm wavelength. The fabrication platform for microrod resonator designed by our laboratory with features of fast (less than 10min), cheap, repeatable and low experimental condition. These features have huge advantages on further scaled sensing application, optoelectronic device. Furthermore, in order to design and fabricate the ultra-high sensitivity temperature sensing device, we demonstrated the frequency shift feature of the fabricated microrod resonator. We heated the microrod resonator from 22 oC to 25 oC , then calculated the experimental data. we demonstrated our microrod resonator has 0.04nm frequency shift, 14.41pm/oC temperature sensitivity, and 6.3♦10−3oC temperature resolution.