Simulation of External Stray Light for FY-3C VIRR Combined with Satellite Orbit Attitude Model

Optical imaging systems mounted on a Sun-synchronous satellite are probably disturbed by stray light when working in the space environment. Existing research has shown that the Visible Infrared Radiometer (VIRR) onboard the FY-3C satellite is affected by external solar stray light radiation when imaging the ground. In this paper, based on analyzing the solar stray light generation mechanism, we propose a simulation and analysis method combined with the given satellite orbit attitude model to investigate the influence of external solar stray light on VIRR’s imaging quality. We use the FY-3C orbit parameters to obtain the variation pattern of the angles between the solar vector and the payload. Based on the VIRR mechanical structure and optical scattering model, light tracing is performed to investigate the spatial distribution of irradiation on the primary mirror. The results of the occurrence time and intensity of stray light obtained by the simulation are consistent with the actual data when imaging the ground, which verifies that the proposed method is a correct and effective way to investigate the regularity of the external stray light of on-orbit payload.

Media Edukasi Berbasis Web Sebagai Upaya Pendukung Pendidikan Karakter Berdasar nilai Kearifan Lokal Pada Pusat Pengembangan Anak Light Generation

PPA Light Generation is one of the Compassion Foundations under the Pentecostal Church in Indonesia Hagios Family Yogyakarta which helps children with poor backgrounds. There are approximately 200 children from various Tribes, Religions, Races, and Intergroups from the age of 1 to 22 years who are sheltered by PPA Light Generation. The form of learning activities focuses on the formation of character and personality in children who are guided by noble values. In addition, the skills and talents of each fostered child are also considered. Coaching involves fostered children and mentors which is carried out regularly every week in the church. However, since the Covid-19 pandemic, physical meetings and material sharing cannot be carried out. The service output is "Edugen" learning management system that can be used by mentors and fostered children. The aim is to facilitate the learning process both in terms of delivering material and communication between mentors and fostered children and to support access to the dissemination of local wisdom values in PPA Light Generation so that by strengthening the value of local wisdom the fostered children can fortify themselves from negative influences. The method used is in the form of socialization, training and assistance in technology, which is carried out online and offline by complying with health protocols. The training and assistance provided is in the form of materials on how to use the Edugen website for mentors and fostered children. The implementation of the activity was successful with an average score of more than 70%.

Nonlinear wavefront engineering with metasurface decorated quartz crystal

In linear optical processes, compact and effective wavefront shaping techniques have been developed with the artificially engineered materials and devices in the past decades. Recently, wavefront shaping of light at newly generated frequencies was also demonstrated using nonlinear photonic crystals and metasurfaces. However, the nonlinear wave-shaping devices with both high nonlinear optical efficiency and high wave shaping efficiency are difficult to realize. To circumvent this constraint, we propose the idea of metasurface decorated optical crystal to take the best aspects of both traditional nonlinear crystals and photonic metasurfaces. In the proof-of-concept experiment, we show that a silicon nitride metasurface decorated quartz crystal can be used for the wavefront shaping of the second harmonic waves generated in quartz. With this crystal-metasurface hybrid platform, the nonlinear vortex beam generation and nonlinear holography were successfully demonstrated. The proposed methodology may have important applications in nonlinear structured light generation, super-resolution imaging, and optical information processing, etc.