For a projector-based virtual reality (VR) or augmented reality (AR) display, a large depth of field and a high-speed image refresh rate are important keys to improve the projector’s performance. Here, we propose a solution that extends the depth of field of the projection using a variable-focus lens and a high-speed projector as well as a control method that synchronizes oscillation of the variable-focus lens with the high-speed projector. The experiment confirms that the proposed system can project the well-focused and dynamically changeable contents on six different planes. Its projection range varies from 0.3 m to 1.5 m, and the refresh rate is 166.7 Hz.

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Advancements in learning analytics allow teachers to track student learning progress and promote learning by providing necessary intervention and support. Multiple data sources are involved in learning analytics, and the major ones are systems that students use in school. To fully comprehend the progress of student learning, out-of-school learning behaviors should be considered an important part of the academic lives of students. In this study, out-of-school learning behaviors of students, particularly home computer use, were measured using four online behavior indicators of students, which were tracked and collected. The learning performance data of the students were analyzed. Results suggested that the out-of-school computer use behaviors of students, such as mutual follow-up and the sharing of learning experiences, were positively related to their academic performance level, regardless of the age and gender of the students. This study provides insight into what may be the missing piece in understanding student learning, that is, out-of-school computer use. With such insights, learning analytics may be enhanced to improve the understanding of learning without being restricted to schools.