Beijing, February 24 (Youth.cn) - In an optical technology museum in Changchun, pupils were playing optical instruments. The OMI band, composed of the staffs of the museum, gave a wonderful performance. They made optical instruments by sensors and other optical elements. Combined with professional electronic sound sources, electrical signals were generated by blocking the light beam with the hand or drum stick, triggering the sound source, producing sound and changing colors. Photo/CFP