Black Friday: lifetime access is on a special offer in the app, until November 30. Black Friday: special offer on lifetime access, until November 30. Download
시준기는 광학 장비에서 빛을 정렬하는 데 사용됩니다.sijungineun gwanghak jangbiseo bicheul jeongnyeolhaneun de sayongdoemnida.The collimator is used to align light in optical equipment.