福衛五號搭載的主要任務酬載即為光學遙測酬載，這顆酬載負責執行福衛五號的主要任務，以推掃 (push-broom) 的方式於 720 公里高的軌道對地球表面進行多光譜影像拍攝。光學遙測酬載使用之多光譜波段包含一個全色態 (PAN, 400－700 nm) 以及四個從藍光至近紅外的多光譜波段，設計的地面解析度為全色態 2 公尺，多光譜波段 4 公尺。光學遙測酬載由各個次系統所組成，包含光學次系統、結構次系統、熱控次系統、聚焦面組合及電子單元。以下逐一簡約介紹組成光學遙測酬載各個次系統以及整合測試過程。

FORMOSAT-5 Remote Sensing Instrument (RSI) is primary payload on FORMOSAT-5 optical remote sensing satellite. RSI will capture earth images by push-broom method from a sun synchronous orbit at 720-km altitude with 98.28-degree inclination angle, which provides 2-m resolution panchromatic (PAN, black & white) and 4-m resolution multi-spectral (MS, color) images. The RSI consists of several sub-systems, including optical sub-system, structure sub-system, thermal control sub-system, focal plane assembly (FPA) and electronic unit (EU). This article will briefly introduces the RSI sub-systems and RSI integration and testing process.