Development of an optical pickup system for measuring the displacement of the micro cantilever in scanning probe microscope

This paper presents the development and the verification of a compact optical sensor system for measuring the displacement of the micro cantilever in scanning probe microscope (SPM). An optical pickup head of commercial compact disc (CD)/digital versatile disc (DVD) read only memory (ROM) drive is applied in this displacement sensor system. For fulfilling our tight measuring requirements of sensibility and reliability, the build-in detection device is replaced with a four-quadrant photodiode. The developed system is well functionally verified by measuring calibration sample of 463 nm (pitch) times 30 nm (height).