OPTICAL-LEVER TYPE OPTICAL SYSTEM FOR INTERATOMIC FORCE MICROSCOPE

摘要

PROBLEM TO BE SOLVED: To provide an optical-lever type optical system for an interatomic force microscope, i.e., an optical-lever type optical sensor, enabling stable detection of cantilever displacement with high precision and excellent optical microscopic observation. SOLUTION: The optical-lever type optical sensor 113 includes a semiconductor laser 208 which emits sensor beams to be applied to a cantilever 114; a position-detecting photodiode 210 for detecting the spotted position of the received sensor beam which moves according to the displacement of the cantilever 114; a quarter wavelength plate 205 and a polarizing beam splitter 206 which cooperate to cause the sensor beam to branch into its forward path and its return path; and an objective lens 115 and a half mirror 116 which serve also as an optical microscope. The half mirror 116 separates and couples the sensor beam from and to the observing light and the illuminating light of the optical microscope and is composed of a rhomboidal half-mirror prism. The end face of the half-mirror prism allowing the sensor beam to pass through is not perpendicular to the optical axis of the optical system of the optical sensor 113.