Patent ID: 7319528

Claim:
A surface texture measuring instrument provided with a near-field measuring unit including a near-field probe that forms a near-field light at a tip end thereof when a laser beam is irradiated, a laser source that generates the laser beam to be irradiated on the near-field probe, a detection element that detects scattering effect of the near-field light generated when the near-field probe is moved close to a workpiece, and an actuator that displaces the near-field probe and the workpiece in a direction moving close to/away from each other, comprising: a laser length-measuring unit that measures a relative distance between a reference position and the workpiece in the vicinity of the tip end of the near-field probe, wherein the laser source generates the laser beam with wavelength λ 1 , the laser length-measuring unit utilizes the laser beam with wavelength λ 2 which is smaller than the wavelength λ 1 , and the near-field probe has an opening through which the laser beams from the laser source and the laser length-measuring unit are input, the opening being larger than wavelength λ 2 and smaller than wavelength λ 1 in diameter.