Patent ID: 7586606

Claim:
A near-field polarized-light measurement apparatus comprising: a light-radiating device for irradiating a sample with light; a polarizer disposed after the light-radiating device, for linearly polarizing the light irradiating the sample; a near-field probe having at a tip thereof an opening smaller than the wavelength of light used for measurement, wherein the opening in the near-field probe is elliptical or slit-shaped, for selectively collecting the linearly polarized light transmitted through the sample to the opening; a light-collection-direction rotating unit for changing the angle of the linearly polarized light collected at the near-field probe by rotating the near-field probe about the optical axis to change the angle of a transmission axis thereof; and a detector for detecting the light collected by the near-field probe, a polarization modulator disposed in an optical path between the polarizer and the detector, for changing the orientation of a plane of polarization of the linearly polarized light, wherein, based on a frequency component corresponding to a modulation frequency of the polarization modulator and/or higher harmonic frequencies thereof in a detection signal from the detector, the angle of the linearly polarized light collected at the near-field probe is changed by the light-collection-direction rotating unit, and the optical rotation of the sample is measured by symmetric angular oscillation using the optical-null principle.