Optical measurement apparatus and optical measurement method

An optical measurement method with an optical measurement apparatus including an irradiation optical system and a measurement optical system, the irradiation optical system being configured to linearly irradiate a measurement target with measurement light having a certain wavelength range, the measurement optical system being configured to output a two-dimensional image by expanding linear measurement interference light in a wavelength direction orthogonal to a longitudinal direction of the measurement interference light, the measurement interference light being transmitted light or reflected light originating from the measurement target as a result of irradiation with the measurement light, the optical measurement method comprising:

• obtaining a distribution of actually measured values when angles of incidence are different for an identical sample;
• calculating a modification factor depending on an angle of incidence on the measurement optical system from each measurement point in association with a region in the two-dimensional image corresponding to each measurement point in the measurement target irradiated with the measurement light;
• and
• calculating optical characteristics including a refractive index of the sample based on a group of pixel values in one row or a plurality of rows along any one direction in the distribution of the actually measured values and corresponding modification factors.