Inspection device

An inspection device for inspecting a sample having a surface formed of a transparent film transmitting light and a non-transparent material, the inspection device comprising:

• a light source;
• a first optical unit configured to irradiate the sample with illumination light emitted from the light source and condense first reflected light reflected by the sample;
• a second optical unit configured to illuminate a reflecting mirror with the illumination light and condense second reflected light reflected by the reflecting mirror;
• an interference optical unit configured to cause the first reflected light and the second reflected light to interfere with each other to obtain interference light;
• a plurality of interference light sensors configured to detect a reflected light intensity of a predetermined polarization component of the interference light;
• and
• a signal processing device configured to process a detected light amount of the interference light sensor, wherein
• the signal processing device identifies, based on the detected light amount of the interference light sensor and refractive indices of the transparent film and the non-transparent material, whether any coordinates of the sample indicate any of the transparent film and the non-transparent material, and measures a surface height or a film thickness of the sample at the coordinates by calculation.