Three-dimensional measurement device

A three-dimensional measurement device, comprising:

• a light emitter that emits a predetermined light;
• a polarizing beam splitter that has first to fourth faces, splits an incident light to the first face from the light emitter into two polarized lights of an object light and a reference light that have polarizing directions perpendicular to each other, irradiates a measurement object with the object light and irradiates a reference plane with the reference light, and recombines the object light and the reference light with each other and emits a combined light;
• an imaging device that comprises an imaging element and takes an image of a light emitted from the second face of the polarizing beam splitter to obtain luminance image data, wherein the imaging element comprises a plurality of light-receiving elements and multiple different types of polarizers, the polarizers having different set angles of transmission axes and being arranged to have one-to-one correspondence with the light-receiving elements;
• a first quarter-wave plate placed between the third face of the polarizing beam splitter and the reference plane, wherein the reference light enters the third face and is emitted from the third face;
• a second quarter-wave plate placed between the fourth face of the polarizing beam splitter and the measurement object, wherein the object light enters the fourth face and is emitted from the fourth face;
• a third quarter-wave plate placed between the second face of the polarizing beam splitter and the imaging device;
• a storage device that stores transmission axis absolute angle data each obtained by a previous actual measurement of an absolute angle of a transmission axis of each of the polarizers;
• and
• a control device that calculates, by a phase shift method, a phase difference between the reference light and the object light at a predetermined measurement position of the measurement object, based on a piece of luminance data of each pixel in the luminance image data and a piece of the transmission axis absolute angle data of each of the polarizers corresponding to the pixel, and measures a height of the measurement object at the measurement position.