Film thickness measuring device and film thickness measuring method

A film thickness measuring apparatus comprising:

• a light irradiator configured to irradiate an object with light in a planar shape;
• an optical filter having a transmittance linearly changing according to wavelengths in a predetermined wavelength range, the optical filter being configured to separate light from the object by transmitting and reflecting the light;
• an imager configured to photograph light separated by the optical filter;
• and
• an analyzer configured to estimate a film thickness of the object based on a signal from the imager photographing light,
• wherein the light irradiator emits light having a wavelength comprised in the predetermined wavelength range of the optical filter,
• wherein the imager includes a first area sensor configured to capture an image of light transmitted through the optical element and to output the transmitted image, and a second area sensor configured to capture an image of light reflected through the optical element and to output the reflected image, and
• wherein the analyzer calculates a wavelength center for each pixel based on a value of each pixel corresponding to the transmitted image and the reflected image, and estimates a film thickness corresponding to each pixel.