Optical interference measuring apparatus and optical interference measuring method

An optical interference measuring apparatus comprising:

• a measuring unit including a light source for emitting an electromagnetic beam, a beam splitter for splitting a the electromagnetic beam into measurement light and reference light, a reference surface for reflecting the reference light, and a detector for acquiring an interferogram of an interference wave by detecting an interference signal between reflected light of the reference light with which the reference surface is irradiated and reflected light of the measurement light with which a measurement target is irradiated;
• and
• an electrical circuit configured to configure an intensity profile in a depth direction by performing Fourier transform of the interferogram,
• the electrical circuit configured to estimate, based on a model formula of an interferogram when it is assumed that a measurement target is a layered structure having at least one reflecting surface, a parameter for the model formula for each assumed surface count in a predetermined assumed surface count range,
• reconfigure an interferogram by using the model formula to which a parameter estimated for each of the assumed surface count is applied, calculate a likelihood between the reconfigured interferogram and an original interferogram, and select an optimal model formula based on an information amount criterion obtained by setting the assumed reflecting surface count as the degree of freedom, and
• reconfigure an intensity profile in the depth direction based on the optimal model formula.