Imaging apparatus, light amount measurement apparatus, recording medium and method of calculating exposure amount

A computer-readable recording medium having a program recorded thereon, the program causing a computer to execute:

• receiving an intensity of a P-polarized component or an intensity of an S-polarized component for a part of one incident light beam divided from the one incident light beam by a light beam division element, and outputting a predicted calculation value of an intensity of a P-polarized component or a predicted calculation value of an intensity of a S-polarized component for a residual light beam of the one incident light beam, from data of reflectance or transmittance of the light beam division element corresponding to the P-polarized component or the S-polarized component.

A method of calculating an exposure amount, the method comprising:

• acquiring, by a first light reception unit, an intensity of a P-polarized component or an intensity of an S-polarized component for a first light beam divided from one incident light beam by a light beam division element;
• and
• predicting, by a signal processing unit, an intensity of a P-polarized component or an intensity of an S-polarized component for a second light beam divided from the one incident light beam by the light beam division element, from the intensity of the P-polarized component or the intensity of the S-polarized component acquired by the first light reception unit, to calculate an exposure amount in a second light reception unit on which the second light beam is incident.